Experimental study on heat transfer performance of pulsating heat pipe solar energy collectors

Using vacuum glass tubes as the carrier,paraffin wax as the phase change heat storage material,pulsating heat pipe and copper pipe as the heat transfer elements,the heat collection performance of pulsating heat pipe solar energy collectors and copper pipe solar energy collectors with liquid filling ratio φ = 50.0% at the same irradiance is compared and analysed.The results show that when the irradiance is greater than 0 W/m2,the wall temperature of pulsating heat pipe solar energy collectors is 40 ℃ higher than that of copper pipe solar energy collectors.Compared with copper pipe solar energy collectors,the higher the heat source temperature is,the stronger the heat absorption capacity of pulsating heat pipe solar energy collectors is,and the better the heat transfer effect is.Under the same irradiance,the time for paraffin wax to reach the melting point in pulsating heat pipe solar energy collectors is 13% shorter than that in copper pipe solar energy collectors.The heat output of pulsating heat pipe solar energy collectors is 0.5 kJ higher than that of copper pipe solar energy collectors,and the heat difference will be larger with the increase of irradiance.The heat transfer working fluid in contact with the wall of the evaporation section and condensation section in the pulsating heat pipe will form a quasi-equilibrium state,and the heat transfer capacity of the evaporation section is inversely proportional to that of the condensation section.When the heat transfer capacity of the evaporation section decreases,the heat transfer capacity of the condensation section will increase,which ensures the stable operation of the collectors.