On the measurement of bond conductance in solar collector absorber plate

A new experimental method for the measurement of bond conductance between the absorber plate the tube of a solar collector was developed. It consists of generating a measured heat flux via an electric resistance heater to simulate solar energy input to the absorber plate. This heat is absorbed by a fluid flowing through the tube and that is also measured. By comparing the energy generated and the energy absorbed, the bond conductance was estimated. Experimental and theoretical methods were compared for absorber plates which contain grooves and tubes embedded to them. Five samples of locally-made fin-and-tube configurations were tested and their bond conductance was found. It was found that the bond conductance of those samples ranged from 6.3 to 1.8 W/m K and that the high conductance was made possible by using the press-fit method in manufacturing those collectors.