EBK FUNDAMENTALS OF THERMODYNAMICS, ENH
9th Edition
ISBN: 9781119321453
Author: Sonntag
Publisher: JOHN WILEY+SONS,INC.-CONSIGNMENT
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Textbook Question
Chapter 5, Problem 5.22P
R−410A enters the evaporator (the cold beat exchanger) in an air−conditioner unit at −20°C,
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The evaporator (a heat exchanger) in an A/C unit has R-410A entering at -20 °C and a quality of 30% and
leaves at the same temperature and a quality of 100%. The COP of the air conditioner is known to be 1.3
and the mass flow rate is given as 0.013 kg/s. Find the power input to the cycle.
(Note that, here, the evaporator is the part of the A/C unit that accepts [i.e., withdraws] heat from the
room maintained at a cold temperature)
A refrigeration system operated on an ideal vapor-compression using R-12 with a vaporizing temperature of -10 degrees Celsius and a condensing temperature of 30 degrees Celsius, it requires 15 hp to drive the motor of the compressor. Find the ff:
Enthalpies at each point of the cycle in kJ/kg
Refrigerating Capacity in TOR • Mass of the Refrigerant in kg/s
Percent Quality in the mixture
Heat Rejected in kW Coefficient of Performance
• Schematic and P-h Diagram
Q.13 A vapour compression refrigeration system using refrigerant F-12 is employed to
produce 8640 kg of ice per day. The condensing and evaporating temperature of
refrigcrant are 48°C and-20°C respectively. Saturated liquid leaves the condenser
and saturated vapour leaves the evaporator. Compression is isentropic, water at
35°C is used to form the ice. The temperature of ice should be-8°C. Heat flow into
the brine tank from surroundings may be taken as 10% of total heat absorbed from
water to form ice. Determine the power required to drive the compressor. Take specific
heat of ice 2.26 kJ/kg-K. Latent heat of ice = 335 kJ/kg. Specific heat of water =
4.2 kJ/kg-K. The following data may be used:
%3D
Temp. Pressure
Enthalpy
Entropy
°C
bar
kJ/lg
kJ/kg-K
Liquid Vapour Liquid
Vapour
48°C
11.64
82.83
205.83
0.2973
0.6802
-20
1.51
17.82
178.74
0.0731
0.7087
Specific heat of vapour 0.82 kJ/kg
%3D
Chapter 5 Solutions
EBK FUNDAMENTALS OF THERMODYNAMICS, ENH
Ch. 5 - Prob. 5.1PCh. 5 - A windowmounted air conditioner removes 3.5kJ from...Ch. 5 - Prob. 5.18PCh. 5 - R410A enters the evaporator (the cold beat...Ch. 5 - A large heat pump should upgrade 4MW of heat at...Ch. 5 - A car engine 5g/s fuel (equivalent to addition of...Ch. 5 - Prob. 5.45PCh. 5 - R134a fills a 0.1m3 capsule at 20°C, 200kPa. It is...Ch. 5 - Air in a piston/ cylinder goes through a Carnot...Ch. 5 - Consider the previous problem and assume the...
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