# Air - Specific Heat at Constant Temperature and Varying Pressure

## Figures and table showing isobaric (Cp) and isochoric (Cv) specific heat of air at constant temperature and varying pressure ranging 0.01 to 10000 bara

**Specific heat **or** heat capacity** **(C)** is the amount of heat required to *change the temperature of a mass unit of a substance by one degree.*

**Isobaric heat capacity****(C**is used for air in a_{p})*constant pressure*(ΔP = 0) system.**I****sochoric heat capacity (C**is used for air in a_{v})*constant-volume*, (=*isovolumetric*or*isometric*) closed system.

The specific heat of dry air - C_{P} and C_{V} - will vary with pressure and temperature. This may influence on the accuracy of industrial air handling process calculations. When calculating mass and volume flow of air in heated or cooled systems with high accuracy - the specific heat (= heat capacity) should be corrected according values in the figures and table below.

See also** Air** Composition and molecular weight, Density at varying pressure, Density and specific weight at varying temperature, Diffusion Coefficients for Gases in Air, Dynamic (absolute) and kinematic viscosity, Prandtl Number, Specific heat at varying temperature, Thermal Conductivity, Thermal Diffusivity, Properties at gas-liquid equilibrium conditions and Air properties, for other **properties of air**

Specific Heat of *dry air* at constant temperature 20^{o}C / 68°F at various pressures:

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Specific Heat of *dry air* at selected temperatures at various pressures:

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Specific Heat of *dry air* at constant temperature 20^{o}C / 68°F at varying pressures:

Pressure | Isobaric heat capacity, Cp | Isochoric heat capacity, Cv | Specific Heat Ratio | ||||||||

[atm] | [psia] | [kPa] | [kJ/(kg K)] | [kWh/(kg K)] | [kcal/(kg °C)],[Btu/(lb °F)] | [kcal/(lb °F)] | [kJ/(kg K)] | [kWh/(kg K)] | [kcal/(kg °C)],[Btu/(lb °F)] | [kcal/(lb °F)] | Cp/Cv |

0.01 | 0.147 | 1.01325 | 1.0045 | 0.00027903 | 0.2399 | 0.1959 | 0.71740 | 0.00019928 | 0.1713 | 0.1399 | 1.4002 |

0.1 | 1.47 | 10.1325 | 1.0049 | 0.00027914 | 0.2400 | 0.1960 | 0.71763 | 0.00019934 | 0.1714 | 0.1399 | 1.4003 |

0.4 | 5.88 | 40.53 | 1.0053 | 0.00027925 | 0.2401 | 0.1960 | 0.71766 | 0.00019935 | 0.1714 | 0.1400 | 1.4008 |

1^{1)} | 14.7 | 101.325 | 1.0061 | 0.00027947 | 0.2403 | 0.1962 | 0.71767 | 0.00019935 | 0.1714 | 0.1400 | 1.4019 |

7 | 102.9 | 709.28 | 1.0162 | 0.00028228 | 0.2427 | 0.1982 | 0.71913 | 0.00019976 | 0.1718 | 0.1402 | 1.4131 |

10 | 147 | 1013.25 | 1.0216 | 0.00028378 | 0.2440 | 0.1992 | 0.72005 | 0.00020001 | 0.1720 | 0.1404 | 1.4188 |

40 | 588 | 4053 | 1.0756 | 0.00029878 | 0.2569 | 0.2098 | 0.72858 | 0.00020238 | 0.1740 | 0.1421 | 1.4763 |

70 | 1029 | 7092.8 | 1.1305 | 0.00031403 | 0.2700 | 0.2205 | 0.73778 | 0.00020494 | 0.1762 | 0.1439 | 1.5323 |

100 | 1470 | 10132.5 | 1.1824 | 0.00032845 | 0.2824 | 0.2306 | 0.74703 | 0.00020751 | 0.1784 | 0.1457 | 1.5828 |

^{1)} Standard atmosphere

**Unit conversion:**

british thermal unit(International table) = [Btu(IT)], degree celcius = [°C], degree fahrenheit = [°F], degree kelvin = [K], degree rankin = [°R], joule = [J], kilocalorie(International table) = [kcal(IT)], kilogram = [kg], kilojoule = [kJ], kilowatthour = [kWh], mole = [mol], pound =[lb]

K in the units can be replaced by °C, and vise versa. °R in the units can be replaced by °F, and vise versa.

- 1 Btu/(lb °F) = 1 Btu/(lb °R) = 1 kcal(IT)/(kg °C) = 1 kcal(IT)/(kg K) = 4186.8 J/(kg K) = 0.81647 kcal(IT)/(lb °F) = 1.163x10
^{-3}kWh/(kg K) - 1 J/(kg K) = 1 J/(kg °C) = 2.3885x10
^{-4}kcal(IT)/(kg^{o}C) = 2.3885x10^{-4}Btu/(lb °F) = 1.9501x10^{-4}kcal(IT)/(lb °F) - 1 kcal(IT)/(kg °C) = 1 Btu/(lb °F) = 4186.8 J/(kg K) = 0.81647 kcal(IT)/(lb °F) = 1.163x10
^{-3}kWh/(kg K) - 1 kcal(IT)/(lb °F) = 1.2248 Btu/(lb °F) = 1.2248 kcal(IT)/(kg °C) = 5127.9 J/(kg K)
- 1 kJ/(kg K) = 1 kJ/(kg °C) = 1000 J/(kg K) = 1000 J/(kg °C) = 0.23885 kcal(IT)/(kg °C) = 0.23885 Btu/(lb °F) = 0.19501 kcal(IT)/(lb °F) = 2.7778x10
^{-4 }kWh/(kg K) - 1 kWh/(kg K) = 0.85985 kcal(IT)/(kg °C) = 0.85985 Btu/(lb °F) = 3.6 kJ/(kg K)
- 1 mol of air = 28.96546 g

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