Glossary
to accompany
Thermodynamics: An Engineering Approach, 5th edition
by Yunus A. Çengel and Michael A. Boles14thermodynamics, and it indicates how well an energy conversion or transfer process is
accomplished.
Efficiency of a cooking appliance is defined as the ratio of the useful energy transferred
to the food to the energy consumed by the appliance.
Efficiency of a water heater is defined as the ratio of the energy delivered to the house
by hot water to the energy supplied to the water heater.
Efficiency of resistance heaters is 100 percent as they convert all the electrical energy
they consume into heat.
Electrical polarization work is the product of the generalized force taken as the electric
field strength and the generalized displacement taken as the polarization of the medium
(the sum of the electric dipole rotation moments of the molecules).
Electrical power is the rate of electrical work done as electrons in a wire move under the
effect of electromotive forces, doing work. It is the product of the potential difference
measured in volts and the current flow measured in amperes.
Electrical work is work done on a system as electrons in a wire move under the effect of
electromotive forces while crossing the system boundary.
Emissivity is a surface property that is a measure of how closely a surface approximates
a blackbody for which the emissivity equal to one.
Energy Balance is the net change (increase or decrease) in the total energy of the system
during a process is equal to the difference between the total energy entering and the total
energy leaving the system during that process.
Energy efficiency rating EER is the performance of refrigerators and air conditioners,
and is the amount of heat removed from the cooled space in Btu’s for 1 Wh (watt-hour)
of electricity consumed.
Energy transport by mass is the product of the mass of the flowing fluid and its total
energy. The rate of energy transport by mass is the product of the mass flow rate and the
total energy of the flow.
English system, which is also known as the United States Customary System (USCS),
has the respective units the pound-mass (lbm), foot (ft), and second (s). The pound
symbol lb is actually the abbreviation of libra, which was the ancient Roman unit of
weight.