- Title: Refrigeration and Air Conditioning
- Department: Mechanical Engineering
- Author: Prof. M.Ramgopal,Prof. R.C.Arora
- University: IIT Kharagpur
- Type: WebLink
- Abstract:
MODULE 1: Introduction
1st Lecture
Definition of Refrigeration and Air Conditioning
History of Refrigeration and Air conditioning
History from conceptual point of view:
Ice production by nocturnal cooling in ancient India and application of
evaporative cooling in India. Use of natural ice, ice houses and ice
trade.
Vapour Compression Refrigeration Systems
Vapour Absorption Refrigeration Systems
Air Cycle Refrigeration Systems
Miscellaneous Systems (Vapour Jet Refrigeration Systems,
Thermoelectric systems, Vortex tube systems, Intermittent-Solar
Refrigeration Systems, Combined Cycles)
2nd Lecture
History from Refrigerant development Point of View
Early refrigerants (SO2, CO2, CH3Cl, CH4, C2H6 etc)
Introduction of CFCs and HCFCs
Ozone layer depletion
HFCs, HCs, NH3, CO2, H2O etc.
History from compressor development point of view
Low-speed steam engine driven compressors
High-speed electric motor driven compressors
Rotary vane compressors
Centrifugal compressors
Screw compressors
Scroll compressors
History of Air Conditioning
MODULE 2: Applications
3rd Lecture
Applications of Refrigeration and Air Conditioning
a) Comfort Air Conditioning
Residential air conditioning
Commercial air conditioning
Industrial air conditioning
b) Industrial Refrigeration
Chemical and process industries
Dairy plants
Petroleum refineries
c) Food processing and food chain
b) Miscellanous
MODULE 3: Methods of producing low temperatures
4th Lecture
Applications of Refrigeration and Air Conditioning
Using enthalpy of mixing (mixing of salt with water)
Expansion in a turbine
Throttling
Thermoelectric effects
Adiabatic demagnetization
MODULE 4: Review of Fundamentals
5th Lecture
a) Thermodynamics:
1st law of thermodynamics for open and closed systems
2nd law of thermodynamics, Kelvin-Planck and Clausius statements, and
Clausius inequality. 3rd law of thermodynamics.
Heat Engines, Heat Pumps and Refrigeration Systems, Maximum COP
Thermodynamic properties
Thermodynamic processes
T-s and p-h diagrams
6th Lecture
a) Fluid Mechanics:
Continuity and Momentum equations
Bernoullis equation and friction factor
b) Heat Transfer:
Modes of heat transfer
Concept of thermal resistance and overall heat transfer coefficient
Radiative heat transfer coefficient
Forced Convection, Free Convection, Boiling and Condensation heat
transfer coefficients
MODULE 5: Air Cycle Refrigeration Systems
7th Lecture
Reverse Carnot Cycle and its limitations
Bell Coleman, Joule or Reverse Brayton Cycle
Aircraft refrigeration cycles
Joule Thompson coefficient and Inversion Temperature
Linde, Claude and Stirling cycles for liquefaction of air.
MODULE 6: Vapour Compression Refrigeration Systems
8th Lecture
Comparison of Vapour Compression Cycle and Gas cycle
Ideal refrigeration cycle Reversed Carnot cycle and maximum COP
Deviations of practical cycles from Carnot cycle
Standard vapour compression refrigeration cycle (SSS cycle),
Superheat horn and throttling loss for various refrigerants, efficiency
9th Lecture
Modifications to standard cycle liquid-suction heat exchangers
Grindlay cycle and Lorenz cycle
Optimum suction condition for optimum COP Ewings construction and Gosneys method.
Actual cycles with pressure drops and heat transfer
Complete Vapour Compression Refrigeration System
10th Lecture
Multipressure, multistage systems, optimum intermediate pressure
Two stage ammonia and halocarbon systems
11th Lecture
Multi-evaporator systems
Cascade systems, optimum intermediate temperature
Manufacture of dry ice and supercritical CO2 cycle
Autocascade cycle
MODULE 7: Vapour Absorption Refrigeration Systems
12th Lecture
Working principle
Maximum COP of the ideal VARS
Properties of Mixtures
Simple absorption refrigeration system
13th Lecture
Lithium bromide-Water Absorption Refrigeration Systems
Operating principles and applications
Refrigerant-absorbent properties using tables and charts
Performance evaluation and methods of improvement
Practical problems crystallization and air leakage
Commercial systems Single and multistage systems
14th Lecture
Aqua Ammonia Refrigeration System
Operating principles and applications
Refrigerant-absorbent properties using tables and charts
Practical problems and Principle of Rectification
15th Lecture
Aqua-ammonia Absorption Refrigeration Systems
Analysis of Generator- Exhausting Column and Rectification column
-Dephelgmator
Three fluid system
Solar energy based adsorption refrigeration systems
MODULE 8: Refrigeration system components
16th Lecture
Compressors
Reciprocating Compressors
Constructional details open , hermetic and semi-sealed compressors
Performance of the ideal compressor
Clearance volumetric efficiency Effects of evaporator and condenser pressures
Actual volumetric efficiency
Effects of cylinder cooling, heating and friction
Empircial equations for actual volumetric efficiency
17th Lecture
Reciprocating Compressors (contd)
Power requirements of ideal and actual compressors
optimum work for given condenser and evaporator pressures, mean effective pressure,
pull down characteristics
Compressor discharge temperatures and need for cooling
Capacity control
18th Lecture
Centrifugal Compressors
Basic principle of dynamic compressor
Velocity diagrams
Efficiency considerations
Construction details, applications and performance characteristics
Comparison with reciprocating compressors
19th Lecture
Screw compressors
Basic principles- single screw and double screw compressors.
Working principle, work requirement and performance characteristics
Comparison with reciprocating and centrifugal compressors
Rotary- single vane and multi-vane compressor
20th Lecture
Condensers
Classification based on type of construction, flow direction etc.
Condensing capacity and Heat Rejection Ratio
Correlations for condensing heat transfer coefficients
Thermal design of condensers
Effects of fouling and noncondensible gases on performance
21st Lecture
Evaporators
Classification based on type of construction, flow direction etc.
Correlations for boiling heat transfer coefficients for various configurations
Design and performance aspects
Effects of pressure drops and frost formation
Use of Wilsons plots
22nd Lecture
Expansion devices
Capillary tubes
Applications, operating characteristics and selection
Thermostatic expansion valves
Applications and operating characteristics
Internal vs external equalizers
Cross charging, gas charging, liquid charging and fade out point
Automatic expansion valves
Float valves Low side and high side float valves
Electronic expansion valves
MODULE 9: Refrigerants
23rd Lecture
Primary and secondary refrigerants
Designation of Refrigerants.
Desirable properties of refrigerants including solubility in water and
lubricating oil, material compatibility, toxicity, flammability, leak detection,
cost, environment and performance issues
Thermodynamic properties of refrigerants
Synthetic and natural refrigerants
Comparison between different refrigerants vis a vis applications
Special issues and practical implications
Refrigerant mixtures zeotropic and azeotropic mixtures
MODULE 10: Properties of moist air (psychrometry)
24th Lecture
Composition of moist air
Methods for estimating moist air properties
Important psychrometric properties
o Dry bulb temperature
o Humidity ratio
o Relative humidity
o Degree of saturation
o Dew point temperature
o Enthalpy
25th Lecture
Psychrometry (contd.)
o Adiabatic saturation
o Thermodynamic wet bulb temperature and wet bulb thermometer
Relations between psychrometric properties
Introduction to humidity ratio vs. dry-bulb temperature psychrometric chart and ASHRAE chart.Use of psychrometric charts and moist air tables, Goff and Gratch tables
MODULE 11: Psychrometric Processes
26th Lecture
Sensible cooling and heating, RSH
Humidification and dehumidification, RLH
Combined heat and mass transfer processes, RTH, RSHF,
o Straight line law coil bypass factor and ADP
o Cooling and dehumidification
o Heating and humidification
o Psychrometric calculations for simple airconditioning system and for
return air systems with bypass factor. RSHF, GSHF and ESHF
27th Lecture
Psychrometric processes (contd.)
o Cooling and humidification (evaporative cooling)
o Adiabatic mixing
o Spray washers and cooling towers
MODULE 12: Air conditioning systems for comfort
28th Lecture
Thermal comfort. Heat transfer from human body by sensible and latent heat transfer. Metabolic heat generation, steady state and unsteady state model for heat transfer, effect of clothing and definition of effective temperatures. PMV and PPD. ASHRAE comfort chart.
Inside and Outside design conditions
Summer air conditioning systems
Winter air conditioning systems
All year air conditioning systems
MODULE 13: Infiltration and IAQ
29th Lecture
Infiltration
o Infiltration and ventilation
o Infiltration due to stack effect, temperature difference and wind velocity
o Air change and crack length methods for estimating infiltration
o Infiltration due to door openings
Indoor Air Quality (IAQ)
o Sources of indoor air pollution
o Methods of control of IAQ
o Fresh air requirements for ventilation and IAQ
MODULE 14: Heating and Cooling load calculations
30th Lecture
Heating and Cooling load calculations
Differences between winter and summer load calculations
Solar radiation
o Distribution of solar radiation
o Direct and diffuse solar radiation
o Earth sun angles and their relationship
31st Lecture
Solar radiation (contd.)
o Solar radiation on horizontal, vertical and inclined surfaces
o Solar radiation through glass, SHGF and shading coefficients
o Effects of internal and external shading devices
32nd Lecture
Heat transfer through building structure
Thermal resistance of various building materials
Periodic heat transfer through walls and roof
o Governing equations
o Methods of solution
o Decrement factor and Time lag method
o Equivalent Temperature difference Method
33rd Lecture
Winter heating load calculations
Heat losses through the structure
Heat losses due to infiltration
Effects of solar radiation and internal heat sources on heating loads
Degree day and BIN methods for estimating energy requirements for heating
34th Lecture
Summer cooling load calculations
Heat gain through walls and roof
Heat gain through glazings
o Cooling Load Factors (CLF)
Heat gain through doors, floor, partition etc.
Internal heat gains
Infiltration and ventilation heat gains
System heat gains (ducts, fans, blowers etc)
35th Lecture
Fixing of supply air conditions for summer air conditioning
o Supply air temperatures and air quantity, RSHF
o Outdoor air quantity
o Bypass factor and coil condition line
o Cooling load on the room and cooling load on the coil, GSHF
o High latent heat load applications
o Use of reheat coils
MODULE 15: Air conditioning Systems
36th Lecture
a) All air systems
b) All water systems
c) Air water systems
d) Unitary systems
Window air conditioners
MODULE 16: Fan and Duct Systems
37th Lecture
Frictional pressure drops in straight ducts of circular and rectangular cross-
section, equivalent diameter for rectangular duct.
Pressure losses in fittings, due to sudden enlargements, contractions etc.
Sizing of ducts
o Velocity Reduction method
o Equal friction method
o Static Regain method
38th Lecture
Selection of fans
o Fan laws and fan characteristic curves
Air distribution in rooms
Selection and location of supply and return grills, diffusers etc.
MODULE 17: Transport air conditioning Systems
39th Lecture
Air conditioning systems for automobiles (cars, buses etc.)
Air conditioning systems for trains
Air conditioning systems for ships
MODULE 18: Control systems for Refrigeration and Air conditioning applications
40th Lecture
Closed loop and open loop control systems
Choice of control systems
Types of control action
Energy sources, controllers and controlled devices
Control based on space temperature
Control based on outside temperature
Control based on heating and cooling medium
Control of humidity
Complete control systems