Experimental Study On Sewage Flow And Heat Transfer Characteristics In Tube With Unsymmetrically Heated Walls

The problem of energy short and environmental pollution is becoming increasingly serious.The popularization and application of sewage source heat pump technology is generally favored by the industry.However,in the actual operation of the sewage source heat pump system,the fouling is seriously deposited in the pipeline and the heat exchanger,resulting in a reduction of the sewage flow rate,a reduction of the convective heat transfer coefficient in the heat exchange tubes,and even the occurrence of no energy saving.The problem of fouling growth hinders the application of sewage source heat pump technology.The study of the fouling growth in the heat exchange tubes is conducive to revealing the flow and heat transfer rules in the sewage pipes and improving the design of the sewage source heat pump system,thereby promoting the development of this green energy-saving technology.First of all,in order to solve the problem that the value of basic physical parameters of sewage in the sewage source heat pump system is difficult to obtain,and there is a lack of uniform scientific value standards,this paper systematically and systematically analyzes the density,fouling concentration,and thermal conductivity of the original sewage from various parts of Shenyang City.The basic physical parameters such as specific heat and viscosity,and their variation with temperature,outline the role of geographical location,building function,and operation mode of sewage pump station on the physical properties of sewage.It provides a reference for the value of sewage physical parameters in the study of sewage source heat pump and the site selection of sewage source heat pump.Secondly,in order to study the effect of fouling growth on the flow and heat transfer characteristics of sewage in the heat transfer tubes of sewage,the paper establishes a test bench for fouling growth in heat exchange tubes under the condensing conditions of the sewage source heat pump according to the fouling thermal resistance method and differential pressure method.The Taiwan has conducted thermal balance,reliability verification,and error analysis.Thirdly,with the raw sewage as the flowing medium and the fouling in the pipe as the research object,this article used the built-up heat transfer tube internal fouling growth test bench to monitor the growth of the fouling in the pipe at different flow speeds.The growth rate,trend and peak value of the fouling were studied.The influence of fouling growth on the flow resistance coefficient in the heat transfer tubes was analyzed.The change of the heat exchange efficiency of the heat exchanger was studied.The fouling growth in the heat exchange tubes at different flow rates was analyzed.A soil accumulation prediction model was established.In this paper,the basic physical parameters of primary wastewater and the fouling growth characteristics in the heat transfer tubes are studied and analyzed,which provides a reference for revealing the flow and heat transfer rules in the sewage pipeline and improving the design of the sewage source heat pump system.