| The solar greenhouse is one of the main forms of future agriculture,and it is also the focus of zero-carbon building research in the carbon neutral business.This research aims to optimize the solar greenhouse solar-assisted nanofluid ground source heat pump(PVT-GSHP)system,and provide a feasible and cost-effective technical path for achieving carbon neutrality.System energy cleanliness rate has important practical significance.This paper studies the optimal configuration of photovoltaic thermal devices PVT,nanofluids,and ground source heat pumps required to achieve the highest energy efficiency in a solar greenhouse system.In this study,a combination of numerical simulation and experiment was used.First,the thermal parameters of the nanofluid and soil were measured according to the experiment,and the environmental parameters were collected at the same time,and the architectural model suitable for the solar greenhouse was established,fully considering the photothermal characteristics of the solar greenhouse,environmental heat transfer,and thermoelectric load requirements.Afterwards,through numerical simulation,the application results of ground source heat pumps under different types of nanofluids and different pipeline configurations were obtained.The optimal PVT configuration ratio suitable for the nanofluid ground source heat pump system was studied,and the change of the energy utilization efficiency of the coupled system was further studied for the typical climate conditions in Guanzhong.Finally,according to the indicators of energy economics and energy environment,the SMA algorithm is used for multi-objective optimization,and the results reveal the optimal system configuration scheme.The main research contents and conclusions are as follows:(1)The thermal conductivity of nanofluids increases with the increase of the doping ratio of nanoparticles,and the doping mass ratio must be lower than 2%,otherwise precipitation will easily occur,and the properties of Cu O and Al2O3 have the same change trend.Parameters such as environmental heat transfer and sunlight temperature have a significant impact on the heat and electricity demand of solar greenhouses,while soil heat parameters mainly affect the heat transfer effect of ground source heat pumps.(2)The selection of pipeline type and nanofluid type will directly affect the equipment performance of ground source heat pump.The introduction of nanofluids has significantly increased the outlet temperature,and the maximum impact can exceed 1.5°C.The optimal fitting tube types of Cu O and Al2O3 nanofluids are not the same,but when the doping ratio of both increases to 2%,the COP in all tube heat exchangers becomes more stable.The spiral pipe may have more heat loss due to more turbulence and impact at the turn,and the heat transfer effect is not outstanding.(3)With the introduction of PVT equipment,the overall COP of the PVT-NFGSHP system has been greatly improved.During the period of strong sunshine from 9:00 to 15:00,the overall COP of the system can be as high as 7.5;and at this time,the outlet temperature increases,PVT work efficiency has also been greatly improved,more than 50%.Heat replenishment from PVT in winter further reduces soil heat loss,which is also important for environmental improvement.In addition,cash crops in greenhouses do not bring high income,and high economic value crops may be a better choice(4)Under the typical Guanzhong climate,according to the indicators of energy and environmental economics,the energy,exergy value,carbon emission and economic changes of the PVT-NFGSHP system in different scenarios are analyzed through the SMA algorithm,and the optimal value under different conditions is given.Optimal configuration and optimization methods.The results show that the optimized PVT-NFGSHP solar greenhouse system can achieve significant emission reduction while maintaining low LCOE and LCOH. |
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