shell-end-tube heat exchanger
shell-end-tube heat exchanger
(OP)
I am designing a shell-end-tube heat exchanger. My shell is a rectangular water tank and my tubes are 1.5in stainless steel pipes. In my design I will not use baffles. The only problem I am facing is calculating the shell-side heat transfer coefficient h(o) (the heat transfer coefficient outside the tube bundle). I used a different sources to calculate h(o) (one of them is Wolverine data book) and they all give me a different results. The calculated value of h(o) is too low which leads to tubes that too long. Can anyone help me with the correct equation for determining h(o). Thank you!





RE: shell-end-tube heat exchanger
I2I
RE: shell-end-tube heat exchanger
(h(o)*D(e))/k = 0.36*Re^0.55*Pr^0.33*(M(b)/M(w))^0.14
Re = (D(e)*G(s))/M(b)
D(e) - equivalent shell diameter
G(s) - shell side mass velocity
M(b) - viscosity at bulk fluid temperature
M(w) - viscosity at pipe wall temperature
Equation for single pass length:
L = q/(U*pi*d*deltaT(lm)*N(p)*N(t))
q - heat transfer rate
U - overall heat transfer coefficient
d - tube diameter
deltaT(lm) - log mean temp. difference
N(p) - number of passes
N(t) - number of tubes
RE: shell-end-tube heat exchanger
Since you are not using baffles, how do you generate turbulence on the shell side ?
RE: shell-end-tube heat exchanger
RE: shell-end-tube heat exchanger
Thank you for the reply. Water temperature in the shell is T(i)=85F, T(o)=106F (approximately); water temperature in the tube is T(i)=120F, T(o)=95F. I am not sure if the tube side temperature is high enough to use free convection heat transfer equation. Also, can I use free convection heat transfer equation since water flow is caused by a pump? Please advice! Thank you!
RE: shell-end-tube heat exchanger
RE: shell-end-tube heat exchanger
Could you please recommend a book providing coil-in-tube design equations?
Thank you!
RE: shell-end-tube heat exchanger
I work in process heating department in my company. Also i have done similar applications here in the TURKIYE. There is a direct heating immersion burner with the immersion tubes. And i can calculate the heater capacity, and the length of pipe.
Also i need the datas; What is the liquid ? (water , Zinc-poshpat, etc. ) And what is entrance temperature of liquid, and the what is the process teperature which is wanted. What is the tank's dimensions?
RE: shell-end-tube heat exchanger
The cooling fluid inside the tubes is de-ionized water and the water in the tank is CSO (Combined Sewer Overflow) water from Chicago Sanitary Canal.
The heat transfer rate each unit generates is 70kW. I have six units but they might be reduced to 4. Water temperature in the shell is T(i)=85F, T(o)=106F (approximately); water temperature in the tube is T(i)=120F, T(o)=95F. Flow rate is 22GPM. Tank dimensions 8.67ft x 9ft, hight=6ft
If you need any more information please let me know. Thank you!
RE: shell-end-tube heat exchanger
If you get help answering your question, can you please advise? I am working on a very similar problem and unfortunately have a lack of information where I am doing work. My fundamentals are around, but it has been a while since I have worked in thermodynamics.
Please let me know, thank you!
RE: shell-end-tube heat exchanger
Unfortunately I am not getting much help so far but as soon as I gather more info I will post it here. In my last message I answered SirCepxat's questions. I hope he would help.
RE: shell-end-tube heat exchanger
GO TO:
PROCEDURE 6-8 DESIGN OF PIPE COILS FOR HEAT TRANSFER
PRESSURE VESSEL DESIGN MANUAL, 3rd EDITION, DENNIS MOSS
Gulf Professional Publishing
RE: shell-end-tube heat exchanger
Unfortunately, one of the reasons you're not getting a lot of responses is that calculating the shell side heat transfer coefficient is one of the hardest things to do in heat exchanger design. Used to be, it was "back calculated" by putting together a heat exchanger based on empirical knowledge, figuring out all the other parameters and solving for it. The formulas are somewhat complex and I, for one, don't want to spend a lot of time typing in the methods I've used. It's one thing when someone provides all the data and somebody can just plug it into their purchased software and another to go through all the steps, not knowing when your question's been answered.
Ok, having finished my rant, I see that no one has directed you to Lienhard's heat transfer book. It probably has the information you need, if you don't already have a good heat transfer book.
The Lienhard textbook can be downloaded (legally and free) here:
http://web.mit.edu/lienhard/www/ahtt.html
Patricia Lougheed
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