Question

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 Performance (COP) of the refrigerator.

Answer #1

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...

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...

- a vapour-compression air-conditioning cycle where the
compressor has an isentropic efficiency of 75%. Refrigerant (R12)
is used as the working fluid with a mass now rate of 0.04kg/s.
saturated vapour eaters the compressor at 0.5 MPa and leaves to the
condenser at 1.2IMPa. The air-conditioner cools down the station to
26°C through an evaporator, and rejects heat to the 34°C ambient
through a condenser. (a) Sketch and label the schematic of the
air-conditioning cycle and its T-S and P-h...

An ice-making machine operates on the ideal vapor-compression
cycle, using refrigerant-134a. The refrigerant enters the
compressor as saturated vapor at 20 psia and leaves the condenser
as saturated liquid at 80 psia. Water enters the ice machine at
55°F and leaves as ice at 25°F. For an ice production rate of 15
lbm/h, determine the power input to the ice machine (169 Btu of
heat needs to be removed. Compressor's efficiency is 90 percent

An ice-making machine operates on the ideal vapor-compression
cycle, using R-134a. The refrigerant enters the compressor as
saturated vapor at 140 kPa and leaves the condenser as saturated
liquid at 600 kPa. Water enters the ice machine at 13oC and leaves
as ice at -4oC, while removing heat at 393 kJ per kg of water.
Estimate the mass flow rate of the refrigerant and the power input
to the ice machine for an ice production rate of 7 kg/h.

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...

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...

An idea vapor-compression refrigeration cycle, with refrigerant
R-22 as the working fluid, has an evaporator temperature of -12 °C
and a condenser pressure of 15 bar. Saturated vapor enters the
compressor, and saturated liquid exits the condenser. The
refrigerating capacity is 4 tons.
a.Determine the compressor power (in kW).
b.Determine the mass flow rate of the refrigerant (in
kg/min).
c.Determine the coefficient of performance.

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.

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