Research On Operation Strategy Of Hybrid Ground Source Heat Pump System Based On Exergy Analysis And Energy Consumption Simulation

The hybrid ground source heat pump technology is an important form of building cold and heat sources in the modern energy system.At the same time,it solves the problem that a single geothermal heat pump system is affected by factors such as the well digging area and capital cost,and can also take into account energy conservation,emission reduction and efficient operation of the system.The most common hybrid ground source heat pump system includes water chillers and gas-fired boilers in addition to the ground source system.For the operation strategy of complex systems,the main way is to customize the operation strategy of the overall system based on experience,which can not fully play the energy-saving advantages of the hybrid geothermal heat pump system.However,China’s clean energy continues to develop rapidly,with a continuous increase in the share of clean energy.The energy structure continues to be optimized,and a series of policies and proposals,such as deepening energy supply reform and prioritizing the development of non fossil fuels,have received strong support.Therefore,it is of great significance to study the efficient operation strategy of the hybrid geothermal heat pump system.This thesis will study the operation strategy based on the exergy analysis method and energy consumption simulation.Firstly,each subsystem of the hybrid ground source heat pump system is analyzed one by one based on the exergy analysis method,and each subsystem is separately modeled with exergy analysis,including five subsystems: cooling tower subsystem,chiller subsystem,buried pipe system,ground source heat pump subsystem,and gas boiler subsystem.Secondly,by constructing the equilibrium equation and using the MATLAB genetic algorithm toolbox,the partial load rate PLR of the unit under typical summer and winter operating conditions is optimized with the goal of minimizing overall system losses.Taking a residential project in Beijing with a building area of 85700 square meters as an example,the summer load is 3810 kW and the winter load is 3397 kW.The compound geothermal heat pump system is used as the cold and heat source,and the geothermal heat pump can bear 60% of the total load in winter at most.Based on this,equipment selection is carried out.Two ground source heat pump units are used,of which the cooling capacity of each unit in summer is 1072 kW and the heating capacity in winter is 1127 kW;2 chillers,each with a summer cooling capacity of 882 kW;Two gas boilers,each with a winter heating capacity of 700 kW.Then based on TRNSYS18,the energy consumption simulation modeling and simulation of the hybrid geothermal heat pump system are carried out.Using the main modules in the software TRNSYS: water chiller module(Type666),cooling tower module(Type162b),geothermal heat pump module(Type225),ground temperature field module(Type557a),gas boiler module(Type700),etc.,a dynamic simulation platform for the composite geothermal heat pump system is established.In the process of model building,the control logic uses the control water pump signal and the heat pump unit signal for start stop control,and optimizes the partial load rate PLR of the unit based on the simulation results.According to the two optimization methods of exergy analysis method and energy consumption simulation,two typical days in summer and two typical days in winter are selected respectively to simulate and analyze the partial load rate of the unit.Select energy loss,power consumption,carbon emissions,and operating costs as evaluation criteria,analyze each operating condition one by one,and calculate the optimization rate separately.The conventional operation and maintenance mode adopts the method of sequentially starting the units based on the size of the load.The research results indicate that:(1)under the typical summer day of July 10 th working conditions,the analysis and optimization ratio of energy loss data is 19.15%,and the energy consumption simulation and optimization ratio is 3.06%;The analysis and optimization ratio of electricity,carbon emissions,and operating cost data is 4.99%,and the simulation and optimization ratio of energy consumption is 4.10%.(2)Under the working conditions of August 1st on a typical summer day,the analysis and optimization ratio of energy loss data is 15.37%,and the energy consumption simulation and optimization ratio is 8.53%;The analysis and optimization ratio of electricity,carbon emissions,and operating cost data is 7.88%,and the energy consumption simulation optimization ratio is 6.74%.(3)Under typical winter conditions from November 20 th to November 20 th,the analysis and optimization ratio of energy loss data is 11.73%,and the energy consumption simulation and optimization ratio is 11.56%;The analysis and optimization ratio of electricity,carbon emissions,and operating cost data is 11.12%,and the simulation and optimization ratio of energy consumption is 10.83%.(4)Under the working conditions of January 15 th on a typical day in winter,the data on energy loss,electricity consumption,carbon emissions,and operating costs were not optimized through analysis,and the energy consumption simulation data increased instead.This is because the energy consumption simulation started the gas boiler to ensure that the unit is in an efficient range.Provide a scoring method through comprehensive analysis of data from four operating conditions.The algorithm score for conventional operation and maintenance mode is 16;The optimal exergy analysis method score is 118.33;Secondly,the rating of the energy consumption simulation method is 29.36.The research conclusions provide two analysis modes for the operation strategy of the hybrid geothermal heat pump system,and provide ideas for the formulation of the system operation strategy in the future.At the same time,the research conclusions can provide reference for the operation of similar projects.