Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Experimental Investigation of Refrigerant Charge Minimisation of a Small Capacity Heat Pump
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Enormous quantities of heat are available in air, soil, water, exhaust air from buildings, and in waste water of any kind. However these heat sources are use-less for heating purposes since their temperatures are lower than the tempera-ture required for heating. Heat pumps can be used to extract heat from these sources with a small expenditure of additional energy and up-grade and deliver the energy as useful heat for room heating.

The heat pump cycle employs the well-known vapour compression cycle. The amount of heat delivered by a heat pump is equal to the amount of energy extracted from the heat source plus the heat equivalent to the compression work of the heat pump. Heat pumps, of course, are being generally accepted as outstanding energy saving units due their coefficient of performance (COP). Heat pumps for house heating have been used extensively in many countries and are especially common in Sweden. The annual growth rate of heat pump usage in Sweden is the same as in rest of Europe. According to the Swedish heat pump association, between 1986 to August 2003, the number of installed heat pump units in Sweden was 332,309. The demand for heat pumps started to increase from the year 1995 and in the year 2002, approximately 40,000 heat pump units were installed. Among the many types available, single-family heat pumps providing heating capacity of about 5 kW are widely popular.

The main drawbacks of heat pumps are the complexity of the systems, high cost, need of technical knowledge, safety hazards and environmental effects of certain refrigerants, etc. An efficient heat pump with small refrigerant charge would have less of some of these drawbacks and could be a competitive alterna-tive to other heating processes.

In this study, methods of refrigerant charge minimisation without reducing the performance of a small capacity (5 kW) heat pump have been investigated. Work has been focused on finding refrigerant charge distribution in different components of the heat pump, on finding out the solubility of refrigerant (pro-pane) with different compressor lubrications oils, on testing different types of compact heat exchangers, on constructing new minichannel heat exchangers and on finding correlations for calculating the heat transfer of minichannel heat exchangers. The results included in this thesis have been presented in four con-ference papers and five journal papers of which two were published and three were submitted for publication.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , xxii, 84 p.
Series
Trita-REFR, ISSN 1102-0245 ; 07/58
Keyword [en]
heat pump, propane, low-charge, Wilson plot method, minichannels, aluminium heat exhangers, single.phase flow
National Category
Energy Engineering
Identifiers
URN: urn:nbn:se:kth:diva-4273ISBN: 978-91-7178-569-5 (print)OAI: oai:DiVA.org:kth-4273DiVA: diva2:11571
Public defence
2007-02-19, Salongen, KTHB, Osquars Backe 31, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20100707Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2010-07-08Bibliographically approved
List of papers
1. Charge Distribution in a 5kW Heat Pump Using Propane as Working Fluid: Part 1: Experimental Investigation
Open this publication in new window or tab >>Charge Distribution in a 5kW Heat Pump Using Propane as Working Fluid: Part 1: Experimental Investigation
2001 (English)In: Proc. 16. Nordiske Kølemøde og 9. Nordiske Varmepumpedage29.-31. August 2001, 2001, 299- p.Conference paper, Published paper (Refereed)
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-6760 (URN)
Conference
16. Nordiske Kølemøde og 9. Nordiske Varmepumpedage 29.-31. August 2001, København
Note
QC 20100707Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2010-07-14Bibliographically approved
2. The Behaviour of Small Capacity (5kW) Heat pump with Micro-Channelled Flat Tube Heat Exchangers
Open this publication in new window or tab >>The Behaviour of Small Capacity (5kW) Heat pump with Micro-Channelled Flat Tube Heat Exchangers
Show others...
2002 (English)Conference paper, Published paper (Refereed)
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-6761 (URN)
Conference
IIRConf. 26-28 August, Stockholm
Note
QC 20100707Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2010-07-14Bibliographically approved
3. The Solubility of Propane (R290) with Commonly Used Compressor Lubrication Oils
Open this publication in new window or tab >>The Solubility of Propane (R290) with Commonly Used Compressor Lubrication Oils
Show others...
2003 (English)In: Compressors and Their Systems, 2003, Vol. 4, 157-166 p.Conference paper, Published paper (Refereed)
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.

Series
IMECHE Conference Transactions, ISSN 1356-1448
Keyword
Thermodynamics; Engineering, Environmental; Engineering, Mechanical
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-6762 (URN)000186286000015 ()1-86058-417-9 (ISBN)
Conference
International Conference on Compressors and Their Systems CASS BUSINESS SCH, CITY UNIV, LONDON, ENGLAND, SEP 07-10, 2003
Note
QC 20100707Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2010-07-14Bibliographically approved
4. Mini-Channel Aluminium Heat Exchangers with Small Inside Volumes
Open this publication in new window or tab >>Mini-Channel Aluminium Heat Exchangers with Small Inside Volumes
2003 (English)In: Proc. 21st IIR International Congress of Refrigeration, Washington DC, August 17-22, 2003, 2003Conference paper, Published paper (Refereed)
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-6763 (URN)
Conference
21st IIR International Congress of Refrigeration, Washington DC, August 17-22, 2003
Note
QC 20100707Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2010-07-14Bibliographically approved
5. A Minichannel Aluminium Tube Heat Exchanger - Part 1: Evaluation of Single-Phase Heat Transfer Coefficients by the Wilson Plot Method
Open this publication in new window or tab >>A Minichannel Aluminium Tube Heat Exchanger - Part 1: Evaluation of Single-Phase Heat Transfer Coefficients by the Wilson Plot Method
Show others...
2008 (English)In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 31, no 4, 669-680 p.Article in journal (Refereed) Published
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.

Keyword
heat exchanger; minichannel; aluminium; experiment; heat transfer; water; refrigerated; flow; laminar; Nusselt
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-6764 (URN)10.1016/j.ijrefrig.2008.02.011 (DOI)000257361700012 ()2-s2.0-44449116496 (Scopus ID)
Note
QC 20100708. Uppdaterad från Submitted till Published 20100708.Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2017-12-14Bibliographically approved
6. A minichannel aluminium tube heat exchanger - Part II: Evaporator Performance with Propane
Open this publication in new window or tab >>A minichannel aluminium tube heat exchanger - Part II: Evaporator Performance with Propane
Show others...
2008 (English)In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 31, no 4, 681-695 p.Article in journal (Refereed) Published
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.

Keyword
heat exchanger, minichannel, evaporator, aluminium, experiment, propane, performance, heat transfer
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-6765 (URN)10.1016/j.ijrefrig.2008.02.012 (DOI)000257361700013 ()2-s2.0-44449086761 (Scopus ID)
Note
QC 20100708. Uppdaterad från Submitted till Published 20100708.Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2017-12-14Bibliographically approved
7. A minichannel aluminium tube heat exchanger - Part III: Condenser Performance with Propane
Open this publication in new window or tab >>A minichannel aluminium tube heat exchanger - Part III: Condenser Performance with Propane
Show others...
2008 (English)In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 31, no 4, 696-708 p.Article in journal (Refereed) Published
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.

Keyword
heat exchanger, minichannel, condenser, aluminium, experiment, propane, performance, heat transfer
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-6766 (URN)10.1016/j.ijrefrig.2008.02.013 (DOI)000257361700014 ()2-s2.0-44449146880 (Scopus ID)
Note
QC 20100708. Uppdaterad från Submitted till Published 20100708.Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2017-12-14Bibliographically approved
8. Propane Heat Pump with Low Refrigerant Charge: Design and Laboratory Tests
Open this publication in new window or tab >>Propane Heat Pump with Low Refrigerant Charge: Design and Laboratory Tests
2004 (English)In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 27, no 7, 761-773 p.Article in journal (Refereed) Published
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.

Keyword
heat pump; water-water; refrigerant charge; propane; design; experiment
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-6767 (URN)000224937600008 ()2-s2.0-7044246309 (Scopus ID)
Note

QC 20100708 QC 20110915. 17th International Compressor Engineering Conference/10th International Refrigeration and Air Conditioning Conference. W Lafayette, IN. JUL 12-15, 2004

Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2017-06-14Bibliographically approved
9. Performance of a single-family heat pump at different working conditions using small quantity of propane as refrigerant
Open this publication in new window or tab >>Performance of a single-family heat pump at different working conditions using small quantity of propane as refrigerant
2007 (English)In: Experimental heat transfer, ISSN 0891-6152, E-ISSN 1521-0480, Vol. 20, no 1, 57-71 p.Article in journal (Refereed) Published
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.

Keyword
heat pump; minichannel; multiport; ground source; minimum charge; low charge; propane; natural refrigerants; flammable refrigerants
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-6768 (URN)10.1080/08916150600977481 (DOI)000243500600004 ()2-s2.0-33847145339 (Scopus ID)
Note
QC 20100708. Uppdaterad från Accepted till Published 20100708.Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2017-12-14Bibliographically approved

Open Access in DiVA

fulltext(1079 kB)5049 downloads
File information
File name FULLTEXT01.pdfFile size 1079 kBChecksum MD5
449b0dde2d1c023162c4b0f07dd3d001780c6ef16fb833c72a6b4530d2cfe29c0a593972
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Fernando, W. Primal D.
By organisation
Applied Thermodynamics and Refrigeration
Energy Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 5049 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1809 hits
CiteExportLink to record
Permanent link

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