Regenerative Heat Exchanger - Disadvantages of Regenerators

Disadvantages of Regenerators

The major disadvantage of a regenerator is that there is always some mixing of the fluid streams, and they can not be completely separated. There is an unavoidable carryover of a small fraction of one fluid stream into the other. In the rotary regenerator, the carryover fluid is trapped inside the radial seal and in the matrix, and in a fixed-matrix regenerator, the carryover fluid is the fluid that remains in the void volume of the matrix. This small fraction will mix with the other stream in the following half-cycle. Therefore regenerators are only used when it is acceptable for the two fluid streams to be mixed. Mixed flow is common for gas-to-gas heat and/or energy transfer applications, and less common in liquid or phase-changing fluids since fluid contamination is often prohibited with liquid flows.

The constant heating and cooling that takes place in regenerative heat exchangers puts a lot of stress on the components of the heat exchanger, which can cause cracking or breakdown of materials.