Hello.. I want to calculate shell side convection coefficient (h), to calculate h i have to know Reynold number, to calculate Re I have to know the equivalent diameter or hydraulic diameter. Anyone know what is the formula to calculate equivalent diameter of 30 degree equilateral pitch in shell and tube heat exchanger ? I had read Coulson's Chemical Engineering book and Kern's Process Heat Transfer but they only provide formula for 60 and 90 degree :(
Very need help because i have to complete my homework. Please provide source of the formula maybe from journal or book.
Oh almost forgot, I calculate it using Kern Method. Big thanks to someone who can help me :(
hi, you can use such elements and define the hydraulic diameter.
Dear Muhamad Miftahul Azhar
http://web.iitd.ac.in/~pmvs/courses/mel709/mel709-23.ppt
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.568.4412&rep=rep1&type=pdf
Article Beneficial design of unbaffled shell-and-tube heat exchanger...
Here are the steps to calculate shell diameter of a shell and tube heat exchanger using preliminary design:
1. Knowing the hot and cold fluid inlet and outlet temperatures and mass flow rate of fluids, calculate heat duty.
2. Assume heat transfer coefficients and fouling resistances of two fluids used in heat exchanger available as tables in various Hand Books of Heat Transfer (als in Text book 1 below) to estimate fouling overall and clean overall heat transfer coefficients.
3. Calculate LMTD and estimate areas when subjected to fouling and clean surface.
4. Check the design is safe or not by taking the ratio of area of fouling (Af)/ area of clean surface (35% over design permitted). If not, again go back and modify the input parameters till the design is safe within limits.
5. Shell diameter is calculated by,
Ds = 0.637 (CL/CTP)1/2 [(Af PR2 do)/L ]1/2, where CL(tube lay out constant) is 0.87 for 30o, CTP (tube count calculation) is 0.93, 0.9, 0.85 for one tube, two tube, three tube pass respectively, PR ( tube pitch ratio), do is outside tube diameter, and L is length of tube.
The text book , reference and TEMA code to refer to the preliminary design and to calculate shell diameter is:
1. Heat Exchangers Selection, Rating and Thermal Design by Sadik Kakac and Hongtan Liu, CRC Press, 1998.
2. Process Heat Transfer by Donald Q. Kern, Tata Mc. Graw Hill for reference.
3. TEMA codes
i think this can help you finding equivalent diameter
p139 process heat transfer by D.Q kern
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