Large negative pressures

Berthold Stoeger bstoeger at mail.tuwien.ac.at
Wed Aug 7 08:40:02 PDT 2019


Hi Robert,

On Mittwoch, 7. August 2019 15:42:26 CEST Robert Helling wrote:

> 1) Conclude that tank pressures of minus some thousand bar are ridiculous
> and cut them off at some value.

That sounds logical to me. Allow perhaps up to -200 bar, but below that I 
don't see the point. I wonder if negative pressures should be marked very 
clearly in the profile plot.

> 2) Make pressure_t (and related variable) int64_t, increase memory footprint
> and slow down pressure computations to accommodate these values.

I doubt that it would give us perfomance problems. But I also don't see the 
need to represent such values.

By the way, I don't understand the pressure calculation. In the attached 
screenshot, shouldn't absolute gas consumption decrease when going up? On the 
contrary, it seems to increase at the ca. 200 min point. Also it appears 
unrealistic to me that you would burn through nearly 12 11l cylinders with a 
SAC rate of 20 l/min and the given profile. It appears that I'm missing 
something fundamental. 

Berthold
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