Analytical Performance Evaluation of Hybrid Desiccant Air Conditioning Systems (Dept.M)

Atheoretical evaluation of a hybrid desiccant air conditioning in post and pre·  cooli ng arrsngemenls is studied and compared versus the trad',tional vapor  compression system {VeSl- The periormance of the rotary desiccant wheel Is  also studied as the hean of the hybrid desiccant cooling syste m. Lithium '   chloride IS applied as the worning desiccant malerial In Ihls investigalioll. A  mathemati cal model of coupled heal and mass Iransfer of the desiccant wheel  is presented and numerica lly solved. The model validity is check.ed 8galnslP'  other work and results are in good agreement. Effect!J01 rotary wheel speed ,  number of transfer units (NTU) and the desiccant surface area to volume on  Ihe performance of the wheell sre investigated. The ellecl of regeneration air  velocily and temperature, slot diameter, evaporator an d condenser  effectiveness and dehumidification effectiveness on the system perlorrnance  is also studied. The post cooling hybrid system is found 10 be an energy  efficient system, it saves up to 30% of cooling coit capaCity compared to  traditional VCS _ The COP of the post cooling arrangement,is nearly Iwice thai  of VCS with reheat. Thelpre cooling arrangement supplies air at lower dew  point lemperalure (down to 6°C) with an increase of COP up 10 80%  compared to VCS wilh reheat.