Consider a packed bed of spheres, each of diameter 2 mm, at an initial temperature of 87.5°C. Cold water at 5.0°C is poured onto the bed at 0, producing a large convection coefficient about each sphere. Determine the magnitude of the rate, in °C/s, at which an individual sphere near the top surface of the bed is cooled at 0.1, 0.25, and 1 s. The spheres have thermophysical properties similar to Pyrex.

An air-conditioning system consists of a heating section and an evaporative cooler. air enters the heating section at 10°c and 70 percent relative humidity at a rate of 30m^3/min, and it leaves the evaporative cooler at 20°c and 60 percent relatively humidity. if the air conditioning system operates at a total pressure of 98 kpa, determine (a) the temperature and relative humidity of the air when it leaves the heating section, (b) the rate of heat transfer in the heating section, and (c) the rate of water added to air in the evaporative cooler