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- Albert, Ludvig, et al.
(författare)
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Icke-azeotropa blandningar i värmepumpar - Förstudie för fullskaleprojekt
- 1990
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In cooperation between STAL Refrigeration AB and the Department of Heat and Power Technology, Chalmers University of Technology, an experimental heat pump with a nonazeotropic mixture as working fluid is being prepared. This will be the first full scale plant in Sweden.This report contains the results from a pre-study to thefull scale project. The influence of a non-azeotropic mixture, as compared with a pure fluid on the design of the components in the heat pump, has been analyzed. This study has partly been done with a previously developed computer program, which has been improved. Some supplementary routines have been added to it, and the specific design of the prepared experimental planthas been inserted.The experimental heat pump which is to be used, has a countercurrent evaporator and a crosscurrent condenser. Since the best design for a non-azeotropic mixture is countercurrent, heat exchanger calculations have been done for this type of condenser. Comparisons indicate that a shell and tube heat exchanger with the non-azeotropic mixture on the shell side is highly interesting to investigate practically. The study of the internal heat exchanger shows that the dependence of COP on the degree of superheat before the compressor is slightly larger for a non-azeotropic mixture than for a pure fluid.During this project and also afterwards a dynamic debate onthe environmental effect of "CFCs" has been going on. Theuse of the mixture HCFC22/CFCl14, suggested in this report,will be forbidden in the future. However, it is stillinteresting to study it, since there are more and betterthermodynamic and physical data available for this mixturethan for other non-azeotropic mixtures. The experience andknowledge acquired in this project are possible to apply onother mixtures. Accurate calculations can be done for thesewhen more reliable data are available.
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| 2. |
- Albert, Ludvig, et al.
(författare)
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Provning av icke azeotropiska arbetsmedieblandningar i större värmepumpar
- 1990
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Ett fullskaleprov har genomförts med en ickeazeotrop blandning av HCFC22 och CFC114 i en enstegs värmepump. Mätningar och utvärdering har gjorts i samarbete mellan Institutionen for Värmeteknik och maskinlära och STAL refrigeration AB. Den använda värmepumpen är en av STALs testriggar vid fabriken i Norrköping. STAL har ansvarat for utförande och utvärdering av mätningarna medan Institutionen for Värmeteknik och maskinlära genomfort en jämförelse mellan matresultat och datorsimuleringar.Fullskaleprovet har visat att användning av arbetsmedieblandningar som ersättning av CFC12 i befintliga aggregat, åtminstone av den typ som provats, ar tekniskt mojlig. Betydande insatser återstår dock for att uppnå den säkerhet, servicevanlighet och lönsamhet som stalls på värmepumpar arbetande med rena arbetsmedier. En del registrativa frågor, sa som faststallande av tillåtet drifttryck, dimensionering av säkerhetsventiler, hantering av arbetsmedier etc, for blandningar måste lösas.Utvärdering av referensprov med HCFC22 visade att förångarens kapacitet inte var sa hög som förväntat. Troliga orsaker kan vara kraftig snedfördelning av arbetsmediet mellan tuberna alternativt att kontakten mellan rörväggen och insaten i tuberna varit dalig. Vid fortsatta simuleringar beaktades förångarens laga kapacitet på samma sätt for rena ämnen som for blandningar. Jämförelser mellan simulering och matning for blandningarna antyder att det masstransportmotstånd som förekommer vid förångning av en blandning inte har sa stort inflytande som man tidigare hävdat. Nar masstransportmotståndet försummades fick vi lika god överensstämmelse mellan matning och simulering för blandningarna av HCFC22/CFC114 som för ren HCFC22.
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| 3. |
- Berntsson, Thore, 1947, et al.
(författare)
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Alternativa medier och processer
- 1989
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Ingår i: Föredrag vid 13. Nordiska Kolemode och 4. Nordiske Varmepumpedager i Loen, Norge, 30/5-3/6 1989.
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Konferensbidrag (refereegranskat)
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| 4. |
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| 5. |
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| 6. |
- Högberg, Marine, 1962, et al.
(författare)
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A residential Heat Pump working with Nonazeotropic Mixture HCFC22-HCFC142b, Experimental Results and Evaluation
- 1991
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Ingår i: Föredrag vid XVIIIth International Congress of Refrigeration Montreal, Quebec, Canada, 10-17 August 1991.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Results from measurements of COP and capacity of a one-stage heat pump are presented. As working fluids CFC 12 and two compositions of the HCFC22/HCFC142b have been used.The COPs of the mixtures are the same as those of CFC12. The mixture containing 60 Mole-% HCFC22 gave the same capacity as that of CFC12.
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| 7. |
- Högberg, Marine, 1962, et al.
(författare)
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Calculation methods for comparing the performance of pure and mixed working fluids in heat pump applications
- 1993
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Ingår i: International Journal of Refrigeration. ; 16:6, s. 403-413
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Tidskriftsartikel (refereegranskat)abstract
- Three methods for comparing cycle performance of working fluids, pure as well as non-azeotropic mixtures, are investigated for two applications and for two mixture pairs, HCFC22-CFC114 and HCFC22-HCFC142b, and their pure components. The methods differ in the way of calculating the heat exchange processes. They assume, respectively, equal minimum approach temperatures, equal mean temperature differences and equal heat transfer areas. Changes of coefficient of performance (COP) with composition are explained for all methods. It is shown that transport properties must be taken into account when making rigorous comparisons between working fluids. To predict the relations between fluids with high accuracy, one must use the method with equal heat transfer areas. By the method with equal mean temperature differences, the COP can be estimated with the same accuracy for mixtures as for pure fluids, and can be used for rough estimations of the COP level with different fluids. The method of equal minimum approach temperatures should be avoided for non-azeotropic mixtures.
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| 8. |
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| 9. |
- Högberg, Marine, 1962, et al.
(författare)
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Energy aspects in CFC-developments
- 1990
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Ingår i: Presented at Workshop on Concepts for Energy Savings in Heat Pumps and Refrigeration Systems, KTH, Stockholm August 29-31, 1990. ; , s. 13-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the search for substitutes for teday's CFC fluids in electrically driven heat pumps the aspect of any changes in the electricity consumption is, of course, crucial. Reliable data on this aspect can only be achieved from full-scale experimental plants. However, in order to identify new fluids of interest, theoretical system simulations must be carried out in parallel with experimental projects. In such simulations the optimal equipment design for each new fluid can also be identified. In this paper some results from heat pump cycle calculations with different CFC substitutes are presented. From these results conclusions are drawn on the possible impact on the electricity consumption in future heat pump systems. A sensitivity analysis on some of the most important uncertainty factors in system simulations with new fluids is also presented.
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| 10. |
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