Simulating and initial experimental results of a novel low-capacity absorption chiller with natural refrigerants

This article presents the initial experimental and simulation results of a novel absorption chiller using only plate heat exchangers. The modeling was developed using energy and mass balances for each component to determine the heat transfer area, heat exchanger length, and system efficiency. The chiller was designed entirely with compact, high-efficiency heat exchangers. For theoretical evaluation and operation, natural refrigerants with low global warming potential, such as ammonia (R717) and water vapor (R718), were selected. After construction, preliminary tests were conducted for a water-lithium bromide solution under simulated operating conditions, such as those using solar energy. The results showed that using tubular heat exchangers with a small diameter ratio is advisable to improve heat transfer. Furthermore, it was found that for operations under either vacuum or gauge pressure, airtight pipe sealing is essential to maintain the operating pressure. With a generation temperature of 63 °C, it was possible to produce 350 W of cooling with a coefficient of performance (COP) of 0.45 using a novel, low-capacity plate absorption chiller. This COP is approximately 20% higher than that of a chiller with a similar cooling capacity.