The Enid Ice Plant, photographed in the 1920s and seen on the EnidBuzz facebook page, inspired this piece:
Ice trade journals from the era list this company as Enid Ice and Fuel, which is a rational business model. They were processing and delivering portable energy, lumps of heat and blocks of cold. The visible tracks in the picture show retail customers driving to the front door, and a loading dock for commercial customers was probably to the left of the front door. After learning how the typical plant operated, I concluded that there must have been a much larger wing, or more likely a separate building to manufacture the ice blocks. The tower on the right is definitely the cooling tower for the condensation stage of the refrigeration process.
My version of the original view:
Here’s my expansion of the back area, showing the coldroom to the left of the main building and the condenser (cooling tower) behind the main building:
Route trucks would have loaded up at the loading dock:
Most industrial systems used ammonia, which is stinky and poisonous but requires low pressure to complete the cycle. Low pressure means less power to the compressor and less chance of leaks. CO2 is harmless, but requires much higher pressure and thus more electricity to the compressor.
This compressor has a double-acting cylinder, with valves at each end. One of the output pipes was always sucking and the other was always blowing.
The compressor sucks in gaseous ammonia at maximum heat and expansion (red arrow). The piston reduces the volume and increases the temperature of the gas. The output of the compressor flows into the cooling tower (orange arrow), in gaseous form at high pressure. The tower takes away enough of the heat to change the phase into liquid form. The liquid ammonia then flows (blue arrow) into the coils in the coldroom, where it is allowed to expand and re-gasify, absorbing heat from the surroundings. In this case the surrounding material is a pool of brine, which we’ll see in the next step.
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Evaporation and condensation (sweat, dew) are instantly familiar in Nature. The other parts of the cycle are not intuitive. Our lungs are compressors and evaporators, but the temperature change at the nose is not obvious. The full picture of Boyle’s Law wasn’t grasped until inventors began developing steam engines and hot-air balloons.