Page 151 - text book form physics kssm 2020

Chapter 4
Heat
Applications of Specifi c Latent Heat in Daily Lifepplications of Specifi c Latent Heat in Daily Life
A
Cooling system in refrigerator

A refrigerator uses the cooling eff ect from evaporation. During circulation of the cooling agent,
heat is absorbed from inside the refrigerator and released outside.

Cooling agent Expansion valve In the evaporator,
(liquid) fl ows cooling agent
through expansion (liquid) evaporates
valve. and absorbs latent
heat from inside
the refrigerator.
Evaporator
In the condenser, Heat is
cooling agent C absorbed
Condenser
(gas) releases
latent heat during Cooling agent (gas)
condensation. fl ows out from
evaporator to
Heat is the compressor.
released

Compressor Compressor
compresses cooling
agent (gas) to
increase pressure
and its temperature.

Figure 4.21 Cooling system in a refrigerator

Evaporation of sweat

We sweat on hot days or while doing
heavy work. When sweat evaporates, Wet your right hand. Put your
heat is absorbed from the body right hand which is wet and
causing a cooling eff ect. Th e rate of your left hand which is dry
evaporation will increase when there in front of a table fan. What
is air circulation. difference can you feel on your
right and left hands?

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4.3.4 145
4.3.4