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 sakthi August 28, 2009 03:50

Heat exchanger design

I am doing the design of heat exchangers......

I need a help for thermal design.... can you help me. Here I have noticed my procedures and problems...

1.Q=m cp dT
2.m1 cp1 dT =m2 cp2 dT
3.Finding U(h) AND ^T
4.A= Q/ U*^T
For finding no.of tubes
5. Flow rate = AREA* VELOCITY
by assumption, average velocity =0.9 m/sec....... will find area.
6.for 5/8 OD i will get no.of tubes n*pi*d2/4 = area
For finding length,
7. surface area = 2*pi*r*h* n
will find h value- length of the tube...
for reducing length i will use correction factor in area formula.
THEN will continue MECHANICAL DESIGN.
HERE I have doubt in
1. HOW TO ASSUME VELOCITY FOR PROPER HEAT TRANSFER.
2.PRESSURE DROP IN CALCULATION AND EFFECTIVE LENGTH OF HEAT EXCHANGER...
3.ANY OTHER METHOD FOR THERMAL DESIGN...
4.FINDING SHELL SIDE HEAT TRANSFER COEFFICIENT...