Research On Variable Flow Reconstruction Of Ground Source Heat Pump Cooling Water System Using Wankel Pump

In recent years,China's economic construction has developed rapidly,the urbanization process has entered an accelerated development stage,the number of populations accommodated in the city has increased rapidly,and the energy consumption of buildings has also been rising.Among them,HVAC accounts for the building energy consumption.A large proportion,in order to adapt to the rapid development of the city and solve the contradiction between people's increasing demand and the limited resources of the city,various HVAC solutions have appeared on the market in recent years,and ground source heat pumps are one of them.Due to its small footprint and high heat exchange efficiency,ground source heat pumps have been widely promoted in recent years.But at the same time,the problems of the ground source heat pump itself are also increasingly apparent.Most of the ground source heat pump units on the market can be controlled by frequency conversion according to changes in building load.However,for the circulating water system of the ground source heat pump,especially the cooling water system,Still use the most traditional fixed frequency operation mode.At the beginning of the design of the building,the power of the ground source heat pump and the flow parameters of the supporting circulating water system were selected according to the maximum cooling load of the building,and the proportion of the total operating time of the time station under part-load operating conditions exceeded 85%.The cooling water system that cannot perform flow control causes a large amount of waste of energy.In order to reduce energy consumption and improve the operating efficiency of the heat pump system.In view of the problem of variable flow control of ground source heat pump cooling water,this paper establishes a flow control model based on refrigerant cooling temperature for ground source heat pump cooling water system through theoretical derivation,indoor test,numerical simulation and other methods,and studies the performance of Wankel pump,Combined with the centrifugal pump as a cooling water pumping system,it is controlled to work with the centrifugal pump through frequency conversion,so that it can meet the heat pump flow demand and minimize energy waste;at the same time based on a Weifang geothermal project,based on theoretical reality,combined On-site thermophysical survey and simulation,to study the optimal range of underground heat exchange flow,in order to establish the flow-based switching strategy of the underground pipe network;finally,through simulation,the energy saving effect of the cooling water pump set was verified,and according to the actual working conditions,Specify the relevant control strategy.The specific research results are as follows:(1)Based on the engineering thermophysical model of the heat pump unit,a flow control model based on the temperature of the refrigerant at the outlet of the condenser is established,and the coupling relationship between the cooling temperature of the refrigerant,the flow of cooling water,and the temperature of the inlet and outlet of the cooling water is established.In order to establish a building heat load model,predict the cooling water flow throughout the day based on the heat load curve.(2)Designed Wankel pump ground source heat pump cooling water pump unit,carried out Wankel pump experiment,systematically studied the relationship between Wankel pump head-flow-efficiency under low-lift conditions,and analyzed Wankel pump based on test results Reasons for changes in efficiency.(3)Based on the quasi-three-dimensional heat conduction model of the buried pipe,the relationship between the outlet temperature of the buried pipe and the inlet temperature and flow rate is obtained,the geological parameters are obtained through on-site thermophysical testing,and the COMSOL model is established to study the establishment of a suitable inlet temperature and flow rate range Determine flow-based switching strategies for buried pipeline networks.(4)Propose a hybrid control system for centrifugal pumps and Wankel pumps,design a corresponding control strategy for different ground source heat pump usage conditions by establishing a flow control model,and compare with existing ground source heat pump cooling water systems by simulation To obtain its energy saving effect.