PHYSICAL PROPERTIES ANALYSIS OF ENVIRONMENTALLY FRIENDLY REFRIGERANT ON THE CONVECTIVE HEAT TRANSFER COEFFICIENT

The negative impacts of synthetic refrigerant on the environment are ozone depletion and global warming. In spite of all the new refrigerants has no ozone depletion potential (ODP), only the existing refrigerant R22 has ODP as 0.055, however, the global warming potential of the new refrigerants are high. Therefore the use of environmentally friendly refrigerants is a must. Propane (R290) and isobutene (R600a) are environmentally friendly refrigerants as the refrigerants have no ODP and negligible GWP. R290 is more efficiently than R22 because R290 has higher COP. One should be noted of two refrigerants, R290 and R600a is their flammability. Therefore, the amount of R290 or R600a should be minimized in refrigeration or air conditioning system. This research is conducted experimentally and theoretically comparing the effect of physical properties on the heat transfer process of the low mass of R290 and R290 - R600a blends. An increase in vapor quality decreases the convective heat transfer coefficient. This is due to the decrease in thermal conductivity and specific heat of the refrigerant with an increase in the vapor quality. R290 has the highest convective heat transfer coefficient while 60%R290 - 40%R600a blend has the lowest convective heat transfer coefficient.