Heat exchanger process calculation problems
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U-tube heat exchanger, with steam as the medium; phase change occurs at an inlet temperature of 100°C and an outlet temperature of 100°C; for air, the inlet temperature is 30°C and the outlet temperature is 40°C. The design pressure is at atmospheric pressure; it determines which side will be the tube side and which will be the shell side. Air handling capacity: 10 t/h. How to calculate the air flow velocity. Please, guys.
Generally, for such media, the conventional design is for water vapor to flow through the shell layer and air to flow through the tube layer. Air flow velocity = flow rate / total area of all tube bundles.
The circulating water flows through the tube side; in actual production, the quality of the circulating water is poor, making it difficult to clean the shell side
What if the flow rate comes out to 80 m/s, which is above the generally recommended value?
To increase the heat exchange area, finned tubes are preferred for the shell side, with air flowing through them!
There is phase change in the tube-side steam, and the heat exchange tubes may vibrate, which is also not very good.
Whenever a phase change occurs, try to avoid using a tubular flow configuration, as this will result in plug flow and pipe vibration. Furthermore, if the design pressure is at atmospheric pressure and the operating pressure is negative, a reasonable flow rate must be determined based on the allowable pressure drop. For reference.
Air flows on the shell side, while steam flows on the tube side; it’s a finned tube, and we use them on site. It’s not clear whether the requirement is for the air flow velocity inside the equipment or that within the pipes; there are different standards for each, and the original poster can look into that.