Modelling non-isothermal absorption of vapour into expanding liquid sheets

Abstract

a b s t r a c tThe problem of non isothermal absorption of vapour into freely expanding liquid sheets is addressed in this study. This is done in the context of four models that characterise the coupled heat and mass transfer in the liquid phase: a nonlinear model retaining the effect of sheet growth, an approximate model for slowly increasing mass flow rate in the sheet, a large Lewis number model and finally, a boundary layer model. These models have been numerically or analytically solved and applied to the comparative anal ysis of two different working pairs, LiBr H 2 O and LiNO 3 NH 3 , under conditions representative of adia batic absorption in refrigeration systems. The limits of applicability of each model have been assessed and the sensitivity of the results to the sheet aperture angle, heat of absorption and initial subcooling has also been tested. For equal initial mass fraction and subcooling, the models indicate that Sherwood number and the rate of absorption in laminar expanding sheets for the LiNO 3 NH 3 solution are always superior to those for the LiBr H 2 O solution.

Experimental assessment of ammonia adiabatic absorption into ammonia–lithium nitrate solution using a flat fan nozzle

“…Absorption ratios found in this work are similar to those theorized by Acosta-Iborra et al [13], although only a qualitative comparison is possible as in that work a steady sheet was considered with no atomization. They are higher than those obtained by Palacios et al [12] using a similar nozzle.…”

“…The last method is an alternative to conventional designs of absorbers that has received increasing attention in the last years; among others, Ryan [3], Ryan et al [4], Summerer et al [5], Venegas et al [6,7], Arzoz et al [8], Warnakulasuriya and Worek [9,10], Palacios et al [11,12], Acosta-Iborra et al [13], Gutiérrez [14], Zacarías [15] and Ventas [16]. In this configuration, the heat and mass transfer processes are separated into two different devices: the single-phase solution subcooler and the absorption chamber.…”

Modeling of conjugated heat and mass transfer in the entrance region of falling liquid film at various values of the Froude number

“…Modelling of the non-isothermal absorption of vapour into expanding liquid sheets was performed by Acosta-Iborra and co-workers [3]. In [4] it has been shown that a significant change of the salt concentration leads to different absorption regimes.…”

Experimental assessment of vapour adiabatic absorption into solution droplets using a full cone nozzle

“…Solution temperature at the absorption chamber inlet has been used to calculate all properties in Eqs. (13)(14)(15)(16). Fig.…”

“…It has received increasing attention in the last years by Ryan [3], Ryan et al [4], Summerer et al [5], Venegas et al [6,7], Arzoz et al [8], Warnakulasuriya and Worek [9,10], Palacios et al [11,12], Acosta-Iborra et al [13], Gutiérrez [14], Zacarías [15], Ventas [16], Zacarías et al [17], Zacarías et al [18], among others. In this configuration, the heat and mass transfer processes are separated into two different devices: the single-phase solution subcooler and the absorption chamber.…”