Regenerátor

Regenerátor, also known as a regenerator, is a device designed to recover thermal energy from a hot process stream and return it to a cooler process stream, thereby increasing overall system efficiency. In regenerative heat exchangers the heat storage medium alternates between absorbing heat from the hot stream and transferring it to the cold stream. This can be achieved with a rotating porous matrix (regenerator wheel), a fixed bed packed with ceramic or metal media, or a plate-type arrangement.

During the hot phase, the medium is exposed to the hot exhaust or gas, gaining heat. In the following cold phase, the medium is brought into contact with the incoming cooler stream, transferring the stored heat and preheating it. In rotary regenerators the cycle is continuous, with a wheel rotating between streams.

Regenerators are used in gas turbines and internal combustion engines to preheat combustion air, in industrial furnaces, in Stirling and external combustion engines, and in HVAC systems as regenerative air heaters. They are also used in solar thermal plants as thermal storage to release heat when needed.

Advantages include reduced fuel consumption and emissions, and improved overall efficiency. Limitations include added cost and complexity, pressure drop, thermal fatigue, and fouling; the effective temperature range is constrained by the storage medium and materials.

Materials commonly used for regenerator media include ceramics and metals with good heat capacity and low thermal expansion, such as ceramic bricks, alumina, or high-temperature alloys.