HVAC Low Side Works

Heat transfer is defined as energy-in-transit due to temperature difference. Heat transfer takes
place whenever there is a temperature gradient within a system or whenever two systems at
different temperatures are brought into thermal contact. Heat, which is energy-in-transit,
cannot be measured or observed directly, but the effects produced by it can be observed and
measured. Since heat transfer involves transfer and/or conversion of energy, all heat transfer
processes must obey the first and second laws of thermodynamics. However unlike
thermodynamics, heat transfer deals with systems not in thermal equilibrium and using the
heat transfer laws it is possible to find the rate at which energy is transferred due to heat
transfer. From the engineer’s point of view, estimating the rate of heat transfer is a key
requirement.
Heating ventilation & Air Conditioning involves heat transfer; hence a good understanding of
the fundamentals of heat transfer is a must for a student of Heating ventilation & Air
Conditioning. This section deals with a brief review of heat transfer relevant to Heating
ventilation & Air Conditioning.
Generally heat transfer takes place in three different modes: conduction, convection and
radiation. In most of the engineering problems heat transfer takes place by more than one
mode simultaneously, i.e., these heat transfer problems are of multi-mode type.