Optimization of operating conditions for energy conservation in a packed-bed absorber

Abstract

Indoor humidity can be adjusted by an absorption air conditioning system; however, reaching zero humidity is not absolutely the purpose of such adjustment. Therefore, one of the purposes of this study was to discuss the suitable operating conditions in the packed-bed absorber under conformable environments. Triethylene glycol (TEG) solution was used in this study to remove water vapor from air in a packed-bed absorber. The JMP software was adopted to run the response surface methodology, and the methodology was used to determine the operating conditions in a packed-bed absorber. Both experimental and statistical results demonstrated that the amount of water vapor removed by the packed-bed absorber increased with increases in the gas/liquid flow rates and TEG concentration. Analysis with the response surface methodology suggested that the liquid flow rate should be 0.013 to 0.015 kg/s and that the gas flow rate should be 0.022 to 0.025 kg/s to achieve 65% to 80% flooding. The suggested concentration of TEG solution is 70.65 to 85 wt.% due to the lower absorption performance below 70.65 wt.% and the larger energy consumption beyond 85 wt.%. With this range, not only is the amount of water vapor removed acceptable, but the requirement of energy-saving is met. The average error between experimental and predicted removal amounts is about 3.6%. The statistical method is recommended to obtain the mass transfer correlation for mass transfer devices in various operating conditions and the mass transfer amount can be predicted by the absorber designer.