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BASIC MECHANICAL BASIC MECHANICAL ENGINEERINGENGINEERING
REFRIGERATION REFRIGERATION AND AIR AND AIR
CONDITIONINGCONDITIONING
Vapour Compression Vapour Compression Refrigeration SystemRefrigeration System
• Basic ComponentsBasic Components
– CompressorCompressor
– CondenserCondenser
– Expansion ValveExpansion Valve
– EvaporatorEvaporator
RefrigeratorRefrigerator
ProcessesProcesses
• 1. Low temp., Low pr., Vapour enters 1. Low temp., Low pr., Vapour enters
CompressorCompressor
• 2. High temp., High Pr., Vapour enters 2. High temp., High Pr., Vapour enters
CondenserCondenser
• 4. High pr. Saturated Liquid enters 4. High pr. Saturated Liquid enters
Expansion Valve (Throttle Valve)Expansion Valve (Throttle Valve)
• 5. Low temp., wet Vapour enters 5. Low temp., wet Vapour enters
EvaporatorEvaporator
Vapour Compression Vapour Compression Refrigeration SystemRefrigeration System
Vapour Absorption Vapour Absorption Refrigeration SystemRefrigeration System
• Difference in method of converting the Difference in method of converting the
refrigerant vapour back into liquid. refrigerant vapour back into liquid.
• Compressor replaced by combination of Compressor replaced by combination of
Absorber and Generator.Absorber and Generator.
• Vapour from evaporator is dissolved in Vapour from evaporator is dissolved in
the cold water in the absorber which thus the cold water in the absorber which thus
turns into a warm strong solution.turns into a warm strong solution.
• The strong solution is heated in generator The strong solution is heated in generator
to separate refrigerant vapour.to separate refrigerant vapour.
• Remaining weak solution is sent back to Remaining weak solution is sent back to
absorber to be used as solventabsorber to be used as solvent
Vapour Absorption Vapour Absorption Refrigeration SystemRefrigeration System
Comparison – Advantages of Comparison – Advantages of Absorption SystemAbsorption System
• Heat is used as major source of Heat is used as major source of
energyenergy
• No moving partsNo moving parts
• Performance is not affected by load Performance is not affected by load
on compressionon compression
• No danger of liquid traces in suction No danger of liquid traces in suction
lineline
• Works on low evaporator pressureWorks on low evaporator pressure
• Automatic operation is easyAutomatic operation is easy
COPCOP
Coefficient of Performance, COP Coefficient of Performance, COP
= Heat extracted / Work by Compressor= Heat extracted / Work by Compressor
Unit & PropertiesUnit & Properties
The rate of heat absorbed by the system The rate of heat absorbed by the system
from the body to be cooled, equivalent from the body to be cooled, equivalent
to the latent heat of fusion of 1 ton of to the latent heat of fusion of 1 ton of
ice from and at 0ice from and at 000C in 24 hours is called C in 24 hours is called
one ton of refrigeration.one ton of refrigeration.
1 ton of refrigeration = 3,5167kJ of heat 1 ton of refrigeration = 3,5167kJ of heat
removal / secondremoval / second
PropertiesProperties
Condensing & evaporation pressures Condensing & evaporation pressures
higher than atmospheric pr., critical higher than atmospheric pr., critical
temp high, low freezing temp., low temp high, low freezing temp., low
sp.heat, high L.H., low sp.volume, low sp.heat, high L.H., low sp.volume, low
viscosity, high thermal conductivity, viscosity, high thermal conductivity,
stability, inflammability….stability, inflammability….
Air ConditioningAir Conditioning
Air ConditioningAir Conditioning
• TerminologyTerminology
– Dry air, Moist airDry air, Moist air
– Specific humiditySpecific humidity
– Relative humidityRelative humidity
– Dry bulb temperatureDry bulb temperature
– Wet bulb temperatureWet bulb temperature
– Dew point temperatureDew point temperature
– Sensible heatSensible heat
– Total heatTotal heat
Physical ProcessesPhysical Processes
• Air PurificationAir Purification
– Air filtration, Air sterilization, Air Air filtration, Air sterilization, Air
ionisation, Odour suppressionionisation, Odour suppression
• Temperature ControlTemperature Control
– Indirect, DirectIndirect, Direct
• Humidity ControlHumidity Control
– Dehumidification, HumidificationDehumidification, Humidification
• Air DistributionAir Distribution
Comfort Air conditioningComfort Air conditioning
• Combination of Dry bulb temp., Combination of Dry bulb temp.,
Relative humidity and Air velocityRelative humidity and Air velocity
• Effective TemperatureEffective Temperature
It is the dbt of a sample of It is the dbt of a sample of
saturated air which will give a saturated air which will give a
particular feeling of comfort to particular feeling of comfort to
the same percentage of people as the same percentage of people as
any other combination of dbt and any other combination of dbt and
RH. RH.
Window Air conditioningWindow Air conditioning
Winter Air conditioningWinter Air conditioning
Summer Air conditioningSummer Air conditioning
Viscous FilterViscous Filter
Wet FilterWet Filter
Air Cooling - IndirectAir Cooling - Indirect
Air Cooling - DirectAir Cooling - Direct
DehumidifierDehumidifier
Atomisation HumidifierAtomisation Humidifier
Forced Evaporation Forced Evaporation HumidifierHumidifier
Air DistributionAir Distribution
Air DistributionAir Distribution