Heat transfer to a horizontal cylinder in a shallow bubble column

Tow, Emily W.; Lienhard, John H.

doi:10.1016/j.ijheatmasstransfer.2014.08.021

Cited by 14 publications

(8 citation statements)

References 35 publications

(51 reference statements)

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“…For example, the humidifier and dehumidifier may both be multistage bubble columns [46,47], which have much lower heat and mass transfer resistances [48] than packed beds or indirect contact heat exchangers. The extraction and injection of water or air from one component to the other in order to balance the humidifier or dehumidifier and increase energy efficiency has also been investigated [49][50][51][52][53].…”

Section: Humidification-dehumidificationmentioning

confidence: 99%

Energy consumption in desalinating produced water from shale oil and gas extraction

et al. 2015

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On-site treatment and reuse is an increasingly preferred option for produced water management in unconventional oil and gas extraction. This paper analyzes and compares the energetics of several desalination technologies at the high salinities and diverse compositions commonly encountered in produced water from shale formations to guide technology selection and to inform further system development. Produced water properties are modeled using Pitzer's equations, and emphasis is placed on how these properties drive differences in system thermodynamics at salinities significantly above the oceanic range. Models of mechanical vapor compression, multi-effect distillation, forward osmosis, humidification-dehumidification, membrane distillation, and a hypothetical high pressure reverse osmosis system show that for a fixed brine salinity, evaporative system energetics tend to be less sensitive to changes in feed salinity. Consequently, second law efficiencies of evaporative systems tend to be higher when treating typical produced waters to near-saturation than when treating seawater. In addition, if realized for high-salinity produced waters, reverse osmosis has the potential to achieve very high efficiencies. The results suggest a different energetic paradigm in comparing membrane and evaporative systems for high salinity wastewater treatment than has been commonly accepted for lower salinity water.

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Section: Humidification-dehumidificationmentioning

confidence: 99%

Energy consumption in desalinating produced water from shale oil and gas extraction

et al. 2015

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“…Conductivity is measured with a Hach conductivity meter, and sodium chloride concentration is interpolated from tabulated data in [27]. The feed is kept well-mixed by a slow stream of air bubbles, which also serve to improve thermal control of the feed by increasing the heat transfer coefficient on the cooling coil [28]. The draw is not actively mixed, but the inlet to the draw pump is placed halfway up the draw tank so that if the tank becomes stratified, draw is taken from the middle of any salinity and temperature gradients.…”

Section: Apparatusmentioning

confidence: 99%

Quantifying osmotic membrane fouling to enable comparisons across diverse processes

Tow

Lienhard

2016

Journal of Membrane Science

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In this study, a method of in situ membrane fouling quantification is developed that enables comparisons of foulant accumulation between desalination processes with different membranes, driving forces, and feed solutions. Unlike the conventional metric of flux decline, which measures the response of a process to fouling, the proposed method quantifies the foulant accumulation. Foulant accumulation is parameterized by two variables, cake structural parameter and hydraulic diameter, that are calculated from flux measurements using a model for salt and water transport through fouled reverse osmosis (RO) and forward osmosis (FO) membranes, including dispersive mass transfer in the FO membrane support layer. Model results show that pressure declines through the foulant layer and can, in FO, reach negative absolute values at the membrane. Experimental alginate gel fouling rates are measured within a range of feed ionic compositions where cake hydraulic resistance is negligible. Using both flux decline and cake structural parameter as metrics, the effect of feed salinity on RO fouling is tested and RO is compared to FO. When RO is fouled with alginate, feed salinity and membrane permeability affect flux decline but not foulant accumulation rate. Between FO and RO, the initial rates of foulant accumulation are similar; however, FO exhibits slower flux decline, which causes greater foulant accumulation over time. The new methodology enables meaningful quantification and comparison of fouling rates with the aim of improving fundamental understanding of fouling processes.

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“…Tow and Lienhard [11,12] also measured heat transfer rates up to more than 8,000 W/m 2 -K in shallow bubble columns, further justifying their use in the dehumidification side of an HDH system.…”

Section: Bubble Column Dehumidifiers In Hdhmentioning

confidence: 94%

Thermodynamic balancing of a fixed-size two-stage humidification dehumidification desalination system

Chehayeb

Narayan²,

Zubair

et al. 2015

Desalination

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Humidification dehumidification (HDH) is a desalination technology that has shown promise in small scale, decentralized applications. Previous studies on the multi-staging of HDH have used fixed-effectiveness models which do not explicitly account for transport processes in the components. However, to fully understand the effect of the variation of the mass flow rate ratio, it is necessary to implement heat and mass transfer models of the HDH system. In this paper, we model an HDH system consisting of a packed-bed humidifier and a multi-tray bubble column dehumidifier. We study the effect of the mass flow rate ratio on the performance of a fixed-size system, and we consider its effect on the entropy generation and the driving forces for heat and mass transfer. In addition, we define a generalized energy effectiveness for heat and mass exchangers. We also implement an air extraction/injection and simulate a wide range of operating conditions. We define criteria for the best system performance, and we study the effect of the distribution of available area between separate stages. We also present a thorough explanation of why the direction of extraction should always be from the humidifier to the dehumidifier.

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Heat transfer to a horizontal cylinder in a shallow bubble column

Cited by 14 publications

References 35 publications

Energy consumption in desalinating produced water from shale oil and gas extraction

Energy consumption in desalinating produced water from shale oil and gas extraction

Quantifying osmotic membrane fouling to enable comparisons across diverse processes

Thermodynamic balancing of a fixed-size two-stage humidification dehumidification desalination system

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