Issues with using HTRI software: Heat exchanger process calculation? Expert reply
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The HTRI software is used for the process calculations of coolers. There are two operating conditions: one with hydrogen and the other with nitrogen. Based on the calculation results, the cooler with a larger heat exchange area is designed and manufactured. Two design firms were engaged, but their process calculation results differed significantly. 1. The diameter, length, and heat exchange area of the cooler are kept constant, while the two operating conditions are distinguished by adjusting the amount of cooling water used; in other words, it’s the same cooler, but with different amounts of cooling water used. 2. Process calculations for the cooler are carried out under each of the two operating conditions, resulting in two different coolers – each with different heat exchange areas, diameters, and lengths. The cooler with the larger heat exchange area is chosen as the final result. Which approach is correct? Furthermore, under the same operating conditions, different designers arrive at different results; one calculates the heat exchange area to be 82 square meters, while another calculates it to be 155 square meters
When using software for calculations, there are still some parameters that need to be entered. For example, the thermal resistance of dirt varies depending on different experts’ experiences, so the values entered will differ as well. Other details such as the tube side and tube length also vary from one case to another. You can refer to the parameters calculated by others, design your own solution, then verify it and compare the parameters to find what works best for you
I’m asking which of the first and second calculation methods is correct/for different operating conditions. Thank you
:hug: These two approaches are actually the same, as in both cases a heat exchanger is used in the end :lol It’s just that the perspective from which they are viewed differs :P When the operating conditions change from a lower heat load to a higher one, the first approach involves adjusting the pumps and valves on the cooling water pipes to change the flow rate, thereby increasing heat exchange. The second approach is equivalent to using a heat exchanger with a large capacity, so it’s sufficient no matter how the conditions change :lol The heat exchanger of 155㎡ mentioned by the original poster must be the second type, right? :lol
The heat transfer calculation for heat exchangers should be carried out separately based on different conditions, right? If only the larger area is considered, 155 should meet the requirements!
Reply to 5# yuri714: Under exactly the same working conditions, one company calculated it as 82 square meters while another calculated it as 155 square meters; one of them must be wrong!
:D It doesn’t matter whether it’s right or wrong; the difference lies in whether the heat exchanger has a large or small margin of safety. Of course, designs created by different people can vary greatly, but they should all meet your heat exchange requirements: lol. Perhaps one company designs systems with a higher flow rate, finer tubes, and greater pressure drops, which increases the heat transfer coefficient and thus reduces the required area. If another company adopts the opposite approach, more area will be needed. Another factor that can lead to significant differences in the heat transfer area is the use of methods to enhance heat transfer, such as low-fin tubes, internal flow disruptors, corrugated tubes, and so on: hug:
What was said upstairs makes sense! In fact, it is still necessary to rely on practice to determine right from wrong; the option that is closer to the actual situation is the correct one! Since the areas are different, their heat transfer coefficients and various other parameters also vary; it’s still necessary to determine which one better corresponds to reality