Use of solar radiation to produce cold water for hospital air conditioning system using the combined organic Rankine-vapor compression cycle

In this paper, the optimal combined organic Rankine-vapor compression cycle is proposed to produce cold water for hospital air conditioning using solar energy. The hospital is located in Esfarayen city and the intensity of solar radiation in all months is calculated. The results show that in the five months of May, June, July, August and September, there is the highest solar radiation in Esfarayen city. The possibility of using daily solar radiation to produce cold water during these five months is examined. Simulation is performed using the Engineering Equation Solver (EES) software. Six refrigerants R22, R134a, R600, R143a, R500, and R11 are considered as working fluids for the cycle and based on energy and exergy analysis, suitable fluid is recommended for this system. The effects of solar radiation, refrigerant, and mass flow rate of the refrigerant on the cooling water temperature outlet from the evaporator, cycle performance, organic Rankin cycle efficiency, performance coefficient of the VCC cycle, and exergy efficiency of the ORC-VCC system are investigated. The results show that using the refrigerant R22 is more suitable than other refrigerants because the cycle with this refrigerant reduced the water temperature up to 8 o C in the evaporator, as well as the cycle performance are obtained 0.72 and organic Rankin cycle efficiency is 13.9%, which will be the highest. The results show that increasing boiler thermal energy (solar radiation) reduces water temperature in the evaporator and exergy efficiency of the system, and increases organic Rankin cycle efficiency and cycle performance.