Consider the flat-plate solar collector of Problem 9.100. The absorber plate has a coating for which ε₁ = 0.96, and the cover plate has an emissivity of ε₂ = 0.92. With respect to radiation exchange, both plates may be approximated as diffuse, gray surfaces.

(a) For the conditions of Problem 9.100, what is the rate of heat transfer by free convection from the absorber plate and the net rate of radiation exchange between the plates?

(b) The temperature of the absorber plate varies according to the flow rate of the working fluid routed through the coiled tube. With all other parameters remaining as prescribed compute and plot the free convection and radiant heat rates as a function of the absorber plate temperature for 50 < T₁ < 100°C.