Do heat pipe exchangers allow temperature cross-over?
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I’ve been working on the calculation for a heat exchanger recently: hot air enters at 250 degrees and exits at 100 degrees, while cold air enters at 25 degrees and exits at 175 degrees. The flow rates of both types of air are equal, and the flow is completely counterflow. I’m wondering if a heat pipe heat exchanger could be used for this purpose
Of course it can, but it’s impossible for the temperature at the outlet of the hot stream in a heat exchanger to be lower than the temperature at the outlet of the cold stream; there might be a deviation in the measurement location.
Firstly, counterflow heat exchange can meet the existing requirements regarding temperature crossover; however, it requires a relatively larger heat exchange area, which is why heat transfer enhancement elements are generally used. Heat pipes are not necessarily required, after all, equipment has a limited lifespan. I have recently worked on several similar projects involving natural gas waste heat recovery using internal flat fin systems (with inlet air temperatures of over 400 degrees, and a temperature overlap range that is even larger than what you mentioned). If you are interested, please provide the detailed parameters so that I can prepare a proposal for comparison.
It’s possible, but in practical design, if your cooling source is air, it’s better to use 35℃