gas hold up/gas volume fraction

CHAKER · March 27, 2009, 07:52

can any one please tell me about the difference between gas hold up and gas volume fraction.
regards

sanbhat · May 7, 2009, 13:58

Typically hold up is termed for liquids.
May be gas holdup = 1-liquid holdup.
Anyways, input GVF= Q_g/(Q_g + Q_l). It is based on the flow rates. It gives an idea on the area fraction covered by the gas, liquid if both are moving with same velocity.

But, if there is slip, the gas tends to move with higher speed than the liquid. During this time, the in-situ volume fractions for both phases will be very different. because, gas occupies less area than the liquid due to mass conservation principle.Typically, liquid holdup is calculated using emperical correlations.

Regards,
sanbhat

CHAKER · May 7, 2009, 18:02

Thanks...
regards
CHAKER

March 27, 2009, 07:52	gas hold up/gas volume fraction	#1
CHAKER New Member chaker rym Join Date: Mar 2009 Posts: 14 Rep Power: 17	can any one please tell me about the difference between gas hold up and gas volume fraction. regards

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May 7, 2009, 13:58		#2
sanbhat New Member Sandeep Join Date: Mar 2009 Location: Blacksburg, US Posts: 3 Rep Power: 17	Typically hold up is termed for liquids. May be gas holdup = 1-liquid holdup. Anyways, input GVF= Q_g/(Q_g + Q_l). It is based on the flow rates. It gives an idea on the area fraction covered by the gas, liquid if both are moving with same velocity. But, if there is slip, the gas tends to move with higher speed than the liquid. During this time, the in-situ volume fractions for both phases will be very different. because, gas occupies less area than the liquid due to mass conservation principle.Typically, liquid holdup is calculated using emperical correlations. Regards, sanbhat

May 7, 2009, 18:02		#3
CHAKER New Member chaker rym Join Date: Mar 2009 Posts: 14 Rep Power: 17	Thanks... regards CHAKER