Research On The Performance Influence Of Vertical Closed-loop Grand-coupled Heat Pump System Under Different Soil Characteristics

With the continuous improvement of living standards,energy consumption increased year by year and environmental pollution has become increasingly serious.The characteristics of green energy saving of ground heat pump make it plays an increasingly role in the building energy conservation industy development.But the current domestic research on combined building load,heat pump unit and ground heat exchanger for dynamic analysis and simulation is less.In addition,most of the current simulation is too simplified on the part of underground,which ignored the influence of soil layered and groundwater seepage.In this article,through the UDF program,established a high degree reduction of underground three-dimensional model of pipe group,which can well solve the above problems.Frist,this article took an office building in Harbin as the research object,obtained the indoor hourly load by DeST,analysis the load,designed the buried pipe size and arranged the pipe group;Selected unit according to load,obtained the performance curve of unit by Matlab and theoretical analysis.Put unit dynamic COP into the numerical calculation of ground heat exchanger by UDF,realized the dynamic coupling of unit and buried pipe.Secondly,based on numerous literatures and the 3D simulation put forward on by the predecessors,this paper set up the mathematical model and physical model.Three kinds of whole structure three-dimensional underground model was established based on ICEM CFD,one is the single uniform physical geological structure model,another is the non-uniform three layers physical geological structure model,the other one is non-uniform three layers physical geological structure model which is Considering the seepage.Boundary conditions and initial conditions are set in Fluent,simulated dataare compared with experimental data in literature,the model was verified and corrected.Once again,according to the UDF compiled and the uniform soil model established,this article has carried on the simulation for the whole year on ground source heat pump system under different soil coefficient of thermal conductivity.Analysis the soil temperature filed in different time and different depth.Quantitative the running parameters of ground source heat pump system under different soil coefficient of thermal conductivity.To alleviate the thermal imbalance in uniform soil,introduced solar energy heating technology in the cooling season,compared the soil temperature filed and the system operation parameters with and without heating in uniform soil.Then,according to the UDF compiled and the layered soil model established,this article has carried on the simulation for the whole year on ground source heat pump system under different layers.Compared the soil temperature field distribution of uniform soil and layered soil,quantitative the running parameters of ground source heat pump system under two soil model.To alleviate the thermal imbalance in uniform soil,introduced solar energy heating technology in the cooling season,compared the soil temperature filed and the system operation parameters with and without heating in uniform soil and layered soil.In the end,according to the UDF compiled and the seepage soil model established,this article has carried on the simulation for the whole year on ground source heat pump system under different seepage velocity.Compared the soil temperature field distribution with and without seepage,quantitative the running parameters of ground source heat pump system under different seepage velocity.In order to studying the effect of heating on soil thermal imbalance,introduced solar energy heating technology in the cooling season,compared the soil temperature filed and the system operation parameters with and without heating under flow velocity of 0.5m/d.This article provide reference for evaluating of complex heat transfer performance of buried pipes under the ground and optimizing operation of ground coupled heat pump system in cold climate,and for taking technical measures to improve the unfavorable effect of soil heat transfer imbalance.