3.58 A closed, rigid tank contains 2 kg of water, initially a two- phase liquid–vapor mixture at 80°C. Heat transfer occurs until the tank contains only saturated vapor with y 5 2.045 m3/kg. For the water, locate the initial and final states on a sketch of the T–y diagram and determine the heat transfer, in kJ.
3.59 As shown in Fig. P3.59, a rigid, closed tank having a volume of 20 ft3 and filled with 75 lb of Refrigerant 134a is exposed to the sun. At 9:00 a.m., the refrigerant is at a pressure of 100 lbf/in.2 By 3:00 p.m., owing to solar radiation, the refrigerant is a saturated vapor at a pressure greater than
100 lbf/in.2 For the refrigerant, determine (a) the initial
9:00 a.m. 3:00 p.m.
m = 75 lb
V = 20 ft3
At 9:00 a.m.,
p1 = 100 lbf/in.2
At 3:00 p.m., saturated vapor at p2 > 100 lbf/in.2 Fig. P3.59
T1 = -10°C
x1 = 80% T2 = 40°C V = 0.01 m3
Resistor 12-volt battery provides a
5-amp current for 5 minutes.
temperature, in °F, (b) the final pressure, in lbf/in.2, and
(c) the heat transfer, in Btu.