New low GWP synthetic refrigerants

In this project, two newly developed refrigerants, R1234yf and R1234ze have been studied as promising drop-in replacements for the common high global warming potential refrigerants. In view of that, thermodynamic and transport properties of new refrigerants were obtained by RefProp version 7.01 to study and compare their cycle performances with current refrigerants. Furthermore, their environmental and safety aspects have been studied in order to predict probable risks and suitable preparations in different applications. Basic cycle data of both new refrigerants have been calculated for most commonly used condensing and evaporating temperatures. According to evaluation of these tables, both refrigerants generally have comparable COP and volumetric cooling capacity with R134a for an isentropic compression.

As the final phase of the project, drop-in experiment was carried out in a refrigeration cycle consists of two plate heat exchangers and one electrical heater which was placed in the brine loop. Experimentation was operated first by R134a and continued by R1234yf with 10 different brine heat loads at two condensing temperatures of 30°C and 40°C. Subsequently, cycle performance and heat transfer coefficients of R134a and R1234yf were evaluated. Experimental results in heat exchangers were compared with those concluded from theoretical correlations. Outcomes of measurements demonstrate R134a has respectively 2-9.2% and 4.4-15 % higher COP as well as 0-3% and 0-3.8 % higher volumetric cooling capacity than R1234yf at condensing temperatures of 30°C and 40°C.

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