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let us start our journey with a question
what is heat transfer when we talk about
heat transfer
we refer to the generation transfer and
conversion of thermal energy
or heat between systems
heat transfer describes the transit of
thermal energy
in a body or across systems due to
temperature differences
like when a hot coffee cools down in a
row
in general the heat is transferred
through different
modes conduction convection and
radiation
depending on the application heat
transfer can be dominated by only one
mode
or all three modes can play a role
in the latter case the analysis can
become
pretty complex
when studying or designing systems that
involve heat transfer
engineers and scientists need to
understand the physical mechanisms
of heat transfer and be able to apply
the heat transfer theory
to analyze and quantify the heat in
those systems
applications of heat transfer are
countless across
all industries and in everyday life
from chemical processes to the oven we
use to bake
a pizza let us analyze
some of these applications and get an
idea of the broad spectrum of systems
where heat transfer is important
whether you warm up your room during
winter or cool down the temperature
during a hot summer you take advantage
of heat transfer
heating ventilation and air conditioning
or
hvac systems use heat transfer
to heat up or cool down the air that is
then
ventilated in the room hvac systems
control the temperature
of houses offices and vehicles
speaking of which you may have heard
about the car radiator
that is a heat exchanger system that
uses two fluids
separated by a solid wall like a metal
tube to enhance heat transfer
in the system the car radiator
uses the external air to cool down the
liquid
that passes through the engine so that
we can avoid overheating
heat exchangers are used in
petrochemical and chemical plants
and even in a common refrigerator
many homes in cold climates use furnaces
to heat the rooms simply heating air
and using air ducts to distribute the
air in all the rooms
boilers are typically used to heat up
and supply hot water
they can also be used to provide steam
for heating another common application
of heat transfer is the thermal power
plants in these plants
the heat generated by burning coal or
natural gas
or even by nuclear reactions is used to
produce steam
from water the high pressure steam is
then used to move
generators to produce electricity
nowadays we are surrounded by electronic
products
such as smartphones and computers
their internal components naturally heat
up during operation
this is a byproduct of the resistance of
circuitry
that the electric current has to
encounter
electronic cooling is extremely
important to avoid
overheating and maintain the electronics
operation
it can be a serious challenge in tightly
packed electronics like smartphones
where heat cannot be removed using fans
the sun is another source of heat
transfer
photovoltaic panels or solar heating
are examples of applications where
the heat transfer is mostly due to solar
irradiation
for example the solar towers in solar
thermal plants
use glass reflectors to concentrate the
sunlight onto the top of the tower
that would heat up the water inside and
generate steam
heat transfer is not only a terrestrial
theme
we can still have heat transfer in outer
space
the only mode of heat transfer through
vacuum is radiation
satellites and spacecrafts can only shed
internally generated heat through
radiation
and this poses several challenges in the
design of such vehicles
now that we have a broad view of
applications of heat transfer
let us move to the next lessons to learn
the theory
of heat transfer
you