Acopper sheet of thickness 2 mm has an initial temperature of 170°c. it is suddenly quenched in liquid water, resulting in boiling at its two surfaces. for boiling, newton’s law of cooling is expressed as , where is the solid surface temperature and is the saturation temperature of the fluid (in this case 100°c). the convection heat transfer coefficient may be expressed as . determine the time needed for the sheet to reach a temperature of 104°c.

Liquid flows at steady state at a rate of 2 lb/'s through a pump, which operates to raise the elevation of the liquid 100 ft from control volume inlet to exit. the liquid specific enthalpy at the inlet is 40.09 btu/lb and at the exit is 40.94 btub. the pump requires 3 btu/s of power to operate. if kinetic energy effects are negligible and gravitational acceleration is 32.174 tt/s, the heat transfer rate associated with this steady state process is most closely 1)-2,02 btu/s from the liquid to the surroundings 2)-3.98 btu/s from the surroundings to the liquid. 3)-4.96 btu/s from the surroundings to the liquid. 4)-1.04 btu/s from the liquid to the surroundings.