Experimental and numerical investigation of the effect of air velocity, temperature and humidity on condensation for different refrigerants

In this thesis, it was investigated that the effects of different velocities, temperatures and relative humidities of the air passing through the outside surface of the condenser on the condensation phenomena occurring in a finned tube condenser inside which the refrigerants including R134a, R1234yf, R507a and R32 flow by means of the thermodynamic analysis, thermal camera monitoring and computational fluid dynamics (CFD) analysis methods. Thermal camera monitoring method was used to obtain temperature images on the condenser surface. In addition, the temperature and flow distributions inside and outside the condenser, whose three-dimensional geometry was created in the computer environment, were analyzed by CFD analysis under steady-state conditions. According to the results obtained from the thesis study, the highest deviation between the results obtained from thermodynamic analysis and CFD analysis was found to be in the refrigerant side convection heat transfer coefficient of R134a with 17.34% for the relative humidity experiment, and it was also observed that the temperature images obtained from the thermal camera monitoring method and the contours obtained from CFD analysis were in good agreement. For the refrigerants used, it was found that with an average increase of 85% in air velocity, the condenser capacity increased by 10.31% and the refrigerant side convection heat transfer coefficient increased by 7.41%, while the degree of vapor quality decreased by 32.56% and the condensation phenomena gradually improved. With an increase of 43.75% in air temperature, the condenser capacity and refrigerant side convection heat transfer coefficient decreased by 15.06% and 8.23%, respectively, and the vapor quality increased by 17.08%, negatively affecting the condensation phenomena. In addition, as a result of 108.33% increase in relative humidity, it was determined that there was an average decrease of 11.69% and 7.08% in condenser capacity and refrigerant side concective heat transfer coefficient, respectively, and an increase of 21.68% in the vapor quality.