Question

A Parabolic trough concentrator with width of 3 m and length of 25 m has an absorbed solar radiation per unit area of aperture of 600 W/m². The receiver is a cylinder with an emittance of 0.3 and is surrounded by an evaluated glass cylindrical envelope. The absorber has a diameter of 50 mm and the transparent envelope has an outer diameter of 100 mm with a thickness of 5 mm. The collector is designed to heat a fluid entering the absorber at 100ºC at a flow rate of 0.0425 kg/s. The collector temperature is assumed as 200^oC. The fluid has a specific heat of 3.89 kJ/kg K. The heat transfer co-efficient inside the tube is 250 W/m² K and the overall loss co-efficient of 5 W/m² K. The tube is made up of stainless steel with a thermal conductivity of 15 W/m K and a wall thickness of 4 mm. If the ambient temperature is 20ºC, estimate the useful heat gain, collector efficiency and the exit fluid temperature.

Answer 1