Recuperative Heat Exchangers
Regenerative type heat exchangers use a media to absorb heat given off by one hotter fluid and transfer it to another colder fluid. … In the first cycle hot gases/fluids passing through the media heat up the media. In the following cycle, the cold gases pass through the media and they are heated by the already hot media.
There are many types of recuperative exchangers, which can broadly be grouped into indirect contact, direct contact and specials. Indirect contact heat exchangers keep the fluids exchanging heat separate by the use of tubes or plates etc.. Direct contact exchangers do not separate the fluids exchanging heat and in fact rely on the fluids being in close contact.
In a regenerative heat exchanger, the flow path normally consists of a matrix, which is heated when the hot fluid passes through it (this is known as the “hot blow”). This heat is then released to the cold fluid when this flows through the matrix (the “cold blow”). Regenerative Heat Exchangers are sometimes known as Capacitive Heat Exchangers. A good overview of regenerators is provided by Walker (1982).
Regenerators are mainly used in gas/gas heat recovery applications in power stations and other energy intensive industries. The two main types of regenerator are Static and Dynamic. Both types of regenerator are transient in operation and unless great care is taken in their design there is normally cross contamination of the hot and cold streams. However, the use of regenerators is likely to increase in the future as attempts are made to improve energy efficiency and recover more low grade heat. However, because regenerative heat exchangers tend to be used for specialist applications recuperative heat exchangers are more common.
- Front end–this is where the fluid enters the tubeside of the exchangers
- Rear end–this is where the tubeside fluid leaves the exchangers or where it is returned to the front header in exchangers with multiple tubeside passes.
- Tube bundle–this comprises of the tubes, tube sheets, baffles and tie rods etc. to hold the bundle together.
- Shell—this contains the tube bundle.