Modern Engineering Thermodynamics

14.4 In the Beginning There Was Ice 541
meat and fish. By 1830, the use of ice to preserve food in American iceboxes was quite common. The standard
of living of average Americans improved between 1830 and 1860, as their diet changed from one of
bread and salted or dried meat or fish to one that regularly included refrigerated fresh meat, fruits, and
vegetables.
Preserving food in a sterilized metal can was patented in 1825, but it did not become a commercial success until
1875, about the same time mechanical refrigeration systems were being marketed.
As the food refrigeration industry grew, the demand for natural ice increased dramatically. Natural ice was harvested
from ponds, lakes, and rivers in rural communities around the world by farmers during the winter
months. New York City used 12,000 tons of natural ice in 1843, 100,000 tons in 1856, and 1 million tons in
1879. Natural ice harvesting in the United States reached its peak in 1886 at 25 million tons. From 1845 to
1860, the mechanical refrigeration systems of Perkins, Gorrie, and Carré were used primarily for making ice to
replace natural (winter) ice.
A common unit of commercial and household refrigeration or air conditioning is the ton. The following example
illustrates the use of this old unit of measurement.
IS IT DANGEROUS TO STUFF A CHICKEN WITH SNOW?
The great British philosopher and statesman Sir Francis Bacon (1561–1626) was keenly interested in the possibility of using
snow to preserve meat. In March 1626, he stopped in the country on a trip to London and purchased a chicken. He had
the chicken killed and cleaned on the spot, then he packed it with snow and took it with him to London (Figure 14.7).
Unfortunately, the experiment only caused his own death a few weeks later. The 65-year-old statesman apparently caught a
chill while stuffing the chicken with snow and came down with terminal bronchitis. Refrigeration was clearly not
something to be taken lightly.
FIGURE 14.7
The price of experimentation.
WHAT IS A “TON” OF REFRIGERATION?
A ton of refrigeration or air conditioning is the amount of heat that must be removed from 1 ton (2000 lbm) of water in
one day (24 hours) to freeze it at 32°F at 1 atmosphere pressure. It is also the amount of heat absorbed by the melting of
1 ton of ice in 24 hours at 32°F at atmospheric pressure. Using more conventional units,
1 ton of refrigeration or air conditioning = 200: Btu=min = 12:0 × 10 3 Btu=h = 214: kJ=min = 12,600 kJ/h