3 replies to this topic

[sargon 1979]

Dear all,
In GTP, i have an air cooled heat exchanger designed as follows:
Duty: 1079.54 kw
air data:
Design air temperature: 45℃
Design air outlet temperature: 47.87℃
Number of fans 4
Air flow/fan: 36.09 m3/s
Altitude: 581 m
Elevation: 6 m
Process data:
Mass flow: 149951 kg/hr
Cp: 2.707 kj/kg/℃
Inlet temperature: 64℃
Outlet temperature: 55℃
What happened to the ACHE if the operating conditions are other than design conditions? Does the ACHE has a constant duty regardless the in/out temperatures?
Please help

[breizh]

https://checalc.com/calc/AirExch.html

 

Hi ,

Is it a unit in service ?

 

Consider the resource attached . BTW did you check the cleanliness of the HX ? Dirt can affect the performance very easily .

 

 

Hope this is helping you.

Breizh

Edited by breizh, 12 August 2017 - 01:10 AM.

[spchauhan12]

Dear sargon 1979,

 

                   I did not understand " operating conditions other than design conditions".

 

I presume your query as - " operating conditions if exceeds design condtions" .

 

My reply: Yes. Depending upon operating parameter under consideration & its value, Heat exchanger duty & performance both can be

 

affected.

 

Your Query: Does the ACHE has a constant duty regardless the in/out temperatures?

 

My reply: No, Duty will change if inlet / outlet temperature is changed keeping other operating parameters constant.

 

Note : As suggested by breizh sir, Dirt factor is one of the most important factor affecting performance of Heat exchanger. Sudden Change in ambient conditions OR relocation of ACHE to other places where air temperature is very low also will affect performance.

 

Kindly look / refer text book of Heat transfer by D.Q. Kern.

 

Hope this helps.

 

Regards,

 

SPC

[rdcrags]

Q = UA(delta T)_LM