Please list the situations you have encountered when heat exchangers perform downstream heat transfer.
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List the downstream heat transfer situations you have designed or encountered. Explain the temperature, pressure and flow parameters of the hot and cold streams and the structural parameters of the heat exchanger. The more detailed the better.
The efficiency of co-current heat exchange is relatively low, and has never been encountered in the heat exchangers we have come into contact with. The coil-wound heat exchanger is counter-current heat exchange, and the others are basically multi-tube cross-flow heat exchange.
I have never encountered it in practice, but I have seen in books that the main purpose of this structure in preheaters is to improve the high temperature resistance of the material. The flue gas temperature at the inlet of the preheater is very high. At this time, allowing the air and flue gas to flow downstream can reduce the temperature of the pipe wall. This is good for the material, although the heat transfer effect is not so good! One more thing, sometimes this structure seems to be adopted in order to prevent some frozen materials from reaching the freezing point. This post was finally written by wode * Edited by aohei on 2009-4-10 10:01 ]
There are two applications for downstream: 1. Prevent the temperature on the high temperature side from dropping too low, or prevent the temperature on the low temperature side from rising too high. 2. Let the cold side heat up quickly, or the hot side cool down quickly.
CNOOC Xijiang Oilfield, oil cooler, oil is cooled from 83 degrees to 70 degrees. Seawater cooling, 450 cubic meters of oil per hour. APV heat exchanger was used before, but it failed to achieve the effect. The main reason is unknown (using downstream flow). It is not possible to add area later. It is estimated that by adding area, the flow rate is low and the heat transfer coefficient is also reduced. Later, our company's M1.6 equipment (single plate 1.6 square heat exchange area) was used. Compared with the original heat exchanger, it is higher and larger! It is also downstream, and now it can be produced normally. Imported titanium plates (our company's pressed plates) and sealing gaskets are used. The reason for the downstream design is that the seawater temperature cannot rise too fast, otherwise it will easily crystallize and cause blockage!
I have encountered that a heat exchanger in a solid polymerization equipment uses nitrogen on both the tube and shell sides. One design temperature is 450°C and the other is 420°C. The pressure does not exceed 1KG. The equipment diameter is 2100. I am not a craftsman. I personally think it may be the heat exchange of the equipment for compensation:)