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Modern Engineering Thermodynamics

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14.4 In the Beginning There Was Ice 539<br />

3. A salesperson from a waste heat recovery company visits you and claims to have a new engine that can convert<br />

50.% of the waste heat in Example 14.1 into useful shaft work. How would you evaluate this claim? Answer: No<br />

engine can be more efficient than a (hypothetical) Carnot engine, and since a Carnot engine is only 38% efficient<br />

for converting this waste heat into useful work, the salesperson’s claim of a 50.% conversion is impossible to<br />

achieve.<br />

Development of refrigeration technology<br />

Natural refrigeration<br />

Artificial refrigeration<br />

Ice and snow<br />

Used from aniquity.<br />

Harvested during<br />

the winter and stored<br />

in pits and ravines<br />

covered with straw.<br />

Extensive ice<br />

harvesting and<br />

storage industries<br />

developed over the<br />

ages to provide ice<br />

during the summer<br />

months and in<br />

southern regions.<br />

Surface<br />

evaporation<br />

Used from aniquity.<br />

Evaporation from the<br />

surface of porous<br />

containers will keep<br />

the contents cool.<br />

Radiation<br />

cooling<br />

Used by the<br />

Egyptians. Shallow<br />

pans filled with water<br />

and exposed to the<br />

night sky will cause<br />

the water to freeze by<br />

radiation heat transfer<br />

to the sky even when<br />

the surrounding air<br />

temperature is above<br />

freezing.<br />

Vaporcompression<br />

Originated by Jacob<br />

Perkins in 1834.<br />

Commercialized by<br />

James Harrison in<br />

1856.<br />

Expanding<br />

gas<br />

Originated by<br />

John Gorrie in<br />

1844.<br />

Commercialized<br />

by Alexander<br />

Kirk in 1862.<br />

Absorption<br />

Originated and<br />

commericalized<br />

by Ferdinand<br />

Carré in 1859.<br />

Miscellaneous<br />

Refrigerating mixtures −<br />

known from antiquity.<br />

Reduced pressure −<br />

Originated by William<br />

Cullen, 1755.<br />

Thermoelectric − Originated<br />

by Jean-Charles Peltier,<br />

1834.<br />

Joule−Thomson −<br />

Originated by James<br />

Prescott Joule and William<br />

Thomson, 1850.<br />

Vortex Tube − Originated by<br />

Georges Ranque, 1931.<br />

FIGURE 14.3<br />

The development of natural and artificial refrigeration technologies.<br />

Two primary types of refrigeration are available, natural (e.g., ice) and artificial. Artificial refrigeration has been<br />

subdivided in this chapter into vapor cycles (specifically vapor-compression and absorption cycles) and gas expansion<br />

(specifically reversed Stirling and Brayton cycles). These refrigeration methods are illustrated in Figure 14.3<br />

and discussed in detail in this chapter.<br />

14.4 IN THE BEGINNING THERE WAS ICE<br />

The use of natural ice for refrigeration spread throughout the world in prehistoric times. China had ice houses<br />

for storing winter ice and snow by 1100 BC. The early Greeks and Romans are known to have used ice and<br />

snow for cooling drinks but not for preserving<br />

foods. In about 300 BC, the king of Macedon had<br />

several trenches dug and filled with snow to cool<br />

kegs of wine given to his troops on the eve of a<br />

major battle, hoping it would make them more<br />

courageous. Ice and snow were harvested by farmers<br />

during the winter throughout the United States,<br />

Europe, and Asia (see Figure 14.4). Ice was stored<br />

in special icehouses, underground, or in pits and<br />

ravines and covered with straw to insulate it from<br />

the daytime sun.<br />

Initially, natural ice refrigeration was merely a convenience,<br />

providing a cool drink or preserving<br />

food a bit longer. However, the development<br />

and extensive use of ice as a refrigeration technologyhadaverysignificantsocialimpact,inthatit<br />

allowed whole populations to change to a healthier<br />

diet. In the distant past, people used salting<br />

and drying as the main technology for preserving<br />

FIGURE 14.4<br />

Ice harvesting in the 19th century.

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