Heat always moves from warmer to cooler objects. There are three main types of heat transfer: conduction, convection, and radiation. Conduction involves direct contact and heat transfer through solids. Convection involves the transfer of heat by fluid movement, such as air currents in an oven. Radiation uses electromagnetic waves to transfer heat over distances without physical contact.

1. PRINCIPLES OF HEAT TRANSFER

2. Heat Transfer
• Heat always moves from a warmer place to a cooler place.
• Hot objects in a cooler room will cool to room temperature.
• Cold objects in a warmer room will heat up to room temperature.

3. 3 Types of Heat Transfer:
Conduction
Convection
Radiation

4. BASIC COOKING PRINCIPLES
Conduction
Heat transfer through direct contact. When cooking on the stovetop, the heat
from the flame or electric grill is applied directly to the frying pan. This means
that only the flat surface of the pan is sufficiently hot enough to cook anything
and we must flip and toss around the food to cook it properly.
It is important to note that most pans are made of metals, like copper, that
conduct heat very efficiently and do not melt on the stovetop.

5. Conduction
When you heat a metal strip at one end, the heat
travels to the other end.
As you heat the metal, the particles vibrate, these
vibrations make the adjacent particles vibrate, and so on
and so on, the vibrations are passed along the metal and
so is the heat.

6. Metals are different
The outer e______ of metal atoms
drift, and are free to move.
When the metal is
heated, this ‘sea of
electrons’ gain k_____
energy and transfer it
throughout the metal.
Insulators, such as w___ and p____, do not
have this ‘sea of electrons’ which is why they
do not conduct heat as well as metals.
lectrons
inetic
ood lastic

7. BASIC COOKING PRINCIPLES
Convection
Heat transfer through a fluid. The fluid can be liquid or gas and in the
case of a convection oven, the fluid we care about is air.
An oven is a confined area that gets hot by flames or electric coils.
The air inside is warmed to a desired temperature and, as a result,
cooks the food from all directions. This method of heat transfer is
responsible for pizzas, cakes, and other baked items.

8. Convection
What happens to the particles in a liquid or a
gas when you heat them?
The particles spread out and
become less dense.
This effects fluid movement.

9. Fluid movement
Cooler, more d____, fluids
sink through w_____, less
dense fluids.
In effect, warmer liquids and
gases r___ up.
Cooler liquids and gases s___.
ense
armer
ise
ink

10. Water movement
Hot water
rises
Cooler
water sinks
Convection
current
Cools at the
surface

11. BASIC COOKING PRINCIPLES
Radiation
The transfer of heat using electromagnetic radiation. A microwave
oven uses very strong radio waves (a form of electromagnetic
radiation), which are very weak and not hot
Microwave ovens work by spinning water, fats, sugars and oils inside
the food. This causes friction, which then heats the food and cooks it
from the inside.

12. The third method of heat transfer
How does heat energy get
from the Sun to the Earth?
There are no particles
between the Sun and the
Earth so it CANNOT
travel by conduction or
by convection.
?
RADIATION

13. What methods of heat transfer are
represented below?