# Air - Specific Heat vs. Pressure at Constant Temperature

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

**Isobaric specific heat (C**is used for air in a_{p})*constant pressure*(ΔP = 0) system.**I****sochoric specific heat (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 other properties of ** Air ** at ** varying temperature and pressure: ** Density and specific weight at varying temperature , Density at varying pressure , Diffusion Coefficients for Gases in Air , Prandtl Number , Specific heat at varying temperature , Thermal Conductivity , Thermal Diffusivity , Properties at gas-liquid equilibrium conditions and Air thermophysical properties at standard conditions and Composition and molecular weight ,

as well as ** Specific heat ** of Ammonia , Butane , Carbon dioxide , Carbon monoxide , Ethane , Ethanol , Ethylene , Hydrogen , Methane , Methanol , Nitrogen , Oxygen , Propane and Water .

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

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

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

For full table with Isochloric Heat Capacity - ** rotate the screen! **

Pressure | Isobaric Specific Heat, Cp | Isochoric Specific Heat, 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

## Related Topics

### • Air Psychrometrics

Moist and humid air calculations. Psychrometric charts and Mollier diagrams. Air-condition systems temperatures, absolute and relative humidities and moisture content in air.

### • Fluid Mechanics

The study of fluids - liquids and gases. Involving velocity, pressure, density and temperature as functions of space and time.

### • Gases and Compressed Air

Properties of air, LNG, LPG and other common gases. Pipeline capacities and sizing of relief valves.

### • Material Properties

Properties of gases, fluids and solids. Densities, specific heats, viscosities and more.

## Related Documents

### Air - Composition and Molecular Weight

Dry air is a mechanical mixture of nitrogen, oxygen, argon and several other gases in minor amounts.

### Air - Density vs. Pressure and Temperature

Air density at pressure ranging 1 to 10 000 bara (14.5 - 145000 psi) and constant selected temperatures.

### Air - Density, Specific Weight and Thermal Expansion Coefficient vs. Temperature and Pressure

Online calculator, figures and tables showing density, specific weight and thermal expansion coefficients of air at temperatures ranging -100 to 1600 °C (-140 to 2900 °F) at atmospheric and higher pressure - Imperial and SI Units.

### Air - Diffusion Coefficients of Gases in Excess of Air

Diffusion coefficients (D_{12}) for gases in large excess of air at temperatures ranging 0 - 400 °C.

### Air - Dynamic and Kinematic Viscosity

Online calculator, figures and tables with dynamic (absolute) and kinematic viscosity for air at temperatures ranging -100 to 1600°C (-150 to 2900°F) and at pressures ranging 1 to 10 000 bara (14.5 - 145000 psia) - SI and Imperial Units.

### Air - Humidity Ratio

The mass of water vapor present in moist air - to the mass of dry air.

### Air - Molecular Weight and Composition

Dry air is a mixture of gases where the average molecular weight (or molar mass) can be calculated by adding the weight of each component.

### Air - Prandtl Number

Prandtl number for air vs. temperature and pressure.

### Air - Properties at Gas-Liquid Equilibrium Conditions

Properties of air change along the boiling and condensation curves (temperature and pressure between triple point and critical point conditions). An air phase diagram included.

### Air - Specific Heat Ratio

Specific Heat Ratio of air at temperatures ranging -40 - 1000 degC (-40 - 1500 degF) at standard atmospheric pressure - Imperial and SI Units.

### Air - Specific Heat vs. Temperature at Constant Pressure

Online calculator with figures and tables showing specific heat (Cp and Cv) of dry air vs. temperature and pressure. SI and imperial units.

### Air - Thermal Conductivity vs. Temperature and Pressure

Online calculator with figures and tables showing air thermal conductivity vs. temperature and pressure. SI and imperial units.

### Air - Thermal Diffusivity vs. Temperature and Pressure

Figures and tables withdry air thermal diffusivity vs. temperarure and pressure. SI and Imperial units.

### Air - Thermophysical Properties

Thermal properties of air at different temperatures - density, viscosity, critical temperature and pressure, triple point, enthalpi and entropi, thermal conductivity and diffusivity and more.

### Ammonia - Specific Heat vs. Temperature and Pressure

Online calculator, figures and tables showing specific heat, C_{P} and C_{V}, of gasous and liquid ammonia at temperatures ranging from -73 to 425°C (-100 to 800°F) at pressure ranging from 1 to 100 bara (14.5 - 1450 psia) - SI and Imperial Units.

### Butane - Specific Heat vs. Temperature and Pressure

Online calculators, figures and tables showing specific heat, Cp and Cv, of gasous and liquid butane, C_{4}H_{10}, at varying temperarure and pressure, SI and Imperial units.

### Dry Air - Thermodynamic and Physical Properties

Thermodynamic properties of dry air - specific heat, ratio of specific heats, dynamic viscosity, thermal conductivity, Prandtl number, density and kinematic viscosity at temperatures ranging *175 - 1900 K*.

### Ethanol - Specific Heat vs. Temperature and Pressure

Online calculators, figures and tables showing specific heat , Cp and Cv, of gasous and liquid ethanol at temperatures ranging from -25 to 325 °C (-10 to 620 °F) at atmospheric and higher pressure - Imperial and SI Units.

### International Standard Atmosphere

International standard atmosphere in elevation *-2000 to 30000 metre* - pressure, temperature, density, viscosity, thermal conductivity and velocity of sound.

### Moist Air - Properties

Psychrometric table with humid air properties like saturation pressure, specific volume, enthalpy and entropy.

### Moist Air - Weight of Water Vapor

Weight of water vapor in air

### Pressure

Introduction to pressure - online pressure units converter.

### Solubility of Air in Water

The amount of air that can be dissolved in water decreases with temperature and increases with pressure.

### Specific Heat - Online Unit Converter

Online specific heat converter with the most commonly used units.

### Specific Heat of common Substances

Specific heat of products like wet mud, granite, sandy clay, quartz sand and more.

### STP - Standard Temperature and Pressure and NTP - Normal Temperature and Pressure

The definition of STP - Standard Temperature and Pressure and NTP - Normal Temperature and Pressure.

### U.S. Standard Atmosphere vs. Altitude

Properties of the US standard atmosphere ranging *-5000 to 250000 ft* altitude.

### Water Vapor - Specific Heat vs. Temperature

Specific heat of Water Vapor - H2O - at temperatures ranging 175 - 6000 K.