Question

An air-conditioning system with R134a as the working fluid operates on an ideal vapor compression refrigeration cycle. The working pressure of the evaporator and the condenser are 200 kPa and 1.0 MPa, respectively. The refrigerant flow rate is 0.03 kg/s.

a) Draw the process cycle on a T-s diagram with labels.

b) Determine the power input and COP of the system.

c) Determine the tons of refrigeration.

d) What is the SEER rating of the system?

e) What is the size of the system in hp .

f) What is the maximum COP based on the reversed Carnot cycle operates at the same temperature range? Determine the percent of increment of the COP compared to the ideal cycle.

g) Suggest ways to improve the COP of vapor compression refrigeration cycl

Answer #1

An air conditioner using refrigerant-134a as the working fluid
and operating on the ideal vapor-compression refrigeration cycle is
to maintain a space at 36°C while operating its condenser at 1600
kPa. Determine the COP of the system when a temperature difference
of 4°C is allowed for the transfer of heat in the evaporator. (Take
the required values from saturated refrigerant-134a tables.)

An ideal vapor-compression refrigeration cycle operates at
steady state with Refrigerant 134a as the working fluid. Saturated
vapor enters the compressor at 1 bar, and saturated liquid exits
the condenser at 4 bar. The mass flow rate of refrigerant is 8.5
kg/min.
Determine the compressor power, in kW.

Consider a 280 kJ/min refrigeration system that operates on an
ideal vapor-compression refrigeration cycle with refrigerant-134a
as the working fluid. The refrigerant enters the compressor as
saturated vapor at 140 kPa and is compressed to 800 kPa. The
saturated refrigerant-134a—pressure table (in SI units) is given
below. Determine the quality of the refrigerant at the end of the
throttling process.

an ideal vapor compression refrigeration cycle using
refrigerant-134a as the working fluid is used to cool a brine
solution to -5degrees Celsius. This solution is pumped to various
buildings for the purpose of air-conditioning. The refrigerant
evaporates at -10 degrees Celsius with a total mass flow rate of
7kg/s and condenses at 600kPa
Determine
a) the COP of the cycle and
b) The total cooling load

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 two-stage cascade refrigeration system is shown below. The
refrigerant is R134a. It consists of two ideal vapor-compression
cycles with heat exchange between the condenser of the
lowertemperature cycle and the evaporator of the higher-temperature
cycle. The hotter cycle operates between 0.7 MPa and 0.35 MPa,
while the cooler cycle operates between 0.35 MPa and 0.12 MPa. If
the ﬂow rate in the hotter cycle is 0.5 mol/s, determine the
following:
What is the ﬂow rate in the cooler cycle?...

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.

- 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...

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...

Refrigerant 134a is the working fluid in a vapor-compression
heat pump system with a heating capacity of 60,000 Btu/h. The
condenser operates at 240 lbf/in.2, and the evaporator temperature
is 0°F. The refrigerant is a saturated vapor at the evaporator exit
and a liquid at 110°F at the condenser exit. Pressure drops in the
flows through the evaporator and condenser are negligible. The
compression process is adiabatic, and the temperature at the
compressor exit is 180°F. Determine (a) the mass...

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