What is thermal energy?
a. thermal energy is a measure of a substance specific heat
b. thermal energy is the measure of movement of the substances molecules
c. thermal energy is the same as the substances temperature
d. thermal energy is measure of a substance vaporization

Air is to be preheated by hot exhaust gases in a cross-flow heat exchanger before it enters the furnace. air enters the heat exchanger at 95 kpa and 20°c at a rate of 0.6 m^3/s. the combustion gases (cp = 1.10 kj/kg°c) enter at 160°c at a rate of 0.95 kg/s and leave at 95°c. determine the rate of heat transfer to the air and its outlet temperature.