Answer: In the precooler, the cold and hot compressed air exchange heat and mass, and the total heat exchanged is equal. However, the saturated hot air flow undergoes phase change during the cooling process, and condensation occurs, which consumes part of the cooling capacity. The heat absorbed by the cold air flow during the heat exchange process is all used for heating, so the temperature change amplitudes of the cold and hot air flows are different. The rule is that the temperature drop amplitude of the hot air flow is smaller than the temperature rise amplitude of the cold air flow. For example, under certain working conditions, the hot air drops from to, with a drop amplitude of, while the cold air can rise fromto , with a rise amplitude of.
