The Study On The Wall Heat Transfer Of Public Bath Wastewater Heat Recovery And Descaling Technology

Energy-saving emission reduction has become the focus of attention in today's society,especially for resources crisis and environmental pollution increasingly prominent.Public bathroom as a large energy consumption of functional buildings,in which a lot of heat is not used while discharged directly with the wastewater.At the same time high temperature wastewater will cause thermal pollution to the waters.To reduce emissions of waste heat temperature,recycling is around the corner.As the public bathroom wastewater containing dirt and other impurities,the wall heat transfer technology is presented in this paper which recover heat from the wastewater.More importantly,the heat transfer area of the wall is important in that it can affect recovery result.For the study of the principle,different heat transfer area under the same condition are studies this paper.In the Fluent environment,the wall heat transfer is simplified as a cavity heat transfer model.The characteristics of velocity,Nu and temperaturewith time changing in the cavity of 1 h are simulated in 7 different heat transfer area.The data are recorded every 5mins.By comparing the variation of water velocity with time in each square cavity,the influence factors of heat transfer between water and refrigerant were analyzed.And by comparing the temperature of water in different model cavities and the variation law of Nu with time changing,the best model of heat exchange efficiency between the seven models is found out.In order to obtain an efficient and economical model,the comparative of the cost of of each model is proposed.In order to solve the problem of dirt,the impurities in wastewater investigations are conducted in this paper,where the influence of water quality on the heat transfer in bathing wastewater is analyzed.Combined with the characteristics of the pool wall device,freeze-thaw cleaning technology is proposed based on the double work condition of the wall.The experimental was adoptd for exploring the results of freeze-thawing in this paper.The feasibility of this technique is verified by comparing the impurities distribution of freeze-thawing,non-freezing-thawing,before & after freezing and thawing.And the mechanism of this phenomenon is explained through the preliminary theoretical analysis.Combined with the actual operation of a university bathing wastewater,the heat pump unit is selected to design the economic and efficient heat transfer model.The wall is used as the evaporator,and the shell and tube is used as the condenser.Mainly for the parameters in the process of actual operation group was calculated,and selected the suitable heat pump type.