Refrigeration
and
Air-conditioning
[ME4333]
L1- Introduction
S. Murugan
Air conditioner
Refrigeration is the process of maintaining
the temperature of a system below its
surrounding temperature with the help of an
external mechanical work.
Refrigeration systems are used in homes,
hotels, restaurants, commercial shops. They
are also in used Fridge, Water Cooler,
Window Air Conditioner, Split Air
Conditioner, Cold storage plant, and Ice Plant.
They are used in the following ;
Chemical and Petrochemicals
Pharmaceutical
Food & Beverages
Hospitals Air conditioner is a device which
Cryogenic applications maintains the temperature of a room
Refrigerator or living space below its surrounding
temperature with the aid of a
mechanical work. It also maintains the
quality of room or living air.
Applications;
Hospitals, Commercial complexes,
cinema theatres, auditoriums, airports,
automotive vehicles
Tentative Lesson Plan
S. No Topic to be covered
Unit-I Basic Concepts 12 Hours
1. Refrigeration and heat pump- basic concepts, Coefficient of performance, Unit of
refrigeration,
2 Problem
3 Vapor Compression Systems: Analysis of Theoretical vapor-compression cycle, T-S and P-
H diagram,
4 Simple Saturated cycle, Sub cooled cycle and superheated cycle,
5 Effect of suction and discharge pressure on performance, Actual vapor-compression cycle.
6 Problem solving
7 Vapour absorption system, Electrolux system
9 Comparison of absorption and vapor compression system. ;
10 Problem solving
11 Refrigerants: Classification of Refrigerants,
12 Halocarbon compounds, Azeotropes, Hydro-carbons, Inorganic compounds, Properties of
refrigerants, Comparison of common refrigerants Uses of important refrigerants, Brines,
Ozone friendly refrigerants. ;
Unit-II Compression and evaporation systems 12 Hours
13 Single stage compression and Multistage compression systems.
14 Different arrangements of compressors and inter cooling, Multi-stage
compression with inter cooling,
15 Problems
16 Problems
17 Multi-evaporator system, Dual compression system
18 Problems
19 Problems
20 multi-evaporator systems
21 Problems
22 Problems
23 Condensers-air cooled, water cooled
24 Cooling tower
Unit-III Other refrigeration systems 12 Hours
25 Expansion devices-Thermostatic
26 Problem solving
27 Throttling and capillary devices
28 Problem solving
29 Steam jet refrigeration, Ejector refrigeration
30 Problem solving
31 Thermoelectric refrigeration
32 Magnetic refrigeration
33 Vortex and Pulse tube refrigeration systems
34 Aircraft refrigeration.
35 Problem solving
36 Problem solving
Unit-IV Psychrometry 12 Hours
S.No Topic to be covered
37 Properties of air-vapor mixtures
38 Psychrometric charts, Law of water vapor-air mixture
39 Enthalpy of moisture and calculations -,.
40 Adiabatic saturation
41 Simple cooling and heating
42 Cooling with dehumidification
43. Heating and humidification; by-pass
factor of coil, Numerical
44 Sensible heat factor; ADP of cooing coil;
45 Mixture of air streams
46 Problem solving
47 Problems solving
48 Problems solving
Unit-V Types of air conditioning and Heat Removal Principles
S.No Topic to be covered 12 Hours
49 Types of Air conditioning systems: Summer air conditioning
50 Winter air conditioning, Year round air conditioning
51 Air filters
52 Requirements of comfort Air-conditioning
53 Thermodynamic of human body
54 The body defense
55 Comfort and comfort chart
56 Effective temperature,
57 Design considerations
58 Requirements of temperature and humidity
59 -do-
60 Inside design considerations
Essential Reading:
1.Refrigeration & air conditioning by C P Arora , Tata McGraw Hill.
2.Course In Refrigeration & Air Conditioning by Arora and Domkundwar, Dhanpat Rai & Sons.
3. Refrigeration and air conditioning by Manohar Prasad, New Age international publishers.
Supplementary Reading:
1. Thermal Engineering ,R. S. Khurmi
2. Refrigeration and Air conditioning by Stoecker& Jones. McGraw-Hill.
3. Principles of Refrigeration by Roy J. Dossat. Pearson Education
Qatm Qhp
W=Qatm-QR
W=Qhp-Qatm
QR
Qatm
Heat Engine Refrigerator Heat pump
Solved Problem. 1
A domestic food freezer maintains a temperature of –10°C. The ambient
air temperature is 30°C. If heat is rejected from the freezer at the
continuous rate of 1.75 kJ/s, what is the least power necessary to pump
this heat out continuously?
Given freezer temperature = 303 K
Atmospheric air temperature = 258
For minimum power requirement = Qatm/Tatm
Solved Problem. 2
A cold storage is to be maintained at –15°C, while the surroundings are at
35°C. The heat leakage from the surroundings into the cold storage is
estimated to be 35 kW. The actual COP of the refrigeration plant is one
third of an ideal plant working between the same temperatures. Find the
power required to drive the plant.
1. Two Carnot refrigerators A and B operate in series. The refrigerator A
absorbs energy at the rate of 1 kJ/s from a body at 300K and rejects
energy as heat to a body at T. the refrigerator B absorbs the same quantity
of energy which is rejected by the refrigerator A from the body at T, and
rejects energy as heat to a body at 1000K. If both the refrigerators have
the same COP, calculate
(i) The temperature T of the body
(ii) The COP of the refrigerators and
(iii) The rate at which energy is rejected as heat to the body at 1000K.
2. A Carnot heat engine draws heat from a reservoir at temperature T1
and rejects the heat to another reservoir at temperature T3. The Carnot
forward cycle engine drives a Carnot reverse cycle engine or Carnot
refrigerator which absorbs the heat from reservoir at a temperature T2
and rejects heat to the reservoir at a temperature T3, if the higher
temperature T1 equal to 600°K and lower temperature T2 equal to 300°K.
Determine the (i) temperature T3 such that heat supplied to the engine Q1
is equal to heat absorbs by the refrigerator Q2. (ii) Efficiency of Carnot
engine and COP of Carnot refrigerator.
