Optimization Analysis Of Waste Heat Recovery Structure Of Sewage Tank In Heat Pump System Based On Temperature Gradient Law

Sewage source heat pump is a branch of water source heat pump.It can extract a large amount of low-grade heat energy from domestic sewage by using a small amount of electric energy and transfer it to high-grade heat energy.Sewage source heat pump has many advantages,such as green environmental protection,efficient energy saving,reliable stability,wide applicability,low cost economy and so on.With the concept of environmental protection deeply rooted in the hearts of the people,more and more scholars put the research of sewage source heat pump system on the topic,but at present,the optimization and improvement of sewage source heat pump mostly focus on the optimization of heat exchanger and the improvement of unit system.This paper puts forward a new idea-the optimization design of sewage tank structure in sewage source heat pump system.In this paper,the sewage heat pump system is optimized from the perspective of sewage tank,and the bath of A11 apartment of Harbin Institute of technology is studied.The specific research contents are as follows:(1)Aiming at the problems existing in the original sewage tank,this paper analyzes them one by one,and puts forward some measures,such as adding diversion partition plate and sewage distributor,to optimize the structure of the sewage tank,so that the vertical fixed flow direction of sewage can be broken,and the heat in the sewage can be fully recovered according to the temperature gradient.(2)Based on ANSYS fluent,the finite element simulation of the newly proposed optimized sewage tank is carried out.The results show that: after optimizing the structure of the sewage tank,the heat transfer in the sewage tank becomes more reasonable,the problems of heat transfer concentration,heat cross reflux and heat transfer dead zone in the original sewage tank are improved,the temperature gradient in the sewage tank is obvious,and the heat transfer is sufficient.At the same time,The stress condition of the heat exchanger is also good.(3)After theoretical design calculation and ANSYS fluent finite element analysis,the actual engineering experiment is carried out in the bath of A11 apartment.The RS485 bus technology is used to accurately measure the real-time data to ensure the accuracy of the experimental data,collect the experimental data: the temperature and flow of sewage and refrigerant,and finally calculate the heating efficiency ratio of the unit.The results show that: in winter,the sewage discharge temperature decreases from10 ℃ to 4.8 ℃,and the heating energy efficiency ratio of the unit increases from 3.5 to4.81.After optimizing the structure of the sewage tank,the waste heat recovery efficiency of the sewage source heat pump unit is improved.