Study On Heat Transfer In Solar Air Collector With Energy Storage

Nowadays,energy shortage and environment pollution is increasingly serious.As a kind of renewable energy,solar energy has bright development prospect.Solar air collector is a device which can collect solar energy and heat the air.The solar air collector with energy storage studied in this paper combines the flat-plate solar air collector with the phase change materials(PCM).Rectangular ribs are used in the air passage to enhance the heat transfer.With the method of numerical simulation and experiment,the paper approaches to the dimension parameter optimization of rectangular ribs and analyzes the heat transfer process of the air and PCM in the collector.In this paper,the heat transfer process of solar air collector with energy storage is analyzed,and the heat loss to surroundings is calculated.Enthalpy-porosity formulation is used as the solution of phase change heat transfer,and the operation control equation is given.In this paper,three-dimensional modeling of the air passage of the collector is carried out with different fin parameters,and the effects of dimensionless height,dimensionless width,dimensionless spacing and installation angle on the heat transfer performance of the air passage of the collector are calculated and analyzed.It is concluded that with the ribs parameters of h/H=0.8,w/W=0.1,p/P=0.1,?=45°,the collector has the best heat transfer performance.A three-dimensional model of the solar air collector with energy storage was also established in this paper.The UDF was used to program the solar energy absorption and temperature of inlet air,which was imported into Fluent as a boundary condition for numerical calculation.The change of PCM and air temperature over time are analyzed with the air flow rate of 0m~3/h?37.72m~3/h?56.58m~3/h?75.44m~3/h.The heat collecting efficiency of the collector under different operating conditions is also calculated and analyzed.At last,the test platform of solar air collector with energy storage is established in this paper,and the experiment of the heat transfer process of the collector is also carried out.The average temperature of PCM,outlet air temperature and collector efficiency of the collector were analyzed and compared with the air flow of the is 0m~3/h,37.72m~3/h,56.58m~3/h,and75.44m~3/h.The difference between the experimental value and the simulated value is compared and analyzed to verify the accuracy of the model.The experiment is also carried out when the collector is running at night.The change of air outlet temperature was measured with the the process of solidification and exothermic of PCM,when the inlet air temperature is 290K and the air flow rate is 30m~3/h,60m~3/h and 90m~3/h.