Analysis of an air cooled ammonia–water vertical tubular absorber

Fernández-Seara, José; Uhía, Francisco J.; Sieres, Jaime

doi:10.1016/j.ijthermalsci.2006.03.005

Cited by 24 publications

(4 citation statements)

References 28 publications

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“…Their results show that the required tube lengths for complete absorption increase in successive rows. Also, it is found that the temperature profiles of the vapor and the solution are similar to those found in their previous study (Fernández-Seara et al , 2007). The cooling temperature increased monotonically across the tube bank.…”

Section: Introductionsupporting

confidence: 86%

Enhancement of the performance of bubble absorber using hybrid nanofluid as a cooled absorption system

Jaballah

Hamida

Saleh

et al. 2019

HFF

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Purpose The purpose of this paper is to investigate the enhancement of the performance of bubble absorber using hybrid nanofluid as a cooled NH3/H2O absorption system to reduce their size and to find the best fitting model. A numerical model for ammonia-water bubble absorber was developed to show the influence of operating conditions and design parameters on the absorber performance. Design/methodology/approach A finite difference numerical method is used to solve the numerical model. The model is subjected to the inlet conditions of liquid, vapor and coolant flow regimes. The absorber modeling was divided into small elements along the absorber length. Findings The model proposed is validated with previously published works. Then agreement between the both is considered as good. Research limitations/implications Numerical results/The use of hybrid nanofluids. Originality/value The results showed that the hybrid nanofluid is the best cooling medium. Very high heat transfer rates are obtained because of the high thermal conductivity and specific heat of hybrid nanofluid, and consequently, the absorber size decreases. It was also found that the absorber thermal load and the mass absorption flux increase with increasing of solid volume fraction. Also, the existence of an optimal absorber length was revealed, required for complete absorption when using hybrid nanofluid as a cooling medium. It is recommended that using hybrid nanofluid to remove the heat from the absorber is the best candidate for NH3/H2O absorption performance enhancement.

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Section: Introductionsupporting

confidence: 86%

Enhancement of the performance of bubble absorber using hybrid nanofluid as a cooled absorption system

Jaballah

Hamida

Saleh

et al. 2019

HFF

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“…Many of these simplifying assumptions are representative of prac tical operating conditions in adiabatic absorption and are also com mon to many models in falling film absorption. At this regard, it is important to note that in non adiabatic absorption large incre ments of absorbate mass fraction and temperature can occur, being in that case recommendable to calculate the local variation of working pair properties with X and T (see for example [28]). This contrasts with adiabatic absorption for which the assumption of unvarying properties in the mixture is particularly suited because potential increments of T and, above all, X are significantly smaller [3,23], as demonstrated in Appendix A.…”

Section: Physical Model and General Assumptionsmentioning

confidence: 99%

Modelling non-isothermal absorption of vapour into expanding liquid sheets

Acosta-Iborra

García

Santana

2009

International Journal of Heat and Mass Transfer

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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.

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“…For the vertical tubular bubble absorber, the heat and mass transfer processes with ammonia-water as working pairs were analyzed by experiments and models (Fernández-Seara et al, 2005, 2007Ferreira et al, 1984;Kim et al, 2003aKim et al, , 2003b. Generally, three kinds of flow patterns, churn, slug and bubble flow patterns will be formed in the absorber.…”

Section: Ammonia Refrigerant Bubble Absorptionmentioning

confidence: 99%

Visual experimental research on the effect of nozzle orifice structure on R124–DMAC absorption process in a vertical bubble tube

Jiang

et al. 2016

International Journal of Refrigeration

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Analysis of an air cooled ammonia–water vertical tubular absorber

Cited by 24 publications

References 28 publications

Enhancement of the performance of bubble absorber using hybrid nanofluid as a cooled absorption system

Enhancement of the performance of bubble absorber using hybrid nanofluid as a cooled absorption system

Modelling non-isothermal absorption of vapour into expanding liquid sheets

Visual experimental research on the effect of nozzle orifice structure on R124–DMAC absorption process in a vertical bubble tube

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