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.

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 CFD Study of Nozzle Configurations for Ultra High Bypass Engines

1993 ◽  
Author(s):  
H. Zimmermann ◽  
R. Gumucio ◽  
K. Katheder ◽  
A. Jula
Keyword(s):  
Engine Performance ◽  
Operating Conditions ◽  
Aerodynamic Design ◽  
Thrust Coefficient ◽  
Optimum Range ◽  
Installation Effects ◽  
Wide Range ◽  
And Performance ◽  
Aircraft Aerodynamics ◽  
Bypass Ratio

Performance and aerodynamic aspects of ultra-high bypass ratio ducted engines have been investigated with an emphasis on nozzle aerodynamics. The interference with aircraft aerodynamics could not be covered. Numerical methods were used for aerodynamic investigations of geometrically different aft end configurations for bypass ratios between 12 and 18, this is the optimum range for long missions which will be important for future civil engine applications. Results are presented for a wide range of operating conditions and effects on engine performance are discussed. The limitations for higher bypass ratios than 12 to 18 do not come from nozzle aerodynamics but from installation effects. It is shown that using CFD and performance calculations an improved aerodynamic design can be achieved. Based on existing correlations, for thrust and mass-flow, or using aerodynamic tailoring by CFD and including performance investigations, it is possible to increase the thrust coefficient up to 1%.

Uncertainty Analysis of Inflow Conditions on an HPT Gas Turbine Nozzle: Effect on Particle Deposition

2020 ◽  
Author(s):  
R. Friso ◽  
N. Casari ◽  
M. Pinelli ◽  
A. Suman ◽  
F. Montomoli
Keyword(s):  
Gas Turbine ◽  
Energy Efficient ◽  
Gas Turbines ◽  
Particle Deposition ◽  
Operating Conditions ◽  
Wide Range ◽  
And Performance ◽  
Gas Turbine Nozzle ◽  
The Impact ◽  
Inflow Conditions

Abstract Gas turbines (GT) are often forced to operate in harsh environmental conditions. Therefore, the presence of particles in their flow-path is expected. With this regard, deposition is a problem that severely affects gas turbine operation. Components’ lifetime and performance can dramatically vary as a consequence of this phenomenon. Unfortunately, the operating conditions of the machine can vary in a wide range, and they cannot be treated as deterministic. Their stochastic variations greatly affect the forecasting of life and performance of the components. In this work, the main parameters considered affected by the uncertainty are the circumferential hot core location and the turbulence level at the inlet of the domain. A stochastic analysis is used to predict the degradation of a high-pressure-turbine (HPT) nozzle due to particulate ingestion. The GT’s component analyzed as a reference is the HPT nozzle of the Energy-Efficient Engine (E3). The uncertainty quantification technique used is the probabilistic collocation method (PCM). This work shows the impact of the operating conditions uncertainties on the performance and lifetime reduction due to deposition. Sobol indices are used to identify the most important parameter and its contribution to life. The present analysis enables to build confidence intervals on the deposit profile and on the residual creep-life of the vane.

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 Current Advances in Ejector Modeling, Experimentation and Applications for Refrigeration and Heat Pumps. Part 2: Two-Phase Ejectors

Inventions ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 16 ◽  
Author(s):  
Zine Aidoun ◽  
Khaled Ameur ◽  
Mehdi Falsafioon ◽  
Messaoud Badache
Keyword(s):  
Heat Pumps ◽  
Operating Conditions ◽  
Industrial Processes ◽  
Experimental Investigations ◽  
Mixing Enhancement ◽  
Data Generation ◽  
Two Phase ◽  
Wide Range ◽  
Potential Applications ◽  
And Performance

Two-phase ejectors play a major role as refrigerant expansion devices in vapor compression systems and can find potential applications in many other industrial processes. As a result, they have become a focus of attention for the last few decades from the scientific community, not only for the expansion work recovery in a wide range of refrigeration and heat pump cycles but also in industrial processes as entrainment and mixing enhancement agents. This review provides relevant findings and trends, characterizing the design, operation and performance of the two-phase ejector as a component. Effects of geometry, operating conditions and the main developments in terms of theoretical and experimental approaches, rating methods and applications are discussed in detail. Ejector expansion refrigeration cycles (EERC) as well as the related theoretical and experimental research are reported. New and other relevant cycle combinations proposed in the recent literature are organized under theoretical and experimental headings by refrigerant types and/or by chronology whenever appropriate and systematically commented. This review brings out the fact that theoretical ejector and cycle studies outnumber experimental investigations and data generation. More emerging numerical studies of two-phase ejectors are a positive step, which has to be further supported by more validation work.

Index-Based Performance Assessment and Condition Monitoring of a Mobile Working Machine

2005 ◽  
Author(s):  
Vesa Ho¨ltta¨ ◽  
Matti Repo ◽  
Lauri Palmroth ◽  
Aki Putkonen
Keyword(s):  
Performance Assessment ◽  
Condition Monitoring ◽  
Operating Conditions ◽  
Multidimensional Data ◽  
Technical Performance ◽  
Machine Performance ◽  
Wide Range ◽  
Data Driven Approach ◽  
And Performance ◽  
Mobile Working

Real-time performance assessment and condition monitoring are potential new features in mobile working machines that have to run in a wide range of operating conditions. Condition monitoring and performance assessment are needed to be able to proactively correct impending faults before severe failures or machine stoppage occur. This paper presents a data-driven approach for machine performance assessment and condition monitoring based on indices representing the performance of a subsystem. Instead of adding new sensors, the indices are computed using existing data from the machine control system. Metrics for machine performance follow-up are derived from these multidimensional data, which have strong nonlinear correlations in certain measurement variables. Although the indices describe primarily the technical performance of the machine, they have proven to be valuable also in terms of condition monitoring of various machine functions. The indices summarize in a concise and easily comprehensible manner changes in performance.

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.

scholarly journals A Variable-Geometry Combustor Used to Study Primary and Secondary Zone Stoichiometry

1983 ◽  
Author(s):  
Daniel Briehl ◽  
Donald F. Schultz ◽  
Robert C. Ehlers
Keyword(s):  
Operating Conditions ◽  
Fuel Quality ◽  
Variable Geometry ◽  
Gas Temperature ◽  
Reference Velocity ◽  
Primary Zone ◽  
Wide Range ◽  
Secondary Zone ◽  
And Performance ◽  
Exhaust Gas Temperature

A combustion program is underway to evaluate fuel quality effects on gas turbine combustors. A rich-lean variable geometry combustor design was chosen to evaluate fuel quality effects over a wide range of primary and secondary zone equivalence ratios at simulated engine operating conditions. The first task of this effort, was to evaluate the performance of the variable geometry combustor. The combustor incorporates three stations of variable geometry to control primary and secondary zone equivalence ratio and overall pressure loss. Geometry changes could be made while a test was in progress through the use of remote control actuators. The primary zone liner was water cooled to eliminate the concern of liner durability. Emissions and performance data were obtained at simulated engine conditions of 80 percent and full power. Inlet air temperature varied from 611 to 665 K, inlet total pressure varied from 1.02 to 1.24 MPa, reference velocity was 18.0 m/sec and exhaust gas temperature was a constant 1400 K.

An Automatic Car Heater System-Description and Performance Prediction

1968 ◽  
Vol 183 (1) ◽  
pp. 125-135
Author(s):  
A. G. Plackett
Keyword(s):  
Performance Prediction ◽  
Digital Computer ◽  
System Parameter ◽  
Operating Conditions ◽  
Comfort Level ◽  
System Description ◽  
Wide Range ◽  
System Components ◽  
Overall Performance ◽  
And Performance

The objective of the system is to control the car heater temperature to ensure an optimum comfort level, without the need for periodic adjustment, despite variations in ambient temperature and vehicle usage. Reasons for choosing a particular type of system are explained. The operation is analysed, and expressed in terms of an equation. Difficulties in solution due to non-linear terms are overcome with the aid of a digital computer. Test data on the system components and vehicle characteristics are used in the computer program to obtain a prediction of the accuracy of temperature control over a wide range of operating conditions. Predicted performance is compared with actual road tests results for an installation. Design optimization is facilitated by using the computer to examine the effect of system parameter changes on the overall performance.

scholarly journals Analysis of Permissibility of the Excitation Loss Mode of the Synchronous Generator in the Conditions of the Industrial Electrical Supply System

2019 ◽  
pp. 12-18
Author(s):  
Olga V. Gazizova ◽  
Alexandr P. Sokolov ◽  
Nikolay T. Patshin ◽  
Yulia N. Kondrashova
Keyword(s):  
Gas Turbines ◽  
Power Plants ◽  
Reactive Power ◽  
High Reliability ◽  
Synchronous Generator ◽  
Electrical Energy ◽  
Operating Conditions ◽  
Asynchronous Mode ◽  
Operating Modes ◽  
Industrial Enterprises

Modern operating conditions of large industrial enterprises require the provision of high reliability of power supply to consumers while reducing the cost of the electricity consumed. These requirements are ensured by the widespread introduction of own sources of electrical energy. These include combined heat and power plants, gas turbines, gas pistons and steam and gas power plants. At the same time, there is a significant complication of the industrial network configuration and possible emergency modes. One of the emergency modes in such networks is the loss of excitation of the synchronous generator. The admissibility of such a regime is specified by regulatory documents. In this situation, the generator goes into asynchronous mode and consumes reactive power from the network. The purpose of this work is to identify the admissibility of the synchronous generator operation for a certain time in the asynchronous mode as a result of the loss of excitation. An algorithm has been developed to calculate the transient electromechanical process of a synchronous generator taking into account the loss of machine excitation. Investigations have been carried out for various operating modes of an industrial power plant taking into account the initial generator load using the KATRAN software. The calculation results allow determining the generator load by active power at which the synchronous generator can operate in the asynchronous mode without excitation.

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