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Heat Transfer Coefficients for CO2 compression intercooling

Heat Transfer Coefficients for CO2 compression intercooling

Heat Transfer Coefficients for CO2 compression intercooling

(OP)
Hi all;

I'm simulating CO2 compression with intercooling.
I'm using and 8 stage compressor.
I'm using water as refrigerant on the shell side (30-40ºC)

At the cooling stages there is some water condensation and as the pressure goes up, gas density (kg/m3) increases as follow:

3.3   6.2   12.1   23.2      42.8      65.2    159.9    231.6

Discharge Pressure (bara)

2.4   4.4    8.5   15.8      27.4      48.2     84.6    148.8


My question is wich Heat Transfer Coefficients (kcal/h·m2 ºC)or (Btu/ft2·°F·h) should I use for the diferent cooling stages.

Thanks in advance

RE: Heat Transfer Coefficients for CO2 compression intercooling

The presence of water vapor complicates the estimates. I could give you an estimate if the waqter vapor could be ignored.

RE: Heat Transfer Coefficients for CO2 compression intercooling

(OP)
Dear srfish;

I enclose estimated vapor fractions for coolers. As you can see Stg 5 and Stg7 won't have cooling and cooling after Stg 8 will liquified CO2.

I don't know if with this vapor fractions, water vapor condensation could be ignored.

Discharge Pressure (bara)
St1   St2    St3   St4    St5       St6      St7     St8

2.4   4.4    8.5   15.8   27.4      48.2     84.6    148.8

Estimate Vapor fraction after cooler

St1     St2     St3     St4     St6       St8

0.975    0.986    0.992    0.996    0.997     0


 

RE: Heat Transfer Coefficients for CO2 compression intercooling

You are already working in metric units, use kcal/h•m2 ºC.  If you have data/correlations in the other units, get the HTC in those units, then convert units.  

Good luck,
Latexman

RE: Heat Transfer Coefficients for CO2 compression intercooling

Following are the estimated overall heat transfer coefficients for a shell-and-tube exchanger expressed in Btu/hr-ft2-F. They are based on a pressure drop of 1 to 2 psi and a total tube travel of 40 ft and 3/4" tubes.

The effect of the small amount water vapor was ignored by assuming the downward deflection of the condensing curve would be offset by the increase in heat transfer.

St1  St2  St3   St4  St6

23.8 30.7 39.9 51.35 75.9

St8 was not calculated because I don't have the physical properties of liquid CO2.

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