Change search
CiteExportLink to record
Permanent link

Direct 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
Latent Heat Thermal Energy Storage for Indoor Comfort Control
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. (Thermal Energy Storage)ORCID iD: 0000-0001-6982-2879
2013 (English)Doctoral 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.

Abstract [sv]

Om vi låter jordens livstid motsvaras av 24 timmar, har mänskligheten endast existerat under de sista fyra sekunderna. Fossila bränslen med utvinning i stor skala kom till vår kännedom under den industriella revolutionen för två sekel sedan, med andra ord fyra millisekunder av jordens dygnslånga livstid. På grund av ohämmad fossilbränsleanvändning förutspår FN:s klimatpanel (IPCC) att den av människor orsakade globala uppvärmningen blir mellan 2°C och 6°C till år 2100. Onormala klimatfenomen förväntas som resultat, till exempel starka tropiska cykloner, extrema värmeböljor, och kraftig nederbörd. Att begränsa klimatförändringarna har blivit en av de viktigaste frågorna i vårt starkt energiberoende samhälle.

Ständigt ökande efterfrågan på energi går hand i hand med förbättrad levnadsstandard på grund av teknologiska och ekonomiska framsteg under det senaste århundradet. Beteendeförändringar, att anpassa vår livsstil, har betraktats som den slutgiltiga lösningen, men en sådan strategi kräver långsiktig utbildning och vilja. I denna avhandling undersöks en ny energiteknik: energilagring, för att minska topplaster och skifta belastningen så att vi kan gå mot ett paradigmskifte i form av ökat nyttjande av förnybara energikällor, förbättrad energieffektivitet och minskade utsläpp av växthusgaser utan att ge avkall på boendekomfort.

System för termisk energilagring med hög densitet (TES) använder fasändringsmaterial som lagringsmedia, där värmeenergi huvudsakligen lagras i form av latent värme (LH). Fördelarna är kompakta komponenter och små variationer i lagringstemperatur. Utmaningar återstår i att integrera LHTES i fastigheter: bristande förståelse för systemdynamiken, osäkerhet i komponentdesign och odokumenterade materialegenskaper.

Målet med denna avhandling är att ta itu med frågor kring materialkarakterisering, studier av värmeöverföring för komponenter och om systemintegration. En metod för att mäta materials entalpi genom Temperature-History definieras genom att identifiera brister i existerande metoder, och implementera förbättringar. Den andra aspekten består i att upprätta gångbara numeriska modellerna för LHTES, där experimentell verifiering har genomförts. Förbättring av den termiska effekten erhålls med flerstegs-fasändringsmaterial-lagring. Känslighetsanalys och teknisk-ekonomisk optimering utförs för integrerad systemdesign med TES. Slutligen görs en uppskattning av hur mycket Sveriges topplast i energisystemet kan minskas genom att studera implementering av TES. Minskningen i topplast som uppnås genom implementation av TES bestämmer mängden marginalenergi från fossila bränslen som kan reduceras för att nå ett mer uthålligt samhälle.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. , xvii, 77 p.
Series
Trita-KRV, ISSN 1100-7990 ; 13:02
Keyword [en]
Thermal Energy Storage, Phase Change Material, Indoor Comfort, Heat Transfer
Keyword [sv]
Termisk Energilagring; Fasändringsmaterial; Inomhuskomfort; Värmeöverföring
National Category
Energy Engineering Energy Systems
Identifiers
URN: urn:nbn:se:kth:diva-119275ISBN: 978-91-7501-679-5 (print)OAI: oai:DiVA.org:kth-119275DiVA: diva2:610403
Public defence
2013-04-09, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20130312

Available from: 2013-03-12 Created: 2013-03-11 Last updated: 2013-03-12Bibliographically approved
List of papers
1. Submerged finned heat exchanger latent heat storage design and its experimental verification
Open this publication in new window or tab >>Submerged finned heat exchanger latent heat storage design and its experimental verification
2012 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 93, no SI, 507-516 p.Article in journal (Refereed) Published
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.

Keyword
PCM, Energy Storage, T-History, Heat Transfer Enhancement, modeling
National Category
Energy Engineering
Research subject
SRA - Energy
Identifiers
urn:nbn:se:kth:diva-34261 (URN)10.1016/j.apenergy.2011.12.019 (DOI)000302836500059 ()2-s2.0-84857996845 (Scopus ID)
Projects
Cold Thermal Energy Storage
Funder
StandUp
Note

QC 20120524

Available from: 2011-05-30 Created: 2011-05-30 Last updated: 2017-12-11Bibliographically approved
2. ­Multistage Latent Heat Cold Thermal Energy Storage Design Analysis
Open this publication in new window or tab >>­Multistage Latent Heat Cold Thermal Energy Storage Design Analysis
2013 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, no SI, 1438-1445 p.Article in journal (Refereed) Published
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.

Keyword
Thermal energy storage, Phase change material, Multistage storage design
National Category
Energy Engineering Energy Systems
Identifiers
urn:nbn:se:kth:diva-117698 (URN)10.1016/j.apenergy.2013.01.054 (DOI)000329377800156 ()2-s2.0-84884210408 (Scopus ID)
Conference
4th International Conference on Applied Energy (ICAE),July 01-04, 2012, Suzhou, China
Note

QC 20140210

Available from: 2013-02-01 Created: 2013-02-01 Last updated: 2017-12-06Bibliographically approved
3. Active Free Cooling Optimization with Thermal Energy Storage in Stockholm
Open this publication in new window or tab >>Active Free Cooling Optimization with Thermal Energy Storage in Stockholm
2012 (English)In: InnoStock The 12th International Conference on Energy Storage: Book of Abstract / [ed] Stock Conference, 2012, 106-107 p.Conference paper, Oral presentation with published abstract (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.

Keyword
Passive Building, Overheating, PCM, TES, Free Cooling
National Category
Engineering and Technology
Research subject
SRA - Energy
Identifiers
urn:nbn:se:kth:diva-95568 (URN)978-84-938793-3-4 (ISBN)
Conference
InnoStock The 12th International Conference on Energy Storage
Projects
Cold Thermal Energy Storage
Funder
StandUp
Note

QC 20121218

Available from: 2012-05-28 Created: 2012-05-28 Last updated: 2013-03-25Bibliographically approved
4. System Integration of Latent Heat Thermal Energy Storage Systems for Comfort Cooling Integrated in district cooling network
Open this publication in new window or tab >>System Integration of Latent Heat Thermal Energy Storage Systems for Comfort Cooling Integrated in district cooling network
2009 (English)In: 11th International Conference on Thermal Energy Storage, EFFSTOCK 2009, Stockholm, Sweden, June 14-17, 2009., 2009Conference paper, Published 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%.

Keyword
TES, PCM, District Cooling, Peak Shave, Load Shift
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-30636 (URN)
Conference
International Conference on Thermal Energy Storage
Projects
Cold Thermal Energy Storage
Note
QC 20110307Available from: 2011-03-07 Created: 2011-03-02 Last updated: 2013-03-12Bibliographically approved
5. A Review of Thermal Energy Storage Systems with Salt Hydrate Phase Change Materials for Comfort Cooling
Open this publication in new window or tab >>A Review of Thermal Energy Storage Systems with Salt Hydrate Phase Change Materials for Comfort Cooling
2009 (English)In: 11th International Conference on Thermal Energy Storage, June 14-17 , 2009, Stockholm, Sweden., 2009Conference paper, Published 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.

Keyword
PCM, TES, salt hydrate
National Category
Energy Engineering Materials Chemistry Production Engineering, Human Work Science and Ergonomics
Research subject
SRA - Energy
Identifiers
urn:nbn:se:kth:diva-26969 (URN)
Conference
EFFSTOCK 2009
Projects
Cold Thermal Energy Storage
Funder
StandUp
Note
QC 20110126Available from: 2011-01-26 Created: 2010-12-01 Last updated: 2013-03-12Bibliographically approved
6. Thermal energy storage for sustainable future: impact of power enhancement on storage performance
Open this publication in new window or tab >>Thermal energy storage for sustainable future: impact of power enhancement on storage performance
2010 (English)In: International Conference on Sustainable Refrigeration and Heat Pump Technology, Stockholm, June 13-16, 2010., 2010Conference paper, Published 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.

Keyword
PCM, TES, Power, Capacity, Modeling
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-30635 (URN)
Conference
Sustainable Refrigeration and Heat Pump Technology
Projects
Cold Thermal Energy Storage
Note
QC 20110307Available from: 2011-03-07 Created: 2011-03-02 Last updated: 2013-03-12Bibliographically approved
7. Thermal Energy Storage: Climate Change Mitigation Solution?
Open this publication in new window or tab >>Thermal Energy Storage: Climate Change Mitigation Solution?
2011 (English)In: International Conference for Sustainable Energy Storage, Belfast, UK: University of Ulster , 2011Conference paper, Published 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.

 

Place, publisher, year, edition, pages
Belfast, UK: University of Ulster, 2011
Keyword
GHG Emission, TES, PCM, Climate Change, Energy, Storage
National Category
Other Environmental Engineering Energy Engineering
Research subject
SRA - Energy
Identifiers
urn:nbn:se:kth:diva-34053 (URN)
Funder
StandUp
Note
QC 20100530Available from: 2011-05-30 Created: 2011-05-24 Last updated: 2013-03-12Bibliographically approved
8. Impact of Convective Heat Transfer Mechanism in Latent Heat Storage Modeling
Open this publication in new window or tab >>Impact of Convective Heat Transfer Mechanism in Latent Heat Storage Modeling
2012 (English)Conference paper, Published paper (Refereed)
Keyword
TES, convection, conduction, phase, change, thermal, latent, energy, storage, numerical, Comsol, Matlab
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-90752 (URN)
Conference
InnoStock 2012, The 12th International Conference on Energy Storage, 16-18 May 2012, Lleida, Spain
Funder
StandUp
Note

QC 20130110

Available from: 2012-02-28 Created: 2012-02-28 Last updated: 2013-03-12Bibliographically approved

Open Access in DiVA

LHTES_Justin_Chiu(4914 kB)2245 downloads
File information
File name FULLTEXT01.pdfFile size 4914 kBChecksum SHA-512
ba23c08d519246322efac2617acd53afd38e98d0d9a58125cfd5a8eb9e4fd091203d3d81c5db99faa9a238c19b1075d49712b3414b1324772052881125f9c508
Type fulltextMimetype application/pdf

Authority records BETA

Chiu, NingWei Justin

Search in DiVA

By author/editor
Chiu, NingWei Justin
By organisation
Heat and Power Technology
Energy EngineeringEnergy Systems

Search outside of DiVA

GoogleGoogle Scholar
Total: 2245 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 705 hits
CiteExportLink to record
Permanent link

Direct 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