Abstract
In response to international regulations, natural refrigerants such as carbon dioxide are more and more frequently used in the refrigeration industry. Due to thermodynamic properties, R-744 is used in the transcritical cycle as an individual refrigerant. In the hereby article, high pressure of CO2 and air temperature values were analysed. The measurements were conducted on the gas cooler side and involved external air temperature values in the summer period between 1 June to 30 September 2018. The “Booster” installation was used in one of Polish supermarkets. Correlations required to determine the optimal pressure of carbon dioxide depending on ambient temperature were presented in the article. The equations presented hereby allowed to maximize the energy efficiency ratio. An optimal high pressure for one of the correlations from literature was calculated on the basis of the measurement of ambient temperature. Actual and optimal pressure values of carbon dioxide were compared in the analysed period of time.
Highlights
Climate changes occurring on the earth trigger the increase of interest in environmental protection, which leads, inter alia, to the reduction of greenhouse gas emissions and the elimination of harmful chemical compounds
In [8], it was observed that the Efficiency Ratio (EER) decreases with increasing air temperature and for each air temperature value it reaches a different maximum at different values of carbon dioxide pressure
Gu in their work [5] dealt with the optimization of pressure in the booster system with the internal heat exchanger (IHX) and they proposed a correlation for calculating the optimal pressure of CO2 [5]: Popt = 2.68 ∙ tair + 0.975 = 2.68 ∙ tCO2,exit − 6.797 (3)
Summary
The “Booster” installation was used in one of Polish supermarkets. Correlations required to determine the optimal pressure of carbon dioxide depending on ambient temperature were presented in the article. The equations presented hereby allowed to maximize the energy efficiency ratio. An optimal high pressure for one of the correlations from literature was calculated on the basis of the measurement of ambient temperature. Actual and optimal pressure values of carbon dioxide were compared in the analysed period of time
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