I m trying to design a steam condenser for solar desalination. The steam is produced from the water of 80 C by reducing the pressure upto 0.06 bar. The cooling water inlet temperature is 20 C .
Consult a fairly comprehensive undergraduate textbook on heat transfer, e.g. Incropera/deWitt/Bergman/Lavine, Holman or Cengel. I practice, this will be an iterative procedure since you do not know the geometry you will perform calculations on. My tip (assuming a shell-and-tube heat exchanger):
1) Guess/estimate heat transfer coefficients e.g 5000 W/(m2K) for both coolant and condensing steam, and calculate the overall heat transfer coeffcient, U=ca. 2500 W/(m2K) (ignore wall resistance.
2) Calculate the heat transfer Surface, A=Q/(U*LMTD)
3) Select a tube diameter and suitable tube length ==> number of tubes and Shell diameter can be determined.
4) Now you have a proposed heat exchanger geometry, You can now calculate the heat transfer coefficients and heat duty, and adjust the geometry as necessary. Don't forget to check the pressure drops (in particular the vapor pressure drop).
Good Luck!
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