An Engineering Method for Asphalt Foaming Modeling Integrating Gas-Liquid Phase Change Process

2012 ◽  
Vol 482-484 ◽  
pp. 1368-1372
Author(s):  
An Lin Wang ◽  
Fei Ling ◽  
Ruo Fan Qiu
Keyword(s):  
Heat Exchange ◽  
Liquid Phase ◽  
Phase Change ◽  
Change Process ◽  
Engineering Method ◽  
Design Parameters ◽  
Physical Parameters ◽  
Contact Heat ◽  
Phase Change Process ◽  
Contact Heat Exchange

The asphalt foaming is a nonlinear kinetics process under high temperature and high pressure with multi-phase medium and multi-field condition. It includes stages like transient contact, heat exchange, phase change and bubble generating process. In order to quantitatively describe the relationship between the asphalt foamability and the asphalt foaming equipment physical parameters, the engineering method for asphalt foaming modeling integrating gas-liquid phase change process is created. Meanwhile, the asphalt foaming dynamic model for design parameters and coupled field distribution, which can express multiphase contact, heat exchange and further phase change, is built. Compared to the old non-phase change model, the new model has a stronger correlation to the asphalt foaming experimental results. Therefore, the study is significant for the redesign of the asphalt foaming equipment.

Energy Storage With Solid/Liquid Phase Change in Presence of Natural Convection

2001 ◽  
Author(s):  
M. Pinelli ◽  
S. Piva
Keyword(s):  
Natural Convection ◽  
Energy Storage ◽  
Liquid Phase ◽  
Phase Change ◽  
Change Process ◽  
Solid Phase ◽  
High Energy ◽  
Heat Transfer Process ◽  
Phase Change Process ◽  
Solid Liquid

Abstract Solid/liquid phase change process has received great attention for its capability to obtain high energy storage efficiency. In order to analyse these systems, undergoing a solid/liquid phase change, in many situations the heat transfer process can be considered conduction-dominated. However, in the past years, it has been shown that natural convection in the liquid phase can significantly influence the phase change process in terms of temperature distributions, interface displacement and energy storage. In this paper, a procedure to analyse systems undergoing liquid/solid phase change in presence of natural convection in the liquid phase based on the utilisation of a commercial computer code (FLUENT), has been developed. This procedure is applied to a cylinder cavity heated from above and filled with a Phase Change Material. It was found that when the coupling with the environment, even if small, is considered, natural convection in the liquid phase occurs. The numerical results are then compared with available experimental data. The analysis shows that the agreement between numerical and experimental results is significantly improved when the results are obtained considering the presence of circulation in the liquid phase instead of considering the process only conduction-dominated. Furthermore, some interesting features of the flow field are presented and discussed.

Solid/Liquid Phase Change in Presence of Natural Convection: A Thermal Energy Storage Case Study

2003 ◽  
Vol 125 (3) ◽  
pp. 190-198 ◽  
Author(s):  
M. Pinelli ◽  
S. Piva
Keyword(s):  
Natural Convection ◽  
Energy Storage ◽  
Liquid Phase ◽  
Phase Change ◽  
Change Process ◽  
Solid Phase ◽  
High Energy ◽  
Heat Transfer Process ◽  
Phase Change Process ◽  
Solid Liquid

Solid/liquid phase change process has received great attention for its capability to obtain high energy storage efficiency. In order to analyze these systems, undergoing a solid/liquid phase change, in many situations the heat transfer process can be considered conduction-dominated. However, in the past years, it has been shown that natural convection in the liquid phase can significantly influence the phase change process in terms of temperature distributions, interface displacement and energy storage. In this paper, a procedure to analyze systems undergoing liquid/solid phase change in presence of natural convection in the liquid phase based on the utilisation of a commercial computer code (FLUENT), has been developed. This procedure is applied to the study of a cylinder cavity heated from above and filled with a phase change material. It was found that when the coupling with the environment, even if small, is considered, natural convection in the liquid phase occurs. The numerical results are then compared with available experimental data. The analysis shows that the agreement between numerical and experimental results is significantly improved when the results are obtained considering the presence of circulation in the liquid phase instead of considering the process only conduction-dominated. Furthermore, some interesting features of the flow field are presented and discussed.

Passive Thermal Management Using Phase Change Materials: Experimental Evaluation of Thermal Resistances

2015 ◽  
Author(s):  
Yash Ganatra ◽  
Amy Marconnet
Keyword(s):  
Thermal Conductivity ◽  
Liquid Phase ◽  
Phase Change ◽  
Change Process ◽  
Phase Change Materials ◽  
Heat Dissipation ◽  
Thermal Control ◽  
Fixed Temperature ◽  
Chip Area ◽  
Phase Change Process

Limited heat dissipation and increasing power consumption in processors has led to a utilization wall. Specifically due to high transistor density, not all processors can be used continuously without exceeding safe operating temperatures. This is more significant in mobile electronic devices which, despite relatively large chip area, are limited by poor heat dissipation — primarily natural convection from the exposed surfaces. In the past, solid-to-liquid phase change materials (PCMs) have been employed for passive thermal control — absorbing energy during the phase change process while maintaining a relatively fixed temperature. However, the lower thermal conductivity of the liquid phase after melting often limits the heat dissipation from the PCM, and in the liquid state, the material can flow away from the desired location. Here we focus on characterization of thermal performance of PCMs with the goal of evaluating dry (gel-to-solid/amorphous-to-crystalline) phase change materials which are intended to mitigate the pumpout issue. Critical thermophysical properties include the thermal conductivity, heat capacity, and latent heat of the phase/state change. The thermal resistance throughout the phase change process is measured by in-house rig which miniaturizes the reference bar method for use with infrared temperature sensing.

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