# Heat exchanger efiiciency?

1. Mar 6, 2009

### cabellos2

heat exchanger efiiciency??

I have done some design work calculations for a double pipe heat exchanger. I have the inlet and outlet temperatures and mass flow rates etc. I have calculated Q the heat transfer rate.

However im confused with the idea of the thermal efficiency of the heat exchanger. In order to select the required capacity of heat exchanger i need to factor in an efficiency somehow.

Do I work out the effectiveness and then when i get this value I choose my capacity of heat exchanger (e.g if the effectiveness is 0.5 then I double the initial Q value to select the heat exchanger capacity)??

2. Mar 20, 2009

### irian

Re: heat exchanger efiiciency??

hallo...

for your problem, may you can get heat exchangher information on air conditioning hand book

irian
blog : http://irianpoo.blogspot.com

3. May 3, 2009

### forster

Re: heat exchanger efiiciency??

Most domestic hvac systems have a rated capacity before they are installed. The technician then comes along, installs the system, charges it with refrigerant, runs a test & then leaves. Whether the system ever reaches the rated capacity would have to tested or simulated.

The operating capacity of each exchanger in the system will certainly be affected by the prevailing local conditions eg. room volume/temp, or outside temperature.

Webb & Kim, Principles of Enhanced Heat Transfer

http://www.mne.psu.edu/webb/" [Broken]

http://www.airresourcellc.com" [Broken]

Last edited by a moderator: May 4, 2017
4. May 5, 2009

### jaap de vries

Re: heat exchanger efiiciency??

You can calculate the effectiveness. e = q/qmax

q max = Cmin (Thi - Tci)

Thi is temperature of the hot fluid at the entrance
Tci is " " of cold " "