Research For A New Style Of District Heating System Based On Ejector Heat Pumps

In this paper, in order to improve the energy efficiency of thermal power plant, a novel method to recover waste heat from circulating cooling water by an ejector heat pump is been presented. At the same time, the ejector heat pump could lower the temperature of return wa-ter of the primary heat network. By this way, waster heat of the circulating cooling water is been added to the primary heat network. The ejector heat pump is defined as a heat pump whose conditional pump is taken place with an ejector. And the primary work of this paper is shown as follows:(1) Analysis of the current thermal power plant shows that the main cause of low thermal efficiency is the large heat loss of circulating cooling water. This part heat is released into the environment every day, and pollutes the surrounding environment. But waste heat in circulat-ing cooling water is difficult to recover for its low temperature. So the key point to recover waste heat from circulating cooling water is to reclaim the heat timely and reasonable use with less cost.(2) Working principle and characteristics of ejector heat pump are described in this paper. The ejector heat pump has advantages of small volume, simple structure and less power con-sumer. It is a good method to use ejector heat pump to recover waster heat in an existing thermal power plant for its small volume. Energy flow in the ejector heat pump is also been studied from a thermodynamic view. Both the primary ejector heat pump and the secondary ejector heat pump are analyzed is this paper.(3) In order to improve the working performance and reduce volume of the ejector heat pump, in this paper, the ejector heat pump uses the plate-fin heat exchanger. And heat transfer equations of both the primary and secondary ejector heat pumps are studied.(4) Experiments for the primary ejector heat pump and the secondary ejector heat pump are taken in this paper. As the result, relationship between performance and temperature of evaporation and condensation of the primary heat pump or the secondary heat pump, and rela-tionship between temperature of return water of primary heat network and temperature of evaporation and condensation of the secondary heat pump have been reached.(5) Performance of the ejector heat pump in an actual heating project is analyzed in this paper. Take an actual thermal power plant for example, transformation of ejector heat pump for it is studied, and benefits of economic and environment are analyzed.