A Self-driven Mechanical Ventilated Solar Air Collector:Design And Experimental Study

The application of solar air collector(SAC)is limited by urban power grid.To overcome this shortcoming,this paper proposed a self-driven mechanical ventilated solar air collector(SDSAC)that can work independently without urban power grid,and carries out corresponding structural and electrical design.The system not only provides hot air that can be used for space heating,crops and wood drying,but also solves its own power supply problem,thus achieving the goal of energy conservation and emission reduction.The proposed collector system uses a mixture of photovoltaic(PV)panel and heat absorber plate in the structure to maintain the system’s thermal performance to the maximum extent and achieve self-driven operation of the system.A set of natural ventilated solar air collector(NVSAC)with the same structural parameters as the target system was established as the comparison system.Based on the built test bench,the system was tested and studied under the condition of sufficient light in summer.Relevant data were collected during the experiment,and the energy index of the system was analyzed through the first law of thermodynamics.The results show that the self-driven operation of SDSAC is realized in the experiment,and the working process can be divided into five stages In particular,the outlet temperature,flow rate and thermal efficiency are almost constant in about two hours at quasi-isothermal stage.The work of NVSAC is unstable and inefficient,and reflux often occurs in the working process.The thermal efficiency of SDSAC is up to 74.2%,and the average thermal efficiency is 49.2%,which is far better than that of NVSAC with the average thermal efficiency of 11.5%.This article continues to discuss the effects of different experimental conditions on the performance of the collector,including the stability of the performance of the collector under the same meteorological conditions,the influence of the collector’s inclination,orientation,and panel position on the performance of the collector.The results show that under the same experimental conditions,the thermal performance of the novel collector can maintain stable operation.By changing the inclination and orientation of the collector,it is found that the inclination of the collector has a significant impact on its photoelectric and photothermal efficiency peaks,and has no significant effect on the peak appearance time.The change of the orientation of the collector has a significant effect on the occurrence time and the value of the peak value of the photothermal efficiency.Under the experimental conditions,the thermal performance of the collector is optimal when it maintains an inclination angle of 45 ° towards 15 ° E.In addition,the use of the cooling effect of the incoming low-temperature air to set the PV panel in the collector’s first cavity can make the collector optimal performance.The transient simulation software TRNSYS is used to establish a flat-plate collector simulation models.The experimental results were compared with the simulation results.After verifying the experimental model,the meteorological parameters,air flow,and panel area were further analyzed to the collector performance influences.The self-driven mechanical ventilation solar air collector proposed in this paper as a new type of collector provides a new idea for researchers.