I am rating an exchanger, but the fluids are reversed on my specification sheet. Why?
Within the heat Exchanger Rating information, very top line under the “Tubes” item asks for the Service, and the options are Supply and Demand. If the Hot fluid is flowing through the tube side, select Supply. If the Cold fluid is going through the tubes, select Demand. This selection follows the Second law of Thermodynamics, that heat always flows from a higher temperature level to a lower temperature level.
