Vapor pressure formulation for ice

Wexler, Arnold

doi:10.6028/jres.081a.003

Cited by 131 publications

(81 citation statements)

References 43 publications

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“…The relative humidity of the inlet air was manually controlled using a desiccant dryer system upstream of the heat exchanger, and measured at room temperature using a humidity sensor. The reading was converted to a relative humidity measurement at the chamber air inlet temperature using standard water/ice vapor pressure formulations [30,31].…”

Section: Methodsmentioning

confidence: 99%

Performance of Proton Exchange Membrane Fuel Cell at High-Altitude Conditions

Pratt

Brouwer

Samuelsen

2007

Journal of Propulsion and Power

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The effects of oxygen concentration and ambient pressure on fuel cell performance are explored both in theory and in experiment. For fuel cells in general the effect due to a change in oxygen concentration is shown to be fundamentally different than the effect due to a change in cathode pressure, even if partial pressure is held constant. For a proton exchange membrane fuel cell, a significant reason for this difference comes from the nature of mass diffusion processes in the fuel cell structure, which infers that there is an optimum fuel cell design (macroscale and microscale) for a given operating pressure and oxygen concentration. In the experimental work a proton exchange membrane fuel cell was subjected to varying atmospheric conditions from sea level to 53,500 ft (16,307 m) with results analyzed up to 35,000 ft (10,668 m). The results showed that at low current density operation a decrease in either cathode pressure or concentration led to an increase in irreversible losses associated with reaction kinetics (activation polarization) and confirmed the differing effects of cathode pressure and oxygen concentration. Consideration of all these effects enables both fuel cell-and system-level optimization of aeronautical fuel cell-based power systems.

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Section: Methodsmentioning

confidence: 99%

Performance of Proton Exchange Membrane Fuel Cell at High-Altitude Conditions

Pratt

Brouwer

Samuelsen

2007

Journal of Propulsion and Power

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“…At 265 K, p i = 2 bar, p o = 1 bar,ṅ = 7.85×10 −5 mol s −1 (≈ 100 sccm) yieldsḣ = 0.7 µm h −1 . Vapor pressure p(H 2 O) over ice is taken from Wexler (1977). Some experiments were carried out using aged ice films: after column preparation, the carrier gas was interrupted and the column was kept at 265 K overnight.…”

Section: Methodsmentioning

confidence: 99%

Gas chromatography using ice-coated fused silica columns: study of adsorption of sulfur dioxide on water ice

Langenberg

Schurath

2018

Atmos. Chem. Phys.

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Abstract. The well established technique of gas chromatography is used to investigate interactions of sulfur dioxide with a crystalline ice film in a fused silica wide bore column. Peak shape analysis of SO 2 chromatograms measured in the temperature range 205-265 K is applied to extract parameters describing a combination of three processes: (i) physisorption of SO 2 at the surface, (ii) dissociative reaction with water and (iii) slow uptake into bulk ice. Process (ii) is described by a dissociative Langmuir isotherm. The pertinent monolayer saturation capacity is found to increase with temperature. The impact of process (iii) on SO 2 peak retention time is found to be negligible under our experimental conditions. By analyzing binary chromatograms of hydrophobic nhexane and hydrophilic acetone, the premelt surface layer is investigated in the temperature range 221-263 K, possibly giving rise to irregular adsorption. Both temperature dependencies fit simple van't Hoff equations as expected for process (i), implying that irregular adsorption of acetone is negligible in the investigated temperature range. Adsorption enthalpies of −45 ± 5 and −23±2 kJ mol −1 are obtained for acetone and n-hexane.The motivation of our study was to assess the vertical displacement of SO 2 and acetone in the wake of aircraft by adsorption on ice particles and their subsequent sedimentation. Our results suggest that this transport mechanism is negligible.

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“…At 265 K, p i = 2 bar, p o = 1 bar, n = 7.85 × 10 −5 mol s −1 (≈ 100 sccm) isḣ = 0.7µm h −1 . Vapor pressure p(H 2 O) over ice is taken from Wexler (1977).…”

Section: Methodsmentioning

confidence: 99%

Gas-Chromatography using ice coated fused silica-columns: Study of adsorption of sulfur dioxide on water-ice

Langenberg¹,

Schurath²

2017

Preprint

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Abstract. The well-established technique of gas chromatography is used to investigate interactions of sulfur dioxide with a crystalline ice film in a fused silica wide-bore column. Peak shape analysis of SO 2 chromatograms measured in the temperature range 205 -265 K is applied to extract parameters describing a combination of three processes: (i) physisorption of SO 2 at the surface; (ii) dissociative reaction with water; (iii) slow uptake into bulk ice. Process (ii) is described by a dissociative Langmuir isotherm. The pertinent monolayer saturation capacity is found to increase with temperature. The impact of process (iii) on 5 SO 2 peak retention time is found to be negligible under our experimental conditions. By analyzing binary chromatograms of hydrophobic n-hexane and hydrophilic acetone, the premelt surface layer is probed in the temperature range 221 -263 K possibly giving rise to irregular adsorption. Both temperature dependencies fit simple van't Hoff equations as expected for process (i), implying that irregular adsorption of acetone is negligible in the probed temperature range. Adsorption enthalpies of −45 ± 5 kJ mol −1 and −23 ± 2 kJ mol −1 are obtained for acetone and n-hexane. 10Our study was motivated to assess the vertical displacement of SO 2 and acetone in the wake of aircraft by adsorption on ice particles and their subsequent sedimentation. Our results suggest that this transport mechanism is negligible.

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Vapor pressure formulation for ice

Cited by 131 publications

References 43 publications

Performance of Proton Exchange Membrane Fuel Cell at High-Altitude Conditions

Performance of Proton Exchange Membrane Fuel Cell at High-Altitude Conditions

Gas chromatography using ice-coated fused silica columns: study of adsorption of sulfur dioxide on water ice

Gas-Chromatography using ice coated fused silica-columns: Study of adsorption of sulfur dioxide on water-ice

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