Study on solid liquid interface heat transfer of PCM under simultaneous charging and discharging (SCD) in horizontal cylinder annulus

2017 ◽  
Vol 53 (7) ◽  
pp. 2223-2240 ◽  
Author(s):  
Adebola Peter Omojaro ◽  
Cornelia Breitkopf
Keyword(s):  
Heat Transfer ◽  
Horizontal Cylinder ◽  
Liquid Interface ◽  
Interface Heat Transfer ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Interface Heat

Analytical Solution on the Relation of Technique Parameters for Continuous Casting with Heated Mould

2011 ◽  
Vol 337 ◽  
pp. 225-231
Author(s):  
Feng Ni ◽  
Shi Zhong Wei ◽  
Rui Long
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Continuous Casting ◽  
Casting Speed ◽  
Specific Conductance ◽  
Liquid Interface ◽  
Mould Temperature ◽  
Interface Position ◽  
Solid Liquid Interface ◽  
Solid Liquid

The technique of continuous casting with heated mould is a kind of near-net-shape processing technology, which combines unidirectional solidification with continuous casting and has been used widely for new material development and processing. A steady-state heat-transfer model was suggested for pure metal case. Some of modeling parameters, such as equivalent specific conductance and equivalent heat-transfer coefficient, etc, had been defined. The analytic solution of temperature profile along the axis of casting rod was obtained for solid-liquid interface to be as origin of position coordinate, by which the relations had been solved among mould temperature, casting speed, solid-liquid interface position, equivalent specific conductance between mould and metal, equivalent heat-transfer coefficient of cooling of cast rod, temperature gradient and cooling rate of melt in front of solid-liquid interface. As an example, the coordinate relations of solid-liquid interface position, mould temperature and casting speed were calculated and compared with experimental results in the case of pure copper. The calculation results conformed very well to the experimental ones. And it was indicated that the cooling rate of melt in front of solid-liquid interface had a nonlinear relation with casting speed during steady continuous casting process.

Nanobubbles on a Very Flat Hydrophobic Surface Prepared by Self-Assembled Monolayers

2013 ◽  
Author(s):  
Takashi Nishiyama ◽  
Koji Takahashi ◽  
Yasuyuki Takata
Keyword(s):  
Heat Transfer ◽  
Gaseous Phase ◽  
Hydrophobic Surface ◽  
Bubble Nucleation ◽  
Liquid Interface ◽  
Self Assembled Monolayers ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Solid Liquid Interface ◽  
Solid Liquid

Boiling is one of the most effective heat transfer methods due to its high heat transfer coefficient. Therefore, boiling heat transfer plays a very important role for various applications in many technological and industrial areas. However, a very complex mechanism of boiling, especially bubble nucleation, is still not sufficiently understood. On the other hand, numerous experiments have revealed the existence of soft domains that called nanobubbles at the solid-liquid interface. In this study, to investigate the influence of the solid-liquid interface nanobubbles on the bubble nucleation, an atomic force microscope (AFM) is used to characterize the morphology of nanobubbles. In order to separate the effect of wettability of a solid surface from that of surface structure, a very flat hydrophobic surface was prepared. 1H,1H,2H,2H-Perfluoro-n-octylphosphonic acid (FOPA) formed the interface of hydrophobic self-assembled monolayers (SAMs). As the result of AFM measurement, many nanobubbles about 100 nm in diameter and 30 nm thick are observed at the interface of the FOPA surface and the pure water. In addition, to prove the existence of gaseous phase, the heat conductance measurement by time-domain thermoreflectance method (TDTR) was introduced. TDTR is an ultrafast optical pump probe technique well suited for thermal measurement of thin films. It enables to resolve the thermal conductivity of the thin film and the thermal conductance of the interface. If nanobubbles are the gaseous phase, the big change of interface heat thermal resistance will be seen and the TDTR signal should also change. The effectiveness of a TDTR to confirm the existence of nanobubbles is shown by the model simulation of TDTR. A clear difference is seen in TDTR signal by the existence of only 1 nm gaseous phase. After confirming the existence of nanobubbles by AFM measurement, it can be proved that the nanobubbles are truly gaseous phase of the TDTR measurement.

Phase Change Heat Transfer During Melting and Resolidification of Melt Around Cylindrical Heat Source(s)/Sink(s)

1989 ◽  
Vol 111 (1) ◽  
pp. 43-49 ◽  
Author(s):  
K. Sasaguchi ◽  
R. Viskanta
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Liquid Interface ◽  
Cylinder Surface ◽  
Storage Unit ◽  
Energy Storage Unit ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Change Material

Melting and resolidification of a phase change material around two cylindrical heat exchangers spaced vertically have been investigated experimentally. Experiments have been performed to examine the effects of the cylinder surface temperatures on heat transfer during the melting and freezing cycle. The processes have been clarified on the basis of observations of timewise variations in the solid/liquid interface and of temperature distribution measurements in the phase change material. The results show that the solid/liquid interface contour during the melting and resolidification of the liquid from the upper cylinder is greatly affected by the surface temperature of the lower cylinder. The results show that multiple liquid regions may develop in the phase change material around the embedded heat sources/sinks, and the temperature swings and melting and freezing periods need to be selected properly in order to effectively utilize the phase change material in a latent heat energy storage unit.

The Solution of a Heat Transfer Problem With Change of State Inside a Spherical Shell

2012 ◽  
Author(s):  
Danillo Silva de Oliveira ◽  
Fernando Brenha Ribeiro
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Spherical Shell ◽  
Outer Surface ◽  
Transfer Problem ◽  
Freezing Temperature ◽  
Liquid Interface ◽  
Inner Surface ◽  
Solid Liquid Interface ◽  
Solid Liquid

The heat transfer problem is solved for the case of cooling, below the freezing temperature, an initially liquid material inside a spherical shell. The shell is limited by a fixed inner surface and by an outer surface, free to radially expand or contract. As boundary conditions it is imposed that the inner surface is kept constant below the freezing temperature of the liquid and the outer surface is maintained constant above it. The solution represents the formation of a solidified layer that expands outward, separated from the liquid by a spherical surface kept constant at the freezing temperature. The problem is solved in the form of two closed form solutions, written in non-dimensional variables: one for the heat conduction equation in the solid layer and the second for the heat conduction – advection equation in the liquid layer. The solutions formally depend of and are linked by the time dependent radius of the spherical solid–liquid interface and its time derivate, which are, at first, unknown. A differential equation describing the solid–liquid interface radius as function of time is obtained imposing the conservation of energy through the interface during the heat exchange process. This equation is non-linear and has to be numerically solved. Substitution of the interface radius and its time derivate for a particular instant in the heat transfer equations solutions furnishes the temperature distribution inside the spherical shell at that moment. The solution is illustrated with numerical examples.

Effect of Plume Dynamics for Heat Transfer Enhancement at Solid-Liquid Interface

2013 ◽  
Author(s):  
Sudhakar Subudhi ◽  
Jaywant H. Arakeri
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Transport ◽  
Smooth Surface ◽  
Liquid Interface ◽  
Bottom Surface ◽  
Heated Plate ◽  
Transfer Enhancement ◽  
Solid Liquid Interface ◽  
Solid Liquid

The present paper analyzes the effects of plumes for heat transfer enhancement at solid-liquid interface taking both smooth and grooved surfaces. The experimental setup consists of a tank of dimensions 265 × 265 × 300 (height) containing water. The bottom surface was heated and free surface of the water was left open to the ambient. In the experiments, the bottom plate had either a smooth surface or a grooved surface. We used 90° V-grooved rough surfaces with two groove heights, 10mm and 3mm. The experiment was done with water layer depths of 90mm and 140mm, corresponding to values of aspect ratio (AR) equal to 2.9 and 1.8 respectively. Thymol blue, a pH sensitive dye, was used to visualize the flow near the heated plate. The measured heat transfer coefficients over the grooved surfaces were higher compared that over the smooth surface. The enhanced heat transport in the rough cavities cannot be ascribed to the increase in the contact area, rather it must be the local dynamics of the thermal boundary layer that changes the heat transport over the rough surface.

Sign in / Sign up

Export Citation Format

Share Document