Study On Performance Characterstics Of Spray Heat Exchanger In Sewage-source Heat Pump System

The urban sewage is the potential cold and heat source of sewage-source heat pump,ithad singnificant energy saving and enviromental protection benefits by developing lowquality heat source.Heat ennergy extracted by sewage-source heat pump from the urbansewage,which can solve the urban ennergy shaortage. The technology of water intaking andheat enhancement is the obstacle of further developing for sewage-source heat pumpsystem.Study on sewage heat exchanger is the technology solving low efficiency ofsewge-source heat pump.Spray heat exchanger introduced in the article,which can increaseefficiency of heat pump as sweage heat exchanger of sweage-source heat pump. The flowcharactrristic and heat transfer charactristic of liquid film is studyed by setting up experimentbench of heat enhancement on spray heat exchanger,at th outside surface of the horizontalpipe in spray heat exchanger.Spray temperature selected as the key factor of influencing heatcharactristic of sewage-source heat pump by applying spray heat exchanger in sewage-sourceheat pump. Main research result as follows:1．Based on the spray heat exchanger as the research object,and the backgrud of sprayheat exchanger was introduced.The article had established math model by selectingexperimental correction interior and exterior, analyzed the flow condition of liquid filmbetween the horizontal pipe,acquired the formula of heat transfer coefficient.2．Study on the flow charactristic of horizontal pipe by selecting influnce factor such aspipe pitch and Re of pipe innor.The transitting Re of adjacent flow was acquired byexperimental observation, the critical Re of droplet flow transitting columnar flow andcolumnar flow transitting film flow is100between200and450between550.3．The influencing factor of heat charactisic on horizontal tube as spray density、spraytemperature、pipe pitch and Re of pipe inner,it was found that the increasing spray densitystrengthed heat exchanging by experiment.It can keep higher heat exchange coefficient at asmall temperature diffrence. Heat transfer coefficient with increasing spray density andshowed an increase at a certain range,the heat transfer coefficient would’t continue increasingover this range.Increasing the pipe pitch can weaken the heat exchanger,it is contrary with Reof pipe inner,these two factor is’t major influencing factor.In the end,fitting coreection of theouter surface of horizontal pipe with experiment data，the result is consistent with result of thetheoretical ananlysis.4．Analysising energy efficiency of sewage-source heat pump using spray heat exchangerunder variant working conditon.According to the manufacture sample,fitting the correctionabout COP、Q1、W and output temperature of the condenser side with sewage inlettemperature of the evaporator side,analyzing the transformation law of COP、Q1、W andoutput temperature of the condenser side in sewage-source heat pump.