REFRIGERATION & AIR CONDITIONINGTwo related areas in Mechanical Engineering.

Refrigeration : Preservation of certain materials by cooling them to predetermined low temperature.

Air conditioning : Maintaining the temperature, humidity and purity of certain closed space to provide human comfort or to facilitate certain industrial processes.

Involves, Heating / Cooling and Humidifying / Dehumidifying.Comfort conditions : 20 to 25°C and 50 to 55 Relative Humidity.

Cryogenics: Study of very low temperatures and how materials behave at these temperatures. Normally below – 150°C.

SPECIFIC & RELATIVE HUMIDITIESSpecific humidity, = =

As more water vapor/moisture is added, ‘’ increases till the air is saturated.

Any further addition of moisture leads to condensation.

Relative humidity, RH = where, mg – max. water vapor air can hold.

REFRIGERANTSWorking fluid in the Refrigerators / Air conditioners

R12 – CCl2F2

R22 – CHClF2

R134 – C2H2F4

Properties:Low Boiling pointHigh value of hfg

Non-flammableNon-toxicNon-corrosiveLow cost, etc.

VAPOR COMPRESSION REFRIGERATION SYSTEM

Schematic and p-h diagrams

DOMESTIC REFRIGERATOR

TONNE OF REFRIGERATION (TR)

It is the measure of cooling capacity.

A cooling that can produce 1 ton (approx. 900 kg) of ice at 0°C from water at 0°C in 24 hours.

1 TR = 12,600 kJ/hr (211 kJ/min.)

WINDOW AIR CONDITIONER

WINDOW AIR CONDITIONER