wilsonudevil
20-11-2008, 11:52 AM
Hi all,
Ok quick question about heat exchangers.
I'm using a finned tube heat exchanger similar to the one below:
http://i35.tinypic.com/eaqn49.jpg
Water is circulating through the tube and air is being passed over the tube.
If I heat the water I can warm the air passing over the tube. Similarly if I chill the water I can cool the air passing over the tube.
Now my question is about the Thermal Effectiveness (E) of the heat exchanger.
Using E = (t1-t2)/(tw-t1)
where:
t1 = air temp before heat exchanger
t2 = air temp after heat exchanger
tw = inlet water temp
Will the thermal effectiveness of the heat exchanger be the same for cooling as it is for heating? (for constant air and water flow rates)
I have an average experimental effectiveness for cooling (around 0.8), but want to know if I can use this same effectiveness for the heating condition. ;)
Or will I have to do another experiment?! :mad:
Many thanks.
Ok quick question about heat exchangers.
I'm using a finned tube heat exchanger similar to the one below:
http://i35.tinypic.com/eaqn49.jpg
Water is circulating through the tube and air is being passed over the tube.
If I heat the water I can warm the air passing over the tube. Similarly if I chill the water I can cool the air passing over the tube.
Now my question is about the Thermal Effectiveness (E) of the heat exchanger.
Using E = (t1-t2)/(tw-t1)
where:
t1 = air temp before heat exchanger
t2 = air temp after heat exchanger
tw = inlet water temp
Will the thermal effectiveness of the heat exchanger be the same for cooling as it is for heating? (for constant air and water flow rates)
I have an average experimental effectiveness for cooling (around 0.8), but want to know if I can use this same effectiveness for the heating condition. ;)
Or will I have to do another experiment?! :mad:
Many thanks.