Performance of Evaporator in Absorption Heat Pump Systems using Water/LiBr as Main Refrigerant

今天的空调市场仍然是由电动压缩循环热泵主导的。虽然吸收技术相对复杂，涉及机械和化学工程学科，但近年来，以水为工质的吸收热泵和制冷系统重新成为人们关注的对象。这不仅是因为获得了更高的性能，而且还因为它们通常使用非氟氯化碳流体。现在，从利用的角度来看，吸收热泵的主要效果有两个。因此，有必要开发一种先进的单效吸收循环，既能达到双效效率，又能保持单效循环的优点，以达到能源的有效利用，降低成本，实现小型化。先进的辅助制冷剂循环的吸收循环优于…为了提高效率和利用低温热源，人们提出了更多的吸收器和蒸发器之间的循环。在循环模拟中，假设每个组分都有一个逆流型换热器，以水/溴化锂为主要制冷剂和吸收剂组合。由于辅助制冷剂应与主液对不相容，因此选择了戊醇作为辅助制冷剂。在此基础上进行了计算机模拟，得到了循环性能。其次，对蒸发器进行了模拟，并通过实验验证了蒸发原理和性能特性。实验和理论上得到了低于常压的水/溴化锂混合物的温度-组成图。提出了一种新型的带辅助制冷剂的逆流型蒸发器，并对其特点进行了分析，该蒸发器的优点是在保持蒸发器内压力恒定的情况下，也能在不同的蒸发温度条件下运行。较少

Today's air-condition market is still dominate by electrically-driven compression cycle heat pump. While absorption technology is relatively complex, involving both mechanical and chemical engineering disciplines, absorption heat pumps and refrigeration systems using water as working fluid have been the object of renewed attention recently. This is due not only to the achievement of higher performances, but also to the fact that they usually operate with non-CFC fluids.Now a day, there are two main effects for absorption heat pump by the view-point of utilization. That is to say the use by heat of low-temperature heat sources and a complicated pump system.It is, therefore, necessary to develop an advanced single effect absorption cycle which could reach the double effect efficiency, and keep the advantages of a single effect cycle for the sake of effective utilization of energy, cost and miniaturization.The advanced absorption cycle with the circulation of the auxiliary refrigerant bet … More ween the absorber and evaporator has been proposed, and this cycle has been studied to improve the efficiency and to utilize low-temperature heat sources.In the cycle simulation, a counter flow-type heat exchanger was assumed for each component with the water/LiBr as the main refrigerant and absorbent combination. Since the auxiliary refrigerant should be immiscible with main fluid pair, pentanol was selected as the auxiliary refrigerant. Computer simulation was carried out based on these fluid combinations and the cycle performance was obtained.Next, we focused on the evaporator simulation and the experiments to verify the evaporating principles and the performance characteristics.The temperature-composition diagram for the water/LiBr mixture at lower constant pressure than the atmosphere pressure was obtained experimentally and theoretically. A new counter flow type evaporator with auxiliary refrigerant was proposed and the characteristics was analyzed.The strong point of evaporator is to be operated also under the different evaporating temperature condition in spite of keeping the pressure in the evaporator constantly. Less