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Offline Peter J Francis  
#1 Posted : 01 August 2017 13:43:27(UTC)
Peter J Francis

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Hi all ,
I'm putting together a sheet using the CoolProp wrapper
It generally works really well except for the following

Where I'm getting strange units for the Specific Heat capacity of Air
I've tried overriding the units but still don't get what I want (J/kg/K)

I've attached an extract from the sheet --> UnitsProblem.sm (8kb) downloaded 15 time(s).

Probably a really simple answer but I can't seem to find it !! Sad

Units.png

Peter J Francis

Twitter: @PeterJFrancis

Thermal Engineer , Maker , Pilot
Offline mkraska  
#2 Posted : 01 August 2017 15:37:11(UTC)
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Can't reproduce. J/(kg*K) works. Paste 'J/{'kg*'K} to the square placeholder to the right of the unit when the region has focus.

2017-08-01 14_35_35-SMath Studio 0.98.6398 - [UnitsProblem.sm_].png
Martin Kraska

Pre-configured portable distribution of SMath Studio: https://en.smath.info/wi...th%20with%20Plugins.ashx
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on 02/08/2017(UTC)
Offline Jean Giraud  
#3 Posted : 01 August 2017 23:05:37(UTC)
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Can't reproduce either "Units don't match",
because there is NO heat capacity unit in Smath.
thanks 1 user thanked Jean Giraud for this useful post.
on 02/08/2017(UTC)
Offline CBG  
#4 Posted : 02 August 2017 00:52:12(UTC)
CBG


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You just have to change the units.

Best Regards

Carlos

Units_Change_1.png
thanks 1 user thanked CBG for this useful post.
on 02/08/2017(UTC)
Offline Peter J Francis  
#5 Posted : 02 August 2017 11:28:04(UTC)
Peter J Francis

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Posts: 7
United Kingdom
Location: Stoke on Trent

Thanks All,
You are all correct (I knew the answer was going to be obvious ) , pasting in the units J/kg K works fine

Its just that Gy/K seems an odd default unit

Thanks for your help

Peter

Peter J Francis

Twitter: @PeterJFrancis

Thermal Engineer , Maker , Pilot
Offline ioncube  
#6 Posted : 04 December 2017 22:09:32(UTC)
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hey fellows, how do I calculate WET steam properties through this extension,lets suppose at 16Bar Pressure & 0.7 quality 7 which IFP standard is currently being used?
Offline Jean Giraud  
#7 Posted : 05 December 2017 16:27:10(UTC)
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Originally Posted by: ioncube Go to Quoted Post
how do I calculate WET steam properties through this extension,lets suppose at [b]16Bar Pressure


Good question. The vapor phase is dry and properties don't change.
That portion of water that drags at the bottom of piping must be
taken into account for massflow calculation.
At the speed steam flows, better be dry. If not => will destroy
my control valves. Puzzling question ?
Offline ioncube  
#8 Posted : 05 December 2017 17:17:30(UTC)
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Originally Posted by: Jean Giraud Go to Quoted Post
Originally Posted by: ioncube Go to Quoted Post
how do I calculate WET steam properties through this extension,lets suppose at [b]16Bar Pressure


Good question. The vapor phase is dry and properties don't change.
That portion of water that drags at the bottom of piping must be
taken into account for massflow calculation.
At the speed steam flows, better be dry. If not => will destroy
my control valves. Puzzling question ?


The property(s) that does change when you add water to steam is NOT its pressure or temperature but its enthalpy ...the most major parameter which defines the amount of work that can be extracted

Yes wet steam at very high velocities can be micro bullets for control valves & turbine blades causing erosion
Offline Jean Giraud  
#9 Posted : 05 December 2017 18:00:21(UTC)
Jean Giraud


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Originally Posted by: ioncube Go to Quoted Post
The property(s) that does change when you add water to steam is NOT its pressure or temperature but its enthalpy ...the most major parameter which defines the amount of work that can be extracted

Yes wet steam at very high velocities can be micro bullets for control valves


Worst than erosion => cavitation.
Can't help more. Steam out of the balloon is dry, isn't ?
If you have wet steam out of the balloon, you have a serious level control problem.

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