Thermodynamic Analysis on Heat Pump with Economizer for Cold Regions

With improvement of the people’s living standard and development of national economy, heat pump for air conditioning has been widely used. With development and enlargement of the cities in these cold regions, the conventional heating method can severely pollute the environment. In order to clean the cities, the governments drew many measures to restrict citizen heating by burning coal and oil and to encourage them to use electric or gas-burning heating. Air-source heat pump is convenient to use and so it is better method for electric heating. A conventional heat pump is unable to meet the heating requirement in cold regions, because its heating capacity decreases rapidly when ambient temperature is below -10°C. This paper presents a new heat pump cycle which can secure heating capacity under low ambient temperature by employing the scroll compressor with supplementary inlets. When the heat pump works in low temperature environment, the refrigerant from the condenser is injected in the compression chambers via the inlets to improve working process of the scroll compressor, so that the performance of the heat pump is increased quickly. The heat pump prototype was experimented and the measured results demonstrate that the heat pump can realize high temperature water supply and high capacity even under the low ambient temperature of –10°C ~ -15°C. The developed heat pump system can be used for heating in cold regions.