Isothermal dehydration of thin films of water and sugar solutions

Heyd, Rodolphe; Rampino, A.; Bellich, Barbara; Elisei, Elena; Cesàro, Attilio; Saboungi, Marie‐Louise

doi:10.1063/1.4868558

Cited by 8 publications

(16 citation statements)

References 40 publications

(36 reference statements)

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“…It is then impossible to envisage any manipulation of the film during drying and furthermore it is necessary to have a sufficiently sensitive and fast weighing method to be able to monitor the evolution of the mass m(t) of the film with adequate accuracy. Several routes can be considered in this case: a high-precision gravimetric monitoring [55], thermogravimetric analysis (TGA) or differential scanning calorimetry (DSC) [57].…”

Section: Experimental Approachmentioning

confidence: 99%

Drying colloidal systems: Laboratory models for a wide range of applications

et al. 2018

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Abstract. The drying of complex fluids provides a powerful insight into phenomena that take place on time and length scales not normally accessible. An important feature of complex fluids, colloidal dispersions and polymer solutions is their high sensitivity to weak external actions. Thus, the drying of complex fluids involves a large number of physical and chemical processes. The scope of this review is the capacity to tune such systems to reproduce and explore specific properties in a physics laboratory. A wide variety of systems are presented, ranging from functional coatings, food science, cosmetology, medical diagnostics and forensics to geophysics and art.

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Section: Experimental Approachmentioning

confidence: 99%

Drying colloidal systems: Laboratory models for a wide range of applications

et al. 2018

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“…(7) Enthalpy of evaporating water from nectar to honey is assumed to be constant for all of the starting nectar concentrations over the range 10-50% with a finishing honey concentration of 80% and to be approximately that of water [8]. (8) Calorific value of the sugars in the honey and nectar are taken to be that of sucrose [50]. (9) The enthalpy of inverting sucrose to fructose and glucose and its use of water are negligible, compared to the volume of evaporated water and the energy needed to vaporize it [50].…”

Section: Assumptionsmentioning

confidence: 99%

Thermal efficiency extends distance and variety for honeybee foragers: analysis of the energetics of nectar collection and desiccation by Apis mellifera

Mitchell

2019

J. R. Soc. Interface.

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The desiccation of nectar to produce honey by honeybees (Apis mellifera L.) is an energy-intensive process, as it involves a quasi-isothermal change in the concentration of sugars from typically 20 to 80% by vaporization (honey ripening). This analysis creates mathematical models for: the collected nectar to honey ratio; energy recovery ratio; honey energy margin; and the break-even distance, which includes the factors of nectar concentration and the distance to the nectar from the nest; energetics of desiccation and a new factor, thermal energy efficiency (TEE) of nectar desiccation. These models show a significant proportion of delivered energy in the nectar must be used in desiccation, and that there is a strong connection between TEE and nest lumped thermal conductance with colony behaviour. They show the connection between TEE and honeybee colony success, or failure, in the rate of return, in terms of distance or quality of foraging. Consequently, TEE is a key parameter in honeybee populations and foraging modelling. For bee keeping, it quantifies the summer benefits of a key hive design parameter, hive thermal conductance and gives a sound theoretical basis for improving honey yields, as seen in expanded polystyrene hives.

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“…The main aim of this work was to fully investigate the parameters affecting water evaporation by using a microcalorimeter in isothermal conditions. To begin with, a summary of the main theoretical concepts developed in a previous paper [12] is presented, and then a series of topics is treated. The setup of the adequate experimental conditions required to consider firstly the effect of the paper as a support for a planar geometry.…”

Section: Resultsmentioning

confidence: 99%

“…This geometry ensures a constant surface separating the liquid and the gas phases, avoiding excessive parametrization in the final equation. Thus, a model aiming at describing the heat and mass transfer during the isothermal dehydration process of a thin film inside a DSC chamber is here briefly described, while a more detailed dissertation is reported in a previous paper [12].…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…In a previous paper [12], after the presentation of a theoretical model for a drying process in a DSC operating under isothermal conditions, the heuristic behavior of water dehydration from a thin film was illustrated giving attention to the role of sugar type and concentration. What appeared to be an extremely difficult problem was the quantitative comparison of theory with experiment in order to describe more complex dehydration processes by determining the value of the various parameters.…”

Section: Introductionmentioning

confidence: 99%

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Isothermal dehydration of thin films

Bellich

Elisei

Heyd

et al. 2015

J Therm Anal Calorim

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The isothermal dehydration process was investigated by calorimetric experiments on water samples, pointing out a substantial correspondence with gravimetric results, even though the heat flow measurement is characterized by a higher resolution on approaching the end of the evaporation. The role of the geometry of the sample on water evaporation rate is analyzed with reference to two model geometries, resembling the spherical and the planar surface. Specific attention was given to the planar surface for the description of the water evaporation from thin film. The development of a theoretical model, which provides information regarding the water activity, was supported by investigating the effect of the several parameters involved in the isothermal dehydration, such as sample mass and temperature. The data collected revealed some limits in the valuable use of the theoretical model when the experimental conditions are outside the range of quasi-equilibrium thermodynamic condition, e.g., at temperature higher that 50°C. Attention has also been given to control the initial thermal unbalance in order to improve the measurements.

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Isothermal dehydration of thin films of water and sugar solutions

Cited by 8 publications

References 40 publications

Drying colloidal systems: Laboratory models for a wide range of applications

Drying colloidal systems: Laboratory models for a wide range of applications

Thermal efficiency extends distance and variety for honeybee foragers: analysis of the energetics of nectar collection and desiccation by Apis mellifera

Isothermal dehydration of thin films

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