How to

[fouadram]

I have 2 aircooled heat exchangers.

The first one has water ( 0.77 wt%) and ( 0.22 wt %) Dextrouse, temp.(from 109.7223 c to 35 c) and press.(137 kpa) with duty of (1.23 E08 KJ/hr) and air temp.(22 c).

The second has water ( 0.4643 wt.%) and ethanol ( 0.5326 wt.), temp.( from 92 c to 35 c) and press. (105 kpa) with duty of (1.91 kJ/hr) and air temp. (22 c).

I have tried to measure the area of both ACHEs by using the equation (Q = U.A.DTlm) and they were as following;

The first is about (1.08 E03 sq.m) and the second is ( 2.36 E03 sq.m).

Please is my answer is correct and if not what is the correct one?
and how I can cost them?

 

[Latexman]

Usually the surface area is given on the equipment drawing or data sheets, or you calculate it from the physical dimensions. Then, with the performance data you have, you calculate U.

You can cost them with historical cost data, estimating correlation, or ask for a quote from a vendor.

Good luck,
Latexman

 

[rmw]

Q=U*A*DTlm was used to size the heater based on some design assumptions. How it actually operates may be entirely different, or that is to say that if it operates per its Q=UADTlm value, it is probably a pure coincidence.

rmw

 

[fouadram]

Tanks for your reply.

I have searched the net and found some sites calculate the area and they got different results in comparison to mine. They give the bundles face area,the number of bundles,number of tube per bundle, number of fans, size of fan, power per fan,..

What is the equation they use to find out the area of bundle?as the cost is measured from the area of bundle(surface bare tube) and the depth of raw bundel or the number of bundle.