Dynamic Simulation And Performance Study Of Solar Photovoltaic/thermal Coupled Heat Pump Heating System

The rapid development and innovation of science and technology have promoted the progress of the entire society,but at the same time,it brought about severe and inevitable problems of rapid energy consumption and environmental contamination.In order to solve the unbalanced relation between energy and environment,we need to choose "open source" and "throttling" as coping methods.Solar energy,geothermal energy,and other energy resources have the advantages of huge development potential,small impact on the surrounding,and sustainable supply.Moreover,the heat pump is an energy-saving and eco-friendly device of high efficiency,so combining the solar and geothermal energy with heat pump has attracted more and more attention from national governments,scientific research institutions and scholars.At the meantime,considering fully of the application of clean heating in the north,this article proposes a unit system of solar photovoltaic light-heat with coupling ground source heat.Based on the construction of a simulation model,this system is dynamically simulated,and its operation performance was analyzed.First and foremost,based on the system principle,the new system proposed early in the article is preliminarily designed.Based on the analysis of existing types of PV/T collectors and heat pump units,the photothermic/photoelectric conversion device is selected as a water-cooling flat PV/T,equipped with a glass cover.The underground heat exchanger is placed in the shallow soil underground.When the heating season comes,the geothermal energy can serve as the status of heat source for the underground heat pump unit.The system can be working throughout the entire year.Also,it can set the its operating mode and make control strategies to output electrical energy through the PV/T collector in non-heating seasons,meanwhile store the thermal energy captured by the PV/T collector in shallow underground soil;in the heat-providing seasons,the geothermal energy in soil is used as the low-temperature source of the heat pump unit underground.Through the circulation of the working medium in the heat pump unit,heat would be provided to the determined object and help meet its heat load demand.On the next stage,the software TRNYSY is used to carry out dynamic simulation of the system newly designed.The whole system is built by creating the meteorological database,and adjusting the modules corresponding to the distinct devices in the system.Then,the model of the necessary parts in the system is established at the same time.Subsequently,we selected the building on the campus of a university in Beijing to provide heat system.Based upon the structure of the building and main rooms,thermal characteristic parameters were set:and the typical annual meteorological database in this area was retrieved.Through DeST software,the system can then be modeled and simulated.Not only the annual cooling and heating load data of the building objects throughout the year was obtained,but also its distribution characteristic was generated and revealed.Last but not least,the generated heat load data of the building was imported into the established solar photovoltaic coupling heat pump unit system,and the dynamic simulation results are obtained from the one-year operation in TRNSYS.Based on the establishment of a rating index for the heat pump system,the operating performance of the it was analyzed from three different aspects throughout the year:typical working days in the heating season and typical working days in the non-heating season.Thinking about that the system might be able to replace the traditional coal-fired heating method in actual engineering and life,the benefit of the system presented in this article is also analyzed from the perspectives of energy saving,sustainability and economic efficiency.Generally speaking from the calculation and analysis all above,it can be drawn that the system described in the article can meet the heat load demand of buildings,output electrical energy,and store the heat collected by the PV T collector in the form of geothermal energy in shallow underground soil,which can at the same time improve the thermal imbalance of the soil.Considering the practical application of heat-providing in the northern part in winter,the system described has considerable engineering value in practice.