Best way to study transient response?

nygrenm · January 21, 2015, 11:47

Hi all. I have a counter flow heat exchanger set up and it works perfectly and gives me good results when I do it in steady state. I have an inlet mass flow rate of 0.028 kg/s for both the hot water which is at 80C and the cold water which is at 15C. When I tried to change it to transient response the results are screwed up.

What I'm trying to do is have both inlets at the same mass flow of 0.028 kg/s and be at 15C and then at some point change the inlet of the hot side to 80C and see how the heat exchanger reacts. If you guys have any idea of how I should set this up please share I would appreciate it very much!

me3840 · February 9, 2015, 01:01

What do you mean by screwed up?

I don't think instantaneously changing the inlet temperature is very realistic for transient.

January 21, 2015, 11:47	Best way to study transient response?	#1
nygrenm New Member Sicher Nygren Join Date: Oct 2014 Posts: 11 Rep Power: 11	Hi all. I have a counter flow heat exchanger set up and it works perfectly and gives me good results when I do it in steady state. I have an inlet mass flow rate of 0.028 kg/s for both the hot water which is at 80C and the cold water which is at 15C. When I tried to change it to transient response the results are screwed up. What I'm trying to do is have both inlets at the same mass flow of 0.028 kg/s and be at 15C and then at some point change the inlet of the hot side to 80C and see how the heat exchanger reacts. If you guys have any idea of how I should set this up please share I would appreciate it very much!

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February 9, 2015, 01:01		#2
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 24	What do you mean by screwed up? I don't think instantaneously changing the inlet temperature is very realistic for transient.