Temperature Variation of N2 Gas in a accumulator?

[arun_mechanical]

I am trying to calculate the variation of temperature of N2 in the accumulator because of the variation in ambient temperature. When the ambient temperature varies a lot, the pressure of N2 also varies accordingly to gas laws. The idea now is to find out what is the time taken for the N2 gas to either increase of decrease in temperature because of the variation of ambient temperature with and without the use of an thermal insulation.

The way I have formulated this problem can be found in the attachment. Initially I formulated the transient heat transfer equation for the barrier fluid in the accumulator and then it is used to calculate the temperature of the gas. Can anyone have a check and put your comments to understand if this approximation is good enough or not. Thanks for your support in advance. If there any additional info required, please advise.

 

[chicopee]

Your final equation appears consistent with some of my past work on other projects, so I would say that you are on the right track. What may be missing is the heat retention of the accumulator unless it is considered a thin wall accumulator. As far as the heat transfer within the N2 gas, you have based it on convection but if the accumulator of not a big system, perhaps consider conduction within the N2 gas instead of convection. There will also be heat transfer loss from the accumulator to ambient surroundings which I did not see included.

 

[chicopee]

Heat transfer thru conduction is to be considered if there is no movement of the gas N2 inside the accumulator.

 

[racookpe1978]

That movement of the N2 gas inside the accumulator depends on the cycle frequency and cycle volume (amount of N2 moving each time the accumulator moves). If the combination of the two is small, it won't matter. Local gas at ambient temp is cycled in and out of the accum - also at ambient temp, and the work of compressing and releasing is small.

 

[LittleInch]

I'll confess I didn't follow the entire path through that set of calculations, but I'm still wondering why you're bothering to find out.

The pressure variation would appear to be about 30K / 280K so a bit more than 10%??

I would normally try and control the pressure directly.

I also think you have too many variables and assumptions to make to get a decent answer in theory as opposed to just testing it.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.