Good Afternoon, I am currently studying for a degree in Instrumentation, Measurement & Control. As part of my learning, I have been asked to write a paper which discusses the effect (if any) that outside temperature has on the Nitrogen pre-charge and thus Hydraulic pressure within an Accumulator. For example, if an Accumulator was charged to 90barg with Nitrogen in a system which required a Hydraulic working pressure (WP) of 100barg, would any change in the outside temperature also change the Nitrogen pre-charge pressure and subsequently alter the performance of the Accumulator?

I am finding it difficult to find any papers or journals which look into this specific matter. Various documents discuss how permeation in both bladder and piston type Accumulators has a detrimental effect on pre-charge over a given time. However, temperature fluctuation does not seem to be considered from what I have read so far. Indeed, the Accumulator calculations currently used in my workplace do not account for temperature. It is assumed that the temperature is constant (isothermal) and that the gas behaves in an ideal manner (P1V1 = P2V2). Would it be as simple as utilising the associated Polytropic or Adiabatic PVT (pressure, volume and temperature)equations and substituting in the before and after temperatures?

What confuses me slightly at this point is the fact that and Adiabatic process has 0 heat transfer (Q). Therefore, is the answer to my question ultimately going to be found be looking into the Polytropic PVT and heat transfer relationships and equations. I have only finished year 1 of my degree, so Have not investigated the effect of Enthalpy or Entropy at this stage, not sure if this should also be considered. To conclude, I would be very interested to hear from anyone who has any thoughts on this subject. Any help / advice would be greatly appreciated.

Thanks& Regards