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A comparative review on cold gas dynamic spraying processes and technologies

  • Authors: Oyinbo, Sunday Temitope , Jen, Tien-Chien
  • Date: 2020
  • Subjects: Cold gas dynamic spraying , Spraying parameters , Deformatiom mechanism
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/436831 , uj:37907 , Citation: Oyinbo, S.T. & Jen, T.C. 2020. A comparative review on cold gas dynamic spraying processes and technologies. , DOI: https://doi.org/10.1051/mfreview/2019023
  • Description: Abstract: Cold gas dynamic spraying (CGDS) is a relatively new technology of cold spraying techniques that uses converging-diverging (De Laval) nozzle at a supersonic velocity to accelerate different solid powders towards a substrate where it plastically deforms on the substrate. This deformation results in adhesion to the surface. Several materials with viable deposition capability have been processed through cold spraying, including metals, ceramics, composite materials, and polymers, thereby creating a wide range of opportunities towards harnessing various properties. CGDS is one of the innovative cold spraying processes with fast-growing scientific interests and industrial applications in the field of aerospace, automotive and biotechnology, over the past years. Cold gas spraying with a wide range of materials offers corrosion protection and results in increases in mechanical durability and wear resistance. It creates components with different thermal and electrical conductivities than that substrates would yield, or produces coatings on the substrate components as thermal insulators and high fatigue-strength coatings, and for clearance control, restoration and repairing, or prostheses with improved wear, and produces components with attractive appearances. This review extensively exploits the latest developments in the experimental analysis of CGDS processes. Cold gas dynamic spraying system, coating formation and deposit development, description of process parameter and principles, are summarized. Industrial applications and prospectives of CGDS in future research are also commented.
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A heat transfer correlation of flow boiling in micro-finned helically coiled tube

  • Authors: Cui, Wenzhi , Li, Longjian , Xin, Ming-dao , Jen, Tien-Chien , Chen, Qinghua , Liao, Quan
  • Date: 2006
  • Subjects: Convective boiling , Heat transfer , Helically coiled tubes , Nucleate boiling
  • Type: Article
  • Identifier: uj:5275 , http://hdl.handle.net/10210/14944
  • Description: Two main mechanisms, nucleate boiling and convective boiling, are widely accepted for in-tube flow boiling. Since the active nuclei on the heated wall are dominant for nucleate boiling and flow pattern governs the convective boiling, the heat transfer coefficient is strongly influenced by the wall heat flux, mass flux and vapor quality, respectively. In practical industrial applications, for example, the evaporators in refrigeration, forced convective evaporation is the dominant process and high heat transfer efficiency can be obtained under smaller temperature difference between wall and liquid. Therefore, it is of importance to develop a correlation of convective boiling heat transfer with a good accuracy. In this paper, a new kind of micro-finned helically coiled tube was developed and the flow boiling heat transfer characteristics were experimentally studied with R134a. Based on the analysis of the mechanisms of flow boiling, heat transfer correlations of the specific micro-finned helically coiled tubes are obtained.
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A molecular dynamics investigation of the temperature effect on the mechanical properties of selected thin films for hydrogen separation

A parametric study of solute redistribution during transient liquid phase bonding process

A passive control method of HAWT blade cyclical aerodynamic load induced by wind shear

  • Authors: Chen, Hong-Sheng , Jen, Tien-Chien
  • Date: 2017
  • Subjects: Wind energy , Wind shear , Passive control
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/231934 , uj:23641 , Citation: Chen, H. & Jen, T. 2017. A passive control method of HAWT blade cyclical aerodynamic load induced by wind shear.
  • Description: Abstract: Modern wind turbines are mainly horizontal axis and operate in bottom atmospheric boundary layer driven by wind shear flow, therefore as the blades rotating the aerodynamic load vary cyclically, with horizontal axis wind turbine (HAWT) large-scaling the cyclical characteristic becomes more obvious, shortening blade life and increasing cost of wind turbine. As the development of wind turbine largescaling is the essential trend, load fluctuation control is more and more critical in HAWT design and manufacture. In common, individual pitch control is introduced to solve the problem, but cost much energy from electric net. In this paper, a concept of telescopic blade root is introduced to reduce fluctuate load induced by wind shear passively, and considering the blades as rigid assessment is operated, meanwhile aerodynamic model based on blade element method in order to analysis the aerodynamic load on NREL Phase VI reference based blade. The result shows that after introducing the equipment the blade fatigue load can be released, lengthening blade life.
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A review of solar thermal systems utilization for industrial process heat applications

A variable heat flux model of heat transfer in grinding with boiling

An experiment study of flow pattern and pressure drop for flow boiling inside microfinned helically coiled tube

  • Authors: Cui, Wenzhi , Li, Longjian , Xin, Ming-dao , Jen, Tien-Chien , Liao, Quan , Chen, Qinghua
  • Date: 2008
  • Subjects: Flow boiling , Pressure drop , Helically coiled tubes , Microfin tubes , Flow patterns , Finned tubes
  • Type: Article
  • Identifier: uj:5278 , http://hdl.handle.net/10210/14947
  • Description: In this paper, flow patterns and their transitions for refrigerant R134a boiling in a microfinned helically coiled tube are experimentally observed and analyzed. All the flow patterns occurred in the test can be divided into three dominant regimes, i.e., stratified-wavy flow, intermittent flow and annular flow. Experimental data are plotted in two kinds of flow maps, i.e., Taitel and Dukler flow map and mass flux versus vapor quality flow map. The transitions between various flow regimes and the differences from that in smooth straight tube have also been discussed. Martinelli parameter can be used to indicate the transition from intermittent flow to annular flow. The transition from stratified-wavy flow to annular or intermittent flow is identified in the vapor quality versus mass flux flow map. The flow regime is always in stratified-wavy flow for a mass flux less than 100 kg/m2 s. The two-phase frictional pressure drop characteristics in the test tube are also experimentally studied. The two-phase frictional multiplier data can be well correlated by Lockhart–Martinelli parameter. Considering the corresponding flow regimes, i.e., stratified and annular flow, two frictional pressure drop correlations are proposed, and show a good agreement with the respective experimental data.
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An improved transient model of tool temperatures in metal cutting

  • Authors: Jen, Tien-Chien , Anagonye, Aloysius U.
  • Date: 2001-02
  • Subjects: Cutting temperatures , Cutting tools , Transient tool temperatures
  • Type: Article
  • Identifier: uj:5250 , ISSN 1087-1357 , http://hdl.handle.net/10210/14856
  • Description: A model for predicting cutting tool temperatures under transient conditions is presented. The model of Stephenson et al. [10] is extended to include the initial transient response to the tool temperature and nonuniform heat flux distributions. The main goal in this paper is to be able to accurately predict the initial transient tool temperature response, or temperatures in interrupted cutting for cases where the cutting time is short. A method to predict the true transient energy partitioning instead of quasi-steady energy partitioning (Stephenson et al., [10]), without seeking the full numerical analysis, has been developed. In this paper, the transient energy partitioning is obtained through a fixed-point iteration process by modifying the quasi-steady energy partitioning method presented by Loewen and Shaw [11]. The predicted transient tool temperatures are compared quantitatively to the experimental data. Utilizing a semi-empirical correlation for heat flux distribution along the tool-chip interface, the temperature distribution is calculated and compared qualitatively to existing experimental data.
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Atomic layer deposition process modeling and experimental investigation for sustainable manufacturing of nano thin films

  • Authors: Pan, Dongqing , Guan, Dongsheng , Jen, Tien-Chien , Yuan, Chris
  • Date: 2016
  • Subjects: Atomic layer deposition; ; , Density functional theory , Sustainability
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/213957 , uj:21218 , Citation: Pan, D. et al. 2016. Atomic layer deposition process modeling and experimental investigation for sustainable manufacturing of nano thin films.
  • Description: Abstract: This paper studies the adverse environmental impacts of atomic layer deposition (ALD) nano-manufacturing technology on ALD of Al2O3 nano-scale thin films. Numerical simulations with detailed ALD surface reaction mechanism developed based on Density Functional Theory (DFT), and atomic-level calculations are performed to investigate the effects of four process parameters including process temperature, pulse time, purge time, and carrier gas flow rate on ALD film deposition rate, process emissions and wastes. Full-cycle ALD simulations reveal that the depositions of nano-thin-films in ALD are in essence the chemisorption of the gaseous species and the conversion of surface species. Methane emissions are positively proportional to the film deposition process. The studies show that process temperature fundamentally affects the ALD chemical process by changing the energy states of the surface species. Pulse time is directly related to the precursor dosage. Purge time influences the ALD process by changing the gas-surface interaction time, and higher carrier gas flow rate alters the ALD flow field by accelerating the convective heat and mass transfer in ALD process.
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Atomistic Simulations of Interfacial deformation and bonding mechanism of Pd-Cu Composite Metal Membrane using Cold Gas Dynamic Spray Process

Bifurcation and hysteresis of flow pattern transition in a shallow molten silicon pool with Cz configuration

Case study and energy analysis of power system management of confectionery factory in Jordan

  • Authors: Ibrahim, Qusay , Akbarzadeh, Rokhsareh , Jen, Tien-Chien
  • Date: 2019
  • Subjects: Energy audit , Cost , Confectionery
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/406925 , uj:34232 , Citation: Ibrahim, Q., Rokhsareh, A., Jen, T. 2019 : Case study and energy analysis of power system management of confectionery factory in Jordan.
  • Description: Abstract : Energy is the essential component of all industries. However, its misuse by untrained staffs, owners of factories and companies increases the rate of consumption which consequently leads to waste of energy. This study aims to find the possible ways to rationalize energy consumption by introducing methods to provide and reduce consumption to maintain non-renewable energy for longer time as much as possible. This study was conducted on a confectionery factory that relies mainly on electrical energy and other sources of energy such as gas and diesel in the operation of furnaces to obtain high quality products while taking into account the reduction of energy consumption. Energy management is the first and most important strategic area to reduce the costs by controlling thermal and electrical energy consumption. First, the facility was analyzed to check the consumption of energy, and then the electrical and mechanical devices were inspected and suggestions were made to save the energy based on this study. The result showed a total energy saving up potential of 30,000 (kWh/year) by improving the electrical systems of the factory.
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Casting and applications of functionally graded metal matrix composites

Characterization and Fabrication of nanostructured TiO2/NiO heterojunction solar cells

Characterization and fabrication of nanostructured TiO2/NiO heterojunction solar cells

Chitosan modified N, S−doped TiO2 and N, S−doped ZnO for visible light photocatalytic degradation of tetracycline

Commuting tillage operations of HRP under hydraulic cylinder movements on plough-breast performance

Comparative study of Hydrogen yield from magnesium waste products in Acetic acid and Iron chloride solution

  • Authors: Hashe, Vuyo T. , Jen, Tien-Chien
  • Date: 2020
  • Subjects: Hydrogen , Waste magnesium , Hydrolysis reaction
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/434772 , uj:37650 , Citation: Hashe, V.T. & Jen, T.C. 2020. Comparative study of Hydrogen yield from magnesium waste products in Acetic acid and Iron chloride solution.
  • Description: Abstract: Low-grade magnesium (Mg) waste from post-consumer products and production waste cannot be recycled efficiently and economically. This work addresses this challenge by converting this waste into hydrogen. Hydrogen (H2) offers a wide range of benefits and the greatest of them all is its ability and flexibility to be used as a green energy carrier. In this work Mg waste is re-melted, loaded on one side of a stainless steel and allowed to solidify at room temperature to form a galvanic Mg stainless steel couple. Mg reacts slowly with water and releases hydrogen at room temperature and this is followed by the formation of magnesium hydroxide on its surface. Stainless steel net is considered as a metallic catalyst and two acids as accelerators reacting with the couples separately. A set of couples were used to generate hydrogen in 3.5% by weight acetic acid (CH3COOH). The experimental results show that a mean accumulated H2 volume of 3.17 – 3.21 litres was produced in 3600 seconds. Another set of couples produced H2 in 1.5 wt. % of iron chloride (FeCl3). The results confirmed FeCl3 as an excellent hydrolysis reaction accelerator with stainless steel as an effective catalyst. On average, the reaction yielded 2700mL of H2 over 3600 seconds which appear to be substantially higher than the litres achieve when CH3COOH was considered as an accelerator.
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Conceptualization of the optimal design of a hydroxyl booster dry cell for enhancing efficiency of internal combustion engines

  • Authors: Chinguwa, Simon , Jen, Tien-Chien , Akinlabi, Esther T.
  • Date: 2020
  • Subjects: Dry cell , Hydroxyl , Internal combusion
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/437148 , uj:37948 , Citation: Chinguwa, S., Jen, T.C. & Akinlabi, E.T. 2020. Conceptualization of the optimal design of a hydroxyl booster dry cell for enhancing efficiency of internal combustion engines.
  • Description: Abstract: Current internal combustion engines (ICEs) are powered by fossil fuels which create the challenges of low combustion efficiency and the emission of greenhouse gases. This has negatively affected the environment, leading to global warming and climate change. Interim technologies can be implemented to reduce these effects whilst alternative technologies are being explored. This research aimed at selecting the most appropriate geometrical design of a hydroxyl booster dry cell, a device which operates on the principles of electrolysis to produce hydroxyl gas commonly referred to as Brown gas or HHO. When a voltage is applied to a body of water, it splits it into its base components, i.e. hydrogen and oxygen cold plasma, a mixture sometimes referred to as hydroxyl gas. The addition of hydroxyl gas into the combustion chamber of an ICE initiates a more complete combustion due to the explosive and diffusive nature of hydrogen accompanied by the cooling effect of water thus reducing potential for NOx formation. This leads to fuel savings, cost savings and reduced emissions. A rectangular hydroxyl booster dry cell was selected and designed, fabricated and tested for effectiveness. The HHO generator is later connected to the ICE system to check mainly on the positive contributions of this Brown’s gas as HHO is popularly known.
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