Chin-Hsiang Cheng

Mechanical Engineering, Engineering Physics

Distinguished Professor


  • Sean Wu · Chin-Hsiang Cheng · Yu-Jen Hsiao · Rei-Cheng Juang · Wen-Fu Wen
    [Show abstract] [Hide abstract] ABSTRACT: This paper reviews solar-selective coatings for concentrating solar power (CSP) applications. CSP systems require direct sunlight and solar tracking and utilize solar absorbers to convert sunlight to thermal electric power. Because this system receives direct sunlight which operating temperatures higher than 600 °C, heat-resistance new materials are needed to cope with. This paper presents a simple and low-cost process for depositing the high-temperature solar absorber. The high selective absorbing Fe2O3 films deposited on stainless steel (SS304) substrates to be absorbers by high thermal process at 850–1050 °C. The crystalline structure, surface microstructure and optic properties of the films were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV/visible spectroscopy (UV–vis–NIR Spectrophotometer, 0.25–2.5 μm). Optimal Fe2O3 films on SS304 substrates at (900–1000 °C) displayed high absorptivity (α) (0.909–0.922) and their emittance values(ε) are relatively low (0.18–0.38). This study proved the possibility of preparing high-temperature solar selective absorbing coatings with high solar absorptance and low emittance by using a simple thermal oxidation process. Those films have very good prospects for solar absorber because of simple process, low-cost, large-area and good performance.
    No preview · Article · May 2016 · Renewable and Sustainable Energy Reviews
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    Hao Lv · Xiao-Dong Wang · Tian-Hu Wang · Chin-Hsiang Cheng
    [Show abstract] [Hide abstract] ABSTRACT: In this work, a new design of thermoelectric cooler (TEC) with variable semiconductor cross-sectional area is proposed to improve its transient supercooling characteristics. Four key evaluation indicators of transient supercooling for the conventional and new designs, including the minimum cold end temperature, maximum temperature overshoot, holding time of transient state, and recovery time ready for next steady-state, are examined and compared by a three-dimensional, transient, and multiphysics model. Two additional effects are observed in the TEC with variable semiconductor cross-sectional area. First, the variable cross-sectional area makes the thermal circuit asymmetric, so that Joule heat is preferentially conducted towards to the end with a larger cross-sectional area. Second, more Joule heat is produced close to the end with a smaller cross-sectional area. The present simulations find that these two effects can be utilized to achieve the desired evaluation indicators by changing the cross-sectional area ratio of hot end to cold end. When a lower cold end temperature, a smaller temperature overshoot, and/or a longer holding time are/is required, a larger cross-sectional area at the cold end is recommended. However, to achieve a shorter recovery time, a smaller cross-sectional area at the cold end is needed.
    Full-text · Article · Feb 2016 · Applied Energy
  • Chin-Hsiang Cheng · Yen-Fei Chen
    [Show abstract] [Hide abstract] ABSTRACT: A topology optimization method that can be used to optimize the conduction path in laminated metallic materials between unequal isothermal surfaces is proposed in this study. The volume-of-solid (VOS) method presented by Cheng and Chen [20] for homogeneous and isotopic materials shape design has been firstly applied to deal with the composite materials. The materials used to make the laminate largely determine the properties, costs, and thereby its suitability for different applications. In this study, three-layer laminated metallic composite materials are considered in the test problems. These metallic layers are made of copper, aluminum, stainless steel or iron. Two possible orientations of the composite materials, vertical and horizontal, are investigated. Optimal shapes of the thermal conduction path between a higher- and a lower-temperature isothermal surfaces are determined in order to maximize three different objective functions, namely . By using the present approach, optimal thermal conduction paths leading to maximum heat transfer rate per unit mass, per unit volume, or per unit cost can be readily yielded.
    No preview · Article · Oct 2015 · International Journal of Thermal Sciences
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    [Show abstract] [Hide abstract] ABSTRACT: The effect of preliminary ion bombardment of 321 stainless steel substrate on crack resistance of TiAlN coatings at uniaxial tension and thermal cycling is studied. The ion-beam treatment of the substrate is shown to substantially improve the adhesion strength of the coatings that prevents their delamination and spalling under uniaxial tension. The resistance to crack propagation and spalling by the thermal shock is higher in the TiAlN coating deposited onto the substrate subjected to Ti ion bombardment as compared to that in the TiAlN coating deposited onto the initial substrate.
    Full-text · Conference Paper · Oct 2015
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    [Show abstract] [Hide abstract] ABSTRACT: The present study is aimed at magnetic and mechanical properties of iron nitride ( γ ′ -Fe 4 N) with elastic deformation. Electronic structure and thermal properties of the iron nitride are also studied to have a comprehensive understanding of the characteristics of γ ′ -Fe 4 N. This study is focused on the variation of the magnetic and the mechanical properties of iron nitride with a change in crystal size represented by lattice constant. As the lattice constant is altered with deformation, magnetic moment of Fe-II atoms is appreciably elevated, while that of Fe-I atoms is nearly unchanged. Dependence of the magnetic moment and the bulk modulus on the lattice constant is examined. Meanwhile, chemical bonds between Fe atoms and N atoms formed across the crystal have been visualized by delocalization of atomic charge density in electron density map, and thermodynamic properties, including entropy, enthalpy, free energy, and heat capacity, are evaluated.
    Full-text · Article · Sep 2015 · Journal of Applied Mathematics
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    Cian-Siang Jhong · Yi-Shen Chen · David T W Lin · Chin-Hsiang Cheng
    [Show abstract] [Hide abstract] ABSTRACT: The purpose of this study is to introduce the reticle fabrication of metamaterials. Metamaterials will apply on the wave-controlled device such as steal technology, photo-absorbed device, planar lens, and ultrasonic sensors. The MEMS fabrication will be used for minimization and applying on the high frequency field. The pattern of this study is to design a single cell split ring resonator. S-parameters of this device of metamaterials will obtain from the vector network analyzer. It can be converted to obtain the permittivity and magnetic permeability. In general, the material can be classified four part as shown in Fig. 1. For the reason of the imaginary value of dielectric constant of the electromagnetic wave transmission in the second quadrant and the fourth quadrant, which results in the evanescent and undeliverable formation of electromagnetic wave. In the third quadrant, while the dielectric constant and the magnetic permeability is negative, and the refractive index is generated and same as one kinds of material in the first quadrant, but it will be different from the general physical properties of the material as mentioned metamaterials. Many previous studies propose a lot of applications of Metamaterials, such as optical, physical and electromagnetic fields. The dielectric constant and magnetic permeability of meatmaterials are simultaneously negative and different from the general natural physical characteristics, such as negative refractive index, reversed of Doppler effect and reversal of vavilov-Cerenkov phenomena etc. [1]. In this study, the metamaterials is fabricated by the reticle technology. The reticle technology is widely used in the communication systems. It can produce the surface acoustic wave devices as a bandpass filter sensors and resonators [2]. Photolithography is one of the most dominant and successful method in MEMS, which has been widely used in semiconductor industry [3]. Photolithography is to generate the pattern on the substrate by a predetermined image and combine with light and photo-resist. The predetermined image, photomask, is printed on the wafer or substrate at a certain predefined scale and fidelity level by an appropriate exposure tool [3]. This study designs a single cell split ring resonator structure by the reticle technology on the glass substrate. The pattern of resonator is made of nano-silver. First, the size of the structure will be designed from the desired frequency. Second, the reticle technology combined with MEMS fabrication is used to fabricate this resonator. The flow chart of the fabricated process and the Reticle technology are shown in Fig. 2. As shown in Fig. 3, the new design of split ring resonator is presented. This split ring resonator design is intended to strengthen the magnetic field effect by the different structural design of inductance and capacitance. The metamaterials device is fabricated by the reticle technology and measured by the vector network analyzer. The measurement setup is set as Fig. 4. The results of S-parameter will obtain by the vector network analyzer. It can observe that the range of the gain of frequency.
    Full-text · Conference Paper · Jul 2015
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    Chin-Hsiang Cheng · Yen-Fei Chen
    Full-text · Article · Jan 2015 · International Journal of Thermal Sciences
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    Hang-Suin Yang · Chin-Hsiang Cheng
    [Show abstract] [Hide abstract] ABSTRACT: This study is aimed to develop a theoretical model to determine criterion of instability and predict performance of a free-piston thermal-lag Stirling engine (FPTLSE). Experiments are conducted to verify the theoretical predictions partly. In the present study, a nonlinear model consisting of non-dimensional equation of motion and energy equation are derived. These governing equations are solved simultaneously by employing a multi-scale method, in which zero-order approximate solutions representing piston motion and temperature variation are obtained. Results show that the FPTLSE can be a self-started engine that may be able to start automatically after heating. In addition, the predictions by the theoretical model are found to agree closely with the experimental data for the oscillation of the piston. The present model is capable of predicting the dynamic behavior of the engine.
    Full-text · Article · Dec 2014 · Energy Procedia
  • Kang-I Chen · Chin-Hsiang Cheng · Sean Wu · Yeu-Long Jiang · Tsung-Chie Cheng
    [Show abstract] [Hide abstract] ABSTRACT: The effects of Ga addition on the wetting properties and tensile properties of Sn-8.55Zn-0.5Ag-xGa lead-free solder alloys are investigated. The x content of the solders investigated is 0 similar to 3 wt%. The results indicate that Ga exhibits a prominent influence on the wetting behavior as well as the mechanical properties of the solders. The wetting properties are improved remarkably with the increase of the Ga content in the Sn-8.55Zn-0.5Ag lead-free solder. The tensile test shows that 1 similar to 2 % Ga alloys have significant improvement in UTS, when compared with that of the binary Sn-Zn and Sn-Zn-OS Ag alloys. As for Sn-Zn-0.5Ag, the addition of Ga elements has provided a good wetting force, wetting time and tensile strength.
    No preview · Article · Dec 2014 · Indian Journal of Engineering and Materials Sciences
  • Tsung-Chieh Cheng · Tao-Hsing Chen · Wen-Shih Lin · Chin-Hsiang Cheng
    [Show abstract] [Hide abstract] ABSTRACT: This paper examines the field emission synthesis of multi-walled carbon nanotubes (MWCNTs) grown on various interlayers on carbon cloth (CC) substrates, such as Ni/CC, Ni/Ti/CC, and Ni/Al/CC, by thermal chemical vapor deposition using ethylene (C2H4) as the carbon source and nickel (Ni) as the catalyst. The Al interlayer activates the substrate for MWCNTs growth on carbon cloth with Ni as the active catalyst. Field emission SEM was utilized to study the morphology of the catalyst and MWCNTs, and a Raman spectrometer was used to characterize the quality of CNTs. As a result, catalyst particles initiate the nanotube growth and the tube diameters were found to be governed by the size of the associated particles. In our experiment, the smallest size and highest density of catalyst nanoparticles was formed on Al/CC substrate, so that the MWCNTs have a smaller diameter and higher density on this than on Ni/CC and Ni/Ti/CC substrate. Therefore, MWCNTs grown on flexible carbon cloth with an Al interlayer have the best quality and field emission characteristics of the materials examined in this paper.
    No preview · Article · Jul 2014 · Current Nanoscience
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    Chin-Hsiang Cheng · Yu-Xian Huang · Shun-Chih King · Chun-I Lee · Chih-Hsing Leu
    [Show abstract] [Hide abstract] ABSTRACT: This study is focused on computation optimization of the geometry for the flow channels in a micro-reformer used for methanol steam reforming. Three-dimensional mass and momentum transport phenomena with a pure fluid simulation in a micro-reformer are predicted using a commercial computational fluid dynamics code. Meanwhile, a simplified conjugate-gradient method is adopted to seek the optimal manifold shape and channel width of the micro-reformer iteratively using a Python interface. In the present study, the geometrical optimization tasks involve the designs of the inlet manifold and outlet manifold shapes as well as channel width distribution, and the design purpose is to obtain a uniform flow distribution throughout the entire micro-reformer so as to increase the hydrogen gas production rate. Cubic-spline interpolation is used in shape design to fit the points on the manifold shape more smoothly. The results show that the velocity standard deviation decreased from 0.14 to 0.048 and 0.051 after searching the optimal manifold shapes and channel widths, respectively. The manifold shapes of the inlet and outlet as well as the channel widths can efficiently lead to significant uniformity in the flow fields using a simplified conjugate-gradient method.
    Full-text · Article · Jun 2014 · Energy
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    [Show abstract] [Hide abstract] ABSTRACT: New energy and energy saving are the two basic energy issues. This study proposes an innovative optimal method to design LEDs with high thermal spreading holder. The optimization uses the FEM combined with the simplified conjugated gradient method (SCGM). The minimal temperature of the MCPCB backside of the LEDs is obtained throughout this design. The simulations have been proofed by the experiment of IR and thermal couple measurement. The optimal temperature decreases at about 4 °C compared with the original temperature without any active cooling device. This design can prolong the LEDs׳ life to benefit the energy saving obviously. In addition, this design combined with the active cooling device will achieve better heat dissipation on cooling of the electronic component.
    Full-text · Article · Apr 2014 · Microelectronics Journal
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    Chin-Hsiang Cheng · Yen-Fei Chen
    [Show abstract] [Hide abstract] ABSTRACT: A novel computational approach based on a non-constrained formulation with a volume-of-solid (VOS) function equation is firstly presented for topology design of heat conductive solid paths between constant-temperature objects. In the first step of the approach, the distributions of the VOS function and the temperature in the original design domain are carried out by simultaneously solving the VOS function equation and the heat conduction equation. Secondly, the shape outline of the heat conduction path leading to a maximum heat transfer rate per unit solid mass is determined by selecting a cut-off value of the VOS function. Performance of this approach is tested for three two-dimensional test cases. Various thermal boundary configurations are taken into consideration to demonstrate the validity of the present method. Results show that the present computational method is capable of predicting the optimal shapes of the heat conduction paths for the test cases efficiently.
    Full-text · Article · Apr 2014 · International Journal of Thermal Sciences
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    [Show abstract] [Hide abstract] ABSTRACT: Residual stress in MEMS is of inherent importance in various respects. This study proposes a specific method using ANSYS including the birth and death method and combined with the optimal method (SCGM) to reduce the residual stresses during the CMOS fabrication process. The suitable cooling temperature for decreasing the residual stress is proposed and available. It demonstrates that the suitable parameter on the fabrication can reduce the residual stress in MEMS devices without any extra manufacturing process or external apparatus. The proposed method can expand to simulate the realistic MEMS model effectively.
    Full-text · Article · Apr 2014 · JOURNAL OF MECHANICS
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    [Show abstract] [Hide abstract] ABSTRACT: A theoretical and experimental analysis of the influence of the dispersed transition layer between a coating and a substrate on the development of deformation structures near the interface has been performed as part of an interdisciplinary study of the deformation and fracture of coating-substrate compositions under contact interaction. Elastic energy transfer from an indenter was simulated using excitable cellular automata taking into account the self-organization of translations and rotations of the structure near the interface. The effect of the transition layer between the coating and the substrate on the development of deformation structures during contact interaction with the indenter in three-point bending was studied experimentally using a TOMSC television-optical measuring complex.
    Full-text · Article · Mar 2014 · Journal of Applied Mechanics and Technical Physics
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    Yu-Xian Huang · Jiin-Yuh Jang · Chin-Hsiang Cheng
    [Show abstract] [Hide abstract] ABSTRACT: The aim of the present article is to study the fractal channel pattern design and the gradient catalyst layer in relation to their effects on the performance of a micro methanol steam reformer. A three-dimensional simulation model is established for the purpose of predicting the effects of bio-channel design on the performance of a micro-reformer. The CO concentration in the production gases, which is necessary to avoid the poisoned catalyst layers of low temperature fuel cells, is also investigated. In addition, the distributions of velocity and gas concentrations are predicted, and the methanol conversion ratios are also evaluated. Due to further decreases of the CO in product gases, a gradient catalyst layer arrangement is proposed to delay the timing of hydrogen generation and thus avoid the presence of hydrogen in the catalyst layer too long. This catalyst arrangement can effectively decrease the possibility of a reverse water gas shift reaction to reduce CO generation. Results showed that the fractal channel design increases the conversion ratio, decrease CO as well as decrease the pressure drop in the channels. Relative to a parallel channel design, the CO and methanol conversion ratio of this fractal channel design pattern with uniform catalyst layer can be decreased and increased by 17% and 8%, respectively, based on a 0.3 cc/min flow rate, respectively. Meanwhile, the pressure drops in the parallel channel design and in the fractal channel design were found to be 254 Pa and 51 Pa, respectively. From an energy consumption point of view, a low pressure drop also implies low input pumping power. Furthermore, compared to the fractal design with a uniform catalyst layer, the gradient catalyst layer was demonstrated to effectively increase the conversion ratio by 8.5% and decrease CO by 11% when the inlet liquid flow rate was fixed at 1.0 cc/min.
    Full-text · Article · Feb 2014 · International Journal of Hydrogen Energy
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    [Show abstract] [Hide abstract] ABSTRACT: The effects of gallium additions on microstructures and thermal and mechanical properties of the Sn-9Zn solder alloys are investigated in this study. The results show that the melting temperature of the alloys decreases with the increase in the Ga concentration, while the pasty ranges of the alloys are simultaneously enlarged. By adding a 0.25-0.5 wt.% Ga element, the Sn-matrix region is slightly increased and the Zn-rich phase becomes slightly coarser; however, the overall microstructure is still very similar to that of the Sn-9Zn alloy. It is found that, when the Ga concentration is less than 0.50 wt.%, the ultimate tensile strength and elongation are maintained at the same values. The addition of a 0.25-0.50 wt.% Ga to the Sn-9Zn alloy also leads to small cup and cone fracture surfaces which exhibit near-complete ductile fracturing. With the addition being increased to 0.75 wt.%, larger cup and cone fractures are observed. The 1.00 wt.% Ga alloy has lower strength and ductility due to the coarser and nonuniform microstructures. However, the fracture surfaces of the 1.00 wt.% Ga alloy show partial cleavage and a partially dimpled fracture.
    Full-text · Article · Jan 2014 · Advances in Materials Science and Engineering
  • Chin-Hsiang Cheng · Hang-Suin Yang
    [Show abstract] [Hide abstract] ABSTRACT: In this study, a beta-type 500-W Stirling engine is developed and tested, and a nonideal adiabatic model is built and applied to predict performance of the engine. Engine torque, engine speed, and shaft power output are measured under various operating conditions. Furthermore, as the charged pressure and the heating temperature are set at eight bars and 800 °C and a No. 50 wire mesh is used in the regenerator, the shaft power of the engine can reach 556 W at 1665 rpm with 1.21-kW input heat transfer rate (45.95 % thermal efficiency). The experimental data are compared with the numerical predictions to verify the theoretical model. It is found that the experimental data of the shaft power output closely agree with the numerical predictions. This implies that the theoretical model is valid and helpful to the engine design.
    No preview · Chapter · Jan 2014
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    Chin-Hsiang Cheng · Hang-Suin Yang · Bing-Yi Jhou · Yi-Cheng Chen · Yu-Jen Wang
    [Show abstract] [Hide abstract] ABSTRACT: The present study is concerned with dynamic simulation of thermal-lag Stirling engines. A dynamic model is built and incorporated with a thermodynamic model to study the engine start process. A prototype engine is designed and simulated by using the dynamic model. In the simulation, different operating modes, including rotating mode, swinging mode, swinging-to-rotate mode, and swinging-to-decay mode, have been observed. The rotating mode is desired and can be achieved if the operating parameters are properly designed. In a poor design, the engine may switch to the swinging or even the swinging-to-decay mode. In addition, it is found that geometric parameters, such as bore size, stroke, and volume of working spaces, also determine the operating mode of the engine. Brake thermal efficiency of the engine is monotonically reduced by increasing engine speed. However, study of the dependence of the shaft power of the engine speed shows that there exists a maximum value of the shaft power at an optimal operating engine speed. The optimal engine speed leading to maximum shaft power is significantly influenced by the geometrical parameters.
    Full-text · Article · Oct 2013 · Applied Energy
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    Yu-Xian Huang · Xiao-Dong Wang · Chin-Hsiang Cheng · David Ta-Wei Lin
    [Show abstract] [Hide abstract] ABSTRACT: This paper develops an inverse problem approach to optimize the geometric structure of TECs (thermoelectric coolers). The approach integrates a complete multi-physics TEC model and a simplified conjugate-gradient method. The present TEC model couples the heat and electrical conductions and accounts for all physical mechanisms occurred within TECs. Three geometric parameters, the semiconductor pair number, N, leg length of semiconductor column, Hpn, and base area ratio of semiconductor columns to TEC, g, are optimized simultaneously at fixed current and fixed temperature difference. The cooling rate on the cold end is the objective function to be maximized to obtain the optimal TEC geometry. The effects of applied current and temperature difference on the optimal geometry are discussed. The results show that at temperature difference of 20 K, the geometry optimization increases the TEC cooling rate by 1.99-10.21 times compared with the initial TEC geometry, and the optimal N decreases from 100 to 47 with invariable r=0.95 and Hpn=0.2 mm, as the applied current varies from 1.0 A to 3.0 A. With the increase in temperature difference, the optimal N increases at smaller currents of I <1.0 A, however, it is almost invariable at larger currents of I > 1.5 A.
    Full-text · Article · Sep 2013 · Energy

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