Performance Analysis Of Wet Heat Source Tower Heat Pump System Under Winter Condition In North China

The serious technological barriers, which prevent air source heat pump to be widely used in North China are as follows: Firstly, since it takes air as heat source directly, heat heat absorption capacity can not be secured with a large range changed environmental temperature. Operating under such condition would lead to insufficient heat supply capacity and possibility of compressor damage. Secondly, low environmental temperature leads to serious frosting problem on outdoor heat exchanger surface. When the exchanger is covered with frost, both heat transfer resistance and air flow resistance would increase dramatically, which lead to decrease in heat transfer efficiency. This paper attempts to introduce heat source tower technology to overcome the frosting problem which air source heat pump encounters.Heat source tower is refers to a type of heat exchange equipment. In this tower air is forced to flow through its inner space and forms direct or indirect contact layer with heat fluid to accomplish sensible heat and latent heat transfer. By replacing outdoor heat exchanger of air source heat pump with heat source tower, heat can be transfer into heat pump system indirectly. Since heat fluid is used as an intermediate heat source. With heat source tower, frosting problem can be solved basically.The following aspects of research have been done for the utilization of heat source tower in North China under winter condition:1. Reviewed heat pump technology and its development in China. Since the study of wet cooling tower is of directive significance for the experimental research and theoretical calculation of wet heat source tower. The development process of research on wet cooling tower performance was summarized.2. Elaborated the fundamental principle of heat source tower heat pump system, and the governing equation for heat and mass transfer between air and heat fluid in pack zone was derived based on Merkel's equation.3. Analyzed the reason which causes the heat absorb limitation of heat source tower was analyzed. The curves of heat absorb limitation of 25% NaCl water solution was presented with experimental method.4. Established heat source tower heat pump experimental system and analyzed the factors which influence heat source tower performance under winter condition in North China.5. Made comparative theoretical calculation of different types of heat pump system and built economic analysis of heat source tower heat pump engineering example.