Comparison of binary mixture heat and mass transfer analysis with single-component heat and mass transfer analysis in the design of GAX absorber/desorber[Generator-Absorber heat eXchange]

The GAX cycle is an elegant way of achieving higher effect performance with single-stage configuration. One of the key components of the GAX cycle is the absorber/desorber heat exchanger, which carries out internal heat recovery. This paper investigated two different models for the design of an absorber/desorber in the GAX system. In model A, single-component forced convective boiling with the physical properties of the mixture was assumed for the cocurrent desorption process, which is basically an approximation technique adopted widely so far. In model B, the multi-component effect of the binary mixture on the forced convective boiling transfer was considered. Significant degradation of heat and mass transfer was observed under binary mixture boiling condition as opposed to the single-component boiling. The results show that about 57% of extra heat transfer area would be needed under the case being investigated if the fluid is considered as a binary mixture rather than a single-component fluid. This paper provides a basic guideline for designing a properly sized GAX absorber-desorber.