Question

A real vapor compression heat pump system, illustrated in Figure 5 below, has a heating capacity of 70,000 Btu/h, and uses 134a as the refrigerant working fluid. The working fluid enters the compressor (State 1) as saturated vapor at a temperature of 20.0°F. The refrigerant exits the compressor (State 2) as a superheated vapor at 180 psi and temperature of 200°F. The refrigerant exists the condenser as a saturated liquid at 115°F. To receive full credit you must include units in your computations. $T_3 = 115°F$ $\dot{Q}_{out} = 70,000 \text{ Btu/h}$ 3 Condenser 180 lbf/in.$^2$ 2 4 Expansion Valve Evaporator $Q_{in}$ Figure 5 $T_2 = 200°F$ $W_c$ Compressor Saturated Vapor 1 Determine the following: (5 points each) a) The mass flow rate of the refrigerant, in lb/min. b) The compressor power input, in horsepower. c) The quality, x, and the temperature $T_4$ in °F at State 4. d) The real isentropic compressor efficiency. e) The coefficient of performance. f) Clearly illustrate this cycle on a T-s diagram with approximate locations for each state and the approximate corresponding temperatures and pressures. (Note: poorly, cryptically, or carelessly drawn T-s diagram representations will not be graded.)

          A real vapor compression heat pump system, illustrated in Figure 5 below, has a heating capacity of 70,000 Btu/h, and uses 134a as the refrigerant working fluid. The working fluid enters the compressor (State 1) as saturated vapor at a temperature of 20.0°F. The refrigerant exits the compressor (State 2) as a superheated vapor at 180 psi and temperature of 200°F. The refrigerant exists the condenser as a saturated liquid at 115°F. To receive full credit you must include units in your computations.
$T_3 = 115°F$
$\dot{Q}_{out} = 70,000 \text{ Btu/h}$
3
Condenser
180 lbf/in.$^2$
2
4
Expansion
Valve
Evaporator
$Q_{in}$
Figure 5
$T_2 = 200°F$
$W_c$
Compressor
Saturated Vapor
1
Determine the following: (5 points each)
a) The mass flow rate of the refrigerant, in lb/min.
b) The compressor power input, in horsepower.
c) The quality, x, and the temperature $T_4$ in °F at State 4.
d) The real isentropic compressor efficiency.
e) The coefficient of performance.
f) Clearly illustrate this cycle on a T-s diagram with approximate locations for each state and the approximate corresponding temperatures and pressures. (Note: poorly, cryptically, or carelessly drawn T-s diagram representations will not be graded.)

A real vapor compression heat pump system, illustrated in Figure 5 below, has a heating capacity of 70,000 Btu/h, and uses 134a as the refrigerant working fluid. The working fluid enters the compressor (State 1) as saturated vapor at a temperature of 20.0°F. The refrigerant exits the compressor (State 2) as a superheated vapor at 180 psi and temperature of 200°F. The refrigerant exists the condenser as a saturated liquid at 115°F. To receive full credit you must include units in your computations.
T3 = 115°F
Q̇out = 70,000 Btu/h
3
Condenser
180 lbf/in.^2
2
4
Expansion
Valve
Evaporator
Qin
Figure 5
T2 = 200°F
Wc
Compressor
Saturated Vapor
1
Determine the following: (5 points each)
a) The mass flow rate of the refrigerant, in lb/min.
b) The compressor power input, in horsepower.
c) The quality, x, and the temperature T4 in °F at State 4.
d) The real isentropic compressor efficiency.
e) The coefficient of performance.
f) Clearly illustrate this cycle on a T-s diagram with approximate locations for each state and the approximate corresponding temperatures and pressures. (Note: poorly, cryptically, or carelessly drawn T-s diagram representations will not be graded.)

Added by Noah A.

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