Heat transfer deterioration in upward and downward pipe flows of supercritical n-decane for actively regenerative cooling

2021 ◽  
Vol 168 ◽  
pp. 107066
Author(s):  
Yong Li ◽  
Christos N. Markides ◽  
Bengt Sunden ◽  
Gongnan Xie
Keyword(s):  
Heat Transfer ◽  
Regenerative Cooling ◽  
Heat Transfer Deterioration ◽  
Pipe Flows

Pressure drop reduction and heat transfer deterioration of slush nitrogen in triangular and circular pipe flows

Cryogenics ◽  
2017 ◽  
Vol 81 ◽  
pp. 60-75 ◽  
Author(s):  
Katsuhide Ohira ◽  
Kizuku Kurose ◽  
Jun Okuyama ◽  
Yutaro Saito ◽  
Koichi Takahashi
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Circular Pipe ◽  
Heat Transfer Deterioration ◽  
Pipe Flows

Numerical Study of Convective Heat Transfer From Expanding Annular Pipe Flows

2016 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Prandtl Number ◽  
Convective Heat Transfer ◽  
Diameter Ratio ◽  
Wall Heat Transfer ◽  
Reattachment Point ◽  
Transfer Rates ◽  
Pipe Flows ◽  
Annular Pipe

Convective heat transfer from suddenly expanding annular pipe flows are numerically investigated within the steady laminar flow regime. A parametric study is performed to reveal the influence of the annular diameter ratio, k, the Prandtl number, Pr, and the Reynolds number, Re, over the following range of parameters: k = {0, 0.5, 0.7}, Pr = {0.7, 1, 7, 100}, and Re = {25, 50, 100}. Heat transfer enhancement downstream of the expansion plane is only observed for Pr > 1. Peak wall-heat-transfer-rates always appear downstream of the flow reattachment point, in the case of suddenly expanding round pipe flows, i.e. k = 0. However, for suddenly expanding annular pipe flows, i.e., k = 0.5 and 0.7, peak wall-heat-transfer-rates always appear upstream of the flow reattachment point. The observed heat transfer augmentation is more dramatic for suddenly expanding annular flows, in comparison with the one observed for suddenly expanding pipe flows. For a given annular diameter ratio and Reynolds number, increasing the Prandtl number, always results in higher wall-heat-transfer-rates downstream the expansion plane.

scholarly journals A Parametrical Study on Convective Heat Transfer between High-Temperature Gas and Regenerative Cooling Panel

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1784
Author(s):  
Jiangyu Hu ◽  
Ning Wang ◽  
Jin Zhou ◽  
Yu Pan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
High Temperature ◽  
Thermal Protection ◽  
Flow Direction ◽  
Heated Surface ◽  
Heat Transfer Process ◽  
Cocurrent Flow ◽  
Regenerative Cooling ◽  
High Temperature Gas

Thermal protection is still one of the key challenges for successful scramjet operations. In this study, the three-dimensional coupled heat transfer between high-temperature gas and regenerative cooling panel with kerosene of supercritical pressure flowing in the cooling channels was numerically investigated to reveal the fundamental characteristics of regenerative cooling as well as its influencing factors. The SST k-ω turbulence model with low-Reynolds-number correction provided by the pressure-based solver of Fluent 19.2 is adopted for simulation. It was found that the heat flux of the gas heated surface is in the order of 106 W/m2, and it declines along the flow direction of gas due to the development of boundary layer. Compared with cocurrent flow, the temperature peak of the gas heated surface in counter flow is much higher. The temperature and heat flux of the gas heated surface both rises with the static pressure and total temperature of gas. The heat flux of the gas heated surface increases with the mass flow rate of kerosene, and it hardly changes with the pressure of kerosene. Results herein could help to understand the real heat transfer process of regenerative cooling and guide the design of thermal protection systems.

Numerical Study of Deteriorated Convection Heat Transfer of Supercritical Fluid Flowing Through Vertical Mini Tube at Relatively Low Reynolds Numbers

2018 ◽  
Author(s):  
Chen-Ru Zhao ◽  
Zhen Zhang ◽  
Qian-Feng Liu ◽  
Han-Liang Bo ◽  
Pei-Xue Jiang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Convection Heat Transfer ◽  
Turbulence Models ◽  
Convection Heat ◽  
Flow Acceleration ◽  
Heat Transfer Deterioration ◽  
Low Reynolds

Numerical investigations are performed on the convection heat transfer of supercritical pressure fluid flowing through vertical mini tube with inner diameter of 0.27 mm and inlet Reynolds number of 1900 under various heat fluxes conditions using low Reynolds number k-ε turbulence models due to LB (Lam and Bremhorst), LS (Launder and Sharma) and V2F (v2-f). The predictions are compared with the corresponding experimentally measured values. The prediction ability of various low Reynolds number k-ε turbulence models under deteriorated heat transfer conditions induced by combinations of buoyancy and flow acceleration effects are evaluated. Results show that all the three models give fairly good predictions of local wall temperature variations in conditions with relatively high inlet Reynolds number. For cases with relatively low inlet Reynolds number, V2F model is able to capture the general trends of deteriorated heat transfer when the heat flux is relatively low. However, the LS and V2F models exaggerate the flow acceleration effect when the heat flux increases, while the LB model produces qualitative predictions, but further improvements are still needed for quantitative prediction. Based on the detailed flow and heat transfer information generated by simulation, a better understanding of the mechanism of heat transfer deterioration is obtained. Results show that the redistribution of flow field induced by the buoyancy and flow acceleration effects are main factors leading to the heat transfer deterioration.

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