Question

Consider a commercial refrigerator which operates on the
refrigeration cycle. R-

134a is used as the working

uid and the refrigerated space is kept at -25oC by rejecting
its

waste heat to cooling water that enters the condenser at room
temperature, that is 20oC, at a

rate of 0.1 kg/s and leaves at 40oC. The refrigerant enters the
condenser at 1.2 MPa and 70oC

and leaves at 40oC. The inlet state of the compressor is saturated
vapor at 100 kPa and the

compressor is estimated to release a net heat of 450 W to the
surroundings. Determine

(a) the quality of the refrigerant at the evaporator inlet,

(b) the rate of heat removal from the refrigerated space,

(c) the coecient of performance of the refrigerator and

(d) the theoretical maximum coecient of performance of the
refrigerator.

Answer #1

A commercial refrigerator with refrigerant R-134a as the working
fluid is used to keep the refrigerated space at -30 C by rejecting
its waste heat to cooling water that enters the condenser at 18 C
at a rate of 0.25 kg/s and leaves at 26 C. The refrigerant enters
the condenser at 1.2 MPa and 65 C and leaves at 42 C. The inlet
state of the compressor is 60 kPa and -34 C and the compressor is
estimated to...

A commercial refrigerator with refrigerant-134a as the working
fluid is used to keep the refrigerated space at −30°C by rejecting
its waste heat to cooling water that enters the condenser at 18°C
at a rate of 0.32 kg/s and leaves at 26°C. The refrigerant enters
the condenser at 1.2 MPa and 65°C and leaves at 42°C. The inlet
state of the compressor is 60 kPa and −34°C and the compressor is
estimated to gain a net heat of 460 W...

R-134a enters the compressor of a refrigerator as superheated
vapour at 0.14 MPa, -10 °C at a rate of 0.12 kg/s, and it leaves at
0.7 MPa and 50 °C.
The refrigerant is cooled in the condenser to 24 °C and 0.65 MPa,
and it is throttled to 0.15 MPa.
Disregard any heat transfer and pressure drops in the connecting
lines between the components.
Show the cycle on a T-s diagram with respect to saturation
lines, and determine
(a) the...

Regarding a Vapor-Compression cycle: A refrigerant (HCFC-22)
enters the compressor of a refrigerator as a superheated vapor at
.14MPa and -20 degrees Celsius at a rate of .05 kg/s and leaves at
.8 MPa and 50 degrees Celsius. The refrigerant is cooled in the
condenser to 26 degrees Celsius and .72MPa and is then throttled
down to .15 MPa. Determine the rate of heat removal from the
refrigerated space and the power input to the compressor and the
Coefficient of...

A cooling plant adopted a two-stage cascade refrigeration system
to meet the required cooling load. In both upper and lower cycles,
the refrigerant leaves condenser as saturated liquid and enters
compressor as saturated vapor. The isentropic efficiency of the
upper cycle compressor is 80 %, while the lower cycle compressor is
70% efficient. The pressure limits of the upper and lower cycles
are 1 MPa and 0.2 MPa with refrigerant-134a, respectively. Heat
rejection from the lower cycle to the upper...

Consider a single-stage refrigeration system operating between the pressure limits of 1.4 MPa and 160 kPa
with refrigerant R134a as the working fluid. The refrigerant is a saturated liquid at the condenser exit and a
saturated vapor at the compressor inlet. The isentropic efficiency for the compressor is 80 percent. If the
mass flow rate of the refrigerant through the cycle is 0.11 kg/s determine (a) the rate of heat removal from the
refrigerated space, and (b) the coefficient of...

An adiabatic capillary tube is used in some refrigeration
systems to drop the pressure of the refrigerant from the condenser
level to the evaporator level. The R-134a enters the capillary tube
as a saturated liquid at 50°C and leaves at -20°C. Determine the
quality of the refrigerant at the inlet of the
evaporator.

A condenser is essentially a type of heat exchanger that is used
to remove heat from a vapor and convert it to liquid. The picture
below shows a condenser that is used in a commercial refrigerator
with refrigerant-134a as the working fluid. Water enters the
condenser at 18ºC at a rate of 0.25 kg/s and leaves at 26ºC. The
refrigerant enters the condenser at 1.2 MPa and 50ºC and leaves at
the same pressure but at T=41.3ºC. a) Find the...

Refrigerant 134a is the working fluid in an ideal
vapor-compression refrigeration cycle operating at steady state.
Refrigerant enters the compressor at 1 bar, -12°C, and the
condenser pressure is 9 bar. Liquid exits the condenser at 32°C.
The mass flow rate of refrigerant is 7 kg/min. Determine:
(a) the magnitude of the compressor power, in kW. (b) the
refrigeration capacity, in tons. (c) the coefficient of
performance.

A vapor-compression refrigeration cycle operates at steady state
with Refrigerant 134a as the working fluid. Saturated vapor enters
the compressor at 2 bar, and saturated liquid exits the condenser
at 8 bar. The isentropic compressor efficiency is 80%. The mass
flow rate of refrigerant is 7 kg/min. Determine: (a) the compressor
power, in kW, (b) the refrigeration capacity, in tons, (1 ton =
3.5168 kW) and, (c) the coefficient of performance, (d) rate of
entropy production in kW/K, for the...

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