Design And Optimization Of Waste Heat Recovery-Heat Pump System With High Humidity And High Heat Condition

With the continuous improvement of people’s requirements for building comfort,the energy consumption of HVAC will continue to increase,and the proportion of domestic hot water will continue to increase.In recent years,with the rapid development of bath and hot spring culture in Northeast China,the energy consumption of this kind of building is still high.This kind of building discharges a large amount of waste heat with high temperature and humidity every day,which contains a large amount of heat energy.The waste water is discharged intensively and the water quality is relatively clean.It is suitable for waste heat recovery and has potential value for reducing building energy consumption.In this paper,a hot spring resort in Harbin is selected for research,and the daily water consumption,water temperature,average discharge of wastewater,indoor temperature and relative humidity of the building are investigated.Based on the research parameters,the design and research are carried out.A heat pump dehumidification system with waste heat recovery is designed to recover a large amount of latent heat and sensible heat contained in the air of hot spring pool and shower room to make up for the heat loss of air and pool water.Through theoretical analysis,it is concluded that the indoor moisture dissipation is 323 kg/h,and the heat recovery from indoor is 249 kW.Three kinds of operation modes of solar hybrid sewage source heat pump hot water system（hereinafter referred to as waste heat recovery heat pump hot water system）are designed,and the operation strategy based on time and temperature difference control is adopted among the systems.Scheme 1 is the separate operation mode of sewage source heat pump,scheme 2 is the mode of series and parallel switching of solar energy and sewage source heat pump,and scheme3 is the mode of parallel connection of solar energy and sewage source heat pump.With the help of TRNSYS software,the simulation models of the three schemes are established.The simulation time is one year and the simulation step is 0.125h.The operation effect of the system is simulated.The simulation output results（average hot water supply temperature,system heat supply,system energy consumption,system cop,solar energy collection and heat collection efficiency,etc.）are analyzed,and the three schemes are compared and analyzed.The total energy consumption,heat pump unit energy consumption,water pump energy consumption and system operation time of the three schemes are analyzed,and the optimal operation scheme is determined according to the analysis results.The simulation results show that the three schemes can meet the heating requirements.The annual heating capacity of high-temperature water tank is about 1.91×10⁶kWh,the total energy consumption of the system is 4.39×10⁵kWh,2.01×10⁵kWh and1.73×10⁵kWh,respectively.The average COP of the system is 4.36,9.52,11.06,and the average COP of the heat pump unit is 4.61,4.73 and 4.56 respectively.Based on the above simulation results,the investment benefit method is used to optimize the optimal scheme to further reduce the energy consumption of the system and improve the operation efficiency of the system.The parameters such as collector inclination angle,plate heat exchanger area,collector area and water tank volume were optimized.After parameter optimization,the optimization scheme was verified by changing collector inclination angle and plate heat exchanger area.The verification results show that the optimization results are tenable.At the same time,from the optimization conclusion,part of the energy saving of the original scheme 3 is sacrificed,so as to achieve the highest economy.Finally,compared with the traditional coal-fired boiler scheme,the analysis of energy conservation and environmental protection is carried out.The three schemes can save 78.9%,75.4%and 46%of standard coal each year.The optimal scheme 3 can reduce 758 tons of CO₂,5.3tons of SO₂,4.3 tons of smoke and dust,and 68.9tons of ash annually,which has good energy conservation and environmental protection.It can be seen that the heat pump system designed in this paper has obvious energy saving and emission reduction effect compared with the traditional coal-fired boiler.