Air - Specific Heat vs. Temperature at Constant Pressure
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 p ) is used for air in a constant pressure (ΔP = 0) system.
- I sochoric specific heat (C v ) is used for air in a constant-volume , (= isovolumetric or isometric ) closed system.
Note! At normal atmospheric pressure of 1.013 bar - the specific heat of dry air - C P and C V - will vary with temperature. This may influence on the accuracy of air conditioning and 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, or found by use of the calculator.
- For ordinary calculations - a value of specific heat c p = 1.0 kJ/kg K (equal to kJ/kg o C) or 0.24 Btu(IT)/lb °F - is normally accurate enough
- For higher accuracy - a value of C p = 1.006 kJ/kg K (equal to kJ/kg o C) or 0.2403 Btu(IT)/lb °F - is better
Online Air Specific Heat Calculator
The calculator below can be used to estimate the specific heat of air at constant volum or constant pressure and at given temperature and pressure.
The output heat capacity is given as kJ/(kmol*K), kJ/(kg*K), kWh/(kg*K), kcal/(kg*K), Btu(IT)/(mol*°R) and Btu(IT)/(lb m *°R)
Choose the actual unit of temperature:
Choose the actual pressure:
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 pressure , 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 .
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Specific heat of air at 1 bar (=0.1 mPa = 14.5 psi):
For full table with Isobaric heat capacity - rotate the screen!
| Temperature | Isochoric specific heat (Cv) | Isobaric specific heat (Cp) | Cp/Cv | ||||||||||
| [K] | [°C] | [°F] | [kJ/mol K] | [kJ/kg K] | [kWh/(kg K)] | [kcal(IT)/(kg K)] | [kcal(IT)/(lb °F)] | [kJ/mol K] | [kJ/kg K] | [(kW h)/(kg K)] | [kcal(IT)/(kg K)] [Btu(IT)/lb °F] | [kcal(IT)/(lb °F)] | [-] |
| 60 | -213 | -352 | 0.03398 | 1.173 | 0.0003258 | 0.2802 | 0.2287 | 0.05506 | 1.901 | 0.000528 | 0.45405 | 0.37071 | 1.621 |
| 78.79 | -194 | -318 | 0.03044 | 1.051 | 0.0002919 | 0.2510 | 0.2050 | 0.05599 | 1.933 | 0.000537 | 0.46169 | 0.37695 | 1.839 |
| 81.61 | -192 | -313 | 0.02172 | 0.7500 | 0.0002083 | 0.1791 | 0.1463 | 0.03154 | 1.089 | 0.000303 | 0.26010 | 0.21237 | 1.452 |
| 100 | -173 | -280 | 0.02109 | 0.7280 | 0.0002022 | 0.1739 | 0.1420 | 0.03012 | 1.040 | 0.000289 | 0.24833 | 0.20276 | 1.428 |
| 120 | -153 | -244 | 0.02093 | 0.7225 | 0.0002007 | 0.1726 | 0.1406 | 0.02953 | 1.022 | 0.000283 | 0.24350 | 0.19930 | 1.415 |
| 140 | -133 | -208 | 0.02081 | 0.7184 | 0.0001996 | 0.1716 | 0.1401 | 0.02937 | 1.014 | 0.000282 | 0.24219 | 0.19774 | 1.411 |
| 160 | -113 | -172 | 0.02077 | 0.7172 | 0.0001992 | 0.1713 | 0.1399 | 0.02928 | 1.011 | 0.000281 | 0.24147 | 0.19716 | 1.410 |
| 180 | -93.2 | -136 | 0.02076 | 0.7166 | 0.0001991 | 0.1712 | 0.1397 | 0.02920 | 1.008 | 0.000280 | 0.24076 | 0.19657 | 1.407 |
| 200 | -73.2 | -99.7 | 0.02075 | 0.7163 | 0.0001990 | 0.1711 | 0.1397 | 0.02917 | 1.007 | 0.000280 | 0.24052 | 0.19638 | 1.406 |
| 220 | -53.2 | -63.7 | 0.02075 | 0.7163 | 0.0001990 | 0.1711 | 0.1397 | 0.02914 | 1.006 | 0.000279 | 0.24028 | 0.19618 | 1.404 |
| 240 | -33.2 | -27.7 | 0.02075 | 0.7164 | 0.0001990 | 0.1711 | 0.1397 | 0.02914 | 1.006 | 0.000279 | 0.24028 | 0.19618 | 1.404 |
| 260 | -13.2 | 8.3 | 0.02076 | 0.7168 | 0.0001991 | 0.1712 | 0.1398 | 0.02914 | 1.006 | 0.000279 | 0.24028 | 0.19618 | 1.403 |
| 273.2 | 0.0 | 32.0 | 0.02077 | 0.7171 | 0.0001992 | 0.1713 | 0.1398 | 0.02914 | 1.006 | 0.000279 | 0.24028 | 0.19618 | 1.403 |
| 280 | 6.9 | 44.3 | 0.02078 | 0.7173 | 0.0001993 | 0.1713 | 0.1399 | 0.02914 | 1.006 | 0.000279 | 0.24028 | 0.19618 | 1.402 |
| 288.7 | 15.6 | 60.0 | 0.02078 | 0.7175 | 0.0001993 | 0.1714 | 0.1399 | 0.02914 | 1.006 | 0.000279 | 0.24030 | 0.19620 | 1.402 |
| 300 | 26.9 | 80.3 | 0.02080 | 0.7180 | 0.0001994 | 0.1715 | 0.1400 | 0.02915 | 1.006 | 0.000280 | 0.24036 | 0.19625 | 1.402 |
| 320 | 46.9 | 116 | 0.02083 | 0.7192 | 0.0001998 | 0.1718 | 0.1403 | 0.02917 | 1.007 | 0.000280 | 0.24052 | 0.19638 | 1.400 |
| 340 | 66.9 | 152 | 0.02087 | 0.7206 | 0.0002002 | 0.1721 | 0.1405 | 0.02923 | 1.009 | 0.000280 | 0.24100 | 0.19677 | 1.400 |
| 360 | 86.9 | 188 | 0.02092 | 0.7223 | 0.0002006 | 0.1725 | 0.1409 | 0.02926 | 1.010 | 0.000281 | 0.24123 | 0.19696 | 1.398 |
| 380 | 107 | 224 | 0.02098 | 0.7243 | 0.0002012 | 0.1730 | 0.1412 | 0.02931 | 1.012 | 0.000281 | 0.24171 | 0.19735 | 1.397 |
| 400 | 127 | 260 | 0.02105 | 0.7266 | 0.0002018 | 0.1735 | 0.1417 | 0.02937 | 1.014 | 0.000282 | 0.24219 | 0.19774 | 1.396 |
| 500 | 227 | 440 | 0.02150 | 0.7424 | 0.0002062 | 0.1773 | 0.1448 | 0.02983 | 1.030 | 0.000286 | 0.24597 | 0.20083 | 1.387 |
| 600 | 327 | 620 | 0.02213 | 0.7641 | 0.0002123 | 0.1825 | 0.1490 | 0.03044 | 1.051 | 0.000292 | 0.25103 | 0.20496 | 1.375 |
| 700 | 427 | 800 | 0.02282 | 0.7877 | 0.0002188 | 0.1881 | 0.1536 | 0.03114 | 1.075 | 0.000299 | 0.25675 | 0.20963 | 1.365 |
| 800 | 527 | 980 | 0.02351 | 0.8117 | 0.0002255 | 0.1939 | 0.1583 | 0.03183 | 1.099 | 0.000305 | 0.26249 | 0.21432 | 1.354 |
| 900 | 627 | 1160 | 0.02415 | 0.8338 | 0.0002316 | 0.1991 | 0.1626 | 0.03247 | 1.121 | 0.000311 | 0.26772 | 0.21858 | 1.344 |
| 1100 | 827 | 1520 | 0.02525 | 0.8716 | 0.0002421 | 0.2082 | 0.1700 | 0.03356 | 1.159 | 0.000322 | 0.27675 | 0.22596 | 1.329 |
| 1500 | 1227 | 2240 | 0.02673 | 0.9230 | 0.0002564 | 0.2204 | 0.1800 | 0.03505 | 1.210 | 0.000336 | 0.28901 | 0.23597 | 1.311 |
| 1900 | 1627 | 2960 | 0.02762 | 0.9535 | 0.0002649 | 0.2277 | 0.1859 | 0.03593 | 1.241 | 0.000345 | 0.29631 | 0.24193 | 1.301 |
Unit conversion:
british thermal unit(International table) = [Btu(IT)], degree celcius = [°C], degree fahrenheit = [°F], 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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