Development and performance analysis of a R744 refrigerant frequency controlled transcritic heat pump

There is an ozone layer in two separate parts of the atmosphere surrounding our world. Ozone gases in these parts, stratosphere and troposphere layers, are of great importance for our world. Thinning of this layer causes bad results such as increasing temperature and melting glaciers. Although the biggest reason for the depletion of the ozone layer was not noticed until 1970, when chlorofluorocarbon (CFC) gases were used, the use of these gases in the world was prohibited by the Montreal Protocol signed in 1987. Our country was included in this protocol on 19 December 1991 and the "Regulation on the Reduction of Substances that Deplete the Ozone Layer" was published in the Official Gazette dated 12 November 2008 and numbered 27052. In this study, the operation of a R744 refrigerated transcritical heat pump system with the help of Electronic expansion valve (EEV) and variable speed compressor has been experimentally investigated. The system is a water-to-water heat pump, and during the experiments it is aimed to bring the water leaving the heat pump to the targeted temperature. During the experiments carried out to reach the target temperature, the compressor was operated at a fixed frequency of 50 Hz and with the help of proportional-integral-derivative controller (PID) at variable speed, and the time to reach the target and the power values spent were recorded. In experiments, electronic circuit boards and software of the circuit containing microcontroller used as PID controller were developed and produced. Experiments were repeated for different water flow rates and different EGV opening percentage values.