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| 2. |
- Berntsson, Thore, 1947, et al.
(författare)
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Heat transfer of nonazeotropic mixtures in a falling film evaporator
- 1985
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Ingår i: ASHRAE:s Annual Meeting, Honolulu, 23-27 June 1985: - ASHRAE Transactions. ; 91:1, s. 1337-1350
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The evaporative heat transfer coefficient for nonazeotropicmixtures of R12 and R114 has been studied in a falling filmheat exchanger. The main aim with the project has been tostudy how the heat transfer coefficient is influenced bythe additional mass transfer resistance that is introducedwhen a mixture is used instead of a pure refrigerant.The test apparatus consisted of one tube, which was heatedfrom the outside and with the refrigerant forming a fallingfilm on the inside. The heating was done by a liquidflowing in an annular space countercurrently to the fallingfilm.From the results it can be concluded that the heat transfercoefficients for the mixtures at surface evaporation conditions are between the corresponding ones for the pure refrigerants at given Re numbers. This indicates that theadditional mass transfer resistance when a mixture is usedis small in a falling film at such conditions. This isprobably due to the small film thickness.The heat transfer coefficients versus the heat flux werealso measured. Again, the values for the mixtures at agiven'heat flux fall between the corresponding for thetwo pure refrigerants, both at surface evaporation andnucleate boiling conditions.
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| 3. |
- Holmberg, Per, 1957, et al.
(författare)
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Technico-economic aspects on heat transformers
- 1991
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Ingår i: Föredrag vid Indo-British Workshop on Industrial Energy Conservation, Pune, Indien, 6-8 februari 1991.
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Konferensbidrag (refereegranskat)
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| 4. |
- Holmberg, Per, 1957, et al.
(författare)
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Technico-economic aspects on heat transformers
- 1990
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Ingår i: Paper to be presented at Workshop on Concepts for energysavings in Heat Pumps and Refigeration Systems August 31st 1990 at The Royal Inst. of techn.,Sthlm.
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Konferensbidrag (refereegranskat)
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| 5. |
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| 6. |
- Munch, Karin, 1954, et al.
(författare)
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Large Heat Pumps Nonazeotropic mixtures as working Fluids - some results from computer simulations
- 1985
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Ingår i: IIR Conference "Comission E2 - Heat Pumps and Energy Recovery, Trondheim, 19-21 June, 1985.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Nonazeotropic mixtures of working fluids have been much discussed during recent years for large heat pumps, although practically no systems have been really installed so far. Hith mixtures it is possible to achieve gliding temperatures in the condenser and the evaporator. This enables several possibilities for improvement of the performance, such as the COP, the heating capacity, variation of the heating capacity with the load, pressure levels. and compressor discharge temperatures.In the following comparisons between some mixtures and pure working fluids regarding the COP and the relative heating capacity are presented. The results shown are computer calculated ones.Most calculation results for mixtures. presented so far in the literature, are valid for a heat pump cycle with infinite heat exchanger areas. In this paper it is shown that the influence on the performance of finite heat exchanger areas and realistic compressor efficiencies is considerable.
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| 7. |
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| 8. |
- Munch, Karin, 1954, et al.
(författare)
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The preformance of large compressor driven heat pumps - System simulations
- 1983
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Ingår i: Föredrag vid "XVIth International Congress of Refrigeration", Paris, September 1983. ; 1983, s. 383-387
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In Sweden there is today a very high interest for large heat pumps in group centrals, district heating systems, and industry. Due to the current price ratiosbetween electricity and oil (apprax. 1:1), practically all are electrically driven. However, the electricity prices in Sweden will probably increase considerably ina l0-year period, which will make e.g. diesel driven systens interesting. Therefore, a big project, sponsored by The Swedish Council for Building Research, has been carried out, in which these two types of heat pumps have been conpared technically and economically. It has been made as a cooperation between the Chalmers University (technical part) and the Battelle Institute, Frankfurt (technicoeconomic comparisons). This paper will deal only with results fran the technical part.In order to investigate various technical parameters, a big computer program was developed. After the presentation of this, sane of the results from it will be discussed.
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