Quantitative Evaluation of the Skin Heat Transfer Characteristics Subjected to a Transient High-speed Helium Gas Impingement

2006 ◽  
Vol 6 (2) ◽  
pp. 231-237 ◽  
Author(s):  
Yi Liu
Keyword(s):  
Heat Transfer ◽  
Quantitative Evaluation ◽  
High Speed ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Helium Gas

Experimental Comparison on the Multi-Hole Steam Spraying Condensation Heat Transfer Characteristics

2018 ◽  
Author(s):  
Yuhao Zhang ◽  
Daogang Lu ◽  
Bin Ouyang ◽  
Yonglong Yuan
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Experimental Results ◽  
Experimental Comparison ◽  
Pressurized Water Reactor ◽  
Heat Transfer Characteristics ◽  
Pressurized Water ◽  
Transfer Characteristics ◽  
Passive Safety System ◽  
Contact Condensation

In the third generation pressurized water reactor AP1000 plant, the Automatic Depressurization System (ADS) is one of the most important passive safety system. As the steam continues to discharge into the IRWST, the high-temperature and high-pressure steam condenses in the IRWST intensely and rapidly. In the present work, multi-hole spargers DCC experimental bench has been built to study the condensation and mixing phenomena in the accidental depressurization events in AP1000. The key parameters including the temperature, velocity, and flow patterns are monitored by the thermocouples, PIV technique, and high speed camera, etc. Based on the experimental results, the heat transfer characteristics of the steam-jet Direct Contact Condensation (DCC) in the ADS depressurization process were analyzed. The experimental comparison shows that the spraying steam behaviors are closely related to the steam mass flux, which determined the ejection patterns. The spraying steam is condensed rapidly in the core region with the flow regime locating in chugging, transitional chugging, and stable ejection stages. The 88-hole experimental results fit well with Fukuda’s condensation oscillation correlations, whereas the 2-hole experimental results are slightly lower than the values predicted by traditional single hole correlation.

Flow and Heat Transfer Characteristics of Liquid Nitrogen in Mini/Micro-Channels

2011 ◽  
Author(s):  
P. Zhang
Keyword(s):  
Heat Transfer ◽  
Flow Visualization ◽  
Liquid Nitrogen ◽  
High Speed ◽  
Flow Boiling ◽  
Flow State ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Micro Channels

Flow and heat transfer characteristics of liquid nitrogen in mini/micro-channels own many particular aspects and are very important for applications. In the present study, the investigation of flow and heat transfer characteristics of liquid nitrogen in mini/micro-channels is presented. It is found that small viscosity enables the flow state in mini/micro-channels to be turbulent state, which proves that the classical theory for pressure drop is still valid if the surface roughness of the passage is properly taken into consideration. Experiments of flow boiling of liquid nitrogen are conducted under both adiabatic and diabatic conditions. It is shown that confinement number Co = 0.5 can be applicable in classifying the heat transfer characteristics of liquid nitrogen in macro- and micro-channels. Flow visualization in micro-channels at low temperatures poses big challenges in image magnification and illumination. These two problems have been subtly overcome in the investigation and clear images have been obtained. The flow patterns and flow regimes of two-phase flow of liquid nitrogen indicate different features from the room-temperature fluidss. Furthermore, a very simple but effective method for 3D flow visualization by one high-speed camera is proposed and implemented. Finally, numerical analysis of the flow boiling of liquid nitrogen in mini/micro-channel is carried out to deepen the understanding of mechanism.

Heat transfer characteristics of high temperature surface cooling by high speed water jet

2018 ◽  
Vol 2018.23 (0) ◽  
pp. B133
Author(s):  
Takayuki MOROKUMA ◽  
Yoshio UTAKA ◽  
Hidetoshi OHKUBO ◽  
Syunichi TAKAMIZU ◽  
Hideki SAITO ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
High Speed ◽  
Water Jet ◽  
Heat Transfer Characteristics ◽  
Surface Cooling ◽  
Transfer Characteristics ◽  
Temperature Surface

Heat Transfer Characteristics of a Train of Droplets Impinging Over a Hot Surface: From Film Evaporation to Leidenfrost Point

2021 ◽  
Author(s):  
Ganesh Guggilla ◽  
Ramesh Narayanaswamy ◽  
Peter Stephan ◽  
Arvind Pattamatta
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Heated Surface ◽  
Contact Angle Hysteresis ◽  
Electronics Cooling ◽  
Spray Cooling ◽  
Heat Fluxes ◽  
High Speed Photography ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Abstract High-performance computing systems are needed in advanced computing services such as machine learning and artificial intelligence. Consequently, the increase in electron chip density results in high heat fluxes and requires good thermal management to maintain the servers. Spray cooling using liquid offers higher heat transfer rates and is efficient when implemented in electronics cooling. Detailed studies of fundamental mechanisms involved in spray cooling, such as single droplet and multiple droplet interactions, are required to enhance the process's knowledge. The present work focuses on studying a train of two FC-72 droplets impinging over a heated surface. Experimental investigation using high-speed photography and infrared thermography is conducted. Simultaneously, numerical simulations using opensource CFD package, OpenFOAM are carried out, emphasizing the significance of contact angle hysteresis. The surface temperature is chosen as a parameter, and different boiling regimes along with Dynamic Leidenfrost point (DLP) for the present impact conditions are identified. Spreading hydrodynamics and heat transfer characteristics of these consecutively impinging droplets till the Leidenfrost temperature, are studied and compared.

Sign in / Sign up

Export Citation Format

Share Document