The Operating Characteristics Of System Of Ground Source Heat Pump Combined With Storage Tank In Hot Summer And Cold Winter Area

Ground source heat pump is a kind of technology which takes soil or ground water as heat source or heat sink to transfer the energy absorbed from soil or ground water to the building through the consumption of a certain amount of high-grade energy.It is a kind of technology widely used in modern heat pump technology,which utilizes sustainable energy to realize heating and cooling.Ground source heat pump usually takes underground pipe as the pipeline of heat transfer medium and takes water as heat transfer medium.The small variations in temperature characteristic of the soil or groundwater can improve the efficiency of heat pump units to achieve energy conservation,emissions reduction,operation cost saving.Furthermore,it can avoid the heat island or cold island effect and the negative influence on the personnel activity area of thermal environment.First of all,the author used DeST to calculate the annual hourly load of the researched building in this paper,and analyzed the load characteristics of the annual and typical day.On the basis of annual hourly load calculation outcomes and experimental results of geotechnical thermal response,the author used TRNSYS software to simulate the whole year energy consumption,outlet water temperature and other parameters.The heat unbalance of ground source heat pump system and the negative impact of heat unbalance on the energy consumption of the system is confirmed,which verified the necessity of cool storage.At the same time,based on engineering experience,the author ultimately set the shape as cylindrical and volume of heat storage water tank as 3320m~3.The operation characteristics of ground source heat pump system combined with storage tank is calculated by TRNSYS,and the parameters such as outlet temperature and energy consumption are compared with the system without storage tank.Otherwise the cost saving,energy saving and emission reduction are also analyzed.All the outcomes above verified that the seasonal cold storage technology for ground source heat pump system is beneficial to thermal balance and energy saving.Next,in order to research the control strategies of thermal storage water tank-ground source heat pump system,the author compared the operation characteristics of the system under several different control strategies and then analysed the pros and cons of different control strategies.On this purpose,the author formulated"upper outlet water limit of 33℃"cooling control strategy and the strategy considering the water tank heat supplying on the basis of original control strategy.The outlet water and energy consumption under three kinds of strategies were compared to analyse the heat balance and energy saving quality.In addition to optimize the system,the author also researched the most suitable tank volume for this system.According to the outcomes,the author observed that increasing the volume of tank is beneficial to energy conservation,however the underground space is limited,so the author ultimately took the cold load undertaken by a unit of volume as an index.As the research outcomes the volume of water tank was ultimately determined as 2075 m~3,which provided a valuable reference for future research and engineering.Furthermore,the author observed that when the tank volume is 17181 m~3,the system can reach 100%heat balance,which indicates that eliminating the heat unbalance by improving tank volume is accessible in theory.Finally,the author studied the feasibility of replacing part of the underground pipes with a certain volume of tank.Based on average number of annual highest outlet temperature,annual lowest outlet temperature and annual average outlet temperature,the mathematical relationship formulation between number of boreholes and tank volume was concluded.Different groups of system were compared according to highest outlet temperature,lowest outlet temperature,annual average outlet temperature and energy consumption.The author drew the conclusion that with the increasing of storage tank volume,the fluctuation outlet temperature of U-tube pipes increases.Meanwhile,the energy consumption of heat pump is not only effected by the average outlet temperature,but also the temperature fluctuation of U-tube pipes.After that,the author certifies that the best system is 3320m~3 tank volume+120 borehole number according to the cold load undertaken by a unit of volume.