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  • 1.
    Ahl, Amanda
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Eklund, Johanna
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Yarime, M.
    Balancing formal and informal success factors perceived by supply chain stakeholders: A study of woody biomass energy systems in Japan2018Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 175, s. 50-59Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Small-scale woody biomass energy systems have an inherent ability to aid in emissions reduction while stimulating local economies and, as collective energy systems, are strongly connected to supply chain design based on local conditions and stakeholder integration. Despite an abundance of forest area alongside the promotion of biomass in energy policies, however, woody biomass utilization still remains low in Japan. The woody biomass supply chain, considered as a socio-technical system, involves a complex, cross-sectoral stakeholder network in which inter-organizational dynamics necessitates well-organized management based on an understanding of formal factors such as technology, as well as informal factors such as social relations and culture. In this paper, success factor perceptions from across the woody biomass supply chain are investigated based on semi-structured interviews with four stakeholders in the Kyushu region of Japan. Identified success factors here are: 1) respect of values & traditions, 2) transportation infrastructure, 3) business model integration, 4) relationship & trust, 5) local vitalization and 6) biomass quality control. A convergence as well as divergence of perceptions are observed, involving both formal and informal dimensions. Aiming to balance perceptions and to enable long-term success of woody biomass in Japan, a series of policy implications are drawn, including cross-ministerial integration, knowledge building on wood logistics, forest certification, local coordinators, biomass quality control standards and a feed-in-tariff for heat. This paper suggests a new arena of policy-making based on the importance of considering both informal and formal dimensions in energy policy.

  • 2.
    Anund Vogel, Jonas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lind, Hans
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande, Bygg- och fastighetsekonomi.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Who is Governing the Commons: Studying Swedish Housing Cooperatives2016Inngår i: Housing, Theory and Society, ISSN 1403-6096, E-ISSN 1651-2278Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study examines current governance structures related to multifamily buildings designed by single actors (developers) and operated in cooperative forms. The study analyses the long-term sustainability of the resource regime of study (multifamily buildings) and inked governance structures by applying Ostrom’s eight design principles for long-term survival of self-organized resource regimes (Common-pool resources or CPR’s). The study also searches for signs of movement towards social innovation and collective action in current governance structures. We argue that the structures governing planning, production and operation of housing cooperatives in Sweden do not fulfil the eight design principles for the long-term survival of the resource regime of study, nor do they encourage movement towards social innovation or collective action. In order to ensure the long-term survival of the resource regime of study and to increase innovation in governance structures, five adjustments are proposed; changes in the structures governing risk/profit distribution, communication, collaboration and information between actors in the Swedish cooperative housing sector.

  • 3.
    Anund Vogel, Jonas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Arias, Jaime
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Blomkvist, Pär
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.), Hållbarhet och industriell dynamik.
    Problem areas related to energy efficiency implementation in Swedish multifaily buildings2015Inngår i: Energy Efficiency, ISSN 1570-646X, E-ISSN 1570-6478Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper investigates problem areas related to energy efficiency implementation in Swedish multifamily buildings. The paper first presents a generic list of (theoretical) problem areas identified through a literature survey. Using a qualitative approach, the paper also investigates if the problem areas identified in the literature also have an impact on the Swedish building sector. Results from the interview study reveal a strong coherence between problem areas in the literature and those expressed by the interviewees. However, this paper identifies seven novel challenges that cannot be derived from the list of barriers in the literature. Moreover, results reveal that as many as 12 problem areas have their origin in national factors such as agreement structures, incentive schemes, and cost calculation methods.

  • 4.
    Arias, Jaime
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Choisir entre récupération de chaleur ou pression de condesation flottante en froid commercial2006Inngår i: Revue J. du Froid, nr 1066, s. 47-54Artikkel i tidsskrift (Fagfellevurdert)
  • 5.
    Arias, Jaime
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Heat Recovery and Floating Condensing in Recent Refrigeration Systems in Supermarkets2005Konferansepaper (Fagfellevurdert)
  • 6.
    Arias, Jaime
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Modelling Supermarket Energy Usage2005Konferansepaper (Fagfellevurdert)
  • 7.
    Arias, Jaime
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, PerKTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.Sawalha, SamerKTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Annex 31: advanced modelling and tools for analysis of energy use in supermarket systems2010Konferanseproceedings (Fagfellevurdert)
  • 8.
    Arias, Jaime M.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per G.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Heat recovery and floating condensing in supermarkets2006Inngår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 38, nr 2, s. 73-81Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Supermarkets are great energy users in many countries. The potential for increased energy efficiency is large. One option is to utilize heat recovery (or heat reclaim) from condensers to heat the premises. Obviously this option is only interesting in relatively cold areas such as northern Europe, Canada, etc. An alternative to heat recovery is floating condensing pressure, which improves the coefficient of performance and decreases the energy consumption of the refrigeration system at lower outdoor temperature. Both heat recovery and floating condensing pressure can be utilized interchangeably depending on the heat requirements of the premises. A computer model that calculates the energy consumption in a supermarket with the possibility to simulate different system solutions for the refrigeration system has been developed at the Royal Institute of Technology, Department of Energy Technology. The software CyberMart is used in the present study to compare the potential of heat recovery and floating condensing in Swedish supermarkets. Measurements of different parameters such as temperatures, relative humidity and compressor power have been carried out in different supermarkets with heat recovery to validate the theoretical calculations. The present study shows that heating requirements can be covered completely by heat reclaim from the condenser. However, practical experiences show that installations are less efficient due to poor system solutions and/or control strategies. According to the results from CyberMart, the highest potential of energy saving is obtained from using a systems solution with both heat recovery and floating condensing.

  • 9.
    Arias, Jaime M.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per G.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Modelling and experimental validation of advanced refrigeration systems in supermarkets2005Inngår i: Proceedings of the Institution of mechanical engineers. Part E, journal of process mechanical engineering, ISSN 0954-4089, E-ISSN 2041-3009, Vol. 219, nr E2, s. 149-156Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effective use of energy and the replacement of CFC and HCFC refrigerants are two factors that have influenced the design and operation of refrigeration systems in supermarkets during recent years. The potential for increasing energy efficiency in refrigeration systems, indoor climate and refrigerated cabinets is large. Since the energy systems of a supermarket are relatively complex, improvements in one subsystem affect other systems, thus making analysis of potential improvements non-additive. A computer model, CyberMart, that predicts building heating and cooling loads, HVAC (heating, ventilation, and air conditioning), and refrigeration system performances of a supermarket, has been developed. The focus of the model is on energy use, environmental impact (TEWI), and life cycle cost (LCC) of the refngeration system. The refrigeration system solutions included in the model are: direct system, completely indirect system, partially indirect system, cascade system, parallel system with mechanical sub-cooling (where the refrigerant in the low-temperature system is sub-cooled with the brine of the intermediate temperature level), and district cooling (that cools the condenser of the refrigeration machines). Measurements of different parameters such as outdoor and indoor temperatures, relative humidity, and compressor power have been carried out in several stores to validate the model. A theoretical description of the model and results from the model and measurements are presented in this paper.

  • 10. Bivens, D.
    et al.
    Lundqvist, PerKTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Supermarket Refrigeration Systems - Climate Change Impact2005Konferanseproceedings (Annet vitenskapelig)
  • 11.
    Chen, Jianyong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Palm, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    A new ejector refrigeration system with zeotropic mixtures2011Inngår i: 23RD IIR INTERNATIONAL CONGRESS OF REFRIGERATION, 2011, s. 2043-2050Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A new ejector refrigeration system (NERS) using zeotropic mixture is theoretical studied in the paper.R32/R134a, R32/R152a, R134a/R142b, R152a/R142b, R290/R600a and R600a/R600 are selected as theworking fluids in the analysis. The comparison between this NERS and the conventional ejector refrigerationsystem (CERS) is made under the same operating condition. It is found that this new system has higherCOPs than the CERS. The effect of operating conditions and the composition on the performance of this newsystem are presented. An exergy analysis is carried out to study the loss within each component of thesystem. It is observed that the irreversibility in the ejector represents more than 50% of the total exergy loss.This also emphasizes the necessity for good ejector design and manufacture.

  • 12.
    Chen, Yang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Analysis of supercritical carbon dioxide heat exchangers in cooling process2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Carbon dioxide transcritical cycles have become more and more investigated during the last decade. For all systems operating with such a cycle, there will be at least one heat exchanger to either heat or cool the supercritical carbon dioxide. Unlike in the sub-critical region, the supercritical carbon dioxide’s thermophysical properties will have sharp variations in the region close to its critical point. This variation has a significant influence on the shape of the heat exchanger’s temperature profile and the heat transfer performance of the heat exchanger. Therefore, the performance of the heat exchanger used for supercritical carbon dioxide cooling or heating process should be evaluated by taking this effect into account. This paper discusses the heat exchangers used for supercritical carbon dioxide refrigeration process including a suction gas heat exchanger in the cycle. Engineering Equation Solver (EES)1 and Refprop 7.02 are used for cycle calculations and for properties calculations.

  • 13.
    Chen, Yang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    The Co2 Transcritical Power Cycle For Low Grade Heat Recovery-Discussion On Temperature Profiles In System Heat Exchangers2012Inngår i: Proceedings of the ASME Power Conference- 2011 Vol 1, ASME Press, 2012, s. 385-392Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Carbon dioxide transcritical power cycle has many advantages in low-grade heat source recovery compared to conventional systems with other working fluids. This is mainly due to the supercritical CO2's temperature profile can match the heat source temperature profile better than other pure working fluids and its heat transfer performance is better than the fluid mixtures, which enables a better cycle efficiency. Moreover, the specific heat of supercritical CO2 will have sharp variations in the region close to its critical point, which will create a concave shape temperature profile in the heat exchanger that used for recovering heat from low-grade heat sources. This brings more advantage to carbon dioxide transcritical power systems in low-grade heat recovery.

  • 14.
    Chen, Yang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Lundqvist, Per Gunnar
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Carbon dioxide cooling and power combined cycle for mobile applications2006Inngår i: Proceedings of 7th IIR-Gustav Lorentzen Conference on Natural Working Fluids, 2006Konferansepaper (Fagfellevurdert)
  • 15.
    Chen, Yang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per Gunnar
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Johansson, Anders
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Platell, P
    A comparative study of the carbon dioxide transcritical power cycle compared with an organic rankine cycle with R123 as working fluid in waste heat recovery2006Inngår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 26, nr 17-18, s. 2142-2147Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The organic rankine cycle (ORC) as a bottoming cycle1The expression "bottoming cycle" refers to the power cycle that uses waste industrial heat for power generation by supplementing heat from any fossil fuel.1 to convert low-grade waste heat into useful work has been widely investigated for many years. The CO2 transcritical power cycle, on the other hand, is scarcely treated in the open literature. A CO2 transcritical power cycle (CO2 TPC) shows a higher potential than an ORC when taking the behavior of the heat source and the heat transfer between heat source and working fluid in the main heat exchanger into account. This is mainly due to better temperature glide matching between heat source and working fluid. The CO2 cycle also shows no pinch limitation in the heat exchanger. This study treats the performance of the CO2 transcritical power cycle utilizing energy from low-grade waste heat to produce useful work in comparison to an ORC using R123 as working fluid. Due to the temperature gradients for the heat source and heat sink the thermodynamic mean temperature has been used as a reference temperature when comparing both cycles. The thermodynamic models have been developed in EES2EES - Engineering equation solver. The thermodynamic properties for carbon dioxide in EES are calculated by the fundamental equation of state developed by R. Span and W. Wagner, A new equation of state for carbon dioxide covering the fluid region form the triple-point temperature to 1100 K at pressures up to 800 MPa, J. Phys. Chem. Ref. Data, Vol. 25, No. 6, 1996. http://www.fchart.com/ees/ees.shtml.2 The relative efficiencies have been calculated for both cycles. The results obtained show that when utilizing the low-grade waste heat with the same thermodynamic mean heat rejection temperature, a transcritical carbon dioxide power system gives a slightly higher power output than the organic rankine cycle.

  • 16.
    Chen, Yang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Lundqvist, Per Gunnar
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Platell, P.
    Theoretical research of carbon dioxide power cycle application in automobile industry to reduce vehicle's fuel consumption2005Inngår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 25, nr 14-15, s. 2041-2053Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The current work discusses means to utilize low-grade small-scale energy in vehicle exhaust gases, to reduce the vehicle's fuel consumption and to make it run more environmental friendly. To utilize the energy in the exhaust gas, a CO2 bottoming system in the vehicle's engine system is proposed. Several basic cycles-according to the different design concepts-are presented, and the efficiencies are calculated using Engineering Equation Solver (EES).1 Several thermodynamic models in EES show that after system optimization, in CO2 Transcritical power cycle with a gas heater pressure of 130 bars and 200 °C expansion inlet temperature, about 20% of energy in the exhaust gas can be converted into useful work. Increasing the pressure in the gas heater to 300 bars and with same expansion inlet temperature, about 12% of exhaust gas energy can be converted. When raising the pressure both in the gas cooler and in the gas heater, the cycle runs completely above the critical point, and the efficiency is about 19%. Besides, in the CO2 combined cycle, the system COP is 2.322 and about 5% of exhaust gas energy can be converted.

  • 17.
    Chen, Yang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Palm, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    A Nobel Gas-Water Heat Exchanger with Minichannels2008Konferansepaper (Fagfellevurdert)
  • 18.
    Chen, Yang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Palm, Björn E.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    A NOVEL GAS-WATER HEAT EXCHANGER WITH MINICHANNELS2009Inngår i: HT2008: PROCEEDINGS OF THE ASME SUMMER HEAT TRANSFER CONFERENCE - 2008, VOL 2, NEW YORK: AMER SOC MECHANICAL ENGINEERS , 2009, s. 157-164Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the current study, a novel gas water heat exchanger with minichannels is designed, built and tested. The heat exchanger is mainly composed of a number of concentric ring shaped plates, which are made tip of several heat exchanger tubes. The ring shaped plates are arranged in parallel and placed in a shell. The heat exchanger is designed as a counter current heat exchanger with laminar flow on the heat exchanger's shell-side (gas side) and therefore has a very low pressure drop on the shell side. The heat exchanger was tested with water and hot air on its tube-side and shell-side respectively. All the necessary parameters like inlet and outlet temperatures on tube-side and shell-side as well as the pressure drop, flow rate of fluids, etc. were measured. Different existing correlations were used to calculate the overall heat transfer coefficient and the results were compared with the measured value. The measured results show that the new designed heat exchanger can achieve a good heat transfer performance and also maintain a low pressure drop on shell-side (gas side).

  • 19.
    Chen, Yang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Pridasawas, Wimolsiri
    King Mongkut’s University of Technology Thonburi, Dept. of Chemical Engineering,Bangkok, Thailand.
    Theoretical Study of a Carbon Dioxide Double Loop System2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the current research, a carbon dioxide double loop system is proposed. The system contains of two sub systems: a CO2power subsystem and a CO2refrigeration subsystem. The power subsystem is able to utilize the energy from the low-grade heat source to produce power. The power is then transferred to the refrigeration subsystem, partly or totally covering the power consumption of the compressor. Furthermore, it is also possible to take advantage of the temperature glides of both subsystems’ heat rejection processes to produce hot water. Engineering Equation Solver (EES) is employed to analyze the system performance. The results show that the proposed system is a very promising way to provide cooling, heating and hot water in a more efficient way comparing to traditional systems.

  • 20.
    Chen, Yang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Workie, Almaz Bitew
    Second Law Analysis of a Carbon Dioxide Transcritical Power System in Low-grade Heat Source RecoveryArtikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Employing Carbon dioxide as a working media in power cycles for low-grade heat source utilization has attracted more and more attentions. However, compared to other well-known cycles that employed in low-grade heat source utilizations, the information about CO2power cycle is still very limited. In the current work, the performance of a CO2power cycle in utilizing the low-grade heat sources is simulated and the results are analyzed with a focus on second law thermodynamics (i.e. exergy and entropy). Different system parameters that influencing the system exergy and entropy change are discussed.

    Engineering Equation Solver (EES) is used for simulation. The simulation results show that the matching of the temperature profiles in the system heat exchangers has crucial influences on their exergy destructions and entropy generations. It is also an essential factor that influences the system thermodynamic efficiencies.

  • 21.
    Chen, Yang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Pridasawas, Wimolsiri
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Dynamic simulation of a solar-driven carbon dioxide transcritical power system for small scale combined heat and power production2010Inngår i: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 84, nr 7, s. 1103-1110Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbon dioxide is an environmental benign natural working fluid and has been proposed as a working media for a solar-driven power system In the current work, the dynamic performance of a small scale solar-driven carbon dioxide power system is analyzed by dynamic simulation tool TRNSYS 16 (Klein et al., 2004) and Engineering Equation Solver (EES) (Klein, 2004) using co-solving technique Both daily performance and yearly performance of the proposed system have been simulated Different system operating parameters, which will influence the system performance, have been discussed. Under the Swedish climatic condition, the maximum daily power production is about 12 kW h and the maximum monthly power production is about 215 kW h with the proposed system working conditions Besides the power being produced, the system can also produce about 10 times much thermal energy. which can be used for space heating, domestic hot water supply or driving absorption chillers The simulation results show that the proposed system is a promising and environmental benign alternative for conventional low-grade heat source utilization system (C) 2010 Elsevier Ltd All rights reserved.

  • 22.
    Chen, Yang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Pridasawas, Wimolsiri
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Low-grade heat source utilization by carbon dioxide transcritical power cycle2007Inngår i: 2007 Proceedings of the ASME/JSME Thermal Engineering Summer Heat Transfer Conference - HT 2007 Volume 1, 2007, s. 519-525Konferansepaper (Fagfellevurdert)
    Abstract [en]

    One way to reduce the fossil fuel consumption and mitigate environmental impact is to utilize low-grade heat sources for power production. In this paper, a transcritical carbon dioxide power cycle is analyzed for its potential in utilizing the low-grade heat sources. Solar thermal is selected as a representative of low-grade heat sources. TRNSYS 16(1) and Engineering Equation Solver (EES)(2) are employed using co-solving technique to analyze the dynamic performance of the proposed system. Both daily performance and annual performance of the proposed system under Swedish climate conditions are simulated. The simulation results show that the proposed system can achieve 8% average thermal efficiency and consequently 2.43 kW average power production during the system working period on a randomly selected summer day with a 30 m(2) solar collector. Over the whole year, the maximum daily power production is about 17 kWh and the maximum monthly power production is about 185 kWh.

  • 23.
    Fernando, W. Primal D.
    et al.
    KTH, Tidigare Institutioner                               , Energiteknik.
    Han, Han
    KTH, Tidigare Institutioner                               , Energiteknik.
    Palm, Björn
    KTH, Tidigare Institutioner                               , Energiteknik.
    Granryd, Eric
    KTH, Tidigare Institutioner                               , Energiteknik.
    Lundqvist, Per
    KTH, Tidigare Institutioner                               , Energiteknik.
    The Solubility of Propane (R290) with Commonly Used Compressor Lubrication Oils2003Inngår i: Compressors and Their Systems, 2003, Vol. 4, s. 157-166Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An ongoing project called "Charge minimisation of a small capacity heat pump" is aimed to minimise the refrigerant charge in heat pumps, refrigeration and air-conditioning systems. The experimental heat pump was run with propane as refrigerant and the designed heat capacity (condenser capacity) was over 5kW. Tests were done to investigate the refrigerant charge distribution in different sections of the heat pump, while it was running. The experiments done so far have shown that the amount of refrigerant in the compressor is higher than expected.

    This paper presents the measured refrigerant masses in a hermetic scroll compressor together in suction line and the calculated refrigerant mass dissolved in the compressor lubrication oil at different evaporation temperatures. Finally, solubility tests of propane with different lubricating oils are presented. The tests show that the propane is more soluble in POE than PAG oils.

  • 24.
    Fernando, W. Primal D.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Palm, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Ameel, Tim
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Granryd, Eric
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    A Minichannel Aluminium Tube Heat Exchanger - Part 1: Evaluation of Single-Phase Heat Transfer Coefficients by the Wilson Plot Method2008Inngår i: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 31, nr 4, s. 669-680Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A prototype liquid-to-refrigerant heat exchanger was developed with the aim of minimizing the refrigerant charge in small systems. To allow correct calculation of the refrigerant side heat transfer, the heat exchanger was first tested for liquid-to-liquid (water-to-water) operation in order to determine the single-phase heat transfer performance. These single-phase tests are reported in this paper. The heat exchanger was made from extruded multiport aluminium tubes and was designed similar to a shell-and-tube heat exchanger. The heat transfer areas of the shell-side and tube-side were approximately 0.82 m(2) and 0.78 m(2), respectively. There were six rectangular-shaped parallel channels in a tube. The hydraulic diameter of the tube-side was 1.42 mm and of the shell-side 3.62 mm. Tests were conducted with varying water flow rates, temperature levels and heat fluxes on both the tube and shell sides at Reynolds numbers of approximately 170-6000 on the tube-side and 1000-5000 on the shell-side, respectively. The Wilson plot method was employed to investigate the heat transfer on both the shell and tube sides. In the Reynolds number range of 2300-6000, it was found that the Nusselt numbers agreed with those predicted by the Gnielinski correlation within +/- 5% accuracy. In the Reynolds number range of 170-1200 the Nusselt numbers gradually increased from 2.1 to 3.7. None of the previously reported correlations for laminar flow predicted the Nusselt numbers well in this range. The shell-side Nusselt numbers were found to be considerably higher than those predicted by correlations from the literature.

  • 25.
    Fernando, W. Primal D.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Palm, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Ameel, Tim
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Granryd, Eric
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    A minichannel aluminium tube heat exchanger - Part II: Evaporator Performance with Propane2008Inngår i: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 31, nr 4, s. 681-695Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents heat transfer data for a multiport minichannel heat exchanger vertically mounted as an evaporator in a test-rig simulating a small water-to-water heat pump. The multiport minichannel heat exchanger was designed similar to a shell-and-tube type heat exchanger, with a six-channel tube of 1.42 mm hydraulic diameter, a tube-side heat transfer area of 0.777 m(2) and a shell-side heat transfer area of 0.815 m(2). Refrigerant propane with a desired vapour quality flowed upward through the tubes and exited with a desired superheat of 1-4 K. A temperature-controlled glycol solution that flowed downward on the shell-side supplied the heat for the evaporation of the propane. The heat transfer rate between the glycol solution and propane was controlled by varying the evaporation temperature and propane mass flow rate while the glycol flow rate was fixed (18.50 l min(-1)). Tests were conducted for a range of evaporation temperatures from -15 to +10 degrees C, heat flux from 2000 to 9000 W m(-2) and mass flux from 13 to 66 kg m(-2) s(-1). The heat transfer coefficients were compared with 14 correlations found in the literature. The experimental heat transfer coefficients were higher than those predicted by many of the correlations. A correlation which was previously developed for a very large and long tube (21 mm diameter and 10 m long) was in good agreement with the experimental data (97% of the data within 30%). Several other correlations were able to predict the data within a reasonable deviation (within 30%) after some adjustments to the correlations.

  • 26.
    Fernando, W. Primal D.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Palm, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Ameel, Tim
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Granryd, Eric
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    A minichannel aluminium tube heat exchanger - Part III: Condenser Performance with Propane2008Inngår i: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 31, nr 4, s. 696-708Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports heat transfer results obtained during condensation of refrigerant propane inside a minichannel aluminium heat exchanger vertically mounted in an experimental setup simulating a water-to-water heat pump. The condenser was constructed of multiport minichannel aluminium tubes assembled as a shell-and-tube heat exchanger. Propane vapour entered the condenser tubes via the top end and exited sub-cooled from the bottom. Coolant water flowed upward on the shell-side. The heat transfer areas of the tube-side and the shell-side of the condenser were 0.941 m(2) and 0.985 m(2), respectively. The heat transfer rate between the two fluids was controlled by varying the evaporation temperature while the condensation temperature was fixed. The applied heat transfer rate was within 3900-9500 W for all tests. Experiments were performed at constant condensing temperatures of 30 degrees C, 40 degrees C and 50 degrees C, respectively. The cooling water flow rate was maintained at 11.90 l min(-1) for all tests. De-superheating length, two-phase length, sub-cooling length, local heat transfer coefficients and average heat transfer coefficients of the condenser were calculated. The experimental heat transfer coefficients were compared with predictions from correlations found in the literature. The experimental heat transfer coefficients in the different regions were higher than those predicted by the available correlations.

  • 27.
    Fernando, W. Primal D.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Palm, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Granryd, Eric
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Performance of a single-family heat pump at different working conditions using small quantity of propane as refrigerant2007Inngår i: Experimental heat transfer, ISSN 0891-6152, E-ISSN 1521-0480, Vol. 20, nr 1, s. 57-71Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The performance of a domestic heat pump that uses a low quantity of propane as refrigerant has been experimentally investigated. The heat pump consists of two minichannel aluminium heat exchangers, a scroll compressor, and an electronic expansion valve. It was charged with the minimum amount of refrigerant propane required for the stable operation of the heat pump without permitting refrigerant vapor into the expansion valve at incoming heat source fluid temperature to the evaporator of +10 degrees C The inlet temperature of the heat source fluid passing through the evaporator was varied from +10 degrees C to -10 degrees C while holding the condensing temperature constant at 35 degrees C, 40 degrees C, 50 degrees C, and 60 degrees C, respectively. The minimum refrigerant charges required at above-tested condensing temperatures were found to decrease when the condensing temperature increased and were recorded as 230 g, 224 g, 215 g, and 205 g, respectively. The results confirm that a heat pump with 5 kW capacity can be designed with less than 200 g charge of refrigerant propane in the system. Due to the high solubility of propane in compressor lubrication oil, the amount of refrigerant which may escape rapidly in case of accident or leakage is less than 150 g.

  • 28.
    Fernando, W. Primal D.
    et al.
    KTH, Tidigare Institutioner, Energiteknik.
    Palm, Björn
    KTH, Tidigare Institutioner, Energiteknik.
    Lundqvist, Per
    KTH, Tidigare Institutioner, Energiteknik.
    Granryd, Eric
    KTH, Tidigare Institutioner, Energiteknik.
    Propane Heat Pump with Low Refrigerant Charge: Design and Laboratory Tests2004Inngår i: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 27, nr 7, s. 761-773Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Independently of the choice of refrigerant, environmental and or safety issues can be minimised by reducing the amount of refrigerant charge per heat pump or refrigeration system. In the investigation reported here, a laboratory test rig was built, simulating a water-to-water heat pump with a heating capacity of 5 kW. The system was designed to minimize the charge of refrigerant mainly by use of mini-channel aluminium heat exchangers. It was shown that the system could be run with 200 g of propane at typical Swedish operating conditions without reduction of the COP compared to a traditional design. Additional charge reduction is possible by selecting proper compressor lubrication oils or by using a compressor with less lubrication oil.

  • 29.
    Grozdek, Marino
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Curko, T.
    Khodabandeh, Rahmatollah
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Soldo, V.
    Performance comparison of a static ice-bank and dynamic ice slurry cool thermal energy storage systems2010Inngår i: 9th IIR Gustav Lorentzen Conference on Natural Working Fluids (GL2010) Paris, France: International Institute of Refrigeration, 2010, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

        In this study theoretical evaluation of performance of a three ice based cool thermal energy storage systems is conducted ; (a) static, indirect, external melt ice-on-coil ; (b) dynamic ice slurry type storage with a water and (c) ice slurry distribution system. In order to investigate and assess possible economic and energy saving potential of an ice slurry storage system over conventional static type a computer simulation models were used. The systems were compared for high temperature application, for the purpose of milk cooling in the dairy industry. The product temperature that has to be achieved is +3 °C which requires a secondary coolant temperature to be less than +1 °C. Calculations have been performed on basis of specific user supplied load data for a design day, acquired as an actual case for dairy plant Prehrambeno industrijski kombinat (PIK) in the city of Rijeka, Croatia, and local electricity billing rate structure. The comparison shows that the dynamic cool thermal energy storage system (CTES) is favourable as to energy consumption in all studied cases.

  • 30.
    Grozdek, Marino
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Khodabandeh, Rahmatollah
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Experimental investigation of ice slurry flow pressure drop in horizontal tubes2009Inngår i: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 33, nr 2, s. 357-370Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pressure drop behaviour of ice slurry based on ethanol-water mixture in circular horizontal tubes has been experimentally investigated. The secondary fluid was prepared by mixing ethyl alcohol and water to obtain initial alcohol concentration of 10.3% (initial freezing temperature -4.4 degrees C). The pressure drop tests were conducted to cover laminar and slightly turbulent flow with ice mass fraction varying from 0% to 30% depending on test conditions. Results from flow tests reveal much higher pressure drop for higher ice concentrations and higher velocities in comparison to the single phase flow. However for ice concentrations of 15% and higher, certain velocity exists at which ice slurry pressure drop is same or even lower than for single phase flow. It seems that higher ice concentration delay flow pattern transition moment (from laminar to turbulent) toward higher velocities. In addition experimental results for pressure drop were compared to the analytical results, based on Poiseulle and Buckingham-Reiner models for laminar flow, Blasius. Darby and Melson, Dodge and Metzner, Steffe and Tomita for turbulent region and general correlation of Kitanovski which is valid for both flow regimes. For laminar flow and low buoyancy numbers Buckingham-Reiner method gives good agreement with experimental results while for turbulent flow best fit is provided with Dodge-Metzner and Tomita methods. Furthermore, for transport purposes it has been shown that ice mass fraction of 20% offers best ratio of ice slurry transport capability and required pumping power.

  • 31.
    Grozdek, Marino
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Khodabandeh, Rahmatollah
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Palm, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Melinder, Åke
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Experimental investigation of ice slurry heat transfer in horizontal tube2009Inngår i: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 32, nr 6, s. 1310-1322Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Heat transfer of ice slurry flow based on ethanol-water mixture in a circular horizontal tube has been experimentally investigated. The secondary fluid was prepared by mixing ethanol and water to obtain initial alcohol concentration of 10.3% (initial freezing temperature -4.4 degrees C). The heat transfer tests were conducted to cover laminar and slightly turbulent flow with ice mass fraction varying from 0% to 22% depending on test performed. Measured heat transfer coefficients of ice slurry are found to be higher than those for single phase fluid, especially for laminar flow conditions and high ice mass fractions where the heat transfer is increased with a factor 2 in comparison to the single phase flow. In addition, experimentally determined heat transfer coefficients of ice slurry flow were compared to the analytical results, based on the correlation by Sieder and Tate for laminar single phase regime, by Dittus-Boelter for turbulent single phase regime and empirical correlation by Christensen and Kauffeld derived for laminar/turbulent ice slurry flow in circular horizontal tubes. it was found that the classical correlation proposed by Sieder and Tate for laminar forced convection in smooth straight circular ducts cannot be used for heat transfer prediction of ice slurry flow since it strongly underestimates measured values, while, for the turbulent flow regime the simple Dittus-Boelter relation predicts the heat transfer coefficient of ice slurry flow with high accuracy but only up to an ice mass fraction of 10% and Re-cf > 2300 regardless of imposed heat flux. For higher ice mass fractions and regardless of the flow regime, the correlation proposed by Christensen and Kauffeld gives good agreement with experimental results. (C) 2009 Elsevier Ltd and IIR. All rights reserved.

  • 32.
    Grozdek, Marino
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Soldo, V.
    Khodabandeh, Rahmatollah
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Curko, T.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Performance Comparison of a Static Ice-Bank and Dynamic Ice Slurry Cool Thermal Energy Storage SystemsArtikkel i tidsskrift (Annet vitenskapelig)
  • 33. Hägg, Cecilia
    et al.
    Arias, Jaime
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    A Comparison Between Single-Phase and Ice Slurry as Secondary Fluid in Supermarket2005Konferansepaper (Fagfellevurdert)
  • 34.
    Hägg, Cecilia
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Arias, Jaime
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Comparaison entre fluide secondaire monophasique et coulis de glace en supermarché2007Inngår i: Revue générale du froid, ISSN 0035-3205, Vol. 97, nr 1073, s. 47-54Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [fr]

    Le coulis de glace est considéré comme une solution novatrice en tant que frigoporteur diphasique. Cet article évalue si la solution coulis de glace est compétitive vis-à-vis des fluides secondaires monophasiques dans les applications en supermarché en froid positif, avec les deux options habituelles : récupération de chaleur et haute pression flottante. Etant donné que le coulis de glace permet une accumulation efficace, les besoins de production de froid en période de pointe peuvent être déplacés. La comparaison est faite entre 24 heures de temps de fonctionnement habituel et 8 heures assurées pendant la période nocturne. Les temps de fonctionnement différents nécessitent des volumes de stockage différents. Les systèmes ont été comparés, en faisant varier pendant un an les conditions de fonctionnement heure par heure, en utilisant un programme de simulation appelé CyberMart. Ce programme est destiné à simuler les systèmes frigorifiques et énergétiques en supermarché. Il a été développé par la division thermodynamique et réfrigération appliquée de l'Institut royal de technologie de Stockholm (KTH). La simulation a été effectuée sur la base d'un magasin alimentaire virtuel de 2 700 m2d'une puissance frigorifique de 90 kW à Karlstad, en Suède. En comparant les consommations énergétiques, l'étude montre que le coulis de glace est favorable dans tous les cas.

  • 35. Hägg, Cecilia
    et al.
    Melinder, Åke
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Pressure Drop Experiments and Background for Choosing Suitable Fluid for Low Temperature Ice SlurrInngår i: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081Artikkel i tidsskrift (Annet vitenskapelig)
  • 36.
    Hägg, Cecilia
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Melinder, Åke
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Martin, C.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    A Proper Fluid for Ice Slurry at -35 ºC,2005Rapport (Annet vitenskapelig)
  • 37.
    Jonsson, Daniel K.
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Miljöstrategisk analys (flyttat 20130630). Swedish Defence Research Agency,Sweden.
    Gustafsson, Stina
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Wangel, Josefin
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Miljöstrategisk analys (flyttat 20130630).
    Höjer, Mattias
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Miljöstrategisk analys (flyttat 20130630). Skolan för datavetenskap och kommunikation (CSC), Centra, KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centre for Sustainable Communications, CESC.
    Lundqvist, Per G.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Svane, Örjan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Miljöstrategisk analys (flyttat 20130630).
    Energy at your service: highlighting energy usage systems in the context of energy efficiency analysis2011Inngår i: Energy Efficiency, ISSN 1570-646X, E-ISSN 1570-6478, Vol. 4, nr 3, s. 355-369Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Increasing energy efficiency has for a long time been identified as an important means of mitigating climate change. However, the full potential for technical energy efficiency has seldom been fully exploited. The traditional approach in energy systems analysis and policy is still largely supply-orientated, i.e. focusing on the management of energy conversion, production and distribution, and final use of energy in the form of energy carriers. This paper contributes to previous discussions on how to highlight and explore the user side in the analysis of energy systems in an efficiency context. The energy usage systems approach, including end-use technologies and the production of service demanded by a human activity system, is used to promote a dynamic bottom-up perspective on energy. In determining the possible potential for change by increasing energy efficiency, the demand for energy should not be considered synonymous with the demand for neither energy carriers, nor the measurable service volumes (such as kilometres travelled, square metre conditioned space, etc.), without considering the sociocultural context in which the service is being used or called upon. In summary, the predominant paradigm dealing with the energy system as a technical system managing resources and providing energy carriers should thus be complemented with the view of a socio-technical system facilitating and/or managing the services.

  • 38.
    Kliatsko, Aleh
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Arias, Jaime
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    A Systematic approach to modelling of energy usage by Human Activity System (HAS) and Energy Usage Systems (EUS)2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The main goal of the paper is to introduce a chosen modelling approach and provide a discussion on this. The article describes modelling of energy use as a consequence of human activities in cities and especially situation where the opportunities for change are significant. We call these Situations of Opportunities (SitOpp). The paper describes a modelling approach aiming at tools to explore these situations further. The methodology is based on the concept of Human Activity Systems (HAS - What people do) and Energy Usage Systems (EUS - the system that supports these activities by aid of energy). The modelling process consists of several steps: conceptual, qualitative and finally quantitative models are built for each SitOpp. The modelling process is supported by the construction of so-called Causal Loop Diagram (CLD) to facilitate multi-stakeholder and cross-disciplinary modelling.

     

    This study presents schematically a process to create conceptual as well as qualitative models, and the modelling process, aiming to quantitatively determine the need for primary energy in three city parts of Stockholm.  The SitOpps are chosen as part of a transformation process to a normative future goal towards the so-called 2000W society (2kW is equivalent to an energy usage of 17 500 kWh per person and year). The CO2 emissions should also be reduced from today’s levels to 1ton/y and person.

     

    One of the main tasks of this project is to develop a methodology to systematically model HAS and EUS, going from the conceptual over the qualitative to the quantitative mode. The project uses the STELLA software program to build the quantitative models. One important aspects of the project is the understanding of the change agents (actors) and the change process. The modelling process is supporting parallel scenario building activities using back-casting techniques.

  • 39.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Advances In Heat Pump Technology And Market Development In Sweden2009Inngår i: Proc. 39th congress on heating, refrigerating and air conditioning, Academic Conferences Publishing, 2009Konferansepaper (Fagfellevurdert)
  • 40.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Efficient refrigeration technologies: a prerequiste for sustainable development2010Inngår i: J, Industria Formazione, nr 7, s. 18-21Artikkel i tidsskrift (Fagfellevurdert)
  • 41.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    IPCC/TEAP Special Report on Safeguarding the Ozone Layer and the Global Climate System2006Rapport (Annet vitenskapelig)
  • 42.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Mitigation of greenhouse gases in refrigeration2005Konferansepaper (Annet vitenskapelig)
  • 43.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Recent And Historical Advances In Heat Pump Technology And Market In Sweden2008Konferansepaper (Fagfellevurdert)
  • 44.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Strategies For Mitigation Of Ghg Emissions From Refrigeration Technologies: Indirect And Direct Effects, Efficiency, Charge Minimization And Working Fluids2009Inngår i: Proc ACRECONF, Academic Conferences Publishing, 2009Konferansepaper (Annet vitenskapelig)
  • 45.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    System Thinking For Efficient Heat Pumps: Experiences and perspectives From Sweden2011Inngår i: Proc. from the Annual Meeting of the Croatian Science and Engineering academy, Academic Conferences Publishing, 2011Konferansepaper (Fagfellevurdert)
  • 46.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    System Thinking For Evaluation Of The Performance Of Heat Pump Systems2011Inngår i: 23rd International Congress of Refrigeration, 2011, s. 3264-3271Konferansepaper (Annet vitenskapelig)
  • 47.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    The Heat Pump In The Refurbishment Of Existing Buildings Perspectives From Sweden2008Inngår i: Proc. Joint REHVA/AICARR Workshop on the Refurbishment of Existing Buildings, Milan, Itly: Academic Conferences Publishing, 2008Konferansepaper (Fagfellevurdert)
  • 48.
    Lundqvist, Per
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    The role of heat pumps in the smart energy systems2015Inngår i: Refrigeration Science and Technology, International Institute of Refrigeration, 2015, s. 90-94Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Heat pumps are needed in the future energy system to save primary energy, increase the share of renewable energy and thus to reduce climate impact. This is manifested in most recent future scenarios for low carbon energy systems that acknowledge the importance of efficient and reliable heat pump system. The role of heat pumps will change and broaden as the energy system becomes smarter. Information and smart controls in heat pumps coupled to storage possibilities will stabilize the electric energy system when the amount of flowing energy sources such as wind and solar energy increases. A stronger focus on resource efficiency and reduction of primary energy will put pressure on required seasonal performance factors for heat pump system. Increased system efficiency and high energy coverage are thus important challenges for heat pump system design. Hybrid systems where heat pumps are coupled to solar thermal energy and solar PV systems are likely to emerge on the market.

  • 49.
    Lundqvist, Per
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Nekså, Peter
    Mitigation of Greenhouse Gas Emissions from Commercial Refrigeration Systems - What Matters?2005Konferansepaper (Annet vitenskapelig)
  • 50.
    Lundqvist, Per
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Öhman, Henrik
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Global Efficiency of Heat Engines and Heat Pumps with Non-Linear Boundary Conditions2017Inngår i: Entropy, ISSN 1099-4300, E-ISSN 1099-4300, Vol. 19, nr 8, artikkel-id 394Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Analysis of global energy efficiency of thermal systems is of practical importance for a number of reasons. Cycles and processes used in thermal systems exist in very different configurations, making comparison difficult if specific models are required to analyze specific thermal systems. Thermal systems with small temperature differences between a hot side and a cold side also suffer from difficulties due to heat transfer pinch point effects. Such pinch points are consequences of thermal systems design and must therefore be integrated in the global evaluation. In optimizing thermal systems, detailed entropy generation analysis is suitable to identify performance losses caused by cycle components. In plant analysis, a similar logic applies with the difference that the thermal system is then only a component, often industrially standardized. This article presents how a thermodynamic "black box" method for defining and comparing thermal efficiency of different size and types of heat engines can be extended to also compare heat pumps of different apparent magnitude and type. Impact of a non-linear boundary condition on reversible thermal efficiency is exemplified and a correlation of average real heat engine efficiencies is discussed in the light of linear and non-linear boundary conditions.

12 1 - 50 of 92
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