Trial Production of a Simple Expander-Compressor Type Heat Pump

本研究旨在发展一种新型的膨胀机-压缩机式热泵系统，并结合惯性式自由活塞。该系统简单地由一个气缸、一个自由活塞和三对位于气缸两端的阀门组成。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，高压和低压流体被供应到气缸中，并且中压流体依次通过右阀和左阀排出。低压流体将热量从房间中抽出用于冷却，或者中压流体用于加热。由于该系统不包括高温热能到电能的转换过程，因此比传统的发电系统能更有效地利用能源，本文采用多节点模型进行了理论研究，并研制了自由活塞膨胀机-压缩机。理论部分考察了活塞质量、吸排流体压力水平、缸内流动与传热、活塞与缸间摩擦以及工作流体性质，估算的性能系数表明该系统足以满足实际应用;实验部分考察了阀门的流动阻力和活塞分隔的室间流体泄漏情况。改进后的两种操作模式进行了研究。在一种称为强制操作的模式中，阀操作的定时是外部控制的，而在另一种称为反馈操作的模式中，阀根据来自检测活塞运动的传感器的信号操作。通过试验，测定了排气压力、流量、活塞运动等基本工作特性及最佳工况。

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.