Optimization Of The Layout Of The Ground Heat Exchanger System Of Ground Source Heat Pump

Ground source heat pump system has been developed and applied because of its low energy consumption,high coefficient of performance and relative environmental protection.Ground heat exchanger is an important part of ground source heat pump,and it is also the focus of ground source heat pump system research.Optimizing the layout form of the buried pipe can reduce the system energy consumption and improve the system performance level.Based on the analysis of the investigation data of the ground source heat pump project,this paper puts forward the relationship between the water system energy consumption and the system performance coefficient of the ground source heat pump.The scale effect of the energy efficiency of the main chiller and the energy efficiency of the transmission and distribution system,and the influence of the energy efficiency of the water system at the user side and the ground source side on the system performance under the scale effect are revealed.Combined with the limit value of relevant specifications,the reference value for judging the operation performance coefficient level of the system is further obtained.In the optimization of the plane layout of the ground heat exchanger system.This paper proposes the isosceles right-angled triangle layout.From the analysis of the pipe network resistance and the heat transfer of the ground heat exchanger system,it is concluded that the resistance of the isosceles right-angled triangles is lower than that of the rectangular pipe network with any aspect ratio;the isosceles right-angled triangles have a ratio of 2:1 The rectangular arrangement has good heat exchange performance.Based on an underground ground source heat pump system case,in 20 years of operation,compared with the original layout,the isosceles right-angled triangle layout can save about 3.7% of operating costs.In the analysis of the hydraulic balance of the underground pipe group,this paper proposes a layout form of the ground heat exchanger system from a three-dimensional perspective: the variable drilling depth and horizontal direct return system.Compared with the conventional equal hole depth horizontal reversed return system,the new ground heat exchanger system design method saves the conventional horizontal reversed return pipe and reduces the resistance of pipe network.Through the analysis of the actual limiting factors such as the unbalance rate of the pipe network,the specific friction resistance of the horizontal pipe,and the pressure strength of the pipe,the variation of variable drilling depth and horizontal direct return system design with the resistance of the pipe network is obtained.Finally,based on the ground source heat pump system case,compared with the original design of local horizontal reversed return system,the variable drilling depth and horizontal direct return system design can reduce the pump head by 4.5%.The above research results can provide a certain reference basis for the design and optimization of the vertical ground heat exchanger system.