Experimental investigation of aqueous LiBr solution absorber bundle with horizontal elliptical tubes

Abstract

This article reports on the results of experimental studies on combined heat and mass transfer in the absorption of water vapor by aqueous LiBr solution under laminar falling film flow on the horizontal elliptical tube (HET) bundle. The performance of the absorber with HET has been calculated based on the measured parameters. The outputs are shown with respect to absorbent inlet mass concentration and Reynolds Number (Re), coolant inlet temperature and flow rate, and absorber vapor pressure. The results are compared with the published experimental results on absorber bundle with horizontal circular tubes (HCT). The results show that the heat and mass transfer coefficients enhanced on HET at aspect ratio (Ar ) > 1 with respect to HCT and improve with the increase of absorbent mass flow rate, absorber vapor pressure, coolant flow rate, and also with the decrease of absorbent concentration and coolant inlet temperature. Because of film thickness increasing and droplet flying off from the tube bundle, the maximum heat transfer coefficient is attained in an optimum absorbent mass flow rate around Re = 45. Finally, the empirical correlations for outside Sherwood number (Sh) and Nusselt number (Nu) are found to depend on the Re, Schmidt number (Sc), mass concentration and absorber vapor pressure.