Design of Plate-Fin Tube Dehumidifiers for Humidification–Dehumidification Desalination Systems

Sievers, Martin; Lienhard, John H.

doi:10.1080/01457632.2014.916153

Cited by 18 publications

(9 citation statements)

References 36 publications

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“…An impractically small (8.7 cm long) "coil" was included to illustrate the trade-off between heat flux and effectiveness. For reference, the largest coil used here (900 cm 2 ) was comparable in length and equivalent in tube diameter to the coils used by Narayan et al [3]. The vertical part of each coil, which connects the immersed portion to the chilled water source, was insulated by 3.2 mm thick, 9.5 mm ID rubber tubing.…”

Section: Experimental Bubble Column Dehumidifiermentioning

confidence: 99%

“…In its most basic form, a HDH system consists of a heater, a humidifier, a dehumidifier, and the pumps and piping necessary to move fluid between components. Dehumidification technology warrants further study because of the high condenser area required [2,3] to overcome the resistance to diffusion of a dilute vapor through air, and because the effectiveness of the dehumidifier dominates the performance of the entire HDH system [4].…”

Section: Introductionmentioning

confidence: 99%

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Experiments and modeling of bubble column dehumidifier performance

Tow

Lienhard

2014

International Journal of Thermal Sciences

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Humidification-dehumidification is a promising technology for decentralized, small-scale desalination, but conventional dehumidifiers are expensive due to the large surface area required. Direct-contact dehumidification in bubble columns has been shown to significantly decrease dehumidifier size and cost. In this paper, the heat flux and parallel-flow effectiveness of a bubble column dehumidifier are investigated experimentally using significantly smaller cooling coils than in previous work. In addition, a model is developed which predicts the heat transfer rate with an average error of less than 3%.It is found that heat flux rises and effectiveness decreases with decreasing coil area. Increasing air flow rate and air temperature both lead to increased heat flux but decreased effectiveness. Neither bubble-on-coil impact nor column height are found to significantly affect heat flux or effectiveness. The conflicting findings of previous research on bubble-on-coil impact are explained by the other trends identified in this work. Modeling results for salt water * Address all correspondence to lienhard@mit.edu April 24, 2014 temperature and tube diameter are presented. Additional heat transfer in the air gap above the column liquid is explored, but found to be minimal for well-designed columns with low temperature pinch. These findings will inform the design of bubble column dehumidifiers for high heat recovery and low capital cost. Keywords: condensation, direct contact heat transfer, HDH desalination

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Section: Experimental Bubble Column Dehumidifiermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experiments and modeling of bubble column dehumidifier performance

Tow

Lienhard

2014

International Journal of Thermal Sciences

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“…Recent studies on the SHDHSDSs mainly focus on the heat transfer enhancement in the evaporators and condensers [4][5][6][7], the configuration and operation parameters analyses [8][9][10][11], and the experimental studies on demonstration systems [12][13][14][15][16][17][18][19]. Sievers and Lienhard analyzed the heat transfer and fluid flow inside the flatplate and finned-pipe condensers using numerical simulations [4,5]. Moumouh et al fulfilled the heat transfer enhancement of flat-plate collectors with siphon water tanks and packed beds through reviewing the SHDHSDSs in the literature [6].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of a Humidification-Dehumidification Seawater Desalination System Combined with the Chimney

Cao

Liu

Xiao

2020

International Journal of Photoenergy

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The solar humidification-dehumidification system is of high significance to the freshwater supply in remote areas. In the present study, a humidification-dehumidification seawater desalination system combined with the chimney is designed and experimentally evaluated. Main parameters influencing its freshwater productivity are analyzed. It is found from this study that the cooling tower is required to obtain long-term steady freshwater generation. Raising the temperature difference between the evaporation and condensation chambers would lead to the rise of the freshwater productivity. There is a turning wind speed, beyond which increasing the wind speed would lead to the decline of both the freshwater productivity and the thermal efficiency. The turning wind speed is relevant to the ambient humanity and the heating power. Decreasing the heat power would increase the turning wind speed. When the heating power is 4.9 kW, the highest freshwater productivity and the highest efficiency are 48 g/min and 32.14%, respectively.

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“…A major issue that made early HDH systems difficult to commercialize was their need for very large dehumidifiers [4,5] (up to 30 m 2 for a 1 m 3 /day system [6]), which increased their cost of water production greatly. Dehumidifiers contain a very large concentration of air, a noncondensable gas, which leads to very low mass transfer coefficients and increases the surface area needed in conventional dehumidifiers.…”

Section: Bubble Column Dehumidifiers In Hdhmentioning

confidence: 99%

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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Design of Plate-Fin Tube Dehumidifiers for Humidification–Dehumidification Desalination Systems

Cited by 18 publications

References 36 publications

Experiments and modeling of bubble column dehumidifier performance

Experiments and modeling of bubble column dehumidifier performance

Experimental Study of a Humidification-Dehumidification Seawater Desalination System Combined with the Chimney

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

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