Field and numerical studies on the thermal performance of air convection embankments to protect side slopes in permafrost environments

Author(s):  
Xiangbing Kong ◽  
Guy Doré ◽  
Fabrice Calmels ◽  
Chantal Lemieux
2021 ◽  
pp. 103334
Author(s):  
Qiang Du ◽  
Liangwei Jin ◽  
Jing Lv ◽  
Changlu Cai ◽  
Runnan Zhang

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4658
Author(s):  
Jiefeng Liu ◽  
Shangxin Yu ◽  
Shichang Yang ◽  
Yiyi Zhang ◽  
Xianhao Fan ◽  
...  

Operating temperature is an important parameter of thyristors to ensure the stable operation of power electronic devices. Thermal management technology is of great significance for improving the reliability of thyristors. In this study, the performance of a phase change material (PCM) mesh-finned heat sink is investigated for the thermal management of thyristors. A multi-physical coupling model of the PCM mesh-finned heat sink is established to analyze the effects of different power losses, air velocities, heights of fins, and thickness of PCM on the thermal performance of the PCM heat sink. The influence of thermal and flow fields on PCM is considered in this model. Furthermore, the heat sink design is optimized to improve the thermal performance based on the calculation results of thermal network parameters. The results show that the power losses, the air velocity, the height of fins, and the thickness of PCM significantly affect the protection ability of the PCM heat sink. After optimizing the heat sink, the PCM heat sink provides 80 s protection time and 100 s recovery time. The PCM mesh-finned heat sink demonstrated good potential for the thermal management of thyristors.


2015 ◽  
Vol 26 (9) ◽  
pp. 1243-1256 ◽  
Author(s):  
Chi-ming Lai ◽  
Shuichi Hokoi

In this study, we integrated a photovoltaic (PV) system, a double-skin structure and a thermal flow mechanism to design ventilated building-integrated photovoltaic (BIPV) curtain walls that can autogenously control an environment using buoyant force. Full-scale experiments and computational fluid dynamics (CFD) simulations were conducted to investigate the flow pattern characteristics for the channel airflow and the thermal performance of the ventilated BIPV curtain walls under various heating conditions, wall thicknesses and types of openings. Channel flows for different channel widths under the same wall heating exhibited different flow patterns and therefore variations in thermal performance. The developed ventilated BIPV curtain walls effectively removed their solar heat gain while maintaining adequate wall thermal performance.


2017 ◽  
Vol 41 (5) ◽  
pp. 445-468 ◽  
Author(s):  
Ana Cristina Briga Sá ◽  
Analisa Martins ◽  
José Boaventura-Cunha ◽  
João Carlos Lanzinha ◽  
Anabela Paiva

The influence of the massive wall material, thickness and ventilation system on the Trombe wall thermal performance was analysed based on an analytical methodology. Results obtained from experimental work will also be added to this study. During the heating season, for the non-ventilated Trombe wall, the global heat gains decrease is not proportional to the thickness increase, and this ratio depends on the massive wall material heat storage capacity. A ventilation system in the massive wall leads to higher heat gains due to the air convection, but this growth is not in the same proportion for the different materials. If solid brick or earth is used, heat gain values are much higher than those obtained if there is no ventilation system, increasing to the double in the case of earth and 2.5 times more in the case of solid brick. When the massive wall is ventilated and made of granite, an increase in the gains of 44.06% is obtained when compared with the non-ventilated. During the cooling season, closing the ventilation system and the external shutter leads to heat gains considerably lower than those obtained during the heating season. In this case, earth can be a suitable material.


Sign in / Sign up

Export Citation Format

Share Document