What are the gas flow characteristics in the heat exchanger
The gas flow in the heat exchanger is different, and its thermal characteristics are also different. When the temperature of the exhaust gas entering the heat exchanger is the same, the counterflow can preheat the air to a higher temperature than the downstream flow. When other conditions are the same, the heat transfer of the countercurrent is larger than that of the downstream, and the structure is more compact than that of the downstream heat exchanger. Judging from the working conditions of the heat exchanger wall, the downstream type is more advantageous. Because the temperature of the heat exchanger wall is almost equal to the two ends of the downstream heat exchanger, its maximum temperature is lower than that of the countercurrent heat exchanger, the heat exchanger is not easy to be deformed and damaged, and the material requirements are not high. On the counterflow heat exchanger, the wall temperature at the high temperature end is close to the temperature of the exhaust gas population, and the temperature difference between the two ends is large. This puts forward higher requirements on the material of the vessel wall, and at the same time, due to the large temperature difference between the two ends, it is easy to deform and damage. In practical applications, most heat exchangers use countercurrent flow.