Definition - What does Waste Heat mean?
Waste heat is heat that is generated due to fuel combustion or chemical reaction. It is normally released into the environment, even though it may still be reused. Recovery of waste heat has become very important from environmental, economic and efficiency points of view.
Waste heat is also known as secondary heat or low-grade heat.
Corrosionpedia explains Waste Heat
Machines converting energy contained in fuels to mechanical work or electric energy produce waste heat as a byproduct. It is necessary for many systems to output heat as a byproduct of their operation due to the laws of thermodynamics. The main sources of waste heat are:
- Power stations
- Industrial processes such as:
- Oil refining
- Steel making
- Glass making
Sometimes waste heat can be utilized by another process, or a portion of heat that would otherwise be wasted can be reused in the same process rather than released into the atmosphere. This is known as recovery of waste heat.
Waste heat can be used for:
- Cogeneration and trigeneration - Utilized in swimming pool heating & paper mills. In some cases cooling can also be produced by the use of absorption refrigerators.
- Pre-heating - Outgoing water gives its waste heat to incoming water in a heat exchanger before heating homes or power plants.
- Electrification of waste heat - Electricity can be generated from waste heat by many different process.
- Greenhouses - Waste heat can be used to provide heat for greenhouses, particularly in colder climates.
Recovery of waste heat has a direct effect on the efficiency of the process. This is reflected by reduction in utility consumption & costs as well as process cost. It also reduces:
- Equipment size
- Auxiliary energy consumption
Waste heat to power (WHP) is the process of recovering waste heat and using it to generate power with no combustion or emissions. WHP systems use the same technologies deployed in a number of industries, including the geothermal industry.