Question

Problem 3: The specifications of a flat-plate collector is as follows: τ = 0.88, α 0.97, U = 1.3 Btu/h ft2 °F. The heat removal factor for the collector is 0.92, the solar insolation is 210 Btu/h ft2, and the ambient air temperature is 60°F. Determine (a) the collector efficiency if the water enters the collector at 115°F and (b) the temperature of water at which the collector efficiency is zero. Take the incident angle modifier to be 1

Answer 1

Write the expression for the useful energy extracted by the collector Write the expression for collector efficiency eu IA IA Ti-T Substitute the given values (112102) 115-60 (0.92) (0.88) (0.97)-(0.92) (1.3) -0.4721 ~ 47.2% From the equation (1)

(부) T -T T.-T T.-T Substitute the given values (210) (0.88)(0.97) +60 197.889 ℉ ~ 197.9 ℉