Question regarding the fact that the total cross-sectional area of the heat exchange tubes in the heat exchanger is much larger than the cross-sectional area of the feed pipeline
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I need to cool a stream of material at the moment; the properties of this material are similar to those of water, and its flow rate is 5000 kg/h. The flow velocity in the feed pipeline is designed to be 1.5 m/s； The feed temperature is 90°C, and it needs to be reduced to 60°C. The material flows through the tube side, while the cooling water flows through the shell side. Based on calculations, the designed heat exchange area is 8㎡. The specifications of the heat exchange tubes are Φ25mm×2mm with a length of L=3m, and there are 34 such tubes in total. If a single-pass shell-and-tube heat exchanger is used, the total cross-sectional area of these tubes is approximately 0.012㎡. As a result, the flow velocity of the fluid inside the tubes drops to 0.116m/s. Will this affect the heat exchange efficiency of the heat exchanger? Is this design reasonable? Please help!
This can be addressed by reducing the number of heat exchange tubes and increasing their length.
The flow rate is low, but what’s important is what the flow rate is intended to be in the design; if it’s much lower than that designed value, it affects heat transfer. Either reduce the number of tubes or increase the process flow
It can also be designed as a U-tube heat exchanger
Thank you for the explanation. In other words, this design indeed doesn’t work; the designed flow rate is 1.5 m/s, but the flow rate of the material inside the tube side is less than 1/10 of that value. In such a case, the tube side must be enlarged
The flow rate is too low, which affects heat transfer; it can be changed to a multi-tube arrangement
Increase the pipe bank or lengthen the heat exchange tubes; if the area is large, a circulation pump can be considered