Development of vapor compression refrigeration cycle with a natural-circulation loop

Vapor compression refrigeration cycle with a natural-circulation loop (VCNC) has been developed to save energy for an air conditioner of shelters of electronic facilities. VCNC consists of a compressor, a condenser, a liquid pipe, an evaporator, a gas pipe, an accumulator and three valves. VCNC has two operating modes; vapor compression mode and natural-circulation mode, which are easily changed by the values. The experiments were carried out to evaluate the cycle performance in natural-circulation mode, and calculations were performed to examine the energy consumption of VCNC using the profile of seasonal environmental temperature in Tokyo. The experimental results indicated that the cooling capacity in natural-circulation mode depended on the amount of charged refrigerant and took a maximum value in the case that the refrigerant at the outlet of the evaporator became saturated vapor. Also, the cooling capacity in natural-circulation mode linearly increased as the outdoor temperature decreased. The calculated results indicated that the operating ratio of the compressor of VCNC was approximately 70% smaller than that of conventional air conditioners (VC). Furthermore, the energy consumption of VCNC was approximately 50% lower than that of VC.