01 part3-real-gases
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real-gasesTRANSCRIPT
Real Gases
S.GunabalanAssociate ProfessorMechanical Engineering DepartmentBharathiyar College of Engineering & TechnologyKaraikal - 609 609.e-Mail : [email protected]
Van Der Wall`s Equation• The laws of mechanics to individual molecules is considered • Equation of ideal gas is modified with addition of 2 correction terms where a, b, and R are the characteristic constants of the particular gas – specific volume (m3/kg)“a” – represents the mutual attraction between molecules, - called force of cohesion.
“b” – represents volume of molecules- called co-volume.
Van Der Wall`s Equation
Real gases confirms the van der wall`s equation at high pressures. But not in all range of pressure and temperature.
Redlich Kwong Equation
Good result at high pressure.
Dietric Equation
Problem-1
• A container of 2 m3 capacity contain 3 Kg of co2 at 30 find the pressure of the container by considering Co2 as – 1. perfect gas – 2. real gas.
Problem-1
• Given data– 2 m3 capacity • (V = 2 m3)
– 3 Kg of co2 at 30 • m = 3 Kg T = 30
– find the pressure• 1. perfect gas
– P = ?
• 2. real gas– P = ?
Problem-1– find the pressure
• 1. perfect gas – P = ?
+ 273) k = ? = 44.01 Kg/K.Mol for co2 = ? = Substitute and find
V = 2 m3
co2 m = 3 Kg T = 30
Gas Molar Weight ( M)Kg/Kmol
Air 28.97
Nitrogen 28.01
Oxygen 32
Hydrogen 2.016
Helium 4.004
Carbon dioxide
44.01
Steam 18.02
Problem-1
– find the pressure• 2. Real gas
– P = ?
Vander – Waals constanta =3628.5 x 102 N.m4/(K.mol)2
b= 3.14 x 10-2 m3/K.mol
V = 2 m3
co2 m = 3 Kg T = 30
Gas Molar Weight ( M)Kg/Kmol
Air 28.97
Nitrogen 28.01
Oxygen 32
Hydrogen 2.016
Helium 4.004
Carbon dioxide
44.01
Steam 18.02
Problem-1
= x = 44.01 x = ? substitute and get p value
V = 2 m3
co2 m = 3 Kg T = 30
Gas Molar Weight ( M)Kg/Kmol
Air 28.97
Nitrogen 28.01
Oxygen 32
Hydrogen 2.016
Helium 4.004
Carbon dioxide
44.01
Steam 18.02
Reference• Rajput, R. K. 2010. Engineering thermodynamics. Jones and Bartlett
Publishers, Sudbury, Mass.• Singh, O. 2003. Applied thermodynamics. New Age International (P) Ltd.,
Publishers, New Delhi.• Nag, P. K. 2002. Basic and applied thermodynamics. Tata McGraw-Hill,
New Delhi.