Comparison between molar- and mass-based approaches to drop evaporation modelling

Three evaporation models for single-component liquid drop floating in a gaseous environment are compared: two of them rely on the widely used assumption of constant (molar or mass) density and yield an explicit formula for the evaporation rate, while the third model relieves the constant density hypothesis yielding an implicit form of the evaporation rate. The comparison is made for a relative wide range of temperature and pressure operating conditions and for three liquids: water, n-octane and n-dodecane.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Mathematical modelling of heating and evaporation of a spheroidal droplet

Objective: Dialysis patients frequently report a change of taste that is reversible after renal transplantation, suggesting that uremic toxins may negatively influence taste. Currently, frequent nocturnal home hemodialysis (NHHD) is the most effective method of hemodialysis, and is associated with the lowest levels of uremic toxins. We studied preferences for various foods as an indicator of taste perception. We questioned whether food preference differs between NHHD patients and those on conventional hemodialysis. Design and Patients: In this transverse, cross-sectional pilot study, we assessed food preference by means of a questionnaire for patients on NHHD (n=6; 8 hours of dialysis per night, for 5 or 6 nights a week) and 3 age-matched and sex-matched control groups: chronic home hemodialysis patients (HHD; n=9; 4 to 5 hours of dialysis per day, 3 days a week), chronic in-center hemodialysis patients (CHD; n=18; 4 to 5 hours of dialysis per day, 3 days a week), and healthy control subjects (HC; n=23). Results: Mean scores for food preference did not differ between groups (P=.32). Similarly, the preference for product groups did not differ between groups. On an individual product level, we found only minor differences. The NHHD patients had a preference for savory snacks, as did the HC and CHD groups, whereas the HHD group had a preference for sweet snacks (P <.05). Hemodialysis patients reported dry mouth more often than did the HC patients (P <.05). Conclusions: Frequent NHHD has no major impact on food preference. The change in taste reported by NHHD patients is not related to their particular food preferences. (C) 2010 by the National Kidney Foundation, Inc. All rights reserved

Quantitative optical techniques for dense sprays investigation: A survey

The experimental study of dense sprays by optical techniques poses many challenges and no methods have proven to be completely reliable when accurate quantitative data are required, for example to validate breakup models and CFD simulations. The present survey is aimed to a critical analysis of optical techniques capable to provide quantitative and reliable data in dense sprays and to point out the conditions necessary to safely obtain such measurements. A single parameter, the optical depth, is proposed to quantify the concept of dense spray and to indicate when multiple scattering becomes predominant and could make the experimental results questionable. Many available optical techniques are divided into two categories: the ‘‘classical’’ ones, like PDA, LDV, PIV, etc., that work well in dilute sprays but show many limitations in dense sprays, and the ‘‘emerging’’ ones more suitable for dense sprays. Among the last ones, those considered more promising are discussed in detail. A number of significant applications are also presented and discussed to better clarify the nature of such complex problem and the feasibility of the new proposed approaches

Experimental Investigation of Gas Density Effects on Diesel Spray Penetration and Entrainment

SAE Paper 1999-01-052

The role of time in single drop splash on thin film

This paper reports on an experimental study of the impact of water drops on thin liquid films. The mor- phology of the impact was studied by still photography, and quantitative results were obtained by a proper image analysis technique. The time evolution of various param- eters like the crown diameter, the crown height, and the secondary drop diameters are reported, and these experi- mental parameters are correlated and compared to avail- able theoretical models. A particular set-up of the acquisition system allowed us to photograph the splash from below the solid wall, allowing the first estimation of the crown thickness and the total number of jets pro- truding from the crown rim as a function of time. The results indicate that, for the range of the parameters investigated, there is not a strong dependence on the film thickness. The evolution of the crown height depends on the impact Weber number, whereas its growing velocity and the crown thickness evolution are almost independent of Weber number