Faculty Publications
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Item Chassis mounted single stage impulse turbine for wind energy harvesting on a cruising transport vehicle(Institute of Electrical and Electronics Engineers Inc., 2016) Hegde, S.S.; Thamban, A.; Ahmed, A.; Arun, M.Fossil fuels have been a means of energy source since a long time, and have tended to the needs of the large global population. These conventional sources are bound to deplete in the near future and hence there is a need for producing energy from renewable energy sources like solar, wind, geothermal, tidal etc. Technologies involving renewable energy are a growing subject of concern. The problem is the excessive pollution caused by conventional sources of energy and their impact on the environment. In particular, one of the main sources of pollution is harmful gases emitting out of automobiles. Wind energy is one among the renewable energy sources which is implemented in large scale energy production. A large amount of research has been done in this field to harness energy and power houses and other amenities are nearby wind farms. The purpose of this study is to consider the use of wind energy along with conventional energy sources to power automobiles. Specifically the concept of an impulse turbine mounted on the chassis of a typical vehicle structure is considered. Computational Fluid Dynamics (CFD) is used to validate the concept and also come up with a design that maximizes energy generation by such turbines. © 2015 IEEE.Item Dynamic performance of microturbine generation system connected to a grid(2008) Gaonkar, D.N.; Pillai, G.N.; Patel, R.N.The interconnection of distribution generation systems into distribution networks has great impact on real-time system operation, control, and planning. It is widely accepted that microturbine generation (MTG) systems are currently attracting a lot of attention to meet customers' needs in the distributed power generation market. In order to investigate the performance of MTG systems, their efficient modeling is required. This article presents the dynamic model of an MTG system, suitable for grid connection to study the performance of the MTG system. The presented model uses back-to-back power electronic converter topology for grid connection, which allows the bidirectional power flow between the grid and MTG system. Thus, the need of separate starting arrangements during launching of the microturbine is avoided. The components of the system are built from the dynamics of each part with their interconnections. The dynamics of the model have been studied under various grid disturbance conditions. The converter control strategies for MTG system operation in grid-connected mode are presented in this article. This article also compares the various grid connection topologies suitable for MTG system interconnection. The simulation results show that the developed model performance is not affected by the grid disturbances considered in the study, and that it has the ability to adjust the supply as per the power requirements of the load within the MTG system rating.Item Seamless transfer of microturbine generation system operation between grid-connected and islanding modes(2009) Gaonkar, D.N.; Pillai, G.N.; Patel, R.N.The intentional islanding operation of grid-connected distributed generation systems can greatly improve the reliability and quality of the power supply. The existing control techniques for distributed generation systems are designed to operate either in the grid-connected or islanding modes of operation, thus, not allowing for both modes to be implemented and transitioned between. In this article, a novel scheme for automatic mode switching of a microturbine-based distributed generation system between the grid-connected and islanding modes of operation is proposed. The presented scheme is based on the phase angle estimated by the phase-locked loop. The developed phase-locked loop provides an accurate estimation of the phase angle even under unbalanced conditions. The presented scheme does not negatively affect the distributed generation system or utility operations and can work even under matching distributed generation and load power ratings. In this work, back-to-back converters are used to interface the microturbine-based distributed generation system to the grid. Converter control strategies developed for both modes of distributed generation operation is also presented. The simulation results show good accuracy of the proposed scheme.Item Evaluation of heat transfer surfaces for compact recuperator using a CFD code(2009) Ashok Babu, T.P.; Talekala, M.S.Exhaust recovery recuperator is mandatory in order to realize a thermal efficiency of 30% or higher for micro turbines. In this work an attempt is made to select the cross corrugated heat transfer surface with minimum core volume of a recuperator matrix using a CFD code. Analysis is carried out for selected cross corrugated heat transfer surface configurations. The relation between the minimum core volume from design calculation and average skin friction coefficient from CFD analysis has been established. © 2008 Springer-Verlag.Item Use of a CFD code in the investigation of cross corrugated heat transfer surfaces(2010) Ashok Babu, T.P.A.; Shekoor, T.M.The variation of main geometric details of cross corrugated surfaces (i.e. aspect ratio and angle of corrugation) makes it increasingly difficult to have a general design method. In the absence of adequate 'database' covering all possible configurations, it is nearly impossible to predict the highly effective configuration. Thus CFD simulation is effective, as it allows computation for various geometries, and study of the effect of various design configurations on heat transfer and flow characteristics. The present paper discusses the use of a CFD code to select the cross corrugated heat transfer surface (CC surface) with minimum core volume of a recuperator matrix. Due to difficulties Induced by geometry and computational time, simple model is used as a first step. The SS T turbulence model was preferred over other flow models for simulations. This simple model, comprised of three corrugated plates having their crest nearly in contact, with hot and cold fluids flow alternately through passage created between the plates. Some selected cross corrugated heat transfer surfaces are used for the analysis. The results for the simplified model, presented in terms of outlet temperatures, heat transfer coefficients and skin friction coefficients, is encouraging to undertake extensive work in CFD simulation and create more 'database' on various configurations. Design calculations of a recuperator matrix for a 10 kW micro turbine have been carried out for the selected surfaces. The relation between the minimum core volume of the matrix from design calculation and average skin friction coefficient from CFD analysis is established to use CFD analysis for selection of heat transfer surfaces with minimum recuperator matrix core volume. The analysis is carried out with air and nitrogen as heat transfer fluids.Item Investigation on electromagnetic transients of distributed generation systems in the microgrid(2010) Gaonkar, D.N.The increasing interconnection of distributed generation sources of diverse technologies to low-voltage grids introduces considerable complexity in its operation and control. The concept of the microgrid is emerging as a solution to this and also to take full advantage of the potential offered by distributed generation. In this article, the performance of a typical microgrid with multiple distributed generation systems in grid-connected and autonomous modes of operation has been investigated through simulation. The developed model of the microgrid consists of a converter-interfaced microturbine generation system, a synchronous-generator-based distributed generation system, and a wind power generation system with an asynchronous generator. Investigation has been carried out to study the typical electromagnetic transients of a microgrid, due to preplanned and unplanned switching events. The performance of the bidirectional grid interface topology for a microturbine generation system in a microgrid is evaluated in this work. It has been observed from the simulation results that the motoring mode operation of the microturbine generation system during starting does not cause any disturbances in the microgrid. The study also indicates that the microgrid can maintain the desired power quality at the point of common coupling. Copyright © Taylor & Francis Group, LLC.Item Development of wave turbine emulator in a laboratory environment(2013) Vinatha Urundady, U.; Vittal, K.P.Wave turbine emulator (WTE) is an important equipment for developing wave energy conversion system. The emulator reflects the actual behavior of the wave turbine by reproducing the characteristics of real wave turbine without reliance on natural wave resources and actual wave turbine. It offers a controllable test environment that allows the evaluation and improvement of control schemes for electric generators. The emulator can be used for research applications to drive an electrical generator in a similar way as a practical wave turbine. This article presents the development of a WTE in a laboratory environment and studies on the behavior of electrical generator coupled to the emulator. The structure of a WTE consists of a PC where the characteristics of the turbine are implemented, ac drive to emulate the turbine rotor, feedback mechanism from the drive and power electronic equipment to control the drive. The feedback signal is acquired by the PC through an A/D converter, and the signal for driving the power electronic device comes from the PC through a D/A converter.Item Performance study of distributed generation system in grid connected/isolated modes(2014) Nayak, S.K.; Gaonkar, D.N.The Microturbine Generations (MTG) system is becoming one of the promising sources of Distributed Generation (DG) due to their fuel flexibility, reliability and power quality. Thus, the accurate model of MTG system is required for the grid connected operation and its perturbations. This article presents the performance study of MTG based DG system in grid connected, islanding and re-closed modes of operation. The developed model of MTG system includes a microturbine as prime mover, Permanent Magnet Synchronous Machine (PMSM) and power electronics interacting circuit along with control schemes. The MTG system uses the turbine speed to control the microturbine output power in comparison with the reference speed and shaft speed. The generated AC power is converted to DC using a passive rectifier and this DC power is inverted back to AC power to mach grid frequency. The DC link power is delivered to the grid, islanding load using a three phase voltage source inverter with Pulse Width Modulation (PWM) techniques. While delivering the DC link power to the grid and islanding load, the respective Active, Reactive Power (PQ) and Voltage Frequency (VF) control strategies are used for inverter operation. The detailed model of MTG system along with control schemes is developed using Matlab/ Simulink environment and the simulation results show the performance of MTG based DG system. From the simulation study, it is ascertained that, the developed model of MTG system can delivers the power to grid and isolated load significantly, by shifting the converter controller manually.Item Evaluation of WEDM performance characteristics of Inconel 706 for turbine disk application(Elsevier Ltd, 2015) Sharma, P.; Dupadu, D.; Narendranath, S.Inconel 706 is a newly developed superalloy, which offers high mechanical strength alongwith easy fabricability thus making it suitable for turbine disk applications. Although Inconel 706 exhibits a substantial increase in stress rupture and tensile yield strength compared to other superalloys, its conventional machining yields poor surface finish and low dimensional accuracy of the machined components. Hence, wire electrical discharge machining (WEDM) of Inconel 706 has been performed and various performance attributes such as material removal rate (MRR), surface roughness (SR), recast surface, topography, microhardness, microstructural and metallurgical changes of the machined components have been evaluated. The experimental results revealed that servo voltage, pulse on time, and pulse off time greatly influence the MRR and SR. Due to high toughness of Inconel 706, no micro cracks were observed on the machined surface. Micro voids and micro globules are significantly reduced at low pulse on time and high servo voltage. But, there is a propensity of thick recast layer formation at high pulse on time and low servo voltage. EDAX analysis of recast surface exposed the existence of Cu and Zn which have migrated from the brass wire. The subsurface microhardness was changed to 80. ?m due to significant thermal degradation. © 2015 Elsevier Ltd.Item Modelling and analysis of a standalone PV/micro turbine/ ultra capacitor hybrid system(International Journal of Renewable Energy Research, 2016) Shalavadi, B.; Chowdary, V.; Yaragatti, R.Y.Nowadays the distributed generation is being vastly implemented due to its various advantages. Generally a non renewable source is connected in parallel to a renewable source. Normally Photo Voltaic (PV) generation gives the power necessary by the load. The output of the PV is varying due to various reasons like temperature, irradiation, etc. Distributed generation using micro turbine is a realistic solution because of its friendliness with environment, small in size and high efficiency of energy. If the load is more than PV power capability, micro turbine supplies the remaining power. Due to the varying load conditions, the micro turbine practically compensates all the PV fluctuations of power. Even so, to reduce the fast fluctuations of power, one need to use an energy storage system like battery, ultra capacitor and flywheel etc. Ultra capacitor has been chosen, because of the its high power density and very fast energy storing capability. This paper documents the simulation and analysis of a standalone Photovoltaic / Micro turbine hybrid system and Photovoltaic / Micro turbine / Ultra capacitor hybrid system using MATLAB/SIMULINK simulation software. The system is implemented based on the concept of a parallel hybrid configuration. The simulation results validate the proposal.