| In recent years,the number of college students has continued to increase,the number and scale of colleges and universities have continued to expand,and the increase in waste heat has accompanied it.As an indispensable public place in the university,the bath consumes a large amount of energy every day and generates a large amount of waste heat directly to the environment,which wastes energy and causes environmental pollution.This project is based on the research and development of the "13th Five-Year Plan" National Science and Technology Support Plan "Low-grade thermal energy efficient recovery and utilization technology and device development(2016YFB0601701)".Objective To design a cascade waste heat cascade utilization system for colleges and universities,and to provide a technical reference for waste heat recovery and utilization in universities and even public institutions.According to surveys and surveys in the baths of 11 colleges and universities in Northeast China,it is known that the waste heat recovery potential of college baths is huge.Based on the theoretical analysis and investigation results,a waste heat cascade utilization system is proposed,which uses sewage heat exchangers to classify,the first-stage sewage heat exchangers pre-heat cold water,and the second-stage sewage heat exchangers and steam heat recoverers provide heat sources for heat pump units.Finally,the experimental bench for the system of cascade utilization of waste heat in college baths was established.The calculation and research determine the theoretical parameters of the system.According to the required heating efficiency of the system,the X80 dual-source heat pump hot water unit with a nominal heating capacity of 82 k W.h is selected.Plate heat exchanger,secondary sewage heat exchanger is 50 k W sewage heat exchanger;2 horizontal fan coils with rated power of 96 k W and rated air volume of 1020m3 / h are selected according to the space of the shower room;two additional 30 k W air exchange The heater absorbs the heat of the surrounding air to build a test system.The system’s cascade heat recovery operating conditions are recorded and data is recorded.After bypassing the first-stage sewage heat exchanger,the data is recorded again for comparison,and it is concluded that the cascade system is more conducive to waste heat recovery and utilization.The heat in the bathing wastewater and the heat in the wet steam in the bath area can be recovered to recover the heat in the wastewater and the steam to obtain the waste heat utilization rate of 73.83%;the total power consumption of the system and the total effective energy can be used to obtain the energy utilization efficiency of 185.5%;the dual-source heat pump The total power consumption and cumulative heating capacity of the unit can be calculated to be 4.8;the energy consumption of the system is lower than other hot water production methods compared with the same period of last year,and the system’s good energy saving,environmental protection and economic benefits are introduced.The experimental data was supplemented by using TRNSYS software to simulate the year-round operation of the system.The operation simulation results show that the unit’s effluent temperature can reach about 55 ° C throughout the year.The main heat source is the sewage source.The air source as the heat source is affected by seasonal factors.Under the full operating condition of the system,the heating capacity of the sewage source side per hour is 78 k W.h,and under the condition of using the air source alone,the heating capacity is 33 k W.h per hour.The power of the heat pump unit is 17 k W.h,the unit COP value is nearly 5.0,the system runs for 8 hours on a working day,and the total energy consumption is 76000 k W.h. |
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