Study On A Following Day Load Simulation Method And Its Application Research On A Solution For Thermal Compensation Of Ground-coupled Heat Pump Systems

Accurate calculation of heating or air conditioning load is the basis for the reasonable design and scientific operation management of HVAC system.However,the existing load forecasting and simulation methods require a large amount of data for training model,and the accuracy of those methods is not stable enough.Moreover,it is very difficult for those models to respond to the drastic changes of the external parameters.Although varies of load and energy simulation softwares were mature and have been widely used in practical engineering,the weather data bases of these software are established based on historical meteorological parameters by statistical method.Under the tendency of global climate change,the meteorological parameter in these weather databases is quite different from the actual weather conditions.While,the development of meteorological science makes the accuracy of the weather forecast data released by the government improved greatly.The accurate weather forecast provides the possibility for the simulation of load using the weather data closer to actual condition.In order to improve the meteorological parameters database of load simulation softwares,so as to reduce the error of load simulation,this paper proposed a following day load simulation method(FDLS)based on weather forecast parameters.In this method,the weather databases in load simulation softwares are modified using prediction models based on weather forecast.The following day load simulation method needs to predict the nest day’s dry bulb temperature,wet bulb temperature and solar radiation intensity.The prediction of the next day dry and wet bulb temperature is based on the modified grey GM(1,1)model proposed by the Hong Kong scholars.Because the prediction of hourly solar radiation intensity is difficult,the official weather forecast does not provide the numerical prediction of next day’s solar radiation intensity.Moreover,the existing prediction methods for the next day’s hourly solar radiation intensity are not precise enough for widely engineering usage.To improve the prediction accuracy of the solar radiation intensity,this paper proposed a modified "solar term similar days group"(STSDG),which predict the next day’s hourly solar radiation intensity based on the DeST weather data library,measured weather data in recent 3 years and next day’s weather forecast data.The accuracy of STSDG method of the prediction the hourly solar radiation intensity is similar with exiting method.Moreover,the accuracy of prediction of the daily accumulated solar irradiance by the STSDG method is better.However,this method ignores the effects of air pollution,and is only applicable to areas or periods with good air quality.According to the feature of serious air pollution in winter in northern China,a modified solar term similar days group(STSDG)method was proposed to improve the accuracy of solar irradiance prediction in hazy weather.This modified STSDG method was based on air quality forecast and AQI(Air quality Index)correction factors and has a higher prediction precision in high AQI weather conditions.In order to make the next day load simulation method(FDLS)play an important role in practical engineering,the application study of this method is conducted in this paper.The application study is mainly about two directions,ice storage systems and heat compensation systems of the ground couple heat pump.In a case study of the FDLS method in an ice storage system,the accuracy of FDLS was proved through the comparison between the predicted load by FDLS and the measured load.The operation strategy of ice storage systems can be set based on the prediction results of the FDLS method.For the purpose of playing advantage of FDLS,two kinds of thermal compensation of ground couple heat pump are proposed in this paper:a thermal compensation system based on exhaust air heat recovery(EHR)and an exhaust air heat recovery and solar energy combined thermal compensation system(ESTC).A low energy-cost calculation model of heat exchanger design was also proposed.Based on the prediction of the next day’s exhaust air temperature and solar irradiance,an optimized thermal compensation(OTC)method was developed in this study as well,in which the exhaust air heat recovery compensator and solar energy compensator in the ESTC system run at high efficiency throughout various times of day.The modified GM(1,1)model based on temperature measurements and weather forecast parameters was used to predict the next day’s hourly dry-bulb temperatures of the ETD room exhaust air.Moreover,this manuscript adopted the modified STSDG method to predict solar irradiance in hazy weather.The operation experiments of EHR-GCHP and ESTC-GCHP were conducted using the exhaust air of kitchen and electricity transformation and distribution(ETD)room,respectively.The experimental results presented that the EHR and ESTC system are all more efficient than normal thermal compensation systems.Furthermore,the energy consumption of the thermal compensation process in ESTC-GCHP system was reduced significantly by using the OTC method.The TEC of this approach was 1.25 times as high as the traditional combined operation method.The main innovative work of this study mainly includes the following points:(1)Based on the DeST simulation software,a following day load simulation method(FDLS)is proposed in this research.Compared with the existing methods of load forecasting,this method doesn’t need large amounts of historical data to train prediction models and can rapidly respond to the drastic changes of the external parameters.Moreover,the FDLS method is more accurate in load prediction.(2)The core of FDLS is using a variety of modified prediction models to predict the meteorological parameters,then replace the parameters in the weather data database of simulation softwares using the predicted value.Thus,the requirements for weather parameters’ prediction are relatively high in FDLS method.In order to improve the prediction accuracy of solar radiation intensity,a new solar term similar days group(STSDG)method was proposed.In addition,according to the characteristics of severe air pollution in winter in northern China,a modified solar term similar days group(STSDG)method based on air quanlity index(AQI)correction coefficient was also proposed.Moreover,the next day’s hourly dry and wet bulb temperatures were predicted using modified grey GM(1,1)model.(3)In order to meet the practical needs of engineering applications,the application study of FDLS method was conducted.The application study is mainly about two directions,ice storage systems and heat compensation systems of the ground couple heat pump.For the purpose of playing advantage of FDLS,two kinds of thermal compensation of ground couple heat pump are proposed in this paper:a thermal compensation system based on exhaust air heat recovery(EHR)and an exhaust air heat recovery and solar energy combined thermal compensation system(ESTC).Moreover,a low energy-cost calculation model of heat exchanger design was proposed.(4)According to the characteristic of ESTC-GCHP system,an optimized thermal compensation(OTC)method was proposed based on the weather parameters prediction models in FDLS method.The OTC method can reduce the energy consumption of the thermal compensation progress significantly for ESTC system.