scholarly journals Experimental Investigation of Zinc Antimonide Thin Film Thermoelectric Element over Wide Range of Operating Conditions

2017 ◽  
Vol 214 (11) ◽  
pp. 1700301 ◽  
Author(s):  
Mojtaba Mirhosseini ◽  
Alireza Rezania ◽  
Anders B. Blichfeld ◽  
Bo B. Iversen ◽  
Lasse A. Rosendahl
Keyword(s):  
Thin Film ◽  
Experimental Investigation ◽  
Operating Conditions ◽  
Thermoelectric Element ◽  
Zinc Antimonide ◽  
Wide Range

scholarly journals Energy Harvesting from a Thermoelectric Zinc Antimonide Thin Film under Steady and Unsteady Operating Conditions

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2365 ◽  
Author(s):  
Mojtaba Mirhosseini ◽  
Alireza Rezania ◽  
Bo Iversen ◽  
Lasse Rosendahl
Keyword(s):  
Thin Film ◽  
High Reliability ◽  
Electrical Energy ◽  
Operating Conditions ◽  
Electrical Load ◽  
Thermal Cycles ◽  
Thermoelectric Element ◽  
Zinc Antimonide ◽  
Wide Range ◽  
And Performance

In practice, there are some considerations to study stability, reliability, and output power optimization of a thermoelectric thin film operating dynamically. In this study stability and performance of a zinc antimonide thin film thermoelectric (TE) specimen is evaluated under transient with thermal and electrical load conditions. Thermoelectric behavior of the specimen and captured energy in each part of a thermal cycle are investigated. Glass is used as the substrate of the thin film, where the heat flow is parallel to the length of the thermoelectric element. In this work, the thermoelectric specimen is fixed between a heat sink exposed to the ambient temperature and a heater block. The specimen is tested under various electrical load cycles during a wide range of thermal cycles. The thermal cycles are provided for five different aimed temperatures at the hot junction, from 160 to 350 °C. The results show that the specimen generates approximately 30% of its total electrical energy during the cooling stage and 70% during the heating stage. The thin film generates maximum power of 8.78, 15.73, 27.81, 42.13, and 60.74 kW per unit volume of the thermoelectric material (kW/m3), excluding the substrate, corresponding to hot side temperature of 160, 200, 250, 300, and 350 °C, respectively. Furthermore, the results indicate that the thin film has high reliability after about one thousand thermal and electrical cycles, whereas there is no performance degradation.

Experimental investigation of isothermal and reacting flow characteristics downstream of axisymmetric bluff body stabilizers under stratified or fully premixed inlet mixture conditions

2020 ◽  
Author(s):  
Γεώργιος Πατεράκης
Keyword(s):  
Experimental Investigation ◽  
Turbulent Flow ◽  
Bluff Body ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Wide Range ◽  
Flow Features ◽  
Air Mixing ◽  
The Impact ◽  
Stratified Flames

The current work describes an experimental investigation of isothermal and turbulent reacting flow field characteristics downstream of axisymmetric bluff body stabilizers under a variety of inlet mixture conditions. Fully premixed and stratified flames established downstream of this double cavity premixer/burner configuration were measured and assessed under lean and ultra-lean operating conditions. The aim of this thesis was to further comprehend the impact of stratifying the inlet fuelair mixture on the reacting wake characteristics for a range of practical stabilizers under a variety of inlet fuel-air settings. In the first part of this thesis, the isothermal mean and turbulent flow features downstream of a variety of axisymmetric baffles was initially examined. The effect of different shapes, (cone or disk), blockage ratios, (0.23 and 0.48), and rim thicknesses of these baffles was assessed. The variations of the recirculation zones, back flow velocity magnitude, annular jet ejection angles, wake development, entrainment efficiency, as well as several turbulent flow features were obtained, evaluated and appraised. Next, a comparative examination of the counterpart turbulent cold fuel-air mixing performance and characteristics of stratified against fully-premixed operation was performed for a wide range of baffle geometries and inlet mixture conditions. Scalar mixing and entrainment properties were investigated at the exit plane, at the bluff body annular shear layer, at the reattachment region and along the developing wake were investigated. These isothermal studies provided the necessary background information for clarifying the combustion properties and interpreting the trends in the counterpart turbulent reacting fields. Subsequently, for selected bluff bodies, flame structures and behavior for operation with a variety of reacting conditions were demonstrated. The effect of inlet fuel-air mixture settings, fuel type and bluff body geometry on wake development, flame shape, anchoring and structure, temperatures and combustion efficiencies, over lean and close to blow-off conditions, was presented and analyzed. For the obtained measurements infrared radiation, particle image velocimetry, laser doppler velocimetry, chemiluminescence imaging set-ups, together with Fouriertransform infrared spectroscopy, thermocouples and global emission analyzer instrumentation was employed. This helped to delineate a number of factors that affectcold flow fuel-air mixing, flame anchoring topologies, wake structure development and overall burner performance. The presented data will also significantly assist the validation of computational methodologies for combusting flows and the development of turbulence-chemistry interaction models.

Modelling of Partially Wetting Liquid Film Using an Enhanced Thin Film Model for Aero-Engine Bearing Chamber Applications

2020 ◽  
Author(s):  
K. Singh ◽  
M. Sharabi ◽  
R. Jefferson-Loveday ◽  
S. Ambrose ◽  
C. Eastwick ◽  
...  
Keyword(s):  
Thin Film ◽  
Contact Angle ◽  
Film Thickness ◽  
Liquid Film ◽  
Flow Rate ◽  
Operating Conditions ◽  
Film Model ◽  
Thin Film Model ◽  
Wide Range ◽  
Aero Engine

Abstract In the case of aero-engine, thin lubricating film servers dual purpose of lubrication and cooling. Prediction of dry patches or lubricant starved region in bearing or bearing chambers are required for safe operation of these components. In the present work thin liquid film flow is numerically investigated using the framework of the Eulerian thin film model (ETFM) for conditions which exhibit partial wetting phenomenon. This model includes a parameter that requires adjustment to account for the dynamic contact angle. Two different experimental data sets have been used for comparisons against simulations, which cover a wide range of operating conditions including varying the flow rate, inclination angle, contact angle, and liquid-gas surface tension coefficient. A new expression for the model parameter has been proposed and calibrated based on the simulated cases. This is employed to predict film thickness on a bearing chamber which is subjected to a complex multiphase flow. From this study, it is observed that the proposed approach shows good quantitative comparisons of the film thickness of flow down an inclined plate and for the representative bearing chamber. A comparison of model predictions with and without wetting and drying capabilities is also presented on the bearing chamber for shaft speed in the range of 2,500 RPM to 10,000 RPM and flow rate in the range of 0.5 liter per minute (LPM) to 2.5 LPM.

scholarly journals Modeling of Partially Wetting Liquid Film Using an Enhanced Thin Film Model for Aero-Engine Bearing Chamber Applications

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
Kuldeep Singh ◽  
Medhat Sharabi ◽  
Richard Jefferson-Loveday ◽  
Stephen Ambrose ◽  
Carol Eastwick ◽  
...  
Keyword(s):  
Thin Film ◽  
Contact Angle ◽  
Film Thickness ◽  
Liquid Film ◽  
Thin Liquid Film ◽  
Operating Conditions ◽  
Film Model ◽  
Thin Film Model ◽  
Wide Range ◽  
Aero Engine

Abstract In the case of aero-engine, thin lubricating film servers dual purpose of lubrication and cooling. Prediction of dry patches or lubricant starved region in bearing or bearing chambers are required for safe operation of these components. In this work, thin liquid film flow is numerically investigated using the framework of the Eulerian thin film model (ETFM) for conditions, which exhibit partial wetting phenomenon. This model includes a parameter that requires adjustment to account for the dynamic contact angle. Two different experimental data sets have been used for comparisons against simulations, which cover a wide range of operating conditions including varying the flowrate, inclination angle, contact angle, and liquid–gas surface tension coefficient. A new expression for the model parameter has been proposed and calibrated based on the simulated cases. This is employed to predict film thickness on a bearing chamber which is subjected to a complex multiphase flow. From this study, it is observed that the proposed approach shows good quantitative comparisons of the film thickness of flow down an inclined plate and for the representative bearing chamber. A comparison of model predictions with and without wetting and drying capabilities is also presented on the bearing chamber for shaft speed in the range of 2500 RPM to 10,000 RPM and flowrate in the range of 0.5 liter per minute (LPM) to 2.5 LPM.

Experimental Investigation of Self-Excited Combustion Instabilities in a Lean, Premixed, Gas Turbine Combustor at High Pressure

2017 ◽  
Author(s):  
Timo Buschhagen ◽  
Rohan Gejji ◽  
John Philo ◽  
Lucky Tran ◽  
J. Enrique Portillo Bilbao ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
High Pressure ◽  
Operating Conditions ◽  
Chamber Pressure ◽  
Dynamic Mode ◽  
Combustion Instabilities ◽  
Compression Phase ◽  
Wide Range ◽  
Lower Amplitude ◽  
Lean Premixed

An experimental investigation of self-excited combustion instabilities in a high pressure, single-element, lean, premixed, natural gas dump-combustor is presented in this paper. The combustor is designed for optical access and is instrumented with high frequency pressure transducers at multiple axial locations. A parametric survey of operating conditions including inlet air temperature and equivalence ratio has been performed, which presents a wide range of peak to peak pressure fluctuations (p′) of the mean chamber pressure (pc). Two cases, Flame A and B with p′ /pc = 28% and p′/pc = 15% respectively, both presenting self-excited instabilities at the fundamental longitudinal (1L) mode of the combustion chamber, are discussed to study the coupling mechanism between flame-vortex interactions and the acoustic field in the chamber. OH*-chemiluminescence is used to obtain a map of global heat release distribution in the combustor. Phase conditioned analysis and Dynamic Mode Decomposition (DMD) analysis is performed, to highlight the contrasting mechanisms that lead to the two distinct instability regimes. Flame interactions with shear layer vortex structures just downstream of the dump plane during the compression phase of the acoustic cycle are found to augment the instability amplitude. Flame A engages strongly in this coupling, whereas Flame B is less affected and establishes a lower amplitude limit cycle.

An Experimental Investigation on the Temperature Distribution in Circular Journal Bearings

1986 ◽  
Vol 108 (4) ◽  
pp. 621-626 ◽  
Author(s):  
Junichi Mitsui ◽  
Yukio Hori ◽  
Masato Tanaka
Keyword(s):  
Experimental Investigation ◽  
Angular Position ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Test Rig ◽  
Clearance Ratio ◽  
Temperature Distributions ◽  
Wide Range ◽  
Lubricant Viscosity ◽  
Good Agreement

The temperature distributions in full circular bearings were measured in a test rig. The effects of journal speed, lubricant viscosity, and clearance ratio on the maximum bearing temperature and its location were discussed. The results were compared with the theoretical analysis by the present authors and good agreement was obtained over the wide range of operating conditions. The maximum bearing temperature is found to increase considerably with the increase of speed or lubricant viscosity and also with the decrease of clearance ratio. Its angular position is found to vary with speed and clearance ratio. These phenomena can be explained by the characteristics of maximum film temperature in the oil film.

Control of Thin Film Growth in Chemical Vapor Deposition Manufacturing Systems: A Feasibility Study

2002 ◽  
Vol 124 (3) ◽  
pp. 715-724 ◽  
Author(s):  
Wilson K. S. Chiu ◽  
Yogesh Jaluria ◽  
Nick G. Glumac
Keyword(s):  
Thin Film ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Design Space ◽  
Chemical Vapor ◽  
Film Deposition ◽  
Operating Conditions ◽  
Design And Optimization ◽  
Wide Range ◽  
Computer Aided

A study is carried out to design and optimize Chemical Vapor Deposition (CVD) systems for material fabrication. Design and optimization of the CVD process is necessary to satisfying strong global demand and ever increasing quality requirements for thin film production. Advantages of computer aided optimization include high design turnaround time, flexibility to explore a larger design space and the development and adaptation of automation techniques for design and optimization. A CVD reactor consisting of a vertical impinging jet at atmospheric pressure, for growing titanium nitride films, is studied for thin film deposition. Numerical modeling and simulation are used to determine the rate of deposition and film uniformity over a wide range of design variables and operating conditions. These results are used for system design and optimization. The optimization procedure employs an objective function characterizing film quality, productivity and operational costs based on reactor gas flow rate, susceptor temperature and precursor concentration. Parameter space mappings are used to determine the design space, while a minimization algorithm, such as the steepest descent method, is used to determine optimal operating conditions for the system. The main features of computer aided design and optimization, using these techniques, are discussed in detail.

Experimental Study of Real Roughness Features Within EHD Point Contacts

2005 ◽  
Author(s):  
I. Krˇupka ◽  
M. Hartl ◽  
M. Lisˇka
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Thickness Distribution ◽  
Operating Conditions ◽  
Phase Shifting ◽  
Accurate Information ◽  
Asperity Contact ◽  
Phase Shifting Interferometry ◽  
Wide Range ◽  
Surface Irregularities

A combination of thin film colorimetric interferometry and phase shifting interferometry has been used to study the effect of slide-to-roll ratio on the micro-elastohydrodynamic action and asperity-contact mechanism on the real asperity scale. The phase shifting interferometry was used to measure in-situ initial undeformed rough surface profiles and thin film colorimetric interferometry provided accurate information about micro-EHD film thickness behaviour over a wide range of operating conditions. Lubricant film thickness distribution within mixed EHD contact has been found to change significantly as a function of a slide-roll ratio. A high resolution color camera has enabled a closer look at film thickness changes in the vicinity of surface irregularities that helped to describe these processes in detail. Obtained results indicate the presence of either a boundary film less than 1 nm thick or some solid-like contact in front of roughness features for positive slide to roll ratios. No such a local film thickness reduction has been found for negative slide-to-roll ratio conditions.

Numerical and Experimental Investigation of Aerodynamic Characteristics of Model Ultra High Bypass Ratio Counter Rotating Fan

2018 ◽  
Author(s):  
Iaroslav Druzhinin ◽  
Victor Mileshin ◽  
Vladimir Korzhnev
Keyword(s):  
Experimental Investigation ◽  
Fuel Efficiency ◽  
Computational Simulation ◽  
Wave Interaction ◽  
Aerodynamic Characteristics ◽  
Operating Conditions ◽  
Test Facility ◽  
Operation Conditions ◽  
Wide Range ◽  
Bypass Ratio

One of the perspective schemes of air breathing engine is a scheme with Ultra High Bypass Ratio (BPR 16...25) Counter Rotating Fan. This solution potentially allows significant increase of fuel efficiency compared to modern conventional turbofans. The model UHBR counter rotating fan named COBRA-1 was developed by CIAM within the framework of European Project COBRA (Innovative Counter rOtating fan system for high Bypass Ratio Aircraft engine). The fan was designed using up-to-date 1D, 2D and 3D methods. COBRA-1 is a 0.7 m diameter model of counter rotating fan driven by a planetary reduction gearbox. The bypass ratio of COBRA-1 is 20. The R2/R1 torque ratio was chosen to obtain 1.42-muliple prevalence in power for 2nd row. The blade numbers are 8/12 for R1/R2 correspondingly. Final geometry of airfoils was defined by 3D profiling process to achieve required aerodynamics and acoustic parameters. Application of control-diffusion airfoils allows reaching high integral performances: specific mass flow equals 211 kg/(s*m^2) and isentropic efficiency at design point is higher than 0.93. The paper presents results of computational simulation of the flow in UHBR fan COBRA-1 based on 3D steady RANS method, 3D URANS and Non-Linear Harmonic method for different operation conditions in comparison with experimental data. Numerical simulation was carried out using Numeca FINE TURBO software package. Steady RANS approach was used during design process to make quick estimation of performances at different rpm. 3D URANS simulation was conducted to analyze unsteady wake-blade and shock-wave interaction and to make a decision about sufficient value of axial gap between rotors. The COBRA-1 fan was tested in CIAM at C3-A test facility which allows conducting a wide range of measurements of local and integral parameters including acoustics of ducted counter rotating fan at different operating conditions. Experimental results demonstrate a high level of integral performances and good agreement with computed values. Significant part of numerical and experimental investigation is devoted to effect of gear-box requirements on aerodynamics. C3-A rig allows to set rotational speed of rotors independently and measure torques at each shaft to achieve required torque ratio and study the influence of small (3–5%) deviation in rpm on aerodynamic characteristics.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

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