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Dear chicopee, thank you for your elaborate reply. I actually found out that in formula 1 I depicted, there is an error I think. When making a dimensional analysis it becomes clear that the area factor is missing on the left hand side. After fixing that, this issue was solved. With regard to...

I am not completely sure, but the standard Gnielinsky correlation gives a better result normally. The Dittus Boelter format is weaker in its performance either in low or high Re, not sure anymore. The factor 0.8 seems to be of empircal nature. If you do not have the paper you need to test it...

Thank you for your reply! The phase change however starts somewhere within the heat exchanger. before and after there are single phase fluids since LNG does not enter at saturation temperature. I am using a mixture between methane and ethane to model an LNG flow. For the work I do it is okay to...

Dear all, I just found that I made a horrible mistake in my calcualion for a phase chaning heat exchanger desing. For the design i wanted to include the change in physical properties, for which I decided to create the heat exchanger in a discretized manner. I did this and calculated the heat...

Hey, thank you for your responses. I'm sorry that I didn't reply instantly since I was very busy in the last time. I am aware that the flow inside the tubes and the one outside of it are of course different. I am confused about the hydraulic diameter purely on the outside. As you can see in the...

Hi all, I currently design a multitube heat exchanger. In this heat exchanger multiple tubes are put in parallel, while the flow goes in parallel, so not with baffels for cross flow (due to very stringent pressure drop reqs). The tubes will be longitudinally finned. I currently struggle a bit...

Thank you guys for your advice! @davefitz I will take that into account. Anyway in my calculations the boiling heat transfer coefficient is extremely high, such that the overall heat transfer coefficient is mainly determined by the shell heat transfer coefficient. The fluids I am using are air...

Hey Christos, if I understood you right, you want to know whether the flue gas or the air should flow in the pipes or the shell respectively? From my point of view it is dependent on many factors what the best configuration should be, however in pure terms of heat transfer the gas with the...

Hello all, For the design of a parametric heat exchanger program I need to determine the above mentioned two phase boiling heat transfer coefficient. Since the design tool shall be kept reasonalbly small in size, semi empirical correlations should be used. I however struggle to find a...