Manufacturing of Porous Coatings With Micro-Scale Features for Improved Boiling Heat Transfer

2006 ◽  
Author(s):  
Peng Chen ◽  
Muammer Koc¸ ◽  
Jun Ni
Keyword(s):  
Heat Transfer ◽  
Manufacturing Process ◽  
Boiling Heat Transfer ◽  
Micro Scale ◽  
Heat Transfer Efficiency ◽  
Porous Surfaces ◽  
Compaction Force ◽  
Micro Features ◽  
Interconnected Pore ◽  
Interconnected Pore Structure

Several recent heat transfer studies indicated that porous surfaces with modulated porous surface features lead to an improved boiling heat transfer efficiency. Thus, the aim of this study is to develop a novel manufacturing process that will produce the modulated porous surfaces cost-effectively. In this study, compaction and sintering experiment were conducted to investigate the consolidation performance of the powder into micro-scale features. The effects of compaction force and sintering on the pore size and mechanical strength of the formed micro-features were investigated. It was found that sintering at 800°C for 20 minutes can significantly increases the strength of the compacted part, while the interconnected pore structure was maintained.

Effect of Additive Manufacturing Process Parameters on Turbine Cooling

2019 ◽  
Author(s):  
Jacob C. Snyder ◽  
Karen A. Thole
Keyword(s):  
Heat Transfer ◽  
Additive Manufacturing ◽  
Surface Morphology ◽  
Process Parameters ◽  
Manufacturing Process ◽  
Pressure Loss ◽  
Cooling Performance ◽  
Micro Scale ◽  
Turbine Cooling ◽  
External Cooling

Abstract Turbine cooling is a prime application for additive manufacturing because it enables quick development and implementation of innovative designs optimized for efficient heat removal, especially at the micro-scale. At the micro-scale, however, the surface finish plays a significant role in the heat transfer and pressure loss of any cooling design. Previous research on additively manufactured cooling channels has shown the surface roughness increases both heat transfer and pressure loss to similar levels as highly-engineered turbine cooling schemes. What has not been shown, however, is whether opportunities exist to tailor additively manufactured surfaces through control of the process parameters to further enhance the desired heat transfer and pressure loss characteristics. The results presented in this paper uniquely show the potential of manipulating the parameters within the additive manufacturing process to control the surface morphology, directly influencing turbine cooling. To determine the effect of parameters on cooling performance, coupons were additively manufactured for common internal and external cooling methods using different laser powers, scan speeds, and scanning strategies. Internal and external cooling tests were performed at engine relevant conditions to measure appropriate metrics of performance. Results showed the process parameters have a significant impact on the surface morphology leading to differences in cooling performance. Specifically, internal and external cooling geometries react differently to changes in parameters, highlighting the opportunity to consider process parameters when implementing additive manufacturing for turbine cooling applications.

Forming of Porous Micro-Features Using Hot Compaction

2007 ◽  
Author(s):  
Peng Chen ◽  
Gap-Yong Kim ◽  
Jun Ni
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Mass Production ◽  
Heat Transfer Characteristics ◽  
High Productivity ◽  
Powder Consolidation ◽  
Micro Scale ◽  
Hot Compaction ◽  
Micro Features ◽  
High Temperature Operation

Porous metallic micro-scale features are becoming important in the modern industry. However, a mass production of such features is a challenge when robustness, cost-effectiveness, and high productivity requirements are considered. In this study, the fabrication of such porous micro-features using hot compaction was investigated. A hot compaction experiment setup was designed and fabricated, which was capable of high temperature operation (up to 700 °C), quick heat-up, and avoiding oxidation of workpiece and tools. A 3D thermal simulation of the experiment setup was conducted to understand the heat transfer characteristics of the system, which was used as a reference for the experiment. The effects of compression loading force and temperature on the compact quality in terms of powder consolidation strength and porosity were studied.

Research on Manufacturing Technology and Heat Transfer Characteristics of Sintered Porous Surface Tubes

2010 ◽  
Vol 97-101 ◽  
pp. 1161-1165 ◽  
Author(s):  
Xue Sheng Wang ◽  
Zheng Bian Wang ◽  
Qin Zhu Chen
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Base Material ◽  
Porous Surface ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Bronze Powder ◽  
New Process ◽  
Porous Surfaces ◽  
Heat Transfers

A new process for manufacturing sintered porous surface tube has been developed. By using this technology, three kinds of sintered porous surface tubes were fabricated, which base material was carbon steel and the sintered layer was bronze powder. And their boiling heat transfer characteristics were investigated experimentally. The experimental results indicated that the boiling heat transfers coefficient and the heat flux of these porous surfaces tubes were increased by 8~14 times and 5~8 times respectively compared with the smooth one. Finally, a new high flux heat exchanger was designed and applied instead of conventional one in a refinery.

scholarly journals Determining the Factors Affecting the Boiling Heat Transfer Coefficient of Sintered Coated Porous Surfaces

2021 ◽  
Vol 13 (22) ◽  
pp. 12631
Author(s):  
Uzair Sajjad ◽  
Imtiyaz Hussain ◽  
Muhammad Sultan ◽  
Sadaf Mehdi ◽  
Chi-Chuan Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermophysical Properties ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Morphological Features ◽  
Porous Surfaces ◽  
Boiling Heat Transfer Coefficient ◽  
Influential Parameters

The boiling heat transfer performance of porous surfaces greatly depends on the morphological parameters, liquid thermophysical properties, and pool boiling conditions. Hence, to develop a predictive model valid for diverse working fluids, it is necessary to incorporate the effects of the most influential parameters into the architecture of the model. In this regard, two Bayesian optimization algorithms including Gaussian process regression (GPR) and gradient boosting regression trees (GBRT) are used for tuning the hyper-parameters (number of input and dense nodes, number of dense layers, activation function, batch size, Adam decay, and learning rate) of the deep neural network. The optimized model is then employed to perform sensitivity analysis for finding the most influential parameters in the boiling heat transfer assessment of sintered coated porous surfaces on copper substrate subjected to a variety of high- and low-wetting working fluids, including water, dielectric fluids, and refrigerants, under saturated pool boiling conditions and different surface inclination angles of the heater surface. The model with all the surface morphological features, liquid thermophysical properties, and pool boiling testing parameters demonstrates the highest correlation coefficient, R2 = 0.985, for HTC prediction. The superheated wall is noted to have the maximum effect on the predictive accuracy of the boiling heat transfer coefficient. For example, if the wall superheat is dropped from the modeling parameters, the lowest prediction of R2 (0.893) is achieved. The surface morphological features show relatively less influence compared to the liquid thermophysical properties. The proposed methodology is effective in determining the highly influencing surface and liquid parameters for the boiling heat transfer assessment of porous surfaces.

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