Conditioning 21st Edition
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Fundamentals of Refrigeration* - ANSWER When studying refrigeration and air
conditioning, it is important to first master the basic physical, mechanical, and
chemical principles explained in this chapter.
Much of the basic materials will be a review of physics and chemistry for those who
have studied these subjects. In addition, however, some engineering principles and
formulas have been included. - ANSWER These principles and formulas have
been simplified and are introduced with practical applications.
This chapter uses the SI "Le Systeme International d'Unites" metric units of
measure. The early refrigeration industry was developed by engineers in England
and the United States. - ANSWER They based their calculations on units of
measure and formulas developed for power, mining, automobile and, ice-making
industries.
British thermal unit, foot pound, pounds per square inch, temperatures in Fahrenheit,
and the like. - ANSWER The SI "metric" system is internationally accepted and the
United States is moving toward it. The refrigeration industry in this country has
recently adopted its usage.
SI units include linear measurements in metres or decimals, mass in kilograms,
temperature in degrees Celsius, pressure in pascals, heat in joules, and the like. -
ANSWER Complete definitions of the units and U.S. conventional equivalents
"equals" are given in Chapter 28.
Users of this text who are unfamiliar with SI metrics have no cause for concern.
Reference is also made to Chapter 28 whenever problems arise affecting metric
usage. - ANSWER *1-1 Development of Refrigeration*
Modern refrigeration has many applications. The first, and probably still the most
important, is the preservation of food.
Most foods kept at room temperature spoil rapidly. This is due to the rapid growth of
bacteria. - ANSWER At usual refrigeration temperatures of about 4.4 degrees C
(4.4oC) "40 F.", bacteria grow quite slowly. Food at this temperature will keep much
longer. Refrigeration preserves food by keeping it cold.
Other important uses of refrigeration include air conditioning, beverage cooling and
humidity control. Many manufacturing processes also use refrigeration. - ANSWER
The refrigeration industry became important commercially during the 18th century.
Early refrigeration was obtained by the use of ice. Ice from lakes and ponds was cut
and stored in the winter in insulated storerooms for summer use.