Chapter 14, Problem 28PE

In some countries, liquid nitrogen is used on dairy trucks instead of mechanical refrigerators. A 3.00-hour delivery trip requires 200 L of liquid nitrogen, which has a density at $\text{8}0\text{8 kg}/{\text{m}}^{\text{3}}$.

(a) Calculate the heat transfer necessary to evaporate this amount of liquid nitrogen and raise its temperature to $\text{3}00°\text{C}$. (Use c_p and assume it is constant over the temperature range.) This value is the amount of cooling the liquid nitrogen supplies.

(b) What is this heat transfer rate in kilowatt−hours?

(c) Compare the amount of cooling obtained from melting an identical mass at $0°\text{C}$ ice with that from evaporating the liquid nitrogen.