Mathematical models for the simulation of thermal regenerators: A state-of-the-art review

Thermal regenerators are compact heat exchangers in which heat is absorbed and released using high heat capacity materials. They have been used in the industries for more than two centuries. There are two applications of the regenerators as a heat recovery system in the processes: fixed-bed and rotary. In the fixed bed regenerators (FBRs) the bed is fixed and the hot and cold streams are periodically passed through the bed while in the rotary type the streams are fixed and the bed is rotating facing each stream. They have been used in the process industries such as aluminum and glass industries and power plants for many years. This paper reviews the basic mathematical models applied in the computer simulation of regenerators over almost 200 years which was taken for the development of Stirling׳s hot engine into a quantitative picture of transient thermal response. A number of original mathematical models are presented for the specific application in the process industries. Three different methods of solutions are introduced and finally, some experimental setup systems used for the verification of simulation results are presented and discussed.