MEMS Rotary Engine Power System

In this paper is presented an analytic, theoretical and numerical study of the Viscous Rotary Engine Power System (VREPS). In addition, a proposed process flow for the fabrication of the VREPS using DRIE of silicon is described. The design premise of the VREPS is to derive mechanical power from the surface viscous shearing forces developed by a pressure driven flow present between a rotating disk or annulus and a stationary housing. The resulting motion of the rotating disk or annulus is converted into electrical power by using an external permanent magnet, embedded nickel-iron magnetic circuits, and an external switched magnetic pole electric generator similar to the design proposed by M. Senesky for the UC Berkeley micro-Wankel Engine [1]. This paper will examine the power output, isentropic efficiency, and operating characteristics of the disk and annular viscous turbines using the lubrication approximation and the Creeping Flow Equations (Stokes Flow). The viscous turbine is optimized for maximum isentropic efficiency using MATLAB numerical optimization routines. Finally, a unique triple-wafer micro-fabrication process for VREPS is presented. The proposed design consists of a 250 μm thick, 3.4 mm OD / 2.4 mm ID annular rotor with embedded magnetic poles and four 10 μm driving channels on each side of the rotor. Electrical power is generated with a switched magnetic pole generator, external permanent magnet, and integrated magnetic circuits. Calculations with water predict an output power of 825 mW at an isentropic efficiency of 25% using a pressure drop of 5 MPa cross the device.

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Apex Seal Design for the MEMS Rotary Engine Power System

Microelectromechanical Systems ◽

10.1115/imece2003-42071 ◽

2003 ◽

Author(s):

Fabian C. Martinez ◽

Aaron J. Knobloch ◽

Albert P. Pisano

Keyword(s):

Power System ◽

Internal Combustion Engine ◽

Combustion Engine ◽

Combustion Process ◽

Internal Combustion ◽

Analytical Models ◽

Planar Geometry ◽

Rotary Engine ◽

Seal Design ◽

Engine Power

Design, modeling, and analysis of a novel in-plane cantilever apex seal for maintaining high compression ratios in a MEMS-based rotary internal combustion engine are presented. This work is part of an effort to create a portable, MEMS-based Rotary Engine Power System (MEMS REPS) capable of producing power on the order of tens of milliwatts and with an energy density better than that of a conventional battery. A Wankel-type rotary engine is advantageous for a MEMS-based internal combustion engine due to its planar geometry, self-valving operation, and few moving parts. Large scale rotary engines typically incorporate a complex apex and face sealing system composed of many parts and involved assembly. A MEMS-based apex seal system can be incorporated as part of the rotor in order to eliminate manual assembly. The seal system must also have a minimal footprint and closely follow the epitrochoid profile in order to effectively integrate with the other engine systems. Based on these objectives, an integrated in-plane cantilever apex seal system can be integrated into the rotor with a small footprint. The first step in the development of the MEMS REPS is an air-powered expander which can be used to demonstrate electrical generator operation, engine rotation, and apex seal operation. The apex seals discussed here are optimized for use in an air-powered expander. A performance analysis of this flexure apex seal design is performed which examines 4 major performance constraints: resonant frequency, strain, pressure, and power dissipation. In addition, the seal design also accounts for fabrication tolerances of thick deep reactive ion etching (DRIE). During operation, dynamic effects due to combustion process and mechanical translation may drive the flexures into resonance, leading to galloping of the cantilever tips. Galloping will result in large leakage paths, thereby, reducing the compression ratio. A 0.25% strain limit is imposed to minimize the effect of fatigue on seal performance. Pre-compressed apex seals are used to counteract forces generated on the apex seal due to a pressure differential. The apex seal is also designed to minimize the power dissipated due to frictional losses. To model the cantilever apex seal, two different loading conditions are examined. One condition is distinguished by point loading at the tip, when contact is made between the seal and housing wall. Another condition is characterized by a distributed loading, due to the changing pressure by both the compression and the combustion events. Analytical models in addition to a finite element analysis were performed.

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Prediction of IC Engine Power System Durability with the Use of Ring Pack Model

Journal of Konbin ◽

10.2478/v10040-008-0156-x ◽

2010 ◽

Vol 13 (1) ◽

pp. 299-310

Author(s):

Grzegorz Koszałka ◽

Andrzej Niewczas

Keyword(s):

Diesel Engine ◽

Power System ◽

Prior Knowledge ◽

Analytical Model ◽

Life Prediction ◽

New Method ◽

Ic Engine ◽

Ring Pack ◽

Engine Life ◽

Engine Power

Prediction of IC Engine Power System Durability with the Use of Ring Pack ModelThe paper presents the new method of engine life prediction, which bases on the results of wear measurements taken on an investigated engine and simulations carried out with the use of the analytical model of ring pack of the engine. In the contrary to traditional methods the proposed method does not require the prior knowledge of the limit wear value, which is essential for the prediction, however its reliable establishing for new engines is difficult. In the presented method its value is determined with the use of the ring pack model. The example of durability calculation for an automotive diesel engine is also presented.

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Theoretical and experimental investigations of a downdraft biomass gasifier-spark ignition engine power system

Renewable Energy ◽

10.1016/j.renene.2011.06.008 ◽

2012 ◽

Vol 37 (1) ◽

pp. 97-108 ◽

Cited By ~ 31

Author(s):

Felipe Centeno ◽

Khamid Mahkamov ◽

Electo E. Silva Lora ◽

Rubenildo V. Andrade

Keyword(s):

Power System ◽

Spark Ignition ◽

Spark Ignition Engine ◽

Experimental Investigations ◽

Engine Power

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Leakage Flow Analysis for a MEMS Rotary Engine

Microelectromechanical Systems ◽

10.1115/imece2003-41868 ◽

2003 ◽

Cited By ~ 1

Author(s):

Joshua D. Heppner ◽

David C. Walther ◽

Albert P. Pisano

Keyword(s):

Power System ◽

Compression Ratio ◽

Flow Analysis ◽

Design Parameters ◽

Working Fluid ◽

Leakage Flow ◽

Engine Operation ◽

Rotary Engine ◽

Leakage Flows ◽

Macro Scale

An internal leakage flow analysis is presented for a MEMS fabricated rotary engine in order to establish design parameters for micro engine sealing systems. This research is part of the MEMS Rotary Engine Power System (REPS) group effort to develop a portable power system based on an integrated generator and Wankel rotary internal combustion engine. In order to have acceptable system efficiency, it is necessary to suppress internal leakage and thereby maintain a critical level of compression ratio. There are two inherent leakage paths in rotary engines, which result in blowby and reduced compression ratio: leakage around the apexes of the rotor and leakage across the rotor faces. These sealing issues arise due to the large pressure gradients, which occur along these leakage paths in the combustion chamber. It is the aim of this work to examine the effects of reduced scale on both traditional and novel rotary engine apex sealing mechanisms. In contrast to the macro scale, viscous forces have an increased importance in micro scale engines since Re~.01. A simplified Poiseuille-Couette flow model has been developed to analyze the leakage flows of rotary type engines. Since the Reynolds number for the MEMS REPS is extremely small, the model assumes that the flow is laminar, viscous, incompressible, and steady with air as the working fluid. The model indicates that if a 1 μm gap can be maintained between the housing and moving parts (rotor apexes and faces), leakage flows at expected engine operation speeds will only reduce the compression ratio from 8.3:1 to 6.1:1 so long as the rotation speed is greater than 10,000 rpm. It is doubtful that a traditional or simple micromachine design will yield such a gap and therefore several novel, integrated sealing approaches are under investigation. The model will determine design specification for one of these approaches, an integrated cantilever flexure apex. In conjunction with the theoretical model, a scaled engine experiment at the macro scale is used to verify the modeling effort. The scaling of the experiment complies with Reynolds scaling and ensures that Hele-Shaw flow within the leakage paths is maintained. The experiment does not operate as a functional engine, rather the experiment is designed to maintain a precise clearance between the rotor and housing. In order to preclude additional pressure driven flow effects, an electric motor is used to spin the rotor and simulate the rotation expected due to the combustion pressure acting on the rotor face.

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An experimental study of combined operation of energy storage system and gas engine power plant in off-grid power system

E3S Web of Conferences ◽

10.1051/e3sconf/202020903020 ◽

2020 ◽

Vol 209 ◽

pp. 03020

Author(s):

Gleb Nesterenko ◽

Gleb Prankevich ◽

Aleksey Savitskiy ◽

Dmitriy Gladkov ◽

Vyacheslav Zyryanov ◽

...

Keyword(s):

Energy Storage ◽

Power System ◽

High Efficiency ◽

Storage System ◽

Lithium Ion ◽

Energy Storage System ◽

Variable Load ◽

Test Results ◽

Gas Engine ◽

Engine Power

Test results of the main industrial prototype of energy storage system (ESS-10-1200-400) of nominal power 1200 kVA, energy capacity 400 kWh and voltage 10 kV based on lithium-ion batteries when operating in combination with gas engine generators (GEG) as a part of experimental power system with active abrupt variable load are given. Its structure, components and parameters, as well as the components and parameters of ESS are described. Tests have shown high operation capacity of the prototype tested, high efficiency of the implemented algorithms and confirmed the expediency of the use of ESS for smoothing power surges/sheddings in the GEG, thus preventing their emergency shutdown resulted from the power surge.

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