Category: Thermal Equilibration
These problems involve different materials initially at different temperatures. The "event" is that the materials are brought together, permitted to communicate thermally. The "equilibration event" is one in which thermal energy of the individuals, initially different, become the same. For such events there is no heat. Heat is a system/surroundings interaction. These problems cast the thermal communication of these materials as being adiabatic, meaning zero.
Great orange juice is made from fresh oranges sliced and squeezed. The alternative is to prepare the juice from a concentrated product. Water and valuable oils are removed from fresh citrus at a processing plant then "concentrate" is shipped to consumers with the instructions,
"Mix concentrate with 3 cans of tap water."
Suppose the precise initial temperature of the solid concentrate and tap water is known:
Once prepared, sausages must be refrigerated promptly. The sketch shows ingredients for a "batch" of sausage (at 15oC) just prior their last pass through the grinder. To hasten chilling, rushed dry ice (solid carbon dioxide) is added this time. Assume the grinder requires four minutes of its 3/4 horsepower (HP) motor for the final grind. The final condition required is that the meats and carbon dioxide exit the grinder at a temperature of 1°C.
Calculate the least amount of Dry Ice that must be added to the mix.
The Indians of the early southwest used stone boiling to cook tender parts of bison, particularly the liver. After a successful hunt the paunch and liver were cut from a bison. Fire wood was gathered and stacked in criss-crossed layers then stones were placed on top and the wood was set afire. Nearby, the paunch was inverted, filled with water and hung on a tripod of branches.
In sweltering summer heat, outdoor pools feel just like hot tubs. It's silly, but some pool owners try to "beat the heat" by dropping hundreds of pounds of ice into their pools. On the day of his daughter's wedding, an architect had 800 pounds of ice dumped into his pool which was completely full of water. In about an hour all of the ice had melted and the water in the pool was still unpleasantly warm. The architect wondered "What went wrong?"