lämpöarvot

Lämpöarvot, or calorific values, refer to the amount of heat released when a substance undergoes complete combustion. This quantity is a fundamental property of fuels and combustible materials. There are two primary ways to express calorific values: the higher heating value (HHV) and the lower heating value (LHV).

The higher heating value, also known as gross calorific value, assumes that the water produced during combustion condenses back into liquid water, and thus its latent heat of vaporization is recovered. The lower heating value, or net calorific value, assumes that the water produced remains as vapor, meaning its latent heat is not accounted for. The difference between HHV and LHV is approximately the latent heat of vaporization of the water formed.

In practice, the LHV is often more relevant for many industrial applications because the water vapor produced in combustion typically leaves the system as a gas, especially in high-temperature processes. The calorific value is typically measured in units of energy per unit mass or volume, such as megajoules per kilogram (MJ/kg) or megajoules per cubic meter (MJ/m³).

Different substances have vastly different calorific values. For example, fossil fuels like natural gas, coal, and oil have high calorific values, making them efficient energy sources. Wood and other biomass also have calorific values, though generally lower than fossil fuels. The calorific value is a crucial parameter in determining the energy content and suitability of a material as a fuel for heating, power generation, and other energy-related applications. Understanding calorific values is essential for energy efficiency calculations and for comparing the energy potential of different fuels.