Saturday, July 9, 2016

Gases - Specific Heats and Individual Gas Constants

specific heat in a constant pressure process


Gases - Specific Heats and Individual Gas Constants

Specific heat at constant volume, specific heat at constant pressure, specific heat ratio and individual gas constant - R - common gases as argon, air, ether, nitrogen and many more ..

The specific heats at constant pressure and constant volume processes, and the ratio of specific heats and individual gas constants - R - for some common used "ideal gases", are in the table below (approximate values at 68oF (20oC) and 14.7 psia (1 atm)):
Gas or VaporFormulaSpecific HeatSpecific Heat RatioIndividual Gas constant
- R -
cp
(kJ/(kg K))
cv
(kJ/(kg K))
cp
(Btu/(lbmoF))
cv
(Btu/(lbmoF))
κ =
cp / cv
cp - cv
(kJ/(kg K))
cp - cv
(ft lbf/(lbmoR))
Acetone
1.47 1.32 0.35 0.32 1.11 0.15
Acetylene C2H2 1.69 1.37 0.35 0.27 1.232 0.319 59.34
Air
1.01 0.718 0.24 0.17 1.40 0.287 53.34
Alcohol C2H5OH 1.88 1.67 0.45 0.4 1.13 0.22
Alcohol CH3OH 1.93 1.53 0.46 0.37 1.26 0.39
Ammonia NH3 2.19 1.66 0.52 0.4 1.31 0.53 96.5
Argon Ar 0.520 0.312 0.12 0.07 1.667 0.208
Benzene C6H6 1.09 0.99 0.26 0.24 1.12 0.1
Blast furnace gas
1.03 0.73 0.25 0.17 1.41 0.3 55.05
Bromine
0.25 0.2 0.06 0.05 1.28 0.05
Butatiene           1.12    
Butane C4H10 1.67 1.53 0.395 0.356 1.094 0.143 26.5
Carbon dioxide CO2 0.844 0.655 0.21 0.16 1.289 0.189 38.86
Carbon monoxide CO 1.02 0.72 0.24 0.17 1.40 0.297 55.14
Carbon disulphide
0.67 0.55 0.16 0.13 1.21 0.12
Chlorine Cl2 0.48 0.36 0.12 0.09 1.34 0.12
Chloroform
0.63 0.55 0.15 0.13 1.15 0.08
Coal gas
2.14 1.59




Combustion products
1
0.24



Ethane C2H6 1.75 1.48 0.39 0.32 1.187 0.276 51.5
Ether
2.01 1.95 0.48 0.47 1.03 0.06
Ethylene C2H4 1.53 1.23 0.4 0.33 1.240 0.296 55.08
Monochlorodifluoromethane, R-22           1.18    
Helium He 5.19 3.12 1.25 0.75 1.667 2.08 386.3
Hexane           1.06    
Hydrochloric acid
0.795 0.567




Hydrogen H2 14.32 10.16 3.42 2.43 1.405 4.12 765.9
Hydrogen Chloride HCl 0.8 0.57 0.191 0.135 1.41 0.23 42.4
Hydrogen Sulfide H2S

0.243 0.187 1.32
45.2
Hydroxyl OH 1.76 1.27     1.384 0.489  
Krypton
0.25 0.151




Methane CH4 2.22 1.70 0.59 0.45 1.304 0.518 96.4
Methyl Chloride CH3Cl

0.240 0.200 1.20
30.6
Natural Gas
2.34 1.85 0.56 0.44 1.27 0.5 79.1
Neon   1.03 0.618     1.667 0.412  
Nitric Oxide NO 0.995 0.718 0.23 0.17 1.386 0.277
Nitrogen N2 1.04 0.743 0.25 0.18 1.400 0.297 54.99
Nitrogen tetroxide
4.69 4.6 1.12 1.1 1.02 0.09
Nitrous oxide N2O 0.88 0.69 0.21 0.17 1.27 0.18 35.1
Oxygen O2 0.919 0.659 0.22 0.16 1.395 0.260 48.24
Pentane           1.07    
Propane C3H8 1.67 1.48 0.39 0.34 1.13 0.189 35.0
Propene (propylene) C3H6 1.5 1.31 0.36 0.31 1.15 0.18 36.8
Water Vapor
Steam 1 psia. 120 – 600 oF

1.93 1.46 0.46 0.35 1.32 0.462
Steam 14.7 psia. 220 – 600 oF
1.97 1.5 0.47 0.36 1.31 0.46
Steam 150 psia. 360 – 600 oF
2.26 1.76 0.54 0.42 1.28 0.5
Sulfur dioxide (Sulphur dioxide) SO2 0.64 0.51 0.15 0.12 1.29 0.13 24.1
Xenon
0.16 0.097




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