Search results
Results from the WOW.Com Content Network
The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it. The calorific value is the total energy released as heat when a substance undergoes complete combustion with oxygen under standard conditions.
The Wobbe index is expressed in MJ/Nm³ (where 'Nm³' indicates'm³ in Normal conditions), or sometimes in BTU/scf.In the case of natural gas (molar mass 17 g/mol), the typical heating value is around 39 MJ/Nm³ (1,050 BTU/scf) and the specific gravity is approximately 0.59, giving a typical Wobbe index of 51 MJ/Nm³ (1,367 BTU/scf).
Unless otherwise stated, the values in the following table are lower heating values for perfect combustion, not counting oxidizer mass or volume. When used to produce electricity in a fuel cell or to do work , it is the Gibbs free energy of reaction (Δ G ) that sets the theoretical upper limit.
Note that the especially high molar values, as for paraffin, gasoline, water and ammonia, result from calculating specific heats in terms of moles of molecules. If specific heat is expressed per mole of atoms for these substances, none of the constant-volume values exceed, to any large extent, the theoretical Dulong–Petit limit of 25 J⋅mol ...
In gas dynamics we are interested in the local relations between pressure, density and temperature, rather than considering a fixed quantity of gas. By considering the density ρ = M / V {\displaystyle \rho =M/V} as the inverse of the volume for a unit mass, we can take ρ = 1 / V {\displaystyle \rho =1/V} in these relations.
is the number of moles of the gas, is the universal gas constant, is the heat capacity ratio (which can be calculated by knowing the number of degrees of freedom of the gas molecule). Using the above two relations, the specific heats can be deduced as follows:
LPG is composed mainly of propane and butane, while natural gas is composed of the lighter methane and ethane. LPG, vaporised and at atmospheric pressure, has a higher calorific value (46 MJ/m 3 equivalent to 12.8 kWh/m 3) than natural gas (methane) (38 MJ/m 3 equivalent to 10.6 kWh/m 3), which means that LPG cannot simply be substituted for ...
This list is sorted by boiling point of gases in ascending order, but can be sorted on different values. "sub" and "triple" refer to the sublimation point and the triple point, which are given in the case of a substance that sublimes at 1 atm; "dec" refers to decomposition. "~" means approximately. Blue type items have an article available by ...