Change search
Refine search result
1 - 42 of 42
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Abdi, Amir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Numerical investigation of melting in a cavity with vertically oriented fins2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 235, p. 1027-1040Article in journal (Refereed)
    Abstract [en]

    This paper investigates the effect of vertical fins, as an enhancement technique, on the heat transfer rate and energy density of a latent heat thermal energy storage system. This contributes with knowledge on the interaction of heat transfer surface with the storage material for optimizing storage capacity (energy) and power (heat transfer rate). For the assessment, numerical modeling is employed to study the melting process in a two-dimensional rectangular cavity. The cavity is considered heated isothermally from the bottom with surface temperatures of 55 degrees C, 60 degrees C or 70 degrees C, while the other surfaces are insulated from the surrounding. Aluminum and lauric acid are considered as fin/enclosure material and phase change material, respectively. Vertical fins attached to the bottom surface are employed to enhance the charging rate, and a parametric study is carried out by varying the fin length and number of fins. Thus, a broad range of data is provided to analyze the influence of fin configurations on contributing natural convection patterns, as well as the effects on melting time, enhanced heat transfer rate and accumulated energy. The results show that in addition to increasing the heat transfer surface area, the installation of vertically oriented fins does not suppress the natural convection mechanism. This is as opposed to horizontal fins which in previous studies have shown tendencies to reduce the impact of natural convection. This paper also highlights how using longer fins offers a higher rate of heat transfer and a better overall heat transfer coefficient rather than increasing the number of fins. Also, fins do not only enhance the heat transfer performance in the corresponding melting time, but also maintain similar total amount of stored energy as compared to the no-fin case. This paper discusses how this is the result of the enhanced heat transfer allowing a larger portion of sensible heat to be recovered. For example, in the case with long fins, the relative mean power enhancement is about 200% with merely 6% capacity reduction, even though the amount of PCM in the cavity has been reduced by 12% as compared to the no-fin case. Although the basis for these results stems from the principles of thermodynamics, this paper is bringing it forward with design consideration. This is because despite its importance for making appropriate comparisons among heat transfer enhancement techniques in latent heat thermal energy storage, it has not been previously discussed in the literature. In the end, the aim is to accomplish robust storage systems in terms of power and energy density.

  • 2.
    Castro Flores, J. Castro
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Chiu, Justin Ningwei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Le Corre, O.
    Lacarrière, B.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Energetic and exergetic analysis of a low- Temperature based district heating substation for low energy buildings2015In: ECOS 2015 - 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems , 2015Conference paper (Refereed)
    Abstract [en]

    District Heating (DH) technology contributes to the low GHG emissions energy system, facilitates a renewable energy usage, and increases the overall system efficiency, while providing the necessary heating services to the built environment. However, the existing DH technology may not be technically and economically effective to service buildings with low-energy demands. Here, low- Temperature based district heating (LTDH) provides a better match between supply and demand in terms of energy quality. This paper deals with the energy and exergy analyses of a LTDH substation supplying a secondary LTDH network as a subnet of the existing DH system. The substation is supplied with a mix of supply and return flows from the main DH network. An energy and exergy analysis was employed based on modelling and simulation to compare the performance of two proposed substation configurations to that of a conventional DH substation operating at low- Temperature. The study was performed for a year round outdoor temperatures scenario under steady-state conditions. The exergy destruction at the system components was identified and compared. The results of this analysis show that by using the low- Temperature flow from the DH return pipe, the final exergy efficiency of the overall system is increased. On the other hand, assuming an adiabatic system the energy performance stays the same. As compared with the conventional DH network, the integration of the proposed LTDH substation reduced the share of energy demand covered by the main DH supply by 20-25% and improved the overall exergy efficiency from 79% to 85-87% depending on the substation configuration. Based on the results, the solution presented is seen as an effective approach to reduce the system's losses, and to increase the quality match between the low-energy heating demands and the supply.

  • 3.
    Castro Flores, José Fiacro
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. École des Mines de Nantes - EMN, Energy Systems and Environment - DSEE.
    Chiu, NingWei Justin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Lacarrière, Bruno
    École des Mines de Nantes - EMN, Energy Systems and Environment - DSEE.
    Le Corre, Olivier
    École des Mines de Nantes - EMN, Energy Systems and Environment - DSEE.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Conceptual study of a solar-assisted low-temperature district heating substation2015In: Book of abstracts: International Conference on Smart EnergySystems and 4th Generation District Heating: Low-temperature district heating and buildings / [ed] Lund, H. (Ed.), & Mathiesen, B. V., Copenhagen, DK: Aalborg Universitetsforlag, 2015Conference paper (Refereed)
    Abstract [en]

    At present, the viability of Low-Temperature District Heating (LTDH) systems has already been tested and demonstrated. Even so, for LTDH to be successfully implemented, further ideas are needed in order to improve the flexibility and effectiveness. In this study, we analyze the performance of a local LTDH network for a multi-dwelling low-energy building supplied by both a roof-mounted solar collector and the conventional DH network via a LTDH substation. The DH network serves as a short-term storage buffer, so no heat storages are required. The collector’s size is chosen based on the available roof area, independently from the building’s loads, and three possible connection configurations were simulated. A mix of both the existing DH forward and return flows are used as thermal energy sources. The results show that more than 15% of the summer heat demand in the LTDH network can be covered by the roof-mounted solar collector. With a feed-in contract, heat costs savings range 3-6% annually according to the Swedish system. System integration in LTDH from the design phase has the potential to enhance the recovery of solar thermal energy, increase its conversion efficiency, and in general, to improve the utilization of low-grade thermal energy sources.

  • 4.
    Castro Flores, José Fiacro
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. École des Mines de Nantes - EMN, Energy Systems and Environment - DSEE.
    Chiu, NingWei Justin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Le Corre, Olivier
    École des Mines de Nantes - EMN, Energy Systems and Environment - DSEE.
    Lacarrière, Bruno
    École des Mines de Nantes - EMN, Energy Systems and Environment - DSEE.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Energetic and exergetic analysis of alternative low-temperature based district heating substation arrangements2016In: International Journal of Thermodynamics, ISSN 1301-9724, Vol. 19, no 2, p. 71-80Article in journal (Refereed)
    Abstract [en]

    District Heating (DH) technology is an efficient and cost-effective solution to provide heating services to the built environment. However, the existing DH technology may not be technically and economically effective to service buildings with low energy demands. Here, low-temperature based district heating (LTDH) can provide a better match between supply and demand in terms of energy quality and quantity. This paper deals with the energy and exergy analyses of a LTDH substation supplying a secondary LTDH network as a subnet of the existing DH system. In order to improve the temperature match, a mix of supply and return streams from the main DH network are used to supply the substation. Based on modelling and simulation, an energy and exergy analysis is employed to compare the performance of two proposed substation configurations to that of a conventional DH substation operating at low temperatures. The results of this analysis show that the proposed LTDH substation reduced the share of energy demand covered by the main DH supply by 20% to 25%. Likewise, by using the flow from the main DH return pipe, the final exergy efficiency of the overall system increased by 5% on average. The exergy destruction occurring at the system components was also identified and compared: during high heat demands the substation heat exchanger is responsible for the largest share of exergy destruction, whereas for low heat demands, it is due to the pumping effort. Based on these results, the proposed system is seen as an effective approach to increase the quality and quantity match between the low-temperature network and the conventional supply.

  • 5.
    Castro Flores, José Fiacro
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. École des Mines de Nantes - EMN, Energy Systems and Environment - DSEE.
    Lacarrière, Bruno
    École des Mines de Nantes - EMN, Energy Systems and Environment - DSEE.
    Chiu, NingWei Justin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Assessing the techno-economic impact of low-temperature subnets in conventional district heating networks2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 116, no C, p. 260-272Article in journal (Refereed)
    Abstract [en]

    The 4th generation Low-Temperature District Heating (LTDH) is envisioned as a more efficient and environmentally friendly solution to provide heating services to the building stock. Specifically, in countries already with a large share of well-established DH systems, conventional DH and LTDH technologies will be operating simultaneously in the near future. Newly built or refurbished buildings have lower heat demands, which in combination with LTDH brings potential savings compared to conventional DH. This work explores the advantages in DH operation by connecting these loads via LTDH subnets to a conventional DH system, supplied by a Combined Heat and Power (CHP) plant. A techno-economic analysis was performed, through modelling and simulation, by estimating the annual DH operating costs and revenues achieved by the reduction in return temperatures that LTDH would bring. The savings are related to: (1) the reduction in distribution heat losses in the return pipe; and (2) lower pumping power demand. Likewise, additional revenues are assessed from: (3) improved Power-to-Heat ratio for electricity production; and (4) enhanced heat recovery through Flue Gas Condensation (FGC). The annual savings per kWh of delivered heat are estimated as a function of the penetration percentage of ‘energy efficient’ loads over the conventional DH network. Key outcomes show the trade-offs between the potential savings in operating costs and the reduction in heat demand: relative losses in this scenario are maintained at 13.1% compared to 15.3% expected with conventional DH; and relative pumping power demand decreased as well. In other words, the costs of supplying heat decrease, even though the total heat supplied is reduced.

  • 6.
    Castro Flores, José Fiacro
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. École des Mines de Nantes - EMN, Energy Systems and Environment - DSEE.
    Rossi Espagnet, Alberto
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Chiu, NingWei Justin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lacarrière, Bruno
    IMT Atlantique - Energy Systems and Environment - DSEE.
    Techno-Economic Assessment of Active Latent Heat Thermal Energy Storage Systems with Low-Temperature District Heating2017In: International Journal of Sustainable Energy Planning and Management, ISSN 2246-2929, E-ISSN 2246-2929, p. 5-17Article in journal (Refereed)
    Abstract [en]

    Thermal energy storage (TES) is a set of technologies with the potential to enhance the efficiency and flexibility of the 4th generation of district heating systems. This study presents a comparative techno-economic assessment of active TES systems suited to operate with low-temperature district heating (LTDH) for short-term heat storage applications. Latent heat systems (LH-TES) are compared qualitatively and quantitatively to water-based sensible heat systems (SH-TES). It is concluded that latent heat TES systems are still more expensive than water-based systems regarding energy storage cost (EUR/kWh) ranging from 1.5 to 4 times more, mainly due to the cost of the storage media. However, considering distributed TES systems integrated to LTDH, small-scale active LH-TES systems will become more cost-competitive as storage media costs are expected to decline in the future. This study represents a step forward in the development and improvement of the DH system through the integration of TES which will play a key role in the future smart energy system.

  • 7.
    Chiu, Justin N. W.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Castro Flores, José Fiacro
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lacarrière, B.
    Industrial surplus heat transportation for use in district heating2016In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 110, p. 139-147Article in journal (Refereed)
    Abstract [en]

    M-TES (Mobile Thermal Energy Storage) technology is explored in this paper for transportation of industrial surplus heat for use in LTDH (low temperature district heating network). LTDH has promising potential in utilizing low grade heat, on the other hand, 20%–50% of industry generated surplus heat is often released to the ambient environment. M-TES is used to match thermal energy supply and demand that occur at different locations and that are shifted in time. In this paper, design of M-TES is conducted, optimization in operating strategies is performed, sensitivity analysis on levelized cost is studied, and environmental impact of CO2 emissions due to transportation is evaluated. The results of the study show an array of transportation means and storage operating strategies under which M-TES is technically, economically and environmentally sound for transportation of industrial surplus heat for use in LTDH network. © 2016 Elsevier Ltd

  • 8.
    Chiu, Justin N. W.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Industrial surplus heat storage in smart cities2015In: ASME 2015 9th International Conference on Energy Sustainability, ES 2015, collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum, American Society of Mechanical Engineers , 2015Conference paper (Refereed)
    Abstract [en]

    Surplus heat generated from industrial sectors amounts to between 20% and 50% of the total industrial energy input. Smart reuse of surplus heat resulted from industrial sectors and power generation companies is an opportunity to improve the overall energy efficiency through more efficient use the primary energy sources. A potential solution to tackle this issue is through use of thermal energy storage (TES) to match user demand to that of the generated surplus heat. A mobile TES (MTES) concept of transportation of industrial surplus heat from production sites to end customers has shown promising results. One commissioned demonstration project using industrial heat for swimming pool water temperature regulation in Dortmund, Germany proved the interest and attention given to this concept. In this paper, a techno-economic case study in Sweden of transportation of surplus thermal energy to district heating in smart cities is presented. The application consists of heat storage at 110°C- 130°C through the use of phase change materials (PCM) based TES, notably with use of Erythritol (90 kWh/ton) for the considered temperature range, to remote district heating network located at 48 km from the thermal energy generation site. The advantages of using latent heat based PCM are the high enthalpy density per unit volume and per unit mass, as well as the quasi-constant temperature during charging and releasing of heat. The M-TES in this study has a total storage capacity of 2.1 MWh, the optimization of charge/discharge time to the amount of stored/released energy and to that of energy transportation rate is presented in this paper. Contrary to logical thinking, it is shown through this work that under certain conditions, it is more cost-effective to operate at partial load of storage units albeit the increased number of transport trips and charge/discharge cycles.

  • 9.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Heat Transfer Aspects of Using Phase Change Material in Thermal Energy Storage Applications2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Innovative methods for providing sustainable heating and cooling through thermal energy storage (TES) have gained increasing attention as heating and cooling demands in the built environment continue to climb. As energy prices continue to soar and systems reach their maximal capacity, there is an urgent need for alternatives to alleviate peak energy use. TES systems allow decoupling of energy production from energy utilization, both in location and in time. It is shown in this thesis that successful implementation of TES in the built environment alleviates peak energy load and reduces network expansion as well as the marginal energy production cost.

    This thesis analyzes phase change material (PCM) based TES systems in terms of material property characterization, numerical modeling and validation of thermal storage, as well as case specific techno-economic feasibility studies of system integration. The difficulties identified in latent heat TES design, such as heat transfer aspects, subcooling and identification of phase separation, have been analyzed through Temperature-History mapping and TES numerical modeling with experimental validation. This work focuses on the interdependency between resource availability, thermal charge/discharge power and storage capacity. In a situation where resource availability is limited, e.g. when using free cooling, waste heat or off-peak storage, the thermal power and storage capacity are strongly interrelated and should always be considered in unison to reach an acceptable techno-economic solution. Furthermore, when considering TES integration into an existing thermal energy distribution network, three adverse aspects are revealed in the Swedish case study: the single tariff system, the low-return temperature penalty, and the low storage utilization rate. These issues can be overcome through better adapted policies and optimized storage control strategies. Finally, despite the currently unfavorable conditions in the Swedish energy system, it is shown that TES has the potential to mitigate climate change through greenhouse gas emission reduction by displacing fossil-fuel based marginal thermal energy production.

  • 10.
    Chiu, Justin NingWei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Gravoille, Pauline
    Ecole Nationale Supérieure de l'Energie, l'Eau et l'Environnement.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Active Free Cooling Optimization with Thermal Energy Storage in Stockholm2012In: InnoStock The 12th International Conference on Energy Storage: Book of Abstract / [ed] Stock Conference, 2012, p. 106-107Conference paper (Refereed)
    Abstract [en]

    In the goal of reaching an environmental benign society, energy saving through green building design has gained increasing attention. Passive buildings may cut down the energy requirement in winter through use of solar based heating, increased insulation and smart design of energy management. However it has also been shown that over insulated structures also create excessive heat gain in summer generating thus an increased cooling demand [1,2].

    In countries where the ambient environment is at sufficiently low temperature at night to act as a heat sink, thermal energy displacement from period when cold is available to period when cooling is needed may alleviate fossil fuel based cooling produced with conventional means. The displacement of thermal energy may be reliably achieved with use of Thermal Energy Storage (TES), such systems in buildings have been shown to provide better indoor thermal comfort by a number of researchers [3,4,5]. Direct advantages of using TESs are reduction in size of cooling equipment, decrease in electricity consumption, and better utilization of renewable sources.

    Phase change materials (PCMs) that rely on use of latent heat for storage of thermal energy prove to lead to more compact design of energy system and a steadier source temperature [6]. An environmentally friendly active free cooling solution with use of Latent Heat Thermal Energy Storage (LHTES) is proposed in this work where an optimization between cost, comfort level and storage design is studied and compared against conventional chillers in Stockholm climate.

  • 11.
    Chiu, Justin NingWei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Gravoille, Pauline
    National Institute of Energy, Hydraulic and Environmental Engineering, Grenoble, France.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Active free cooling optimization with thermal energy storage in Stockholm2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 109, no SI, p. 523-529Article in journal (Refereed)
    Abstract [en]

    Latent heat thermal energy storage (LHTES) integrated active free cooling stores night time cold and serves as heat sink for cooling when demand rises. Passive buildings, albeit their advantages in limiting heat loss during winter time, are often paired with excessive internal overheating in summer, as shown in the first part of this study. Under the climate condition in Stockholm, LHTES systems may provide solutions for sustainable cooling with use of renewable cooling sources. This study presents a multi-objective optimization on system cost and cooling supply for various LHTES configurations followed with a sensitivity analysis on phase change material cost and energy price. Results indicate that optimized LHTES may meet cooling needs while retaining economic viability. However, LHTES based cooling systems may require substantially higher electricity demand than conventional air conditioning unit for applications where high cooling thermal power rate is to be met, a tradeoff to indoor comfort level needs to be considered to reach the concept of sustainable free cooling. We here provide a novel techno-economic feasibility study of active free cooling LHTES in Stockholm as well as new insights to cost, comfort level and energy requirement with use of multi-objective optimization algorithm.

  • 12.
    Chiu, Justin NingWei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Furberg, Richard
    Advanced Thermosyphon Cooling with Nanoporous Structured Mini Channel Evaporators2010In: PROCEEDINGS OF THE ASME MICRO/NANOSCALE HEAT AND MASS TRANSFER INTERNATIONAL CONFERENCE, VOL 3, NEW YORK: AMER SOC MECHANICAL ENGINEERS , 2010, p. 183-189Conference paper (Refereed)
    Abstract [en]

    Attention has been given to enhance boiling surfaces in order to decrease the temperature difference and to increase heat transfer coefficient. Structured surfaces may provide both surface enlargement and artificial nucleation sites, thus ameliorate the heat transfer coefficient. The goal of the present experimental work is to analyze the influence on heat transfer coefficient (HTC) of enhanced surface structures coated on mini channel heat exchanger working in a closed loop thermosyphon system. Experimental tests were carried out with three types of surface enhanced mini channel evaporators: smooth surface, threaded structure and nanoporous coating. The evaporators are single channel half circularly shaped, adapted for filming purpose, measuring 30mm in length and 3mm in diameter. Surface areas of channels are 1.41cm(2). Experiments were conducted in refrigerant 134a at 4.87bar (reduced pressure pr=0.12) and at heat fluxes ranging from 0.7W/cm(2) to 63.8W/cm(2). A high speed video camera was used for visualization of the two-phase flow in the evaporator channel. It is shown that threaded surface provides the highest heat transfer coefficient (HTC) from no load to heat flux of 7.1W/cm(2), the nanoporous structure shows the highest performance between 7.1W/cm(2) and 49.6W/cm(2), and the smooth surface channel exhibits the best HTC from 49.6W/cm(2) and higher. In this paper, the influences of heat flux and surface structures on HTC are discussed, and the impact of refrigerant flow regimes on heat transfer performance is also highlighted.

  • 13.
    Chiu, Justin NingWei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    ­Multistage Latent Heat Cold Thermal Energy Storage Design Analysis2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, no SI, p. 1438-1445Article in journal (Refereed)
    Abstract [en]

    Thermal energy storage in cooling applications contributes to improvements in overall system efficiency as well as to better energy quality management. Latent heat thermal energy storage (LHTES) is used to provide load shifted thermal energy at small temperature swing with high storage density, hence an overall more compact energy system. However, the low thermal conductivity of the majority of the phase change materials (PCMs) necessitates delicate design of the active storage unit to meet power demand (high enough energy extraction/storage per amount of time).

    A performance analysis of two LHTES configurations is carried out in this work. Thermal charge and discharge rate of single PCM is compared with multistage LHTES using a cascade design of multiple PCMs at various phase change temperatures in a submerged finned pipe heat exchanger design. The work is conducted with a validated finite element based numerical simulation for evaluation of both full charge/discharge cycle and continuous half charge/discharge cycles.

    The results show that in full charge/discharge mode, the thermal performance of a multi-PCM LHTES may be improved by 10% to 40% as compared to that of a homogeneous­­ single-PCM storage unit in terms of thermal charge/discharge rate. This is due to the capability of the multistage LHTES to maintain a higher driving temperature difference for the heat transfer process in the charging and discharging processes. In half charge/discharge cycling mode, however, the thermal power rating performance of multi-PCM storage converges towards that of the single-PCM storage in melting process, reducing thus the multi-PCM enhancement. This work provides preliminary insights to multistage latent heat cold thermal energy storage design with finned pipe heat exchanger.

  • 14.
    Chiu, Justin NingWei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Submerged finned heat exchanger latent heat storage design and its experimental verification2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 93, no SI, p. 507-516Article in journal (Refereed)
    Abstract [en]

    Thermal energy storage (TES) has shown potential in improving the overall performance in energy systems, through shifting of thermal load demand, and through matching of uneven energy availability in time and in space. Latent heat TESs demonstrate advantages over sensible heat TESs for their high storage density and small temperature swing; however, lack of accurate knowledge in novel material properties and lack in a holistic design protocol often lead to difficulties in reaching technically viable storage design. With the aim of proposing a sound latent heat based TES design-to-validation protocol, this paper covers material property characterization through Temperature-history (T-history) method, heat exchanger design through heat transfer modeling, and model validation through experimental verification. A model for submerged cylindrically finned heat exchanger latent heat storage unit with phase change material was built. The results show that performance of gelled salt-hydrate based TES can be assessed with a pure conduction based model. This material property characterization-to-model verification approach may serve as a standard in providing accurate storage design for performance evaluation.

  • 15.
    Chiu, Justin NingWei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermal Energy Storage: Climate Change Mitigation Solution?2011In: International Conference for Sustainable Energy Storage, Belfast, UK: University of Ulster , 2011Conference paper (Refereed)
    Abstract [en]

    Environmental well being and technology development are on the verge of collapsing. It has been asserted by IPCC that 30% of fauna and flora will face extinction by mid 21st century in the pursuit of business as usual path with current economic development pace. In order to minimize the anthropogenic related damage to the environment, a maximum level of 450ppm CO2 emission has to be maintained at all cost. Technologies that provide climate change mitigation solution and economic growth are hence the highlight; thermal energy storage (TES) is one among them. Energy storage provides the possibility to shift load from on peak energy demand to off peak thermal and electricity production, this results in lower energy flux in the system and therefore cuts down the marginal thermal and electricity production. This reduction in peak power demand translates to a decrease in marginal power production which, in today’s fossil fuel based economy, often pars with auxiliary and high carbon emitting thermal and electric power plants. This study provides a scenario analysis which quantifies the environmental benefit of TES implementation for the Swedish energy system. In the studied scenario, thermal energy storage will be implemented to the existing energy grid to alleviate peak electric and thermal power demand. The rate of implementation is paired with decrease in technology cost, reproduced from typical Learning Curve Model. The study shows that for the Swedish energy system, the total amount of fossil fuel used in heating of residential and service sectors is 19TWh, while reduction that can be achieved cost effectively with implementation of TES amounts to 2.5TWh. This corresponds to a Green House Gas (GHG) emission reduction of 620kton/year or 13% of total fossil fuel based emissions from heating in residential and service sectors.

     

  • 16.
    Chiu, Justin NingWei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermal energy storage for sustainable future: impact of power enhancement on storage performance2010In: International Conference on Sustainable Refrigeration and Heat Pump Technology, Stockholm, June 13-16, 2010., 2010Conference paper (Refereed)
    Abstract [en]

    Sustainable future may be reached by means of maximizing the use of renewable energies through energy storage solutions. Active thermal storage exploits the potential of storing low cost, off-peak thermal cooling and heating for use at later time. Many studies have been carried out for optimization of energy storage systems through proactive planning of storage capacity design, fine tuning of control systems, and realization of cost effective scenario modeling. In the field of latent heat based thermal energy storage with use of phase change materials (PCM), low material thermal conductivity has shown to be one of the main barriers for providing sufficient cooling and heating power to the system. Thus, despite the apparent benefit of PCM-technology when it comes to large storage energy density, practical implementation of the technology has been hampered in many cases. Although a large number of available power enhancing techniques have been reported, the influence of power enhancement to the energy storage capacity has so far not been thoroughly assessed. In this paper, we perform an evaluation of power enhancing solutions and their impact on thermal energy storage density through theoretical modeling of a set of enhancement techniques. The techniques considered are: extended surfaced heat exchangers with various fin geometries (e.g. radial fins around circular piping) as well as PCM enhanced through blending with high conductive materials. Results analyses show the importance of balancing usable power with storable energy in the design of power enhancement technology, so as to achieve the maximum storage capacity while maintaining required extraction power load.

  • 17.
    Chiu, Justin NingWei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Setterwall, Fredrik
    A Review of Thermal Energy Storage Systems with Salt Hydrate Phase Change Materials for Comfort Cooling2009In: 11th International Conference on Thermal Energy Storage, June 14-17 , 2009, Stockholm, Sweden., 2009Conference paper (Refereed)
    Abstract [en]

    This paper presents a review of cold thermal energy storage technologies. Latent heat thermal energy storage (LHTES) with phase change materials (PCMs) deserves attention as they provide high energy density and small temperature change interval upon melting/solidifying. Salt hydrates are especially interesting since they demonstrate high latent heat of fusion, high thermal conductivity, low flammability, and facilitate the use in buildings as compared to organic PCMs. A review of system performance obtained from experimental work, theoretical analyses and real case studies has however shown some material shortcomings. To reach cost effectiveness, future work in the field of LHTES with salt hydrates lies in finding suitable methods for limiting incongruent melting and subcooling without compromising the storage density. Also, system integration of LHTES in cold applications can be further developed in terms of innovative design for high power and storage capacity, load optimized sizing, controls, and elimination of PCM encapsulation.

  • 18.
    Chiu, Justin NingWei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Setterwall, Fredrik
    Next Generation Cost Effective Phase Change Materials: TUD Action COST-STSM-TU0802-052552009Report (Other academic)
  • 19.
    Chiu, Justin NingWei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Setterwall, Fredrik
    System Integration of Latent Heat Thermal Energy Storage Systems for Comfort Cooling Integrated in district cooling network2009In: 11th International Conference on Thermal Energy Storage, EFFSTOCK 2009, Stockholm, Sweden, June 14-17, 2009., 2009Conference paper (Refereed)
    Abstract [en]

    Latent heat thermal energy storage for comfort cooling with phase change materials (PCMs) has increasingly gained attention. For effective system integration, an optimized strategy for load shifting to cut down peak hour energy use is needed. With the focus on overall system performance, this paper addresses matching of a cold storage capacity and power to a demand while assessing the cost effectiveness of the PCM technology. A simulation model based on one office building cooling load in Stockholm Sweden was used. Storage capacity, power output and PCM cost were shown to be the predominant factors in a system design. It has been found that load leveling can cost effectively reduce the peak load by 5% to 9% in a fixed tariff system. However, with 50% reduction in today’s PCM price combined with removal of district cooling return temperature penalty, the peak power reduction rate may be increased to 30%.

  • 20.
    Chiu, NingWei Justin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Latent Heat Thermal Energy Storage for Indoor Comfort Control2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Equating Earth’s existence to 24 hours, we, the Homo sapiens, came about in the last four seconds. Fossil fuel came to our knowledge with mass extraction dating from the Industrial Revolution two centuries ago, in other words 4 milliseconds out of Earth’s 24-hour equivalent lifetime. With the unruly use of fossil fuel based resources, global temperature increase due to anthropogenic emission is projected by the Intergovernmental Panel on Climate Change (IPCC) to increase between 2 °C and 6 °C by 2100. The expected results are unprecedented climatic phenomena, such as intense tropical cyclones, extreme heat waves, and heavy precipitation among others. Limiting climate change has become one of the most discerning issues in our highly energy dependent society.

    Ever-increasing energy demand goes in hand with improved living standard due to technologic and economic progress. Behavioral change is one of the ultimate solutions to reduce energy demand through adequate life style change; however such approach requires societal paradigm shift. In this thesis, we look into using energy storage technology to peak shave and to load shift energy so as to attain increased renewable energy source utilization, improved system’s energy efficiency, and reduced Greenhouse Gas (GHG) emission without compromising living comfort.

    High energy density thermal energy storage (TES) systems utilize phase change materials as storage mediums where thermal energy is principally stored in the form of latent heat (LH). Advantages of such systems are compact components and small storage temperature swing. However, challenges remain in implementing LHTES to the built environment, namely lack of understanding of system dynamics, uncertainty in component design, and non-documented material property are to be addressed.

    The goal of this thesis is to address the issues on material property characterization, on component heat transfer study and on system integration. A methodology in measuring material’s thermo physical property through T-History setup is defined. Caveats of existing methodology are presented and improvements are proposed. The second part of this thesis consists of establishing valid numerical models of LHTES component for both shape stabilized and free flowing PCMs. Experimental verifications were performed and models were validated. Improvement to the thermal power performance was studied and was reached with multistage multi-PCM storage design. Techno-economic optimization and parametric study were carried out for transient TES integrated system study. Finally, an estimation of the Swedish peak energy demand reduction was performed through study of TES implementation to the existing energy systems. The peak energy shave attained through TES implementation determines the amount of fossil fuel based marginal energy that can be reduced for a greener environment.

  • 21.
    Chiu, NingWei Justin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Recent Development in Phase Change Materials for Thermal Energy Storage2012In: BIT's 1st Annual World Congress of Advanced Materials 2012: Innovation, Cutting-Edge and Smartness / [ed] International Research Center of International Talent, Beijing China, 2012, p. 299-300Conference paper (Refereed)
    Abstract [en]

    Phase change materials (PCMs) have in the past years been in the center of research focus as an energy saving alternative. They have large potential for use in applications where intermittent energy sources are present and where shift of energy supply from user demand in time and in space is required. Examples are solar heating, night time ambient air cooling, and waste heat utilization amongst others. The materials store and release heat through change of phase from solid to liquid in endothermic process and from liquid to solid in exothermic process.

    There are currently two major axes of PCM development driven application-wise. In passive thermal energy storage (TES) systems where the predominant role of PCMs is to serve as insulating material, thermal properties of the PCMs are tailored towards low thermal conductivity so as to limit heat transfer rate. In active TES, however, the research interest has been put in ameliorating the overall thermal power output. Various methods are dispersion of highly conductive particles, impregnation of PCM in graphite matrices, and novel design of heat exchanger apparatus.

    The second research axe lies in improvement of material compatibility with the considered applications. Inorganic PCMs are characterized with subcooling effect, this means start of heat release well below the phase change temperature. While this can be used in the advantage for long term seasonal heat storage, in active cold storage systems where the working temperature range is relatively small, subcooling is to be limited in order to provide efficient thermal charge and discharge cycle. Furthermore, efforts have been put in limiting phase separation; this has a predominant role in assuring the energy storage stability for repeated charge/discharge cycles.

    This presentation will provide insights to the recent material development in the field of thermal energy storage.

  • 22.
    Chiu, NingWei Justin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Castro Flores, José Fiacro
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Le Corre, Olivier
    École des Mines de Nantes, Energy Systems and Environment.
    Lacarrière, Bruno
    École des Mines de Nantes, Energy Systems and Environment.
    Environomic Assessment of Industrial Surplus Heat Transportation2015In: Smart Energy Infrastructure and Storage Options, 2015Conference paper (Refereed)
    Abstract [en]

    The fourth generation low temperature district heating network (LTDH) has to meet challenges in supplying low temperature heat, achieving low grid losses, integrating renewable heat sources, assimilating smart energy system and ensuring suitable planning structure. The new generation LTDH has promising potential in utilizing low grade waste heat where heat at temperature of as low as 55°C can be injected into the system. Industry generated surplus heat is often released to the ambient environment due to their remote location from end users. A solution is presented here to exploit the potential of recycling low grade industrial surplus heat for use in LTDH network.

    Mobile Thermal Energy Storage (M-TES) is used for shifting thermal energy to meet supply and demands that occur in different locations and that are shifted in time. M-TES technology is explored in this paper for utilization of industrial surplus heat in LTDH. Technical feasibility has been previously established with finned pipe and tube & shell type heat exchangers, however the economic justification is not always demonstrated. In this paper, parametric study on operating conditions, operating strategies and component costs will be performed. Furthermore, environmental impact from CO2 emissions due to different transportation means production will be evaluated against other heat production possibilities, such as conventional natural gas boilers. The results of the study show the optimal transportation distance, transportation means, partial/full storage operating conditions, storage means and power to energy ratio (PER) under which M-TES are technically, economically and environmentally sound for transportation of industrial surplus heat for use in the 4th generation LTDH network.

  • 23.
    Chiu, NingWei Justin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Meany, Bechara Hage
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Industrial Surplus Heat Utilization through Mobile Thermal Energy Storage with Enhanced Operating Strategy2015In: Greenstock: Industrial Energy Storage Application/ Transportation Energy Storage/ Grid integration, Beijing, 2015Conference paper (Refereed)
    Abstract [en]

    In Europe, 40% of the total energy use originates from the building sector and amounts to 36% of Europe’s Greenhouse Gas (GHG) emission (European Commission, 2013). With the smart use of a Phase Change Material (PCM) integrated Mobile Thermal Energy Storage (M-TES), industrial surplus heat may be transported to a District Heating (DH) network for building space heating and domestic hot water supply. Here, 2D and 3D numerical models were constructed for the design analysis of a latent heat (LH) M-TES. Thermal power performance is shown to be a tradeoff to storage capacity and varies exponentially to the shell and tube’s pitch to diameter ratio (PDR). For a fixed PDR configuration, the performance curve varies nonlinearly. Operating strategy with partial charge is shown to provide high thermal power when the demand arises, reducing thus the additional capital expenditure for extra tailor designed M-TES units. Partial storage is an essential control strategy for reaching economic sound mobile energy storage solution.

  • 24. Fujii, S.
    et al.
    Kanematsu, Y.
    Kikuchi, Y.
    Nakagaki, T.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Techno economic analysis of thermochemical energy storage and transport system utilizing "zeolite Boiler": Case study in Sweden2018In: Energy Procedia, Elsevier, 2018, p. 102-111Conference paper (Refereed)
    Abstract [en]

    Thermochemical energy storage and transport system utilizing zeolite steam adsorption and desorption cycle is one of the methods to resolve the mismatch between industrial surplus heat and heat demands. To generate 60°C hot water utilizing zeolite 13X, zeolite boiler employing moving bed and indirect heat exchanger was developed. Pressurized water is heated up and flash steam is injected into the zeolite bed for adsorption. A quasi - 2D model solving heat and mass conservation equations was developed, leading to a performance characterization of this zeolite boiler. The developed simulation model was used to predict performance of a heat charging device employing moving bed as well. Based on this calculation, a case study, heat transporting between a local steel works and a hotel was examined and all corresponding cost were fixed. The Levelized Cost of Energy (LCOE) results in around 60 €/MWh which is comparable cost against conventional pellet boiler. Sensitivity analysis showed both of cheaper transportation cost and larger zeolite capacity on the one trailer give a comparable impact on the LCOE.

  • 25.
    Gunasekara, Saman Nimali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Binary Phase Equilibrium Study of the Polyols Blend Erythritol-Xylitol with the T-History Method for Phase Change Materials Design2015In: The 13th International Conference on Energy Storage- Greenstock 2015, 2015Conference paper (Refereed)
    Abstract [en]

    Polyols are emerging PCM with attractive melting temperatures and enthalpies. The binary phase diagram of the system Erythritol-Xylitol is constructed using the Temperature-history method, and evaluated for its PCM-suitability. With blending, lowering of the melting points was expected, also verified with a recent study presenting the system as a simple eutectic. Herein, the tests covered the full compositional range, with thermal cycling around the previously reported eutectic. Some compositions exhibited possible glass transition after the first melting. For these, by seeding the starting material to the supercooled liquid, a preceding melting with heating was achieved. The results show several PCM suitable points in the phase diagram: eutectics and congruent melting compounds. This appears to be a partially isomorphous type, but not simple eutectic type. Microstructural evaluations for phase and miscibility verifications can further clarify this. For some compositions secondary phase changes were observed, indicating probable polymorphs, of solid-solid PCM interest.

  • 26.
    Gunasekara, Saman Nimali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Phase Diagrams as Effective Tools in Thermal Energy Storage (TES) Design using Phase Change Materials (PCM)2013In: ICAE2013, 2013Conference paper (Refereed)
    Abstract [en]

    Phase diagrams are invaluable in the design of thermal energy storage systems using phase change materials (PCM). They provide important information such as the phase change composition and constitution of the system, as well as an understanding of phenomena like incongruent melting, phase segregation, and subcooling. In this work, the significance of phase diagrams to evaluate a chemical system’s behavior and it’s suitability as a candidate PCM is analyzed along with discussing example systems based on salt, paraffin, fatty acid and sugar alcohol. For a binary system, a number of specific phase changing behaviors are found appropriate for a PCM due to their sharp, definite melting temperatures and proper melting/freezing behaviors. For example, isomorphous minimum or maximum melting types and eutectics of immiscible (non isomorphous) or partially miscible types are all suitable. A system’s miscibility distribution thus governs its suitability as a PCM since it determines the type of phase change. For determining miscibility and constructing theoretical phase diagrams the Gibbs free energy derivatives as well as experiments are useful. In conclusion it is here presented that phase equilibrium studies should be included in a derived protocol for determining suitable PCM candidates for the future. 

  • 27.
    Gunasekara, Saman Nimali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Phase equilibrium in the design of phase change materials for thermal energy storage: State-of-the-art2017In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 73, p. 558-581Article, review/survey (Refereed)
    Abstract [en]

    This paper presents a review of phase equilibrium as a tool for accurately identifying suitable blended phasechange materials (PCMs) to be used for thermal energy storage (TES). PCM storage increases the overall energyefficiency for many applications, however, high cost and complex phase change phenomena in blends oftenundermine the benefits. The study of phase equilibrium as derived from phase diagrams is the key to solve theseissues. It enables the evaluation of PCM-suitability through indication of temperature-composition points, e.g.congruent melting compositions, eutectics and peritectics. To clearly stake out the opportunities of a phaseequilibrium-based design methodology, this paper reviews the state-of-the-art based on findings from fourdecades (1977–2016). On one hand, eutectics, salts-based systems, fatty acids, and alkanes dominate theexisting PCM literature. Here peritectics have often been erroneously praised as suitable PCMs despite the manyproblems depicted from a phase equilibrium point of view. On the other hand, the most PCM-ideal congruentmelting systems, as well as the blends of polyols, fats, metal alloys and organic-inorganic combinations lack fullattention. This work brings forward the knowledge on these insufficiently explored yet extremely suitable phaseequilibrium characteristics. In addition, comprehensive PCM-design thermal properties of these various blendsare presented, as a basis to further extensive explorations, and material category-based predictions.

  • 28.
    Gunasekara, Saman Nimali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Pan, Ruijun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Polyols as phase change materials for low-grade excess heat storage2014In: Energy Procedia: Volume 61, International Conference on Applied Energy, ICAE2014, Elsevier, 2014, p. 664-669Conference paper (Refereed)
    Abstract [en]

    Polyols are an emerging phase change materials (PCM) category for thermal energy storage (TES), with moderate phase change temperatures and considerable enthalpies. These can be employed in systems for harvesting surplus energy from, industrial and power generation processes. However, knowledge on the properties of polyols in relation to desirable PCM properties is presently sparse and rather inconsistent. This work summarizes a literature review on polyols as PCM for TES. In addition, preliminary T-History characterization of some selected polyols was done. This study is expected to be an initiation of an extensive polyol phase equilibrium evaluation.

  • 29.
    Gunasekara, Saman Nimali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Pan, Ruijun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Department of Chemistry, Ångström Laboratory, Uppsala University, Box 538 75121 Uppsala, Sweden.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Polyols as phase change materials for surplus thermal energy storage2016In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 162, p. 1439-1452Article in journal (Refereed)
    Abstract [en]

    Storing low-temperature surplus thermal energy from industries, power plants, and the like, using phasechange materials (PCM) is an effective alternative in alleviating the use of fossil based thermal energyprovision. Polyols; of some also known as sugar alcohols, are an emerging PCM category for thermalenergy storage (TES). A review on polyols as PCM for TES shows that polyols have phase change temperaturesin the range of 15 to 245 C, and considerable phase change enthalpies of 100–413 kJ/kg. However,the knowledge on the thermo-physical properties of polyols as desirable PCM for TES design is presentlysparse and rather inconsistent. Moreover, the phase change and state change behaviors of polyols need tobe better-understood in order to use these as PCM; e.g. the state change glass transition which manypolyols at pure state are found to undergo. In this work preliminary material property characterizationwith the use of Temperature-History method of some selected polyols, Erythritol, Xylitol andPolyethylene glycol (PEG) 10,000 were done. Complex behaviors were observed for some of the polyols.These are: two different melting temperatures, 118.5–120 C and 106–108 C at different cycles and anaverage subcooling 18.5 C of for Erythritol, probable glass-transition between 0 and 113 C for Xylitol,as well as a thermally activated change that is likely an oxidation, after three to five heating/coolingcycles for Xylitol and Erythritol. PEG 10,000 had negligible subcooling, no glass-transition nor thermallyactivated oxidation. However a hysteresis of around 10 C was observed for PEG 10,000. Therefore thesematerials require detailed studies to further evaluate their PCM-suitability. This study is expected to be an initiation of an upcoming extensive polyol-blends phase equilibrium evaluation.

  • 30.
    Gunasekara, Samman Nimali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Hedström, Peter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    The Experimental Phase Diagram Study of the Binary Polyols System Erythritol-Xylitol2017In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 174, p. 248-262Article in journal (Refereed)
    Abstract [en]

    A comprehensive phase diagram for the binary polyols system erythritol-xylitol has been mapped with a transparent characterization approach. Here, the phase equilibrium of the system has been studied experimentally using a combination of methods: Temperature-history (T-history), X-Ray Diffraction (XRD), and Field-Emission Scanning Electron Microscopy (FESEM), and linked to Tammann plots. Existing literature has previously shown the system to be a non-isomorphous type forming a simple eutectic, by combining experimental data with theoretical modelling. The present investigation shows that the system’s phase diagram is a partially isomorphous type forming a eutectic, but not a non-isomorphous type forming a simple eutectic. Here, the eutectic was found within 25-30 mol% erythritol and at 77 °C, which differs from the previous studies identifying the eutectic respectively at 25 or 36 mol% erythritol and at 82 °C. The reasons for the differences are hard to deduce since the research approach is not presented as fully transparent from the past studies. In the present study, only the temperature-composition plot of the first melting (of the two components in a physical mix, but not of a single blend) indicated the shape of a simple eutectic in a non-isomorphous system. The cycles after the first melting in contrast started from the real blend, and displayed eutectic and solid-solid phase changes in T-history. These were verified as forming solid solutions with XRD and FESEM. This eutectic melts at a temperature suitable for low-temperature solar heating, but displayed glass transition, supercooling, and thermally activated degradation, thus affecting its practical aspects as a PCM.

  • 31.
    Gunasekara, Samman Nimali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ignatowicz, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermal conductivity measurement of erythritol, xylitol, and their blends for phase change material design: A methodological study2019In: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 43, no 5, p. 1785-1801Article in journal (Refereed)
    Abstract [en]

    This work presents and discusses a detailed thermal conductivity assessment of erythritol, xylitol, and their blends: 25 mol% erythritol and 80 mol% erythritol using the transient plane source (TPS) method with a Hot Disk Thermal Constants Analyzer TPS‐2500S. Thereby, the thermal conductivities of xylitol, 25 mol% erythritol, 80 mol% erythritol, and erythritol were here found for respectively in the solid state to be 0.373, 0.394, 0.535, and 0.589 W m−1 K−1 and in the liquid state to be 0.433, 0.402, 0.363, and 0.321 W m−1 K−1. These obtained results are comprehensively and critically analyzed as compared to available literature data on the same materials, in the phase change materials (PCMs) design context. This study clearly indicates that these thermal conductivity data in literature have considerable discrepancies between the literature sources and as compared to the data obtained in the present investigation. Primary reasons for these disparities are identified here as the lack of sufficiently transparent and repeatable data and procedure reporting, and relevant standards in this context. To exemplify the significance of such transparent and repeatable data reporting in thermal conductivity evaluations in the PCM design context, here focused on the TPS method, a comprehensive measurement validation is discussed along various residual plots obtained for varying input parameters (ie, the heating power and time). Clearly, the variations in the input parameters give rise to various thermal conductivity results, where choosing the most coherent result requires a sequence of efforts per material, because there are no universally valid conditions. Transparent and repeatable data and procedure reporting are the key to achieve comparable thermal conductivity results, which are essential for the correct design of thermal energy storage systems using PCMs.

    The full text will be freely available from 2020-02-22 10:37
  • 32.
    Gunasekara, Samman Nimali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Ignatowicz, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Thermal Conductivity Measurement of Erythritol, Xylitol and Their Blends for Phase Change Materials Design: a Methodological Study2018In: The 14th International Conference on Energy Storage, Adana, Turkey: IEA ECES , 2018, p. 364-378, article id 82Conference paper (Refereed)
    Abstract [en]

    This work presents and discusses a detailed thermal conductivity assessment of erythritol, xylitol and their blends: 25 mol% erythritol and 80 mol% erythritol using the Transient Plane Source (TPS) method with a Hot Disk Thermal Constants Analyzer TPS-2500S. Their thermal conductivities were here found to be respectively: 0.59; 0.37; 0.39 and 0.54 W/(m·K) in the solid state, and to be 0.32; 0.43; 0.40 and 0.36 W/(m·K) in the liquid state. These obtained results are comprehensively and critically analyzed as compared to available literature data on the same materials, in the phase change materials (PCMs) design context. This study clearly indicates that the literature has considerable discrepancies among their presented thermal conductivities, and also as compared to the values found through the present investigation. Primary reason for these disparities are identified here as the lack of sufficiently transparent and repeatable data and procedure reporting, and relevant standards in this context. To exemplify the significance of such transparent and repeatable data reporting in thermal conductivity evaluations in the PCM design context, here focused on the TPS method, a comprehensive measurement validation is discussed along various residual plots obtained for varying input parameters (i.e., the heating power and time). Clearly, the variations in the input parameters give rise to various thermal conductivity results, where choosing the most coherent result requires a sequence of efforts per material, but there are no universally valid conditions. Transparent and repeatable data and procedure reporting is the key to achieve comparable thermal conductivity results, which are essential for the correct design of thermal energy storage systems using PCMs.

  • 33.
    Gunasekara, Samman Nimali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Kumova, Sofia
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Gubkin Russian State University of Oil and Gas, Russia.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental Phase Equilibrium Study of Dodecane-Tridecane System for Phase Change Materials Design for Thermal Energy Storage2016Conference paper (Other academic)
  • 34.
    Gunasekara, Samman Nimali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mao, Huahai
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Bigdeli, Sedigheh
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermodynamic Assessment of Binary Erythritol-Xylitol Phase Diagram for Phase Change Materials DesignManuscript (preprint) (Other academic)
    Abstract [en]

    Here, the experimental phase equilibrium data of the erythritol-xylitol system were thermodynamically optimized, to explore compositions suitable as phase change materials (PCMs) for thermal energy storage (TES). A previous experimental study revealed that erythritol-xylitol was a partially isomorphous system with a eutectic. In the thermodynamic evaluation, the CALPHAD method was employed coupling the phase diagram and thermodynamic property information. There, both unary and binary systems’ experimental data were taken into account, and all phases were described using the substitutional solution model. Finally, a self-consistent thermodynamic description for the erythritol-xylitol system was achieved. The calculated eutectic point is at 76.7 °C and 26.8 mol% erythritol, agreeing well with the experimental data. The calculated phase diagram better-verifies the systems’ solidus and the solvus, disclosing the stable phase relations. Based on the Gibbs energy minimization, phase diagrams can be predicted for the binary and higher order systems, provided the component subsystems are thermodynamically assessed beforehand. In conclusion, to move forward beyond e.g. non-isomorphous simple eutectic systems, methods using Gibbs free energy minimization from a fundamental point-of-view such as CALPHAD are essential.

  • 35.
    Gunasekara, Samman Nimali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Stalin, Joseph
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Marçal, Mariana
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Delubac, Regis
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. University of Pau and Pays de l'Adour, France.
    Karabanova, Anastasiya
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Gubkin Russian State University of Oil and Gas, Russia.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Erythritol, Glycerol, their Blends, and Olive Oil, as Sustainable Phase Change Materials2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 135, p. 249-262Article in journal (Refereed)
    Abstract [en]

    In searching for new candidates to be used in latent heat storage, it is desirable to explore food-grade materials of renewable origin. Here, erythritol, glycerol, and olive oil have been characterized as PCMs. An assessment of the production process of erythritol (melting between 117-120 °C with an enthalpy around 300 kJ/kg) indicates its renewable aspects as a PCM. In addition, a simplified cost assessment of high-purity erythritol production, using glycerol, indicates a potential cost reductions up to 130-1820 times lower than the current laboratory-grade prices. Glycerol already is cost-effective. However, the glycerol-erythritol system, evaluated using the Temperature-history (T-history) method, did not exhibit phase change suitable for PCMs. Glycerol, and up to 30 mol% erythritol compositions had no phase change due to glass transition; the remainder froze but with large supercooling; and the system underwent thermally activated change. Hence, to realize glycerol or the glycerol-erythritol system as PCMs, further research is needed primarily to device fast-crystallization. Olive oil is a cost-effective food commodity, with potential for further cost reductions by mass-production. An olive oil sample, containing the fatty acids: linoleic, palmitic, oleic, margaric, and stearic was evaluated using the T-history method. This olive oil melted and froze between -4.5 to 10.4 °C and -8 to -11.9 °C respectively, with the respective enthalpies 105 and 97 kJ/kg. As the specific heat (cp) profiles of olive oil displayed two peaks, the composition adjustment of olive oil could yield a eutectic or confirm a polymorph. In either case, olive oil has a potential to be a PCM e.g. in chilling applications, while its properties such as thermal conductivity need to be determined. As a whole, this study exemplifies the potential of renewable organic materials, in pure and blend forms, as sustainable PCMs, making TES with PCMs sustainable.

  • 36.
    Johansson, Petter
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Business Development and Entrepreneurship.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Impact of Convective Heat Transfer Mechanism in Latent Heat Storage Modeling2012Conference paper (Refereed)
  • 37.
    Oró, Eduard
    et al.
    GREA UdL.
    Castell, Albert
    GREA UdL.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Cabeza, Luisa
    GREA UdL.
    Stratification analysis in packed bed thermal energy storage systems2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 109, no SI, p. 476-487Article in journal (Refereed)
    Abstract [en]

    District cooling and heating networks are increasing in many countries, especially in the Scandinavian countries. Some of the systems have become small for the needs of the population and they have to be enhanced in order to reach the cooling or heating necessities. Here, thermal energy storage system of a district cooling network is studied. Phase change material (PCM) is used in order to enhance the energy density and the stratification of the water tank. The experimental set up consists mainly of a cylindrical storage tank with a capacity of 3.73 L filled with spherically encapsulated PCM. The PCM used is PK6 from Rubitherm GmbH with a storage capacity of 175 kJ/kg between −2 °C and 13 °C. Many methods to characterize water tank stratification, such as graphical (dimensional and non-dimensional) and numerical figures based on temperature distribution (degree of stratification, first law efficiencies, second law efficiencies, other efficiencies as MIX number), are used to analysed and characterized two storage tanks, one of them with the inclusion of PCM packed bed during both charging and discharging processes.

  • 38.
    Oró, Eduard
    et al.
    GREA UdL.
    Castell, Albert
    GREA UdL.
    Chiu, NingWei Justin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Miro, Laia
    GREA UdL.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Cabeza, Luisa
    GREA UdL.
    Enhancement of the stratification with packed bed thermal energy storage systems2012In: InnoStock The 12th International Conference on Energy Storage: Book of Abstract / [ed] Stock Conference, 2012, p. 284-285Conference paper (Refereed)
    Abstract [en]

    Scandinavian countries have a high demand of heating and cooling in indoor thermal comfort, representing 45% of the total energy use in Swedish residential and service sector [1]. Nowadays the utilization of this district cooling or heating networks is increasing in the modern societies and some researchers have been studied its possibilities for future enhancements of the systems [2], [3].

    The improvement of the storage efficiency results in a higher performance of the whole system, and thermal stratification is commonly used for this purpose [4]. Stratification of the water in storage tanks is created by the difference in density between the cold and the hot water. Due to this density difference, cold water remains at the bottom of the tank while the hot water is placed at the top. The larger the temperature difference between these hot and cold water the better the efficiency of the storage. The intermediate region is called the thermocline which has been deeply studied over the years [5], [6]. Some researchers have been focusing on the inlet distribution manifold which has holes drilled around the circumference to remove the momentum of the incoming fluid and inhibits mixing while allowing buoyancy forces. Yee and Lai [7] developed a numerical model for a rigid manifold to investigate the effect of various design parameters on the formation of thermal stratification in a water storage tank. Hence, Brown and Lai [8] investigated the effectiveness of a vertical porous manifold in the formation and maintenance of thermal stratification in a liquid storage tank.

    It is well known that thermal energy storage (TES) plays an important role in both industrial and domestic applications, storing heat and cold when available and using it when needed. Therefore, it is of great interest for the researchers to study this type of TES system, enhancing the stratification and the energy storage density of them. One of the most attractive latent cold TES systems is the spherically capsulated phase change material (PCM) filled packed bed. And it also seems to be one of the most effective and convenient methods of encapsulation [4].  Mehling et al. [9] studied numerically and experimentally the addition of PCM modules at the top of a hot water storage tank with stratification, adding higher storage density in the top layer. Nallusamy et al. [10] studied the thermal performance of a packed bed latent heat TES unit integrated with solar water heating system, concluding that the utilization of packed bed PCM reduces the size of the storage tank appreciably compared to conventional storage tank system. Some other researchers have been focusing in the numerical studies of heat transfer in packed bed latent heat storage [11], [12], [13].

    Hence, in this study a packed bed storage tank with encapsulated PCM is analysed and compared with the same storage system without PCM during a charging process of the low phase change temperature PCM. As the temperature profile does not give the information in the best way to characterize clearly the stratification in a water storage tank dimensionless numbers which condense this information in a single parameter are studied [14]. Therefore the aim of this paper is to analyse the stratification and the thermal characteristics of a water storage tank filled with PCM packed bed and compare it with the same tank without PCM.

  • 39.
    Oró, Eduard
    et al.
    GREA UdL.
    Chiu, NingWei Justin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Cabeza, Luisa
    GREA UdL.
    Comparative study of different numerical models of packed bed thermal energy storage systems2013In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 50, no 1, p. 384-392Article in journal (Refereed)
    Abstract [en]

    This paper presents, compares and validates two different mathematical models of packed bed storage with PCM, more specifically the heat transfer during charge of the PCM. The first numerical model is a continuous model based on the Brinkman equation and the second numerical model treats the PCM capsules as individual particles (energy equation model). Using the Brinkman model the flow field inside the porous media and the heat transfer mechanisms present in the packed bed systems can be described. On the other hand, using the energy equation model the temperature gradient inside the PCM capsules can be analysed. Both models are validated with experimental data generated by the authors. The experimental set up consists mainly of a cylindrical storage tank with a capacity of 3.73 L full of spherically encapsulated PCM. The PCM used has a storage capacity of 175 kJ/kg between −2–13 °C. The results from the energy equation model show a basic understanding of cold charging. Moreover, three different Nu correlations found in the literature were analysed and compared. All of them showed the same temperature profile of the PCM capsules; hence any of them could be used in future models. The comparison between both mathematical models indicated that free convection is not as important as forced convection in the studied case.

  • 40.
    Rossi Espagnet, Alberto
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Castro Flores, José Fiacro
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. École des Mines de Nantes - EMN, Energy Systems and Environment - DSEE.
    Chiu, NingWei Justin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lacarrière, Bruno
    École des Mines de Nantes - EMN, Energy Systems and Environment - DSEE.
    Techno-economic assessment of Thermal Energy Storage integration into Low Temperature District Heating networks2016In: Book of abstracts: 2nd International Conference on Smart Energy Systems and 4th Generation District Heating / [ed] Henrik Lund, Aalborg Universitetsforlag, 2016Conference paper (Other academic)
    Abstract [en]

    Thermal energy storage (TES) systems are technologies with the potential to enhance the efficiency and the flexibility of the coming 4th generation low temperature district heating (LTDH). Their integration would enable the creation of smarter, more efficient networks, benefiting both the utility and the end consumers. This study aims to develop a comparative assessment of TES systems, both latent and sensible heat based. First, a techno-economic analysis of several TES systems is conducted to evaluate their suitability to be integrated into LTDH. Then, potential scenarios of TES integration are analysed in a case study of a LTDH network. This is complemented with a review of current DH legislation focused on the Swedish case, with the aim of taking into consideration the present situation, and changes that may support some technologies over others. The results of the analysis show that sensible heat storage is still preferred to latent heat when coupled with LTDH: the cost per kWh stored is still 15% higher for latent heat in systems below 5MWh of storage size; though, they require just half of the volume. However, it is expected that the cost of latent heat storage systems will decline in the future, making them more competitive. From a system perspective, the introduction of TES systems into the network results in an increase in flexibility leading to lower heat production costs by load shifting: by running the production units with lower marginal heat production costs for longer periods and with high efficiency, and thus reducing the operating hours of the other more expensive operating units during peak load conditions. These results may also be extended to the case when heat generation is replaced by renewable, intermittent energy sources; thus increasing profits, reducing fuel consumption, and consequently emissions. This study represents a step forward in the development of a more efficient DH system through the integration of TES which will play a crucial role in future smart energy system.

  • 41.
    Vadiee, Amir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Chiu, Justin Ning Wei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Gunasekara, Samman Nimali
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermal energy storage systems in closed greenhouse with component and phase change material design2013Conference paper (Refereed)
  • 42.
    Xu, Tianhao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. KTH.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Sawalha, Samer
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Experimental investigation on cylindrically macro-encapsulated latent heat storage for space heating applications2019In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 182, p. 166-177Article in journal (Refereed)
    Abstract [en]

    The integration of latent heat thermal energy storage (LHTES) units with heating systems in buildings is regarded as a promising technology for heating load management; however, so far a limited number of experimental studies have been reported that focus on space heating applications on a representative scale. In this study, we develop and test a 0.38 m3 LHTES unit containing cylindrically macro-encapsulated phase change materials (PCMs) with a melting temperature range of 44–53 °C and with gross mass of 154 kg. The unit has been tested with two tank orientations, horizontal and vertical. In the horizontal orientation tests, parametric studies show that increasing the difference between heat transfer fluid (HTF) supply temperatures and phase-change temperatures of PCMs, as well as increasing HTF flowrates, can both reduce the complete melting/solidification and complete charging/discharging time. Non-linear charging/discharging rates in PCMs are observed. The vertical orientation enables the forming of either a stratified or mixed flow regime in the tank. For charging, the stratified flow provides higher charging rates in PCMs compared to the mixed flow. When discharging the unit with a stratified HTF flow at 35 °C, lower HTF flowrates prolong the discharging time during which the released heat sustains an outlet temperature above 45 °C. Finally, comparisons between horizontal and vertical orientation tests reveal that although the vertical orientation can shorten the charging/discharging time by up to 20% for the entire unit to reach an energy density of 30 kWh/m3, it leads to decrease in PCM thermal capacity by at most 8.2%. The speculated cause of this loss is phase segregation suggested by observed fluid motions in PCM cylinders. This study comprehensively characterizes an LHTES unit providing insights to optimizing its operating strategies considering its coupling with space heating systems.

1 - 42 of 42
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf