Simulation And Optimization Of Ground Source Heat Pump System Based On TRNSYS

With the development of social economy,a series of problems,such as the deterioration of ecological environment,the shortage of energy supply,and the intensification of greenhouse effect,has become increasingly prominent.As a big energy consuming country,the government has issued a series of policies on energy conservation and emission reduction.In order to actively respond to the government's call for energy conservation and emission reduction,ground source heat pump technology came into being.As a renewable energy application technology utilizing geothermal energy,ground source heat pump has been playing an important role in sustainable development.In this paper,the ground source heat pump system of an office building in hot summer and cold winter area is taken as the research object,and by testing and analyzing the operating parameters of the system in winter and summer,the aim is to find out the operation rule of each parameter of the ground source heat pump system and the key influencing factors of COP of the heat pump unit.Its annual operation data are tested by building monitoring system.The user side supply and return water temperature,the ground source side supply and return water temperature,unit performance coefficient and power consumption were analyzed.The results showed that the average unit coefficient of performance in summer was 3.92,and the average unit coefficient performance in winter was 4.09.The heat and cold imbalance of the ground source heat pump system was serious and the operating efficiency of the system is worse in summer than in winter.Then the monitoring data obtained are taken as the basic data and the importance of each operating parameter that affects the unit coefficient of performance is analyzed by using the random forest model.The results show that the partial load rate is the most important factor affecting the variation of unit coefficient of performance,followed by the return water temperature at the ground source side.Next,the TRNSYS simulation software was used to establish the simulation system with the source heat pump system as the prototype,and the aim is to simulate and analyze the long-term operation state of ground source heat pump system and improve the system performance.The accuracy of the simulation model was verified by comparing the measured value with the simulated value.Then,taking the total power consumption as the objective function,the optimal control strategy was proposed for the existing problems of the system and the variables with high importance to the variation of unit coefficient of performance.Firstly,variable water temperature control is adopted according to the load rate of the heat pump unit,and the return water temperature of the user side is indirectly controlled by controlling the water supply temperature.Secondly,the cooling tower is opened on the ground source side under the refrigeration condition,and the control strategy of regular start and stop is adopted.In addition,the start and stop time of the pump and the unit remains unchanged.Finally by using the simulation model to simulate the effect of optimization of ground source heat pump system after long-term operation,the results show that under the optimal control strategy,the system runs in 10 years with soil temperature rise is only 2.0?,compared with before optimization decreased by 4.7?,and the system can effect comparing with the coefficient of performance for the whole year during summer and winter seasons are higher than the benchmark control strategy.The optimized system saved 143155 kWh of power in 10 years,and the energy saving was 16.2%.