Calculating Exit Temperature of a Heat Exchanger
Calculating Exit Temperature of a Heat Exchanger
(OP)
Hi all, recently join the eng-tips forum here
I have a question regarding to the outlet temperature of a heat exchanger.
A standard set up of a fan and a radiator like in a car system. The fan is behind the radiator to draw the cold air to the radiator to heat up a room. As far as I know, there are two types of basic analysis on a heat exchanger: LMTD method and NTU method.
However, the information that I know is really limited to both analysis. Here is the information i know:
Heat Exchange Fluids: Air/Water
The radiator generates 20,000 BTU/h
The air flow rate of the fan is 800 cfm
Ambient temperature is around 10 ºC
What i am looking for is the exit temperature of the fan (actually use the fan to heat up a container)
Therefore, i cannot use the LMTD method.
The problem that I have right now is the following:
1. Inlet temperature of the radiator is unknown
2. Heat transfer surface is unknown
3. Flow rate inside the radiator is unknown
Not sure if i am using the right method or calculation set to solve this problem. If anyone has any experience with this, i appreciate all the suggestion there is.
Thanks
I have a question regarding to the outlet temperature of a heat exchanger.
A standard set up of a fan and a radiator like in a car system. The fan is behind the radiator to draw the cold air to the radiator to heat up a room. As far as I know, there are two types of basic analysis on a heat exchanger: LMTD method and NTU method.
However, the information that I know is really limited to both analysis. Here is the information i know:
Heat Exchange Fluids: Air/Water
The radiator generates 20,000 BTU/h
The air flow rate of the fan is 800 cfm
Ambient temperature is around 10 ºC
What i am looking for is the exit temperature of the fan (actually use the fan to heat up a container)
Therefore, i cannot use the LMTD method.
The problem that I have right now is the following:
1. Inlet temperature of the radiator is unknown
2. Heat transfer surface is unknown
3. Flow rate inside the radiator is unknown
Not sure if i am using the right method or calculation set to solve this problem. If anyone has any experience with this, i appreciate all the suggestion there is.
Thanks





RE: Calculating Exit Temperature of a Heat Exchanger
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RE: Calculating Exit Temperature of a Heat Exchanger
RE: Calculating Exit Temperature of a Heat Exchanger
RE: Calculating Exit Temperature of a Heat Exchanger
Q = 1.1 * CFM * ΔT
Rearrange and solve for ΔT = 20,000 / (1.1 * 800) = 22.7°F = 12.6°C
So your leaving air temperature is 22.6°C
RE: Calculating Exit Temperature of a Heat Exchanger
RE: Calculating Exit Temperature of a Heat Exchanger
RE: Calculating Exit Temperature of a Heat Exchanger
TTFN

FAQ731-376: Eng-Tips.com Forum Policies
Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers
RE: Calculating Exit Temperature of a Heat Exchanger