Research On Performance Prediction And Operation Strategy Of Ground Source Heat Pump System Based On Data Mining

Under the circumstances of energy conservation and emission reduction,clean and renewable energy used in buildings has been vigorously promoted in China.The ground source heat pump(GSHP)systems were typical shallow geothermal energy utilization technology which were widely used in buildings.Compared with the traditional central air-conditioning system,the main disadvantage of the GSHP system was the relatively high initial investment.Therefore,it was very important to ensure that the GSHP system can maintain its long-term high efficient operation to reduce its operating costs.In addition,due to the problem of unbalanced cooling and heating loads in most areas of China,the GSHP system was usually used in conjunction with other equipment,such as cooling towers,solar panels,and air source heat pumps(ASHP),for preventing the phenomenon of "heat accumulation in the soil".That increased the difficulty of the promotion and application of ground source heat pump technology.This paper studied the performance prediction and operation strategy of ground source heat pump systems.It had important theoretical and practical significance for the efficient operation of ground source heat pump systems.In view of the application status of GSHP system,firstly,this study summarized and analyzed the application situation of 39 GSHP demonstration projects in Wuhan.It was found that GSHP technology has a good application situation in Wuhan.The indoor temperature and humidity reached an overall standard.The overall energy efficiency of each project was good.The average energy efficiency coefficient was slightly higher than the average level of energy efficiency coefficients of some domestic published projects.At the same time,however,there were also many problems: high energy consumption in the transmission and distribution system,system operating conditions do not meet the design requirements,energy efficiency measurement conditions are not up to standards.For the problem that the short-term monitoring of GSHP systems was difficult to respond to its long-term performance,data mining technology was brought in to this study.Based on an actual GSHP system,the application process of data mining technology used in GSHP system modeling was introduced.Then,used the data mining model,the relationship between short-term assessment results and long-term performance prediction results was discussed.It was showed that if the number of days for short-term evaluation is guaranteed,the results of short-term evaluation can be used in place of long-term performance prediction.For systems which had similar climate areas and capacity to the projects in the study,the number of days needed for short-term assessment were 75(in winter),31(without cooling tower)and 12(with cooling tower)to obtain the long-term energy efficiency ratio of the GSHP system.Moreover,it had also been found that the accuracy of energy efficiency measurement has a significant relationship with the load rate of the unit and the system in monitoring.Then,a GSHP+ASHP+RCT(Radiant-Capillary Terminal)system was proposed in this study.The experiments of GSHP+RCT system and ASHP+ RCT system were conducted in winter and summer,respectively.Basing on the experimental system,TRNSYS models of GSHP+ RCT system and the ASHP+RCT system were established.And the accuracy of the models were verified using the experimental data.Using results of the experimental and models,the application situation of the GSHP+RCT system and the ASHP+RCT system were analyzed.And the performances of the GSHP system and the ASHP system under different working conditions were compared.Following that,the operating strategy of the GSHP+ASHP+RCT system was formulated combined with the classification decision tree algorithm models,which were trained and verified by the time-stimulated data of the GSHP+RCT system and ASHP+RCT system from the TRNSYS models.Then the TRNSYS model of GSHP+ASHP+RCT system was established under this operating strategy.It was found through simulation that the average temperature of the soil in the 20 th year increased by 3.87°C.The overall energy efficiency of the system increased by 3.79% and 6.9% compared with GSHP+RCT system and the ASHP+RCT system,respectively.That verified the feasibility of GSHP+ASHP +RCT system.Finally,the primary energy efficiency and life cycle cost of the GSHP+ASHP+RCT system were compared with the other three types of systems(chiller+gas boiler,GSHP+cooling tower,and ASHP system)in this study.It was found that the system has high primary energy efficiency,higher than other three types of systems with 4.5%,1.8%,and 10%,respectively.And the life cycle cost was the lowest,lower with 20.6%,8.3% and 25.5%,respectively.It shown that the joint system has a good application value from the perspective of energy saving and economy.This study introduced the long-term performance prediction method of GSHP system and its operation strategies combined with ASHP and RCT.The performance evaluation method of GSHP system was optimized.And the application of GSHP systems had been expanded.This had a positive significance on the promotion and application of GSHP systems used in architecture.