I’m a chemical engineering student and I’m learning about heat exchangers,I came across this question and had a doubt ,
Cold water is heated from 20 degree C to 85 degree C while hot process stream is cooled from 130 to 55. Overall heat transfer coefficient is $348 W/m^2 . DegreesC$ .
Surface area of each tube is 0.092$m^2$ , how many tubes would be required to construct this heat exchanger ?
Rate of heat transfer = 165800W
I calculated LMTD = 39.79
And I calculated the area , which is about 11.97$m^2$
Number of tubes = $11.97/0.092 = 130.4$ tubes.
In this case, I need 130.4 tubes . Do I round up to 131 or round down to 130? and why ?