Study On Seawater Heat Pump Air Conditioning’s Characteristic Under The Condition Of Low Seawater Temperature

Seawater heat pump air conditioner is an important energy project of national "Twelfth Five Year Plan". It has been adopted by many coastal cities in China and abroad, because of its advantages of high efficiency, energy saving, environmental protection. However, the promotion of seawater heat pump air conditioner is confronted with many obstacles, including its low reliability and low efficiency under low seawater temperature condition in winter. In order to solve this problem, this paper focus on the running performance of seawater heat pump air conditioner under the condition of low seawater’s temperature.First, the structure and properties of double-pipe heat exchanger and spraying-plate heat exchanger was introduced and analyzed, the mathematical model of their heat transfer process were respectively built and solved. So that we acquired the influence of seawater inlet temperature, water velocity and other key parameters on fluidity, heat transfer performance, heat pump’s COP and heating capacity when they are used as intermediate heat exchanger of seawater heat pump. And we analyzed the causes of these effects and rules.Secondly, the heat transfer process of two types heat exchangers during freezing was analyzed and mathematical model was established and solved. Then their freezing characteristics were achieved. Including that double-pipe heat exchanger are blocked by ice flow, the heat transfer cannot continued, so that the heat pump unit shut down, and spraying-plate heat exchanger can continuously work with ice, but after the ice thickness reaching to a certain extent, the heat transfer performance will decrease sharply. At the same time, the concept of double-pipe heat exchanger’s ice blocking rate and spraying-plate heat exchanger’s thermal resistance ratio were defined. Their safe operating range were gave was put forward a proposal and solutions of deicing.Finally, we set the performance testing platform of seawater heat pump intermediate heat exchanger under the condition of cold seawater source. Respectively, the heat transfer performance of double-pipe heat exchanger and spraying-plate heat exchanger, the influence of heat pump system(COP) and heating capacity, and the mathematical model were tested and verified.