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A wall subject to intense radiative and convective heating is to be protected by sweat cooling

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A wall subject to intense radiative and convective heating is to be protected by sweat cooling. For this purpose water is injected onto the surface through a porous stainless steel plate at a rate sufficient to keep it wetted and to keep the surface temperature at 360 K. Bone-dry air at 840 K and 1 atm flows past the surface and causes a convective transport to the surface. In addition there is a radiation of 461 W/m2 impinging on the surface. The heat and mass transfer coefficients are estimated from the boundary layer. We use the following values: km = 0.02 m/s and h = 250 W/m2 · K. (i) Calculate the water flow rate needed to keep the surface at the desired temperature. (ii) If the water comes from a cold reservoir, find the water temperature in this reservoir which would be required in order to maintain a steady state.