Transient heat flow

saisanthoshm88 · June 1, 2011, 12:49

I'm totally new to transient simulations. I had a newbie question. I was simulating the air flow inside a power amplifier cabinet which had Fans, Power sources and power amplifiers inside.

The power emanation from the amplifiers is of a transient nature and is described by the following details:

Output Power = 200 W

Duty cycle: Transient attribute:Gaussian, Total pulse duration: 6400 ms

So I see that I need to consider 6400 ms as the total time with a time step of 400 ms. But this is something relevant to a single duty cycle so will it be fine to analyze the heat flow inside the cabinet just for a single duty cycle on these lines.

Can some one please suggest me regarding this.

ghorrocks · June 1, 2011, 19:29

In most electronics heat modelling things of this time scale can be averaged out and the avergae heat load used. So I would average the heat load out and apply a constant heat load. But if you are doing a transient simulation anyway then it is easy to apply the transient heat load.

saisanthoshm88 · June 7, 2011, 13:02

Glenn could you please tell me how to calculate this average heat load. I apologize for raising such novice question but my experience is really too limited in this.

ghorrocks · June 7, 2011, 20:00

Integrate the heat load over a long time. If it is 11W for 1s and then 1W for 4s, and then repeats that pattern forever, then integrating over the full 5s cycle gives (11*1+1*4)/5 = 3W average load.

June 1, 2011, 12:49	Transient heat flow	#1
saisanthoshm88 Senior Member --------- Join Date: Oct 2010 Posts: 303 Rep Power: 18	I'm totally new to transient simulations. I had a newbie question. I was simulating the air flow inside a power amplifier cabinet which had Fans, Power sources and power amplifiers inside. The power emanation from the amplifiers is of a transient nature and is described by the following details: Output Power = 200 W Duty cycle: Transient attribute:Gaussian, Total pulse duration: 6400 ms So I see that I need to consider 6400 ms as the total time with a time step of 400 ms. But this is something relevant to a single duty cycle so will it be fine to analyze the heat flow inside the cabinet just for a single duty cycle on these lines. Can some one please suggest me regarding this. __________________ Best regards, Santhosh.

June 7, 2011, 13:02		#3
saisanthoshm88 Senior Member --------- Join Date: Oct 2010 Posts: 303 Rep Power: 18	Glenn could you please tell me how to calculate this average heat load. I apologize for raising such novice question but my experience is really too limited in this. __________________ Best regards, Santhosh.

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June 1, 2011, 19:29		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	In most electronics heat modelling things of this time scale can be averaged out and the avergae heat load used. So I would average the heat load out and apply a constant heat load. But if you are doing a transient simulation anyway then it is easy to apply the transient heat load.

June 7, 2011, 20:00		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	Integrate the heat load over a long time. If it is 11W for 1s and then 1W for 4s, and then repeats that pattern forever, then integrating over the full 5s cycle gives (111+14)/5 = 3W average load.