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.

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

PZT and Electrode Enhancements of Mems Based Micro Heat Engine for Power Generation

2002 ◽  
Vol 730 ◽  
Author(s):  
A.L. Olson ◽  
L.M. Eakins ◽  
B.W. Olson ◽  
D.F. Bahr ◽  
C.D. Richards ◽  
...  
Keyword(s):  
Bottom Electrode ◽  
Mechanical Energy ◽  
Electrical Power ◽  
Heat Engine ◽  
Mems Devices ◽  
Stress Concentrations ◽  
Process Yield ◽  
Micro Heat Engine ◽  
Reducing Stress ◽  
And Diffusion

AbstractThe P3 Micro Heat Engine relies on a thin film PZT based transducer to convert mechanical energy into usable electrical power. In an effort to increase process yield for these were used on sputtered Ti/Pt bottom electrodes to compare roughness, grain size, and diffusion for annealing temperatures between 550 and 700 °C. For an optimized bottom electrode, process yield for various sized top electrodes were then studied for PZT thickness between 0.54 and 1.62 for reducing stress concentrations. Two PZT etching geometries on 2.3 μm thick Si/SiO2 membranes, with 1.5-3.5 mm side-lengths, were examined and one was used to increase the strain at failure by at least 40%. Integrating improvements in process yield and strain at failure, single PZT based MEMS devices capable of generating power of up to 1 mW and in excess of 2 volts have been demonstrated operating at frequencies between 300 and 1,100 Hz.

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.

Innovative Research in the Organic Rankine Cycle

Impact ◽  
2020 ◽  
Vol 2020 (6) ◽  
pp. 76-78
Author(s):  
Tzu-Chen Hung ◽  
Yong-Qiang Feng
Keyword(s):  
Phase Change ◽  
Mechanical Energy ◽  
Heat Engine ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Vapour Phase ◽  
Working Fluid ◽  
Low Grade ◽  
Initial State ◽  
Thermodynamic Cycles

Thermodynamic cycles consist of a sequence of thermodynamic processes involving the transfer of heat and work into and then out of a system. Variables, such as pressure and temperature, eventually return the system to its initial state. During the process of passing through the system, the working fluid converts heat and disposes of any remaining heat, making the cycle act as a heat engine, where heat or thermal energy is converted into mechanical energy. Thermodynamic cycles are an efficient means of producing energy and one of the most well-known examples is a Rankine cycle. From there, scientists have developed the organic Rankine cycle (ORC), which uses fluid with a liquid to vapour phase change that occurs at a lower temperature than the water to steam phase change. Dr Tzu-Chen Hung and Dr Yong-Qiang Feng, who are based at both the Department of Mechanical Engineering, National Taipei University in Taiwan, and the School of Energy and Power Engineering, Jiangsu University in China, are carrying out work that seeks to design and build improved ORC systems which can be used for low-grade heat to power conversion.

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.

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.

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%.

Experimental Study of the Minto Engine—A Heat Engine for Converting Low Grade Heat to Mechanical Energy

2004 ◽  
Vol 126 (1) ◽  
pp. 661-667 ◽  
Author(s):  
Terence I. Quickenden ◽  
Kathryn M. Hindmarsh ◽  
Kean-Guan Teoh
Keyword(s):  
Experimental Study ◽  
Mechanical Energy ◽  
Heat Engine ◽  
Heat Energy ◽  
Working Fluid ◽  
Low Grade ◽  
Long Period ◽  
Short Period ◽  
Low Grade Heat ◽  
Liquid Piston

The Minto engine is a liquid piston heat engine that converts heat energy into mechanical energy. Evaporation of the heated, volatile working fluid pushes it upwards against gravity. This causes the device to tip over and rotate. A 500 mm diameter Minto engine which used petroleum ether as the working fluid, was built and was operated between 344 K and 294 K. Thermal efficiencies of up to 0.25% (i.e. 1.7% of the Carnot maximum) were measured. This engine behaves as a power amplifier. It absorbs low grade heat over a long period of time and suddenly releases it as a pulse of mechanical energy over a short period of time.

scholarly journals Action and Entropy in Heat Engines: An Action Revision of the Carnot Cycle

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 860
Author(s):  
Ivan R. Kennedy ◽  
Migdat Hodzic
Keyword(s):  
Heat Engine ◽  
Working Fluid ◽  
Field Energy ◽  
Carnot Cycle ◽  
Gibbs Potential ◽  
Atmospheric Gases ◽  
Temperature Dependent ◽  
Expansion Phase ◽  
Heat Engines ◽  
The Difference

Despite the remarkable success of Carnot’s heat engine cycle in founding the discipline of thermodynamics two centuries ago, false viewpoints of his use of the caloric theory in the cycle linger, limiting his legacy. An action revision of the Carnot cycle can correct this, showing that the heat flow powering external mechanical work is compensated internally with configurational changes in the thermodynamic or Gibbs potential of the working fluid, differing in each stage of the cycle quantified by Carnot as caloric. Action (@) is a property of state having the same physical dimensions as angular momentum (mrv = mr2ω). However, this property is scalar rather than vectorial, including a dimensionless phase angle (@ = mr2ωδφ). We have recently confirmed with atmospheric gases that their entropy is a logarithmic function of the relative vibrational, rotational, and translational action ratios with Planck’s quantum of action ħ. The Carnot principle shows that the maximum rate of work (puissance motrice) possible from the reversible cycle is controlled by the difference in temperature of the hot source and the cold sink: the colder the better. This temperature difference between the source and the sink also controls the isothermal variations of the Gibbs potential of the working fluid, which Carnot identified as reversible temperature-dependent but unequal caloric exchanges. Importantly, the engine’s inertia ensures that heat from work performed adiabatically in the expansion phase is all restored to the working fluid during the adiabatic recompression, less the net work performed. This allows both the energy and the thermodynamic potential to return to the same values at the beginning of each cycle, which is a point strongly emphasized by Carnot. Our action revision equates Carnot’s calorique, or the non-sensible heat later described by Clausius as ‘work-heat’, exclusively to negative Gibbs energy (−G) or quantum field energy. This action field complements the sensible energy or vis-viva heat as molecular kinetic motion, and its recognition should have significance for designing more efficient heat engines or better understanding of the heat engine powering the Earth’s climates.

scholarly journals A simple interferometric method to measure the calibration factor and displacement amplification in piezoelectric flextensional actuators

2010 ◽  
Vol 21 (6) ◽  
pp. 577-587 ◽  
Author(s):  
Francisco de Assis Andrade Barbosa ◽  
Gilder Nader ◽  
Ricardo Tokio Higuti ◽  
Cláudio Kitano ◽  
Emílio Carlos Nelli Silva
Keyword(s):  
Modulation Depth ◽  
Low Cost ◽  
Michelson Interferometer ◽  
Laser Interferometry ◽  
Optimization Method ◽  
Calibration Factor ◽  
Simple Method ◽  
Interferometric Method ◽  
Established Technique

Laser interferometry is a well-established technique for the characterization of piezoelectric actuators. In this work, by using a low cost Michelson interferometer, the measurement of the calibration factor and the displacement amplification of a novel piezoelectric flextensional actuator (PFA), designed by using the topology optimization method, is performed. A simple method, based on small phase modulation depth when the PFA is driven by a triangular waveform, allows the absolute interferometer calibration. The free-displacement of the PFA for various drive voltages is measured and the displacement amplification is determined. The linearity and frequencyresponse of the PFA are evaluated up to 20 kHz

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