Temperature and heat
Associations: 0°C = 273,15 K = 32°F
Difference in temperature: Δ 1°C = 1K = 1,8°F
Kelvin [K] | ° Celsius [C] | ° Fahrenheit (F) | |
Kelvin = | 1 | K - 273,15 | K · 1,8 − 459,67 |
° Celsius = | 273,15 + °C | 1 | 1,8 x °C + 32 |
° Fahrenheit = | (°F + 459,67) x 0,5555555 | (°F - 23) x 0,5555555 | 1 |
Heat
SI Units | joule [J] | kilojoule [kJ] | megajoule [MJ] | wattseconds [Ws] | kilowatt hour [kWh] | calorie [cal] |
1 joule = | 1 | 0,001 | 1,0000·10-6 | 1 | 2,7778·10-7 | 0,2388 |
1 kilojoule = | 1.000 | 1 | 0,001 | 1.000 | 0,0002778 | 238,85 |
1 megajoule = | 1.000.000 | 1000 | 1 | 1.000.000 | 0,2778 | 238.846 |
1 wattsesond = | 1 | 0,001 | 1,0000·10-6 | 1 | 2,7778·10-7 | 0,2388 |
1 kilowatt hour = | 3.600.000 | 3.600 | 3,6 | 3.600.000 | 1 | 859.845 |
1 calorie = | 4,1868 | 0,004187 | 4,1868·10-6 | 4,1868 | 1,1630·10-6 | 1 |
Heat quantity
Heat quantity= specific heat capacity x mass x difference in temperature
Q = c x m x Δt [J] unit of specific heat capacity [J / kg K]
- The amount of heat necessary for heating a body is proportionate to the mass of the body and difference in temperature that is to be achieved
- c is not constant but depending on temperature
- By cooling down Δt becomes negative, amount of heat becomes negative which means that it must not be added but dissipated
Specific heat capacity of textile raw materials
Unit | glass wool |
cotton viscose |
wool silk |
polyamide (PA) | polyester (PES) | polyethen (PE) | PVC |
kJ / kg K | 0,657 | 1,325.... 1,356 | 1,356 / 1,386 | 1,85 | 1,3 | 2,50 | 1,3 - 2,1 |
Specific heat capacity for substances in textile finishing
Unit | iron | steel | stone/fireclay | water at 20°C |
air | air (steam) 100% humidity |
kJ / kg K | 0,439 | 0,477 - 0,5 | 0,75 - 0,84 | 4,182 | 1,005 | 1,030 |
Enthalpy
- Enthalpy is the heat energy based on 0°C that a material possesses at a certain temperature.
- SI-unit of enthalpy: Q1 = [J]
- For temperatures t > 0°C enthalpy is positive
- For temperatures t < 0°C enthalpy is negative
- For temperatures t = 0°C enthalpy is zero
Heat values
Heat value H is the proportion of the amount of heat to be released from combustion and the mass of the burned material.
released amount of heat (Q) = mass (m) x heat value (H)
heat value (H) | |
Brown coal |
18 MJ/kg |
Black coal, coke | 28 MJ/kg |
Petroleum/heating oil/fuel | 41 MJ/kg |
Diesel | 38 - 41 MJ/kg |
Source: SI-Systeme