Design of an Energy-Efficient Condensing Unit of a Split-Cascade Refrigeration and Air Conditioning System for Office Use

The paper aimed to enhance office cooling efficiency by eliminating freezer heat discharge recycling through the design and operation of an energy-efficient condensing unit. The performance of a 200-square-foot room with a 0.352 m2 evaporator using a total load of 1 kW, five inhabitants,two lamps, a printer, and 1 kg of water was assessed. R407C and R134a refrigerants were chosen for the freezer and air conditioner (A/C) due to their higher quality thermodynamic properties for efficiency testing. Experimental data was collected for 20 days to evaluate the performance of dual systems in terms of refrigerating capacity and COP based on work-input, evaporator, and condenser temperatures. The experiment revealed that the average work input, coefficient of performance(COP), and refrigerating effect in the freezer and air conditioner are 30.29 W and 36.49; 5.96 and 5.23; and 180.3 kJ/kg and 189.4 kJ/kg, respectively. The freezer with a centralized condensing unit had a higher COP of 12.25% compared to A/C, whereas A/C used 16.99% more energy and had a4.8% cooling effect. The study revealed that a central outside condensing unit significantly reduced hybrid systems' energy consumption, improved cooling effects, and prevented freezer heat recycling and dispersion in the office setting.