Trial Production of a Simple Expander-Compressor Type Heat Pump

本研究的目的是开发一种新型的带惯性自由活塞的膨胀机-压缩机热泵系统。该系统简单地由一个气缸、一个自由活塞和气缸端部的三对阀门组成。该系统将高压工作流体中的能量转换为活塞的动能，然后用于压缩低压流体。当循环运行时，高压和低压流体在气缸中供应，中压流体通过右阀和左阀依次排出。低压流体从房间中吸出热量以供冷却，或中压流体用于加热。由于该系统不包含高温热电转换过程，因此比常规发电系统能更有效地利用能源。采用多节点模型进行了理论研究，制造了自由活塞膨胀机-压缩机。在理论部分，对活塞质量、吸排液压强、缸内流动与换热、活塞与缸内摩擦及工质性能进行了分析，估算的性能系数表明该系统能够满足实际使用要求；在实验部分，阀门的流动阻力和活塞隔开房间间的流体泄漏是非常重要的。在对其进行改进后，对两种运行模式进行了研究。在一种名为强制操作的模式中，阀门操作的时间由外部控制，而在另一种名为反馈操作的模式中，阀门按照检测到活塞运动的传感器的信号进行操作。通过实验测量了排气压力、流量、活塞运动和最佳工况等基本运行特性。

The purpose of this research is to develop a new expander-compressor type heat pump system incorporated with an inertial type free piston. The system is simply composed of one cylinder, one free piston in it and three pairs of valves at the cylinder ends. The system converts an energy in high pressure working fluid to kinetic energy of the piston, then it is used to compress the low pressure fluid. While the cycle runs, high pressure and low pressure fluids are supplied in the cylinder and medium pressure fluid is exhausted through the right and left valves in turns. The low pressure fluid draws heat out of a room for cooling, or the medium pressure fluid is used for heating. Since this system does not include conversion process form high temperature heat to electricity, it can use energy resources more effectively than conventional power generation system.The theoretical research was conducted using the numerical simulation called the multi node model, then the free piston expander-compressor was manufactured. In the theoretical part, the piston mass, pressure level of suction and exhaust fluid, flow and heat transfer in the cylinder, friction between the piston and the cylinder and properties of the working fluid were examined and the estimated performance coefficient showed this system is sufficient for practical use.In experimental part, the flow resistance of valves and the fluid leakage between rooms divided by the piston were very important. After improvement of them, two operation mode was investigated. In one mode named forced operation the timing of valve operation was externally controlled, while in the other mode named a feedback operation the valve was operated as following a signal from sensors which detected a piston motion. Through the experiment the basic operation characteristics like exhaust pressure, flow rate, piston motion and optimum condition were measured.