Analysis on Control Strategy in Compound Ground-Source Heat Pump System of the Office Building of the Typical Climate Zone
|Course||Heating,Gas Supply, Ventilation and Air Conditioning Engineering|
|Keywords||Compound Ground-source Heat Pump System Geothermal Balance Control Strategy Optimizing Operation|
Nowadays it is very concerned about the issues of energy, environment andsustainable development worldwide. At present, our country is still in the developingcountries of the coal-fired, this irrational energy structure has resulted in the energyexhausting and the environment worsening. Therefore, seeking a kind of new energywhich is energy-saving, environmental protection and sustainable development, andusing it in the HVAC field has become a common and arduous task of our scientific andtechnological workers. Ground-source heat pump system is the best choice in newenergy and new technology wothy of promotion and development for its energy-saving,environmental protection and sustainable development. Our country has a vast territory,larger climate difference between the north and the south, both summer load primarilyin southern hot summer and cold winter zone and winter load primarily in northern coldregions, so the application of ground-source heat pump system appeared big geothermalimbalance. In view of this situation, it is proposed that the compound ground-sourceheat pump system can ease the geothermal imbalance during the operation of groundsource heat pump system. Therefore, in our current situation and conditions, we shouldmake great efforts to strengthen the research and development of compoundground-source heat pump system, to promote its application and development.This paper references the developments of compound ground-source heat pumpsystem at home and abroad, considers a variety of problems in engineering design andapplication, is mainly on cooling tower compound ground-source heat pump system andboiler compound ground-source heat pump system used in the office building of twotypical climate zones which are summer load primarily in hot summer and cold winterzone and winter load primarily in cold regions.This paper researches the climatic conditions and the type of construction of theoffice building in Chongqing and Harbin on behalf of the two typical climate, accordingto three building dynamic load characteristic parameters influenced on theground-source heat pump system： the accumulation of total load characteristics, theload change characteristic and the load of persistent, analyzes the characteristics ofdynamic load of office building in the typical climate zone, finds that it is adverse to theperformance of the underground heat exchanger of the ground-source heat pump and thesystem operating for a long time is likely to cause a problem of the imbalance of geothermal.In this paper it designs the compound ground-source heat pump system, determinesit using the series system and parallel system, and uses the recommended method toselect equipment type for the system. It establishes considering unit start-stop control,heat transfer model of dynamic EER heat pump units, heat transfer model of thethree-dimensional underground heat exchanger tube bundle, plate heat exchanger heattransfer model, heat transfer model of cooling tower based on the Merkel enthalpypotential method and heat transfer model of boiler. In the establishment of the variouscomponents of the system energy consumption model, we get the operating can effectcomparing mathematical model of compound ground-source heat pump system. Theestablishment of the model lay the foundation for the simulation of operational featuresand the analysis of the running effect of compound ground-source heat pump system.In this paper it is from the economy, energy conservation and reliability tocomprehensive evaluation the earth thermal equilibrium method, is index respectively inthe initial investment, operation cost cumulative value, year average of system operationcan effect comparing and ground-source side heat pump units outlet temperature, basedon the analysis of operating characteristics of compound ground-source heat pumpsystem and learning from the commonly used control strategies at home and abroad todevelop a control strategy of compound ground-source heat pump system. Through thegeothermal balance evaluation method, it evaluates the geothermal balance of officebuilding ground-source heat pump system in the typical climate zone, and compares thegeothermal balance of compound ground-source heat pump system in different systemsand different control strategies. It analyzes and summarizes the following conclusion：Office building in typical climate zone to use ground-source heat pump system hascertain geothermal imbalance, and can use compound ground-source heat pump systemto improve its geothermal balance.For cooling tower compound ground-source heat pump system, series systemdifferential temperature control strategy is optimal. The control strategy has a bettereconomy, energy efficiency and reliability. It also has the best long-running geothermalbalance.For boiler compound ground-source heat pump system, parallel system lowesttemperature control strategy is optimal. The control strategy has a better economy,energy efficiency and reliability. It also has the best long-running geothermal balance.This paper is not only in order to put forward optimal control strategy suitable for different system, the main purpose is to provide the ways and methods for theoptimizing operation of compound ground-source heat pump system,and providecertain theory reference and guidance meaning for its further promotion and application.