One day I found a nice and short article about the difference between terminology used to express heating values: Gross Heating Value (GHV), High Heating Value (HHV), Net Heating Value (NHV), and Low Heating Value (LHV).
As mentioned in my previous post about how to convert high heating value (HHV) to low heating value (LHV), the difference between those terms is if energy used to vaporize water include in the value.
During combustion, fuel react with oxygen molecules to form carbon dioxide, water, and to release heat. The heat released is called heat of combustion. Some of the heat released are used to vaporize existing moisture in the fuel and the water product.
Because all combustion reactions occur at temperatures above water boiling point, both existing water in fuel and water product are in vapor state after combustion. In a bomb calorimeter, the water in vapor state (existing as fuel moisture and water product) is cooled and condensed to room temperature. Therefore, the heat of condensation is recovered. All the heat of combustion are measured by the bomb calorimeter. The total heat of combustion measured by a bomb calorimeter per unit mass is called “high heating value” (HHV) or “gross heating value” (GHV). Read More
