Surface temperature transition of a controllable evaporating droplet

Soft Matter ◽  
2020 ◽  
Vol 16 (41) ◽  
pp. 9568-9577
Author(s):  
Lu Shen ◽  
Junheng Ren ◽  
Fei Duan

Controlled ethanol droplet evaporation shows a five-phase surface temperature evolution and two transitions among the three radial surface temperature distributions.

2021 ◽  
Vol 13 (5) ◽  
pp. 957
Author(s):  
Guglielmo Grechi ◽  
Matteo Fiorucci ◽  
Gian Marco Marmoni ◽  
Salvatore Martino

The study of strain effects in thermally-forced rock masses has gathered growing interest from engineering geology researchers in the last decade. In this framework, digital photogrammetry and infrared thermography have become two of the most exploited remote surveying techniques in engineering geology applications because they can provide useful information concerning geomechanical and thermal conditions of these complex natural systems where the mechanical role of joints cannot be neglected. In this paper, a methodology is proposed for generating point clouds of rock masses prone to failure, combining the high geometric accuracy of RGB optical images and the thermal information derived by infrared thermography surveys. Multiple 3D thermal point clouds and a high-resolution RGB point cloud were separately generated and co-registered by acquiring thermograms at different times of the day and in different seasons using commercial software for Structure from Motion and point cloud analysis. Temperature attributes of thermal point clouds were merged with the reference high-resolution optical point cloud to obtain a composite 3D model storing accurate geometric information and multitemporal surface temperature distributions. The quality of merged point clouds was evaluated by comparing temperature distributions derived by 2D thermograms and 3D thermal models, with a view to estimating their accuracy in describing surface thermal fields. Moreover, a preliminary attempt was made to test the feasibility of this approach in investigating the thermal behavior of complex natural systems such as jointed rock masses by analyzing the spatial distribution and temporal evolution of surface temperature ranges under different climatic conditions. The obtained results show that despite the low resolution of the IR sensor, the geometric accuracy and the correspondence between 2D and 3D temperature measurements are high enough to consider 3D thermal point clouds suitable to describe surface temperature distributions and adequate for monitoring purposes of jointed rock mass.


Author(s):  
Tadeusz Orzechowski

Abstract The investigations involved a large water droplet deposited on the heating surface, the temperature of which was higher than the Leidenfrost point. The main element of the experimental setup was the heating cylinder with K-type shielded thermocouple located in its centre just below the surface. The measuring system was located on highly sensitive scales. The analysis of the droplet behaviour in time was conducted based on measured droplet mass changes over time and also photographic data recorded with high resolution digital camera. The energy balance equation is given for the assumption that evaporation from the droplet upper surface is small compared with the amount of heat dissipated from the bottom surface. The formula for the heat transfer coefficient depends on two slope values and an orthogonal projection of the drop onto the heating surface. The slopes are estimated based on the droplet diameter linear time dependence and mass versus the contact zone relationship. The solution provides a good representation of droplet evaporation under Leidenfrost conditions. The investigations, reported in the study, which concern water droplet at atmospheric pressure deposited on a hot surface with the temperature higher than the Leidenfrost point, indicate the following regularities: droplet orthogonal projection onto the heating surface changes linearly with the droplet mass, evaporation of the same amount of mass decreases linearly with an increase in the heating surface temperature, slope of the graph showing mass loss versus the heating surface temperature successively decreases.


1999 ◽  
Author(s):  
Vladimir Shvedchenko ◽  
Ivan Yegorov ◽  
Wolfgang Fischer ◽  
Johann Antonenko ◽  
Boris Zhestkov ◽  
...  

Author(s):  
Ali Y. Alharbi ◽  
Deborah V. Pence ◽  
Rebecca N. Cullion

Heat transfer to liquid flow through fractal-like branching flow networks is investigated using a three-dimensional computational fluid dynamics approach. Results are used to assess the validity of, and provide insight for improving, assumptions imposed in a previously developed one-dimensional model to predict wall temperature distributions along a fractal-like flow network. Assumptions in the one-dimensional model include (1) reinitiating thermal and hydrodynamic boundary layers following each bifurcation, (2) negligible minor losses at the bifurcations, and (3) constant thermo-physical fluid properties. It is concluded that temperature varying fluid properties and minor losses should be incorporated in the one-dimensional model to improve its predictive capabilities. No changes to the redevelopment of the boundary layers at each wall following a bifurcation are recommended. Surface temperature distributions along heat sinks with parallel and fractal-like branching flow networks are also investigated and compared. For the same observed maximum surface temperature between the two heat sinks, considerably lower temperature variations and pressure drops, greater than 50 percent, are noted for the fractal-like heat sink.


RSC Advances ◽  
2015 ◽  
Vol 5 (46) ◽  
pp. 36434-36448 ◽  
Author(s):  
S. Liparoti ◽  
A. Sorrentino ◽  
G. Guzman ◽  
M. Cakmak ◽  
G. Titomanlio

It is widely accepted that mold temperature has a strong effect on the amount of molecular orientation and morphology developed in a non-isothermal flowing melt.


1998 ◽  
Vol 13 (09) ◽  
pp. 695-699 ◽  
Author(s):  
HARET C. ROSU

This is a short note on the black hole remote-sensing problem, i.e. finding out "surface" temperature distributions of various types of small (micron-sized) black holes from the spectral measurements of their Hawking grey pulses. Chen's modified Möbius inverse transform is illustrated in this context.


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