Supermarket refrigeration systems are large emitters of high GWP refrigerants, and due to the Montreal protocol and F-gas regulation, which aim to phase out high GWP refrigerants, refrigeration systems with alternative refrigerants must be implemented in order to secure climate friendly and efficient refrigeration. One increasingly more popular alternative is transcritical refrigeration systems using only CO2 as a refrigerant. The aim of this master thesis was to investigate one of these transcritical CO2-systems in order to determine how cooling capacity, power and efficiency varies over a year and what the variations depend on. Another aim was to try to compare the transcritical CO2-system with the two refrigeration systems used earlier in the same supermarket. Simulations based on dimensional data from the manufacturers were executed for the three different systems, and the transcritical CO2-system was simulated over one year, using monthly averages of parameter data. Field measurements of power were also performed in order to determine how simulations and reality corresponded. The simulations with dimensional data indicated that the transcritical system had the best system performance in all categories investigated, although the results depend on the amount of transcritical operation during the year. The transcritical system generally demonstrates better results in the winter, due to a lower ambient temperature, which has a positive effect on parameters crucial to the efficiency of the system, such as condensing pressure and temperature and evaporating temperatures. One advantage of transcritical systems is the possibility to recover heat, but the heat recovery system in the supermarket was non-functioning during the project. It has however been estimated that considerable monetary savings can be obtained with functional heat recovery compared to purchased district heating that is currently used for space and water heating.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-385451 |
| Date | January 2019 |
| Creators | Lööf, Maria |
| Source Sets | DiVA Archive at Upsalla University |
| Language | Swedish |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | UPTEC ES, 1650-8300 ; 19 010 |
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