Effect of Inlet Pressure, Size and Wind Speed of an Evaporator on Amount of Refrigerant Charge and Performance of a Portable Propane Air Conditioner

Previous studies show that propane refrigerant has good performance in air conditioners, but the drawback of its flammability needs attention. The propane air conditioner should be designed for minimum refrigerant charge. In this work, the amount of refrigerant charge and cooling capacity of the air conditioner are the focus of analysis. The effect of the evaporator's variation of inlet pressure and variation of air speed over the evaporator on cooling capacity and amount of refrigerant within the evaporator are discussed. This research is mainly computational work with limited experimental validation. We found that, for a single duct portable propane air conditioner, cooling capacity increases from 0.956 kW to 4.319 kW when the inlet pressure of the evaporator is changed from 0.8 MPa to 0.4 MPa. Under the same condition, the accumulated refrigerant mass within the evaporator decreases from 176.846 g to 67.768 g. Increase in air speed over the evaporator increases the cooling capacity from 3.208 kW to 4.275 kW when the air speed increases from 1.0 m/s to 3 m/s, while refrigerant mass decreases from 110.307 g to 68.033 g. It should be noted that, at the lower inlet pressure of the evaporator, frost quickly appears on evaporator coils.