Question 11.CSGP.179b: Consider an ideal refrigeration cycle that has a condenser t......

Fundamentals of Thermodynamics – Solution Manual [1477300]

Consider an ideal refrigeration cycle that has a condenser temperature of 45°C and an evaporator temperature of −15°C. Determine the coefficient of performance of this refrigerator for the working fluid R-12.

Step-by-Step

The 'Blue Check Mark' means that this solution was answered by an expert.
Learn more on how do we answer questions.

Ideal refrigeration cycle

$\begin{aligned}& T _{\text {cond }}=45^{\circ} C = T _3 \\& T _{\text {evap }}=-15^{\circ} C = T _1\end{aligned}$

The value of $h_2$ is taken from the computer program as it otherwise will be a double interpolation due to the value of $P_2$ .

R-12	Property for:
180.97	$h _1, kJ / kg$	Compressor
0.7051	$s _2= s _1, kJ / kg K$
1.0843	$P _2, MPa$
54.7	$T _2,{ }^{\circ} C$
212.63	$h _2, kJ / kg$
31.66	$w _{ C }= h _2- h _1$
79.71	$h _3= h _4, kJ / kg$	Exp. valve
101.26	$q _{ L }= h _1- h _4$	Evaporator
3.198	$\beta= q _{ L } / w _{ C }$

Related Answered Questions

Question: 11.CSGP.61

A steam power plant operates with with a high pressure of 5 MPa and has a boiler exit temperature of of 600°C receiving heat from a 700°C source. The ambient at 20°C provides cooling for the condenser so it can maintain 45°C inside. All the components are ideal except for the turbine which has an ...

Verified Answer:

Take CV around each component steady state in stan...

Question: 11.CSGP.180d

The refrigerant R-22 is used as the working fluid in a conventional heat pump cycle. Saturated vapor enters the compressor of this unit at 10°C; its exit temperature from the compressor is measured and found to be 85°C. If the compressor exit is at 2 MPa what is the compressor isentropic efficiency ...

Verified Answer:

R-22 heat pump: Computer Table State 1:

...

Question: 11.CSGP.180c

Consider an ideal refrigeration cycle that has a condenser temperature of 45°C and an evaporator temperature of −15°C. Determine the coefficient of performance of this refrigerator for the working fluid R-22. ...

Verified Answer:

Ideal refrigeration cycle

\begin{aligned}T ...

Question: 11.CSGP.180b

Do problem 11.24 with R-22 as the working fluid. A flow with 2 kg/s of water is available at 95°C for the boiler. The restrictive factor is the boiling temperature of 85°C. Therefore, break the process up from 2- 3 into two parts as shown in the diagram. ...

Verified Answer:

\begin{gathered}-\dot{ Q }_{ AB }=\dot{ m }...

Question: 11.CSGP.180a

Do Problem 11.21 with R-22 as the working fluid. A supply of geothermal hot water is to be used as the energy source in an ideal Rankine cycle, with R-134a as the cycle working fluid. Saturated vapor R-134a leaves the boiler at a temperature of 85°C, and the condenser temperature is 40°C. Calculate ...

Verified Answer:

CV: Pump (use R-22 Computer Table)

\begin{...

Question: 11.CSGP.179d

In an actual refrigeration cycle using R-12 as the working fluid, the refrigerant flow rate is 0.05 kg/s. Vapor enters the compressor at 150 kPa, −10°C, and leaves at 1.2 MPa, 75°C. The power input to the compressor is measured and found be 2.4 kW. The refrigerant enters the expansion valve at 1.15 ...

Verified Answer:

Actual refrigeration cycle 1: compressor inlet ...

Question: 11.CSGP.179c

A refrigerator in a meat warehouse must keep a low temperature of -15°C and the outside temperature is 20°C. It uses R-12 as the refrigerant which must remove 5 kW from the cold space. Find the flow rate of the R-12 needed assuming a standard vapor compression refrigeration cycle with a condenser ...

Verified Answer:

Basic refrigeration cycle:

T _1= T _4=-15^...

Question: 11.CSGP.179a

A refrigerator with R-12 as the working fluid has a minimum temperature of −10°C and a maximum pressure of 1 MPa. Assume an ideal refrigeration cycle as in Fig. 11.21. Find the specific heat transfer from the cold space and that to the hot space, and the coefficient of performance. ...

Verified Answer:

Exit evaporator sat. vapor −10°C from B.3.1: [lat...

Question: 11.CSGP.133

A jet ejector, a device with no moving parts, functions as the equivalent of a coupled turbine-compressor unit (see Problems 9.157 and 9.168). Thus, the turbine-compressor in the dual-loop cycle of Fig. P11.122 could be replaced by a jet ejector. The primary stream of the jet ejector enters from ...

Verified Answer:

\begin{aligned}& T _1= T _7=10^{\circ} ...

Question: 11.CSGP.132

The effect of a number of open feedwater heaters on the thermal efficiency of an ideal cycle is to be studied. Steam leaves the steam generator at 20 MPa, 600°C, and the cycle has a condenser pressure of 10 kPa. Determine the thermal efficiency for each of the following cases. A: No feedwater ...

Verified Answer:

a) no feed water heater

\begin{aligned}w _{...