Heat Transfer
HEAT TRANSFER TERMINOLOGY
Summary
The important information in this chapter is summarized below.
Heat Transfer Terminology Summary
Heat is energy transferred as a result of a temperature difference.
Temperature is a measure of the amount of molecular energy contained
in a substance.
Work is a transfer of energy resulting from a force acting through a
distance.
The Second Law of Thermodynamics implies that heat will not transfer
from a colder to a hotter body without some external source of energy.
Conduction involves the transfer of heat by the interactions of atoms or
molecules of a material through which the heat is being transferred.
Convection involves the transfer of heat by the mixing and motion of
macroscopic portions of a fluid.
Radiation, or radiant heat transfer, involves the transfer of heat by
electromagnetic radiation that arises due to the temperature of a body.
Heat flux is the rate of heat transfer per unit area.
Thermal conductivity is a measure of a substance’s ability to transfer heat
through itself.
Log mean temperature difference is the DT that most accurately represents the
DT for a heat exchanger.
The local heat transfer coefficient represents a measure of the ability to transfer
heat through a stagnant film layer.
The overall heat transfer coefficient is the measure of the ability of a heat
exchanger to transfer heat from one fluid to another.
The bulk temperature is the temperature of the fluid that best represents the
majority of the fluid which is not physically connected to the heat transfer site.
Rev. 0
Page 5
HT-02
