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E.S.D |
Gas/Gas plate heat exchanger. The heat exchanger is of a relatively simple construction, consisting of stacks of flat steel plates separated by side bars and pins. The gas flow is directed through alternate layers of the stack, such that each plate has cold gas on one side and hot gas on the other. The hot and cold gas are arranged to flow counter-currently along the long axis of the plates, but in order to accommodate the gas entry and exit pipework the gas flows change direction at the ends of the plates. By running a simulation with equal pressure loss through each channel it is possible to determine the velocity in each of them. With regard to the heat transfer coefficients, it might be expected that the reduction associated with low flow regions would be offset by higher values in higher flow regions. However, the construction of the heat exchanger ensures that the low flow regions (with low local heat transfer coefficients) on one side of the heat exchanger are associated with the high flow regions (with high local heat transfer coefficients) on the other side. |
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The result is that the overall heat transfer coefficient is in all locations lower than would be expected for evenly distributed flow and reduce the overall performance. |
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