Study On Optimal Regulation Of Hydraulic Balance Of Jet Pump Heating System

At present,the voices of energy conservation,emission reduction and environmental protection are getting higher and higher,and reducing energy waste is an urgent task.In the northern part of China,the energy consumption of urban central heating system accounts for about 40%of the total energy consumption of buildings,and the phenomenon of uneven hydraulic power and uneven heat distribution in traditional heating systems not only causes high system energy consumption,but also reduced the heating quality of the system.Therefore,a jet pump heating system is proposed,that is,an injection pump device is installed in the front tube well or the basement of the hot user building to increase the user flow adjustability.The main research content of this paper is based on the design theory of jet pump,analyzes the basic performance equation of jet pump,and combines the hydraulic requirements of heating system to design the structural parameters of HLN series jet pump.By established the jet pump heating system test bench,the operating parameters of the jet pump under different working conditions were tested,the working performance curve was drawn,and the internal flow of the jet pump was numerically simulated by Ansys software,and its velocity field and pressure field is analyzed.The experimental results are compared with the numerical calculations to explore the optimal operating conditions of the jet pump.The experimental results show that when the flow ratio of the jet pump increases,the pressure ratio gradually decreases,and the efficiency value first increases and then decreases,the efficiency of the jet pump HLN-A17 reaches the maximum when the flow ratio is 1.10,the peak value of HLN-A21 was 29.1%when the flow ratio was 1.18.The numerical calculations show that with the increase of the flow ratio,the mixing zone formed by the internal fluid of the jet pump in the mixing chamber is larger,the pressure field deviation phenomenon is more obvious,the outlet pressure of the diffuser is gradually reduced,and the mixing chamber section center area velocity and boundary layer thickness is gradually increased,combined with the characteristics of the fluid pressure in the actual heating system,the optimum working conditions for selecting the HLN-A21 jet pump are 0.21 MPa for ejector fluid pressure,0.50 MPa for working fluid pressure,and 0.26 MPa for compressed fluid pressure.Based on theoretical research,jet pumps are used in conventional heating systems.The original system was investigated,hydraulic calculation,jet pump selection,installation and other technical transformation work.The operating parameters of the jet pump heating system are tested during the heating season,and compared with the original system,the energy saving,the indoor temperature,the degree of hydraulic imbalance,as well as the energy saving and emission reduction of the jet pump heating system are analyzed.The test results show that in this technical transformation project the jet pump heating system compared with the original system the energy saving rate is 37.1%and the heat saving rate is 14.5%,which can consume the surplus head of the heat user to improve system hydraulic stability,the degree of heat users“far”and“near”is greatly reduced,the indoor temperature of the user at the end of the system is increased by 4°C on average,and the indoor temperature of the near-end heat user is reduced by 2³°C,at the same time,226t of standard coal can be saved,which is equivalent to emission reduction 592t of CO₂,2t of SO₂,2t of NO_x,and 3t of smoke quantity.Improve system heating quality while reducing system energy consumption and reducing pollutant emissions.