scholarly journals Design of a convective cooling system for a Mach 6 hypersonic transport airframe

1972 ◽  
Author(s):  
F. ANTHONY ◽  
R. HELENBROOK
Keyword(s):  
Cooling System ◽  
Convective Cooling

scholarly journals Human response to the thermal indoor environment created by a radiant, and a combined radiant and convective cooling system

2019 ◽  
Vol 111 ◽  
pp. 02060
Author(s):  
Ongun B. Kazanci ◽  
Dolaana Khovalyg ◽  
Takayoshi Iida ◽  
Yoshitaka Uno ◽  
Tomo-oki Ukiana ◽  
...  
Keyword(s):  
Human Subject ◽  
Indoor Environment ◽  
Cooling System ◽  
Human Subjects ◽  
Whole Body ◽  
Indoor Environments ◽  
Climate Chamber ◽  
Convective Cooling ◽  
Physical Measurements ◽  
Two Systems

This study reports the main findings from a series of human subject experiments, where the subjects were exposed to the different indoor environments created by different cooling systems. The studied systems were a radiant cooling system (chilled ceiling and mixing ventilation, CCMV), and a combined radiant and convective cooling system (radiant diffuse ceiling ventilation, RDCV). The experiments were conducted in a climate chamber under controlled conditions. The climate chamber was configured as a two-person office room. 24 human subjects (12 female and 12 male) were chosen. The exposure lasted three hours and the participants were allowed to work on their own tasks (normal office work) during the exposure. The cooling load was 54 W/m2 and the room temperature at a reference location was kept constant at 26°C (summer conditions). The results show that under both systems, whole body thermal sensation was between slightly warm and neutral (closer to neutral with the RDCV system), and the overall thermal acceptability was almost the same for both systems (close to clearly acceptable). The satisfaction of the human subjects with the thermal environment was very close under the two systems; between satisfactory and slightly satisfactory (closer to satisfactory). Air movement acceptability (slightly higher and closer to clearly acceptable with the RDCV system) was also very close with the two systems. The results of the human subject experiments agree well with the physical measurements of the thermal indoor environment and confirm that the studied systems created very similar thermal indoor environments.

Numerical Analysis on Evaporation Assisted Convective Cooling: Effect of Surface Morphology

2019 ◽  
Author(s):  
Sudipta Saha ◽  
Amitav Tikadar ◽  
Jamil Khan ◽  
Tanvir Farouk
Keyword(s):  
Heat Flux ◽  
Thermal Resistance ◽  
Liquid Film ◽  
Phase Change ◽  
Surface Structure ◽  
Change Process ◽  
Cooling System ◽  
Structure Modification ◽  
Convective Cooling ◽  
Cooling Method

Abstract With an escalating need to find ways to reduce the water consumption in industrial cooling system, on-demand hybrid cooling has been a topic of great interest. The main concept of this cooling method is centered upon the utilization of huge exchange of enthalpy associated with phase change process in a conventional convective cooling system. In this study, a multidimensional multi-physics model has been employed to study a system that undergoes this dual mode cooling process where both convection and evaporation contribute to the heat transfer process. The computational domain considered is comprised of a thin liquid film that undergoes evaporation with constant heat flux provided from the bottom and a convective loading of laminar air flow above it. Evaporation takes place at the liquid-gas interface and the evaporated mass is being carried away by the incoming air, hence augmenting the convective cooling through the phase change process. This is an extension of our prior work where the surface structure modification (i.e. undulated surface) on the performance of this proposed hybrid cooling method is numerically investigated. Array of hemispherical structures have been introduced as the surface introducing the heat flux to the liquid film. The objective is to increase the surface to volume ratio and decrease the thermal resistance across the liquid film. The predictions indicate that with the increase in the height of the undulated surface the thermal resistance across the liquid film tends to decrease. Results from these simulations show that a ∼50% reduction in the thermal resistance can be achieved by the surface structure modification while the net evaporation flux can be doubled compared to a flat film configuration.

Effect of Turning Vane Configurations on Heat Transfer and Pressure Drop in a Ribbed Internal Cooling System

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Wei Chen ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Turbulence Model ◽  
Cooling System ◽  
Turbulence Models ◽  
Loss Coefficient ◽  
Test Cases ◽  
Convective Cooling ◽  
Blade Cooling ◽  
Turn Region

The ribbed serpentine blade cooling system is a typical configuration in the modern gas turbine airfoil. In this study, experimental and the numerical efforts were carried out to investigate the local heat transfer and pressure drop distribution of a ribbed blade cooling system with different configurations in the turn region. A test rig containing a ribbed rectangular U-duct with a 180 deg round turn was built in Tsinghua University for this study. The transient liquid crystal method was applied to get the heat transfer distribution. Nine test cases with three turn configurations under three Reynolds numbers were carried out in the experiment. Pressure was measured along the duct in order to determine the influence of turning vane configurations on pressure drop. The test cases were also analyzed numerically based on Reynolds-averaged Navier-Stokes (RANS) with three different turbulence models: the k-ε model, the SST reattachment model, and the Omega Reynolds stress (ORS) turbulence model. Both the experimental and numerical results showed a significant influence of the turning vane configuration on the heat transfer and pressure drop in the convective cooling channel. Among the three configurations, the loss coefficient of turn in configuration 2 was lowest due to the introduction of turning vane. Even the ribs were added in the turn region of configuration 3, the loss coefficient and friction factor are reduced by 23% and 17.5%, respectively. Meanwhile, the heat transfer in baseline configuration is still the highest. As the introduction of turning vane, the heat transfer in the region after turn was reduced by 35%. In configuration 3, the heat transfer in the turn region was enhanced by 15% as the ribs installed in the turn region. In the before turn region, the pressure drop and heat transfer was not influenced by the turn configuration. All the turbulence models captured the trend of heat transfer and pressure drop distribution of three test sections correctly, but all provide overpredicted heat transfer results. Among the models, the ORS turbulence model provided the best prediction. While aiming at high heat transfer level and low pressure drop, it is suggested that a suitable turn configuration, especially with the turning vane and/or the ribs, is a promising way to meet the conflicted requirements of the heat transfer and pressure drop in the convective cooling system.

scholarly journals Comportamiento Térmico de fachada ventilada opaca en clima cálido seco extremo

2019 ◽  
pp. 20-28
Author(s):  
Cristina Sotelo-Salas ◽  
Carlos Esparza-López ◽  
Carlos Escobar-Del Pozo
Keyword(s):  
Surface Temperature ◽  
Climate Adaptation ◽  
Cooling System ◽  
Ansys Fluent ◽  
Convective Cooling ◽  
Living Space ◽  
Solar Control ◽  
Control Devices ◽  
Temperature And Pressure ◽  
Ventilated Facade

Energy consumption attributed to buildings amounts to approximately 30% globally. This consumption is even greater in buildings that lack climate adaptation strategies. In warm climates, solar control devices protect from thermal gains by direct solar radiation as a strategy to avoid overheating in buildings. Ventilated facades increase the energy efficiency of said devices when harnessing the convective cooling produced by the temperature and pressure differential inside the ventilated facade. The present research shows the thermal behaviour of an opaque ventilated facade through numerical modelling in ANSYS Fluent® computational fluid dynamics software in an extreme hot dry climate. The objective of the study was to analyze the effect of a ventilated facade on the thermal performance of the wall immediately adjacent to the living space as a passive convective cooling system. The variables analyzed were thickness of the air cavity, ambient temperature and wind speed of the external environment, as well as its effect on the surface temperature of the wall adjacent to the living space. The results show a decrease in the surface temperature of the wall, which reduces the total cooling load of the building.

Effect of Turning Vane Configurations on Heat Transfer and Pressure Drop in a Ribbed Internal Cooling System

2010 ◽  
Author(s):  
Wei Chen ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Turbulence Model ◽  
Cooling System ◽  
Turbulence Models ◽  
Loss Coefficient ◽  
Test Cases ◽  
Convective Cooling ◽  
Blade Cooling ◽  
Turn Region

The ribbed serpentine blade cooling system is a typical configuration in the modern gas turbine airfoil. In this study, the experimental and the numerical efforts were carried out to investigate the local heat transfer and pressure drop distribution of a ribbed blade cooling system with different configurations in the turn region. A test rig containing a ribbed rectangular U-duct with a 180° round turn was built in Tsinghua University for this study. Transient liquid crystal method was applied to get the heat transfer distribution. Nine test cases with three turn configurations under three Reynolds numbers were carried out in the experiment. Pressure was measured along the duct in order to determine the influence of turning vane configurations on pressure drop. The test cases were also analyzed numerically based on RANS with three different turbulence models: the k-ε model, the SST reattachment model, and the Omega Reynolds Stress turbulence model. Both the experimental and the numerical results showed a significant influence of the turning vane configuration on the heat transfer and pressure drop in the convective cooling channel. Among the three configurations, the loss coefficient of turn in configuration 2 was lowest, due to the introduction of turning vane. Even the ribs were added in turn region of configuration 3, the loss coefficient and friction factor are reduced by 23% and 17.5%, respectively. Meanwhile, the heat transfer in baseline configuration is still the highest. As the introduction of turning vane, the heat transfer in the region after turn was reduced by 35%. In configuration 3, the heat transfer in the turn region was enhanced by 15% as the ribs installed in the turn region. In the before turn region, the pressure drop and heat transfer was not influenced by the turn configuration. All the turbulence models captured the trend of heat transfer and pressure drop distribution of three test sections correctly, but all provide overpredicted heat transfer results. Among the models, the ORS turbulence model provided the best prediction. While aiming at high heat transfer level and low pressure drop, it is suggested that, a suitable turn configuration, especially with the turning vane and/or the ribs, is a promising way to meet the conflicted requirements of the heat transfer and pressure drop in the convective cooling system.

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