Question

1. Consider an opaque, horizontal square plate (Im by 1m) with an electrical heater on its backside. The front side is exposed to ambient quiescent air that is at 20° C, solar irradiation (from sun at 5800° K) of 600 W/m2, and an effective sky temperature of -40° C. The plate surface temperature is kept at Ts 60 C (at steady state condition). Calculate natural convection heat transfer coefficient from the plate. (10 points) What is the electrical power (W/m2) required to maintain the plate surface temperature at Ts 600 C (at steady state condition) if the plate is diffuse and has designated spectral, hemispherical reflectively as shown? (10 points) a. b. Ts Sky Grs 0.7 Air h, T o, 2 Plate HaterInsulatien

Answer 1

600 W/m2 ー 580 S k 60° con v healer elec alanc conv-e E Scanned with amScanner

ol. 〉,s here Os = ·TTI it _ot_ he mis pherical Shage Emissiyi (I- Fo-24m) C1-07) Fo-24m 1-0.2) + CamScanner

O-3 Total ehemisphexical absamptivity tor 4 ax 5.67316 x283 e ec Scanned wit CamScanner