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Old Feb 3rd 2016, 05:04 AM   #1
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Energy efficiency C02 store with throttle valve

Hi,
Is 3 weeks that I am trying to solve this problem, and I don't know if anyone ever attempted before.

I have a canister containing co2 at saturated state. I drain co2 from the bottle to a throttling valve where it will make its isenthalpic transformation. lets assume that the store is used from a vapour quality from 0 to 1

I steady state is easy.... saturated, i look in the tables and i get my values of entropy. but... Now the problem is that we ar not in steady state and the vapour quality should be model in some way.

anyone has ever see anything like that? A model of vapour quality variation in time?

Thank you
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Old Feb 3rd 2016, 02:00 PM   #2
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Clarification Please

Your post is a bit unclear.

You have liquid CO2 under pressure in a canister.
You are draining this via a valve.

Is it passing to atmosphere through this valve or to another canister?
Is the pressure in the system constant throughout, so the liquid CO2 is flowing under gravity
or is the pressure after the valve lower so that the pressure in the canister dropping such that the liquid CO2 in the canister is starting to boil?
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Old Feb 7th 2016, 11:11 AM   #3
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Sorry, so i begin again....

CO2 canister with a pressure regulator.
The canister is initially full with CO2 liquid.
When I begin to drain the CO2 the pressure remain constant because is saturated until the vapour quality reach x=1. Then the pressure will drop. But lets assume that we have all the condition to maintain P constant, ergo the het flow.

i would like to know if there is a way to model the vapour quality x throughout the time that de canister is emptying.

once I know that I can try to calculate the increase in entropy in the pressure regulator so that i can calculate the energetic efficiency from the store to an hypothetical other store at lower pressure
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Old Feb 7th 2016, 11:14 AM   #4
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I could model it also like that

bu with a pressure regulator between the piston and the canister
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Energy efficiency C02 store with throttle valve-screen-shot-2016-01-31-22.38.47.png  
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c02, efficiency, energy, entropy, isenthalpic, saturated, store, throttle, unsteadystate, valve



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