Simulation And Optimization Study Of Ground Source Heat Pump Coupled With Water Storage Tank By TRNSYS

In recent years,many projects use the system of ground source heat pump coupled with water tank.However,in the practical engineering,the percentage of the energy capacity of water tank storage accounts for the total design daily load is different.Therefore,the percentage of saving initial cost and running cost are different.This paper uses TRNSYS to do a dynamic simulation of the whole year about the system that ground source heat pump coupled with water tank.On the basis,this paper studies the configuration range and optimal configuration about the coupled system,then analysis the effects of different design approach and peak-valley price.The results show that: in the mode of energy storage is priority,when the capacity of the heat pump is constant,the lager the storage water tank,the less the running cost.The payback period is increasing with the volume of the storage tank increases.When the storage proportion is less than or equal to 25%,the payback period of the coupled system is less than 5 years.As the storage proportion is varies from 10% to 100%,under the principle that meet the energy storage requirement and load requirement,when the storage proportion is 40%,the annual cost is the smallest,the economy of the coupled system is the optimal.When the storage proportion is less than or equal to 60%,the annual cost of the coupled system is all less than conventional ground source heat pump system.When the storage proportion is bigger then or equal to 70%,the initial investment of the coupled system is greater than the conventional system,when the storage proportion is 70% or 80%,the payback period of the coupled system are 1.07 years and 7.71 years respectively.When the storage proportion is 90% and 100%,the coupled system has a poor economic returns with a payback period more than 10 years.With the increase of the peak-valley price ratio,the running cost of the coupled system is decreasing,however,the running cost of the conventional system is increasing.When the peak-valley ratio is 2,the running cost of the coupled system are all less than the conventional ground source heat pump system.When the energy storage volume is constant,design of the coupled system with two different method,one has the minimum initial investment,the other has the minimum running cost.Compared with the design method which has a minimum running cost,the running cost and the annual cost of the design method that has minimum initial investment is bigger than 11.08% and less than 25.40% respectively.Compare the two different design methods comprehensively,the design method with a minimum initial investment is better.