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Sawalha, Samer
Publications (10 of 13) Show all publications
Xu, T., Chiu, J. N., Palm, B. & Sawalha, S. (2019). Experimental investigation on cylindrically macro-encapsulated latent heat storage for space heating applications. Energy Conversion and Management, 182, 166-177
Open this publication in new window or tab >>Experimental investigation on cylindrically macro-encapsulated latent heat storage for space heating applications
2019 (English)In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 182, p. 166-177Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-241056 (URN)10.1016/j.enconman.2018.12.056 (DOI)000458227700017 ()2-s2.0-85059382278 (Scopus ID)
Funder
Swedish Energy Agency
Note

QC 20190117

Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-10-28Bibliographically approved
Karampour, M., Carlos, M.-R., Rogstam, J. & Sawalha, S. (2019). Geothermal Storage Integration into a Supermarket’s CO2 Refrigeration System. International journal of refrigeration, 106, 492-505
Open this publication in new window or tab >>Geothermal Storage Integration into a Supermarket’s CO2 Refrigeration System
2019 (English)In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 106, p. 492-505Article in journal (Refereed) Accepted
Abstract [en]

This paper investigates the integration of geothermal storage into state-of-the-art CO2 trans-critical boostersystems. The objective is to evaluate the impact of this integration on energy efficiency. Three scenarios of integration are studied including stand-alone and integrated supermarket building systems. The results show that for a stand-alone average size supermarket, heat recovery from the CO2 system should be prioritized over a separate ground source heat pump. Extracting heat from the ground by an extra evaporator in the CO2 system has also little impact on this supermarket annual energy use. However, in the case of supermarket integration with a neighbouring building where the supermarket provides heat to the neighbour, geothermal storage integration can reduce the total annual running cost of the two non-integrated buildings by 20-30% with a payback time of less than 3.5 years. The results also show there is no need for a separate ground source heat pump.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
state-of-the-art CO2 system, Supermarket, Geothermal energy storage
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-252294 (URN)10.1016/j.ijrefrig.2019.05.026 (DOI)000489835600042 ()2-s2.0-85068503242 (Scopus ID)
Note

QC 20190527. QC 20191111

Available from: 2019-05-24 Created: 2019-05-24 Last updated: 2019-11-11Bibliographically approved
Karampour, M., Carlos, M.-R., Rogstam, J. & Sawalha, S. (2019). Integration of Supermarket’s CO2 Refrigeration System and Geothermal Storage. In: : . Paper presented at 25th IIR International Congress of Refrigeration, August 24-30, 2019, Montreal. MontReal, Canada: International Institute of Refrigeration
Open this publication in new window or tab >>Integration of Supermarket’s CO2 Refrigeration System and Geothermal Storage
2019 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

This paper investigates the energy efficiency of geothermal storage integration into the state-of-the-art CO2 trans-critical booster systems. Three scenarios of integration are studied including stand-alone and integrated supermarket building systems.

The results show that for a stand-alone supermarket, heat recovery from the CO2 system should be prioritized over extracting heat from the ground, which this heat extraction can be done either by an extra evaporator in the CO2 system or by a separate ground source heat pump. In the case of supermarket integration with a nearby district heating consumer, geothermal storage integration with extra evaporator in the CO2 refrigeration system can reduce the total annual running cost of the two buildings by 19-31% and with a payback time of less than three years.

This integration is beneficial if the full efficient heat recovery capacity of the CO2 system is not sufficient to provide the entire demands.

Place, publisher, year, edition, pages
MontReal, Canada: International Institute of Refrigeration, 2019
Keywords
state-of-the-art CO2 trans-critical booster system, Supermarket, Geothermal storage
National Category
Engineering and Technology
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-257895 (URN)10.18462/iir.icr.2019.570 (DOI)
Conference
25th IIR International Congress of Refrigeration, August 24-30, 2019, Montreal
Note

QC 20190909

Available from: 2019-09-08 Created: 2019-09-08 Last updated: 2019-09-09Bibliographically approved
Sawalha, S. & Karampour, M. (2018). Dagens effektivaste livsmedelsbutik är definierad; den kommer att byggas och verifieras i en verklig livsmedelsbutik.
Open this publication in new window or tab >>Dagens effektivaste livsmedelsbutik är definierad; den kommer att byggas och verifieras i en verklig livsmedelsbutik
2018 (Swedish)Other (Other (popular science, discussion, etc.))
Abstract [sv]

Projektet ”Morgondagens energieffektiva livsmedelsbutik” avslutades i februari 2018. Det har letts av KTH och genomförts i samarbete med en grupp industripartner, och medfinansierats av Energimyndigheten inom ramen för Effsys EXPAND-program. Projektet har utforskat en ökning av effektiviteten hos standardkoldioxidkylsystem i livsmedelsbutiker genom att undersöka ändringar av utformningen och möjligheterna att integrera systemen med andra energisystem i livsmedelsbutiken.

Publisher
p. 2
Series
Kyla och värme, ISSN 1100-343X ; 6
National Category
Energy Engineering
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-236092 (URN)
Note

QC 20181019

Available from: 2018-10-16 Created: 2018-10-16 Last updated: 2018-10-19Bibliographically approved
Karampour, M., Sawalha, S., Carlos, M.-R. & Rogstam, J. (2018). Geothermal Storage Integration into Supermarket’s CO2 Refrigeration System. In: Proceedings of the IGSHPA Research Track 2018: . Paper presented at IGSHPA Research Track, Stockholm, September 18-20, 2018.
Open this publication in new window or tab >>Geothermal Storage Integration into Supermarket’s CO2 Refrigeration System
2018 (English)In: Proceedings of the IGSHPA Research Track 2018, 2018Conference paper, Published paper (Refereed)
Abstract [en]

This paper investigates the integration of geothermal storage into the state-of-the-art CO2 trans-critical booster systems. The objective is to evaluate the impact on energy efficiency of this integration. Three scenarios of integration are studied including stand-alone and integrated supermarket building systems. The results show that for a stand-alone supermarket, heat recovery from the CO2 system should be prioritized over extracting heat from the ground, which can be done either by an extra evaporator in the CO2 system or by a separate ground source heat pump. In the case of supermarket integration with a nearby district heating consumer, geothermal storage integration with extra evaporator in the CO2 refrigeration system can reduce the total annual running cost of the two buildings by 20-30%. The determining factors on profitability of geothermal storage integration are the heating demand of the supermarket and possibilities of coupling its heating system to another nearby consumer. This integration is beneficial if the full efficient heat recovery capacity of the CO2 system is not sufficient to provide the entire demands.

National Category
Energy Engineering
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-235325 (URN)10.22488/okstate.18.000029 (DOI)
Conference
IGSHPA Research Track, Stockholm, September 18-20, 2018
Projects
Effsys Expand
Funder
Swedish Energy Agency
Note

QC 20180921

Available from: 2018-09-21 Created: 2018-09-21 Last updated: 2018-09-21Bibliographically approved
Raka Adrianto, L., Grandjean, P.-A. & Sawalha, S. (2018). Heat Recovery from CO2 Refrigeration System in Supermarkets to District Heating Network. In: : . Paper presented at 13th IIR Gustav Lorentzen Conference. Valencia
Open this publication in new window or tab >>Heat Recovery from CO2 Refrigeration System in Supermarkets to District Heating Network
2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

In the process of moving towards sustainable energy systems for future cities, the district heating system will have to be more dynamic and accessible to the different heating sources available in the society. A main potential heat source to be connected to the district heating network is the heat rejected from refrigeration systems in supermarket applications.

 

This paper investigates the main possible scenarios for recovering heat from supermarket refrigeration system with CO2 as the refrigerant. The efficiency of the refrigeration system under the different heat recovery scenarios is studied with the aid of computer modelling. The cost of producing the recoverable heat is calculated and compared to market price from local district heating company. The total energy cost for running the system in the winter season in the different scenarios is also calculated.

 

This study shows that the best scenario is to recover heat for space heating in the supermarket building as a priority and then recover all or part of the remaining available heat to district heating. In an average size supermarket in Sweden, all the space heating demand can be recovered from the refrigeration system with space heat recovery COP (i.e. heating COP) of about 4.5 in average. To produce 1 kW heat supplied to district heating, 2/5 to 1/8 kW of compressor power is used; i.e. district heating recovery COP is 2.5-8. This scenario results in the lowest annual energy cost of the system, about 40% lower than the reference scenario, where the refrigeration system runs at floating condensing and space heating is delivered by district heating.

Place, publisher, year, edition, pages
Valencia: , 2018
Keywords
Heat recovery, District heating, CO2 refrigeration, Supermarkets, Modelling
National Category
Energy Engineering
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-236090 (URN)2-s2.0-85049841171 (Scopus ID)
Conference
13th IIR Gustav Lorentzen Conference
Note

QC 20181019

Available from: 2018-10-16 Created: 2018-10-16 Last updated: 2018-10-19Bibliographically approved
Purohit, N., Sharma, V., Sawalha, S., Fricke, B., Llopis, R. & Dasgupta, M. S. (2018). Integrated supermarket refrigeration for very high ambient temperature. Energy, 165, 572-590
Open this publication in new window or tab >>Integrated supermarket refrigeration for very high ambient temperature
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2018 (English)In: Energy, ISSN 0360-5442, Vol. 165, p. 572-590Article in journal (Refereed) Published
Abstract [en]

This paper analytically investigates and compares the performance of a proposed ‘all-natural’ NH3/CO2 cascaded booster system to a conventional R404A direct expansion system as well as to an ‘all-CO2’ system with multi-ejector unit and flooded evaporator. Performance comparison is made based on the annual combined COP and Life Cycle Climate Performance (LCCP) for operation in selected cities of Middle East and India. Our results show that in extreme warm climate, the energy efficiency of the proposed configuration exceeds that of all-CO2 configuration by a maximum of about 12.23% and the total emissions are lower by up to 11.20%. However, the all-CO2 multi ejector system performs better in cold and mild warm climate. In the NH3/CO2 cascade, the high temperature NH3 system can be designed to be isolated from the accessible locations of the supermarket. The work presented is expected to help adoption of natural refrigerants such as CO2 and NH3 for commercial application in extreme warm climate conditions prevailing in many cities of Middle East and India.

Keywords
CO2; NH3/CO2 cascade; Supermarket; Integrated; Natural; Warm climate
National Category
Energy Engineering
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-236472 (URN)10.1016/j.energy.2018.09.097 (DOI)000450377000044 ()2-s2.0-85054843824 (Scopus ID)
Note

QC 20181019

Available from: 2018-10-17 Created: 2018-10-17 Last updated: 2018-12-11Bibliographically approved
Mateu-Royo, C., Karampour, M., Rogstam, J. & Sawalha, S. (2018). Integration of geothermal storage in CO2 refrigeration systems of supermarkets. In: Refrigeration Science and Technology: . Paper presented at 13th IIR Gustav Lorentzen Conference on Natural Refrigerants: Natural Refrigerant Solutions for Warm Climate Countries, 18 June 2018 through 20 June 2018 (pp. 1265-1272). International Institute of Refrigeration
Open this publication in new window or tab >>Integration of geothermal storage in CO2 refrigeration systems of supermarkets
2018 (English)In: Refrigeration Science and Technology, International Institute of Refrigeration, 2018, p. 1265-1272Conference paper, Published paper (Refereed)
Abstract [en]

The aim of this paper is to study the benefits of integrating CO2 trans-critical booster refrigeration system with geothermal storage. The ground is used as a heat sink for sub-cooling during the summer period and as a heat source for extracting heat in the winter season. Using field measurements from medium size supermarkets in Sweden, proposed and the existing system solutions for integrating geothermal storage in CO2 refrigeration systems are modelled and compared with standard CO2 trans-critical booster system. The techno-economical comparative analysis shows that hybrid CO2 trans-critical booster system with ground source heat pump (GSHP) as an integrated geothermal solution has 6% lower annual energy use compared to a stand-alone CO2 system with heat recovery.

Place, publisher, year, edition, pages
International Institute of Refrigeration, 2018
Keywords
CO2 trans-critical booster system, Field measurements, Geothermal storage integration, Modelling, Refrigeration, Supermarkets, Carbon dioxide, Geothermal energy, IIR filters, Models, Refrigerants, Retail stores, Solution mining, Waste heat, Booster system, Comparative analysis, Existing systems, Field measurement, Groundsource heat pump (GSHP), Refrigeration system, Winter seasons, Geothermal heat pumps
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-236385 (URN)10.18462/iir.gl.2018.1387 (DOI)2-s2.0-85049826281 (Scopus ID)9782362150265 (ISBN)
Conference
13th IIR Gustav Lorentzen Conference on Natural Refrigerants: Natural Refrigerant Solutions for Warm Climate Countries, 18 June 2018 through 20 June 2018
Note

QC 20181105

Available from: 2018-11-05 Created: 2018-11-05 Last updated: 2018-11-05Bibliographically approved
Xu, T., Navarro-Peris, E., Piscopiello, S., Sawalha, S., Corberán, J. M. & Palm, B. (2018). Large-Capacity Propane Heat Pumps for DHW Production in Residential Buildings. In: Refrigeration Science and Technology: . Paper presented at 13th IIR Gustav Lorentzen Conference on Natural Refrigerants: Natural Refrigerant Solutions for Warm Climate Countries, Valencia, Spain, 18 June 2018 through 20 June 2018 (pp. 1222-1230). Valencia, Spain
Open this publication in new window or tab >>Large-Capacity Propane Heat Pumps for DHW Production in Residential Buildings
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2018 (English)In: Refrigeration Science and Technology, Valencia, Spain, 2018, p. 1222-1230Conference paper, Published paper (Refereed)
Abstract [en]

Using heat pump technology to provide Space Heating (SH) and to produce Domestic Hot Water (DHW) for residential buildings has been widely applied during past decades. In this study, two scenarios adopting large-capacity propane heat pumps are defined and evaluated. These two scenarios, which are named after Scenario A and Scenario B respectively, provide SH and DHW either separately by two units or integrally by one unit. The COP1s of two scenarios are compared based on the simulation results from experimentally validated models. The results show that two scenarios have almost equal efficiency; the relative difference is within 6%. In the optimization analysis of Scenario B, varying DHW heating capacity produced by the desuperheater in the heat pump is modelled. The DHW demand ratio varies from approximately 9% to 20% with no detectable influences on the COP1. The corresponding COP1s and temperature profiles in the heat exchangers are demonstrated. The simulation results indicate that increasing DHW capacity in Scenario B can narrow down the temperature approach in the condenser and insignificantly improves the overall COP1s.

Place, publisher, year, edition, pages
Valencia, Spain: , 2018
Series
Refrigeration Science and Technology, ISSN 0151-1637 ; 2018
Keywords
Propane, Heat Pump, Space Heating, Domestic Hot Water, COP
National Category
Energy Engineering
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-236097 (URN)10.18462/iir.gl.2018.1382 (DOI)2-s2.0-85049850958 (Scopus ID)9782362150265 (ISBN)
Conference
13th IIR Gustav Lorentzen Conference on Natural Refrigerants: Natural Refrigerant Solutions for Warm Climate Countries, Valencia, Spain, 18 June 2018 through 20 June 2018
Note

QC 20181019

Available from: 2018-10-16 Created: 2018-10-16 Last updated: 2018-11-12Bibliographically approved
Karampour, M. & Sawalha, S. (2017). Energy Efficiency Evaluation of Integrated CO2 Trans-critical System in Supermarkets: A Field Measurements and Modelling Analysis. International journal of refrigeration, 82, 470-486
Open this publication in new window or tab >>Energy Efficiency Evaluation of Integrated CO2 Trans-critical System in Supermarkets: A Field Measurements and Modelling Analysis
2017 (English)In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 82, p. 470-486Article in journal (Refereed) Published
Abstract [en]

This paper investigates energy efficiency of an integrated CO2 trans-critical booster system installed in a supermarket in Sweden. The supermarket has applied several features to improve energy efficiency including space and tap water heating, air conditioning (AC), and parallel compression.  

Using field measurements data, the system performance is evaluated in a warm and a cold month. Furthermore, this integrated energy system concept is modelled and compared with stand-alone HFC-based energy systems. 

The results show that the system provides the entire AC demands and recovers a great share of the available heat, both with high COP values. The comparative analysis shows that integrated CO2 system uses about 11% less electricity than stand-alone HFC solutions for refrigeration (i.e. indirect HFC), heating and AC in North of Europe.

Energy efficiency analysis of the integrated CO2 system proves that this system is an environmentally friendly all-in-one energy efficient solution suitable for cold climate supermarkets.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
CO2 trans-critical booster system, Supermarket, Field measurements, Systems integration, Modelling
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-211852 (URN)10.1016/j.ijrefrig.2017.06.002 (DOI)000410699800039 ()2-s2.0-85028728678 (Scopus ID)
Projects
Effsys Expand, EP04
Funder
Swedish Energy Agency, 40338-1
Note

QC 20170815

Available from: 2017-08-14 Created: 2017-08-14 Last updated: 2017-10-20Bibliographically approved
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