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Monfared, B. & Palm, B. (2017). Corrigendum to “Optimization of layered regenerator of a magnetic refrigeration device” (International Journal of Refrigeration (2015) 57 (103–111)(S0140700715001267)(10.1016/j.ijrefrig.2015.04.019)). International journal of refrigeration, 78
Open this publication in new window or tab >>Corrigendum to “Optimization of layered regenerator of a magnetic refrigeration device” (International Journal of Refrigeration (2015) 57 (103–111)(S0140700715001267)(10.1016/j.ijrefrig.2015.04.019))
2017 (English)In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 78Article in journal (Refereed) Published
Abstract [en]

The authors regret that, in three instances on page 105 the term “Maxwell equations” is used mistakenly instead of “thermodynamic relations”. However, this does not affect any results or conclusions and is just a correction in the terminology. The authors would like to apologise for any inconvenience caused.

Place, publisher, year, edition, pages
Elsevier Ltd, 2017
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-216479 (URN)10.1016/j.ijrefrig.2017.03.011 (DOI)2-s2.0-85018629928 (Scopus ID)
Note

QC 20171201

Available from: 2017-12-01 Created: 2017-12-01 Last updated: 2018-05-11Bibliographically approved
Monfared, B. & Palm, B. (2016). New magnetic refrigeration prototype with application in household and professional refrigerators. In: Refrigeration Science and Technology Proceedings: . Paper presented at 7th International Conference on Magnetic Refrigeration at Room Temperature.
Open this publication in new window or tab >>New magnetic refrigeration prototype with application in household and professional refrigerators
2016 (English)In: Refrigeration Science and Technology Proceedings, 2016Conference paper, Published paper (Refereed)
Abstract [en]

The number of magnetic refrigeration prototypes with high cooling capacity and large temperature span islimited and there is ample room for new designs and improvements. In this paper a new prototype, designedand built, aiming at 200 W cooling capacity and about 40 K temperature span is presented. Such a unit issuitable for applications in household and professional refrigerators. In the current work, design of theprototype is described, practical issues solved to make the prototype running are explained, and preliminarytest results are presented.

Keywords
magnetic refrigeration, prototype, high capacity, rotary
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-192594 (URN)10.18462/iir.thermag.2016.0142 (DOI)000402542400036 ()2-s2.0-85017664180 (Scopus ID)978-2-36215-016-6 (ISBN)
Conference
7th International Conference on Magnetic Refrigeration at Room Temperature
Note

QC 20160921

Available from: 2016-09-15 Created: 2016-09-15 Last updated: 2017-06-30Bibliographically approved
Monfared, B. (2016). Simulation of magnetic refrigeration systems with thermal diodes and axial conductive heat transfer. In: Refrigeration Science and Technology Proceedings: . Paper presented at 7th International Conference on Magnetic Refrigeration at Room Temperature.
Open this publication in new window or tab >>Simulation of magnetic refrigeration systems with thermal diodes and axial conductive heat transfer
2016 (English)In: Refrigeration Science and Technology Proceedings, 2016Conference paper, Published paper (Refereed)
Abstract [en]

In conventional magnetic refrigeration cycles with heat transfer fluid, the achievable cycle frequency, andtherefore, specific cooling capacity is limited. Furthermore, ineffective use of magnet in low frequencydevices makes them expensive. In this work, as an alternative technique, utilizing conductive heat transfercontrolled by two different types of thermal diodes, gas-liquid and contact-break diodes, is investigated. Forthat purpose two software models are made to simulate the performance of a magnetic refrigerator with eachof the diodes. The results of simulations are presented and comparison is made between these results andthe results of older studies which used ideal properties. According to the results, due to the limited thermalconductivity of the magnetocaloric materials, the increase in the capacity becomes small with too highfrequencies. Among the thermal diodes and materials studied, the liquid metal Galinstan as the conductingfluid in an active diode gave the best results.

Keywords
magnetocaloric, refrigeration, solid-state, thermal diode, heat gate, heat switch
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-192595 (URN)10.18462/iir.thermag.2016.0143 (DOI)000402542400037 ()2-s2.0-85017613159 (Scopus ID)978-2-36215-016-6 (ISBN)
Conference
7th International Conference on Magnetic Refrigeration at Room Temperature
Note

QC 20160921

Available from: 2016-09-15 Created: 2016-09-15 Last updated: 2018-05-11Bibliographically approved
Monfared, B. & Palm, B. (2015). Optimization of layered regenerator of a magnetic refrigeration device. International journal of refrigeration, 57, 103-111
Open this publication in new window or tab >>Optimization of layered regenerator of a magnetic refrigeration device
2015 (English)In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 57, p. 103-111Article in journal (Refereed) Published
Abstract [en]

Magnetic refrigeration, as an alternative to vapor-compression technology, has been the subject of many recent investigations. A technique to enhance the performance of magnetic refrigerators is using layers of different materials in the regenerator of such devices. In this study the choice of magnetocaloric materials in a multi-layered packed bed regenerator is investigated in order to optimize the performance. A numerical model has been developed to simulate the packed bed in this study. Optimized packed bed designs to get maximum temperature span or maximum efficiency are different. The results indicate that maximum temperature span can be achieved by choosing the materials with the highest magnetocaloric effect in the working temperature range, while maximum Carnot efficiency is achieved by choosing materials with Curie temperatures above the average layer temperature.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Magnetic refrigeration, Magnetocaloric, Layering, Optimization, Temperature span, Efficiency
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-175372 (URN)10.1016/j.ijrefrig.2015.04.019 (DOI)000361908200012 ()2-s2.0-84937408356 (Scopus ID)
Note

QC 20151015

Available from: 2015-10-13 Created: 2015-10-13 Last updated: 2018-05-11Bibliographically approved
Monfared, B., Furberg, R. & Palm, B. (2014). Magnetic vs. vapor-compression household refrigerators: A preliminary comparative life cycle assessment. International journal of refrigeration, 42, 69-76
Open this publication in new window or tab >>Magnetic vs. vapor-compression household refrigerators: A preliminary comparative life cycle assessment
2014 (English)In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 42, p. 69-76Article in journal (Refereed) Published
Abstract [en]

This paper seeks to shed light on the question whether a magnetic household refrigerator with permanent magnets is more environmentally friendly than a conventional, vapor-compression refrigerator. Life cycle assessment has been used as a tool to investigate the environmental impacts associated with the life cycle of a magnetic refrigerator. The results of the assessment have been compared with those of a conventional, vapor-compression refrigerator with the same functionality. The comparison reveals that the magnetic refrigeration has higher environmental impacts mainly due to the use of rare-earth metals used in the magnet material. The possibility of compensating for this shortcoming through reuse of the magnetic materials or improving the design and efficiency of the magnetic refrigerator has been examined. In addition, the effect of the electricity mix consumed during the use phase, as one of the key factors determining the life cycle environmental impacts, has been investigated.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Magnetic, Refrigeration, Life cycle assessment, Environment
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-147579 (URN)10.1016/j.ijrefrig.2014.02.013 (DOI)000338804200009 ()2-s2.0-84901675794 (Scopus ID)
Funder
Swedish Energy Agency, 33847-1
Note

QC 20140812

Available from: 2014-06-30 Created: 2014-06-30 Last updated: 2018-05-11Bibliographically approved
Monfared, B. & Palm, B. (2012). Small Ammonia Heat Pump with Variable Speed Compressor. In: : . Paper presented at 10th IIR Gustav Lorentzen Conference on Natural Refrigeration, Delft, The Netherlands.
Open this publication in new window or tab >>Small Ammonia Heat Pump with Variable Speed Compressor
2012 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Ammonia is a natural refrigerant which has been used continuously for more than 100 years. From almost any technical perspective, it is an attractive refrigerant, having good cycle efficiency, good heat transfer properties and low pressure drop compared to most other refrigerants. The volumetric refrigerating effect is also higher than for other fluids of the same vapor pressure. Applications are nowadays restricted almost exclusively to large industrial or commercial systems.

We have previously demonstrated that ammonia is also a viable refrigerant for small systems (Palm 2008, Monfared and Palm 2011). In this paper we report on additional tests with a small capacity (7.2 kW) water to water heat pump for sanitary hot water production and space heating. Particularly, the losses in the compressor, electric motor and variable speed drive are investigated under full and part load conditions. New data for the general performance of the heat pump in terms of heat delivered at 60 °C for sanitary hot water production and at 40 °C for space heating, energy efficiency, etc. will also be reported.

Keywords
domestic, ammonia, heat pump, variable speed, inverter, minichannel, COP, efficiency, tap water heating, space heating, domestic hot water
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-98865 (URN)978-2-913149-90-8 (ISBN)
Conference
10th IIR Gustav Lorentzen Conference on Natural Refrigeration, Delft, The Netherlands
Note

QC 20121212

Available from: 2012-07-04 Created: 2012-07-04 Last updated: 2017-05-15Bibliographically approved
Monfared, B. & Palm, B. (2011). Design and Test of a Domestic Heat Pump with Ammonia as Refrigerant. In: 4th IIR Conference: Ammonia Refrigeration Technology. Paper presented at 4th IIR Conference: Ammonia Refrigeration Technology, Ohrid, Macedonia, April 14-16, 2011. France: International Institute of Refrigeration
Open this publication in new window or tab >>Design and Test of a Domestic Heat Pump with Ammonia as Refrigerant
2011 (English)In: 4th IIR Conference: Ammonia Refrigeration Technology, France: International Institute of Refrigeration, 2011Conference paper, Published paper (Other academic)
Abstract [en]

Among alternative refrigerants, ammonia with zero Ozone Depleting Potential (ODP) and Global Warming Potential (GWP), and favorable thermodynamic properties is a sensible choice as a replacement for the synthetic refrigerants, which are powerful greenhouse gases.

In this paper, the results of experiments done on a new ammonia water-to-water heat pump prototype at different evaporation temperatures and compressor speeds are reported. The heat pump is designed to deliver 7 kW heat at evaporation temperature of -5°C and condensation temperature of 40°C. The hot discharge gas from compressor is utilized to provide sanitary hot water, and the rest of the heat is used for preheating the tap water and space heating of a single-family house. The compact design of the heat pump helps reducing the refrigerant charge. To reduce the charge further and to prevent oil accumulation at the bottom of evaporator, a minichannel aluminum heat exchanger is used as evaporator.

Place, publisher, year, edition, pages
France: International Institute of Refrigeration, 2011
Keywords
ammonia, heat pump, COP, performance, minichannel heat exchanger, tap water heating, domestic hot water
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-76029 (URN)
Conference
4th IIR Conference: Ammonia Refrigeration Technology, Ohrid, Macedonia, April 14-16, 2011
Note

QC 20120413

Available from: 2012-02-06 Created: 2012-02-06 Last updated: 2017-05-15Bibliographically approved
Monfared, B. & Palm, B. (2011). Design and Test of a Small Ammonia Heat Pump. In: 10th IEA Heat Pump Conference 2011: . Paper presented at 10th IEA Heat Pump Conference 2011, Tokyo, June 27-August 31, 2011 (pp. s3_p18).
Open this publication in new window or tab >>Design and Test of a Small Ammonia Heat Pump
2011 (English)In: 10th IEA Heat Pump Conference 2011, 2011, p. s3_p18-Conference paper, Published paper (Other academic)
Abstract [en]

Since synthetic refrigerants may cause environmental damages, by depleting the ozone layer or by contribution in global warming, many researchers, in recent years, have focused on the use of natural refrigerants such as ammonia to replace the synthetic ones. Although ammonia has been used in large refrigeration systems, its application in small units, say a small heat pump, is quite rare.

The work presented in this paper is design and test of a small water-to-water ammonia heat pump, providing about 7 kW heat, sufficient for space heating and tap water heating of a single-family house. To reduce the charge and to overcome the problem of accumulation of oil at the bottom of evaporator, a minichannel heat exchanger is used as evaporator. Oil miscible in ammonia is also used to facilitate the oil return to compressor. A permanent magnet motor together with an inverter is used to run the compressor. Supplying the 7 kW heat, the heat pump runs efficiently with heating capacity to compression work ratio of 5.1 at evaporation and condensation temperatures of -5 °C and 40 °C.

Keywords
ammonia, heat pump, refrigerant charge, minichannel heat exchanger, ground source
National Category
Energy Engineering
Research subject
SRA - Energy
Identifiers
urn:nbn:se:kth:diva-62588 (URN)
Conference
10th IEA Heat Pump Conference 2011, Tokyo, June 27-August 31, 2011
Funder
StandUp
Note

QC 20120416

Available from: 2012-01-24 Created: 2012-01-19 Last updated: 2017-05-15Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9592-0202

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