A MEMS-Based Micro Heat Engine With Integrated Thermal Switch

2006 ◽  
Author(s):  
L. W. Weiss ◽  
J. H. Cho ◽  
D. J. Morris ◽  
D. F. Bahr ◽  
C. D. Richards ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Heat Engine ◽  
Working Fluid ◽  
Operating Pressure ◽  
Work Output ◽  
Silicon Membrane ◽  
Thermal Switch ◽  
Silicon Nitride Membrane ◽  
Micro Heat Engine ◽  
Membrane Deflection

This work details the effect of top membrane compliance on the performance of a MEMS based micro-heat engine and integrated thermal switch at operating speeds of 20, 40, and 100Hz and heat inputs of up to 60mJ per cycle. The engine consists of two flexible membranes encapsulating a volume of saturated working fluid. A thermal switch is used to intermittently reject heat from the engine to a constant temperature cooling sink. Mechanical work output is measured based on the engine's top membrane deflection and internal operating pressure. Three top membranes are considered; a 2micron thick silicon membrane, a 300nm thick silicon-nitride membrane, and a 3micron thick corrugated silicon membrane. The engine is shown to produce 1.0mW of mechanical power when operated at 100Hz.

Characterization of a dynamic micro heat engine with integrated thermal switch

2006 ◽  
Vol 16 (9) ◽  
pp. S262-S269 ◽  
Author(s):  
L W Weiss ◽  
J H Cho ◽  
K E McNeil ◽  
C D Richards ◽  
D F Bahr ◽  
...  
Keyword(s):  
Heat Engine ◽  
Thermal Switch ◽  
Micro Heat Engine

Interferometer Type Pressure Microsensor

2005 ◽  
Vol 888 ◽  
Author(s):  
A. Heredia-J ◽  
Alonso Ramirez-Pichon ◽  
J. Sánchez Mondragón ◽  
A. Andrade Lucio ◽  
M. Basurto Pensado ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
High Sensitivity ◽  
Maximum Pressure ◽  
Silicon Membrane ◽  
Maximum Deformation ◽  
Silicon Nitride Membrane ◽  
Type Pressure

AbstractIn this work, the fabrication of waveguide and nitride silicon membrane is presented. The measurement configuration chosen to detect the variation produced in the light properties is an Interferometer configuration of the Mach Zehnder Type (MZI), because of its high sensitivity. One of its arms is positioned on a floating silicon nitride membrane that becomes deformed under small pressures on the range of MPa. According to the parameters of the membrane and the waveguide we obtain a maximum deformation of 176 nm that produces a change of phase of 180° between the two waves, producing therein a null interferometer output for the maximum pressure.The analyses of theory suggest that this device will be able to sense a pressure value up to 13.376MPa.

Power production by a dynamic micro heat engine with an integrated thermal switch

2007 ◽  
Vol 17 (9) ◽  
pp. S217-S223 ◽  
Author(s):  
J H Cho ◽  
L W Weiss ◽  
C D Richards ◽  
D F Bahr ◽  
R F Richards
Keyword(s):  
Heat Engine ◽  
Power Production ◽  
Thermal Switch ◽  
Micro Heat Engine

Characterization of the Thermodynamic Working Cycle in a MEMS-Based Micro Heat Engine

2003 ◽  
Author(s):  
S. A. Whalen ◽  
L. W. Weiss ◽  
C. D. Richards ◽  
D. F. Bahr ◽  
R. F. Richards
Keyword(s):  
Mechanical Energy ◽  
Michelson Interferometer ◽  
Heat Engine ◽  
Working Fluid ◽  
Resistance Thermometer ◽  
Working Cycle ◽  
Displacement Profile ◽  
Micro Heat Engine ◽  
Center Deflection

This work examines the conversion of thermal to mechanical energy in a micro heat engine by characterizing the heat engine’s working cycle. Results are given for dynamic measurements of pressure, volume, and temperature throughout the working cycle of the engine. Engine pressure is determined from the deformation of the two membranes in contact with the working fluid. A Michelson interferometer is used to measure the center deflection and displacement profile of both of these membranes. Pressure is determined from the membrane deflection using experimental static pressure-deflection curves. Engine temperature is measured using electrical resistance thermometry, via a micro resistance thermometer fabricated on the surface of a silicon membrane exposed to the working fluid in the engine cavity.

The Mechanical Behavior of a Micromachined PZT Membrane

2003 ◽  
Author(s):  
I. Demir ◽  
R. F. Richards ◽  
D. F. Bahr ◽  
C. D. Richards
Keyword(s):  
Thin Film ◽  
Mechanical Behavior ◽  
Material Properties ◽  
Energy Minimization ◽  
Variational Approach ◽  
Piezoelectric Ceramic ◽  
Electrical Power ◽  
Heat Engine ◽  
Silicon Membrane ◽  
Micro Heat Engine

The mechanical behavior of a micromachined PZT membrane for power applications is investigated. The membrane is a bulk-micromachined silicon membrane that supports a thin film of piezoelectric ceramic (PZT) sandwiched between platinum and gold electrodes. The membrane undergoes large periodic deflections to convert mechanical power to electrical power in a micro heat engine. An analysis using a variational approach is developed to find an approximate closed from solution based on energy minimization. Experiments were conducted to obtain material properties, residual stresses, and pressure deflection relationships. The modeled results compare well to the experimental results.

Development of Scaling Model for a MEMS-Based Micro Heat Engine

2010 ◽  
Author(s):  
H. Bardaweel ◽  
B. S. Preetham ◽  
R. Richards ◽  
C. Richards ◽  
M. Anderson
Keyword(s):  
Combustion Engine ◽  
Heat Engine ◽  
Working Fluid ◽  
Thin Membranes ◽  
Micro Heat Engine ◽  
Heat Of Evaporation ◽  
Major Factors ◽  
Engine Components ◽  
External Combustion ◽  
Thermal Physical Properties

In this work we investigate issues related to scaling of a MEMS-based resonant heat engine. The engine is an external combustion engine made of a cavity encapsulated between two thin membranes. The cavity is filled with saturated liquid-vapor mixture working fluid. We use both model and experiment to investigate scaling of the MEMS-based resonant heat engine. The results suggest that the performance of the engine is determined by three major factors: geometry of the engine, speed of operation, and thermal physical properties of engine components. Larger engine volumes, working fluids with higher latent heat of evaporation, slower engine speeds, and compliant expander structures are shown to be desirable.

A Micro Heat Engine Executing an Internal Carnot Cycle

2008 ◽  
Author(s):  
Eli Lurie ◽  
Abraham Kribus
Keyword(s):  
Strong Dependence ◽  
Heat Engine ◽  
Thermodynamic Cycle ◽  
Maximum Power ◽  
Working Fluid ◽  
Carnot Cycle ◽  
Heating And Cooling ◽  
Engine Design ◽  
Power Point ◽  
Micro Heat Engine

A micro heat engine, based on a cavity filled with a stationary working fluid under liquid-vapor saturation conditions and encapsulated by two membranes, is described and analyzed. This engine design is easy to produce using MEMS technologies and is operated with external heating and cooling. The motion of the membranes is controlled such that the internal pressure and temperature are constant during the heat addition and removal processes, and thus the fluid executes a true internal Carnot cycle. A model of this Saturation Phase-change Internal Carnot Engine (SPICE) was developed including thermodynamic, mechanical and heat transfer aspects. The efficiency and maximum power of the engine are derived. The maximum power point is fixed in a three-parameter space, and operation at this point leads to maximum power density that scales with the inverse square of the engine dimension. Inclusion of the finite heat capacity of the engine wall leads to a strong dependence of performance on engine frequency, and the existence of an optimal frequency. Effects of transient reverse heat flow, and ‘parasitic heat’ that does not participate in the thermodynamic cycle are observed.

Optimum Criteria on the Important Parameters of an Irreversible Otto Heat Engine With the Temperature-Dependent Heat Capacities of the Working Fluid

2007 ◽  
Vol 129 (4) ◽  
pp. 348-354 ◽  
Author(s):  
Yingru Zhao ◽  
Bihong Lin ◽  
Jincan Chen
Keyword(s):  
Compression Ratio ◽  
Relevant Literature ◽  
Heat Engine ◽  
Heat Capacities ◽  
Working Fluid ◽  
Cylinder Wall ◽  
Work Output ◽  
Heat Leak ◽  
Temperature Dependent ◽  
Compression And Expansion

An irreversible cycle model of the Otto heat engine is established, in which the temperature-dependent heat capacities of the working fluid, the irreversibilities resulting from the nonisentropic compression and expansion processes, and heat leak losses through the cylinder wall are taken into account. The adiabatic equation of ideal gases with the temperature-dependent heat capacity is strictly deduced without using the additional approximation condition in the relevant literature and used to analyze the performance of the Otto heat engine. Expressions for the work output and efficiency of the cycle are derived by introducing the compression ratio of two isochoric processes. The performance characteristic curves of the Otto heat engine are presented for a set of given parameters. The optimum criteria of some important parameters such as the work output, efficiency, compression ratio, and temperatures of the working fluid are given. Moreover, the influence of the compression and expansion efficiencies, the variable heat capacities, the heat leak, and other parameters on the performance of the cycle is discussed in detail. The results obtained are novel and general, from which some relevant conclusions in literature may be directly derived. This work may provide a significant guidance for the performance improvement and optimal design of the Otto heat engine.

scholarly journals Maximum work output of multistage continuous Carnot heat engine system with finite reservoirs of thermal capacity and radiation between heat source and working fluid

2010 ◽  
Vol 14 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Jun Li ◽  
Lingen Chen ◽  
Fengrui Sun
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Heat Sink ◽  
Heat Engine ◽  
Thermal Capacity ◽  
Working Fluid ◽  
Work Output ◽  
Maximum Work ◽  
Engine System ◽  
Maximum Work Output

Optimal temperature profile for maximum work output of multistage continuous Carnot heat engine system with two reservoirs of finite thermal capacity is determined. The heat transfer between heat source and the working fluid obeys radiation law and the heat transfer between heat sink and the working fluid obeys linear law. The solution is obtained by using optimal control theory and pseudo-Newtonian heat transfer model. It is shown that the temperature of driven fluid monotonically decreases with respect to flow velocity and process duration. The maximum work is obtained. The obtained results are compared with those obtained with infinite low temperature heat sink.

On the Thermodynamic Cycle of a MEMS-Based External Combustion Resonant Engine

2010 ◽  
Author(s):  
H. Bardaweel ◽  
R. Richards ◽  
C. Richards ◽  
M. Anderson
Keyword(s):  
Heat Transfer ◽  
Heat Engine ◽  
Fluid Motion ◽  
Thermodynamic Cycle ◽  
Working Fluid ◽  
Thermal Mass ◽  
Compression Pressure ◽  
Heat Addition ◽  
Irreversible Effects ◽  
Micro Heat Engine

In this work we investigate the thermodynamic cycle of a resonant, MEMS-based, micro heat engine. The micro heat engine is made of a cavity encapsulated between two membranes. The cavity is filled with saturated liquid-vapor mixture working fluid. Heat is added/rejected from the engine at a frequency equal to its resonant frequency. Both pressure-volume and temperature-entropy diagrams of the resonant engine are used to investigate the thermodynamic cycle of the resonant micro heat engine. The results show that the thermodynamic cycle of the engine consists of four major processes: heat addition, expansion, heat rejection, and compression. pressure-volume and temperature-entropy diagrams are bounded by two constant temperature processes and two constant volume processes. The temperature-entropy and pressure-volume diagrams show deviations from this ideal description and are rounded due to the presence of irreversible effects. Major sources of irreversibility in the engine are heat transfer over finite temperature differences during heat addition and rejection, heat transfer into and out of engine thermal mass and viscous losses due to liquid working fluid motion. The measured second law efficiency of the micro heat engine is about 16%.

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