Using the Energy BalanceOne kg of Refrigerant 22,

QUESTION:

One kg of Refrigerant 22, initially at \(p_1=0.9 \mathrm{MPa}\), \(u_1=232.92 \mathrm{~kJ} / \mathrm{kg}\), is contained within a rigid closed tank. The tank is fitted with a paddle wheel that transfers energy to the refrigerant at a constant rate of \(0.1 \mathrm{~kW}\). Heat transfer from the refrigerant to its surroundings occurs at a rate Kt, in kW, where K is a constant, in kW per minute, and t is time, in minutes. After 20 minutes of stirring, the refrigerant is at \(p_2=1.2 \mathrm{MPa}, u_2=276.67 \mathrm{~kJ} / \mathrm{kg}\). No overall changes in kinetic or potential energy occur.  (a) For the refrigerant, determine the work and heat transfer, each in kJ. (b) Determine the value of the constant K appearing in the given heat transfer relation, in \(\mathrm{kW} / \mathrm{min}\).