HEAT AND MOISTURE TRANSFER IN ENERGY WHEELS DURING SORPTION, CONDENSATION, AND FROSTING CONDITIONS

A numerical model for coupled heat and moisture transfer with sorption , condensation, and frosting in rotary energy exchangers is presented and validated with experimental data. The model is used to study conde nsation and frosting in energy wheels. Condensation/frosting increases with humidity and at some humidity level, water/frost will continuall y accumulate in the wheel. The sensitivity of condensation and frostin g to wheel speed and desiccant type are studied. The energy wheel perf ormance is also presented during both sorption and saturation conditio ns for a desiccant coating with a Type I sorption isotherm (e.g., mole cular sieve) and a linear sorption isotherm (e.g., silica gel). Simula tion results show that the desiccant with a linear sorption curve is f avorable for energy recovery because it has better performance charact eristics and smaller amounts of condensation/frosting for extreme oper ating conditions.