Microfabricated Self-Oscillating Fluidic Heat Engine (SOFHE) With Enhanced Phase Change Through Corner Capillaries

Karami, Nooshin; Tessier-Poirier, Albert; Nikkhah, Alihossein; Léveillé, Étienne; Amnache, Amrid; Fréchette, Luc

doi:10.1109/powermems56853.2022.10007564

Cited by 3 publications

(3 citation statements)

References 19 publications

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“…This was first performed by forming a square cross-section microchannel with sharp corners to imitate the role of the fiber observed in the mesoscale SOFHE. The initial results of this approach were presented at the PowerMEMS 2022 conference [6]. The current study extends this work by adding etched capillary paths to enhance and engineer wicking behavior.…”

Section: Introductionmentioning

confidence: 68%

“…The advantage of the latter is their flexibility in terms of design and room for optimization. The selfoscillating fluidic heat engine (SOFHE) is a novel micro heat engine first introduced and studied by the same research group [4][5][6][7][8][9][10][11]. The SOFHE was proposed to power wireless sensors when coupled with an electromechanical transducer [4] as a TEH.…”

Section: Introductionmentioning

confidence: 99%

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Capillary enhanced phase change in a microfabricated self-oscillating fluidic heat engine (SOFHE)

Karami,

Tessier-Poirier,

Leveille

et al. 2023

J. Micromech. Microeng.

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This paper reports the design, fabrication, and characterization of a miniaturized version of a self-oscillating fluidic heat engine (SOFHE) for thermal energy harvesting. This new design includes capillary corners of a square cross-section, as well as an etched capillary path on the bottom wall that improves the performance in terms of stability and mechanical power owing to the enhanced phase change. The engine consists of a vapor bubble trapped in a microchannel by an oscillating liquid plug (acting as a piston) set in motion by periodic evaporation and condensation in the vapor bubble. The underlying physics of the oscillations is similar to those of a single-branch pulsating heat pipe. The channel is microfabricated by anodically bonding a grooved glass wafer (top and sidewalls) to a silicon wafer (bottom wall). To further increase the phase change, two more channels are fabricated with an etched capillary path on the bottom wall at two different widths of 25 and 50 µm and a depth of 100 µm. This is the first miniaturized SOFHE that generates a reliable amplitude in the millimeter range. By measuring the change in the volume of the vapor bubble and the frequency, we calculated the change in pressure using the momentum balance on the liquid plug, and then calculated the work, mechanical power, and power density. We observed that the addition of the etched capillary path at a width of 50 µm led to a twofold increase in the amplitude (from 1.6 to 4 mm) and consequently a fivefold increase in the generated power (from 7 to 39 µW). This study opens a new path towards designing different wicking structures to maximize the amplitude and power density of SOFHE, making it a promising thermal energy harvester to power wireless sensors.

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Section: Introductionmentioning

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Capillary enhanced phase change in a microfabricated self-oscillating fluidic heat engine (SOFHE)

Karami,

Tessier-Poirier,

Leveille

et al. 2023

J. Micromech. Microeng.

Self Cite

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show abstract

“…Alternatively, approaches to increase the phase change could also be used instead of changing the evaporator length. For example, increasing the thin film area provided by the fiber [14] and adding wicking microstructures [17] have been shown to increase the amplitude, without noticeable effect on the frequency. This approach circumvents the compromise between amplitude and frequency observed here.…”

Section: Discussionmentioning

confidence: 99%

Effect of evaporator length on the performance of a self-oscillating fluidic heat engine (SOFHE)

Karami,

Tessier-Poirier,

Léveillé

et al. 2023

Progress in Canadian Mechanical Engineering. Volume 6

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This paper reports the effect of evaporator length on the performance of a self-oscillating fluidic heat engine (SOFHE). The SOFHE is a thermal energy harvester, when coupled with an electro-mechanical transducer that was proposed to power wireless sensors widely used in the Internet of Things (IoT). The mechanical power of the SOFHE is in the order of fraction of milliwatts, which makes it a promising power supply for a range of wireless sensors with the power requirements of 10s µW. The SOFHE consists of a vapor bubble trapped by an oscillating liquid plug acting as a piston. The working principle of the SOFHE is similar to a singlebranch pulsating heat pipe. The engine is a small tube (inner diameter of 2 mm) filled with deionized water heated from a closed end and cooled from the opposite open end. By perturbing the equilibrium of the vapor bubble-liquid plug, oscillation start and are sustained by cyclic evaporationcondensation from a thin film in the vapor bubble. To characterize SOFHE's mechanical power as a function of the evaporator length, measurements of pressure, oscillation amplitude, and frequency are conducted. As the evaporator length decreases (from 7 cm to 1 cm), the oscillation amplitude decreases (from 5.9 mm to 1.5 mm) while the frequency increases (from 27 Hz to 52 Hz). In theory, the power of SOFHE is proportional to the square of frequency and amplitude, so the trend in power is not obvious given the opposing effects. The results show a decrease in the mechanical power from 380 µW to 180 µW, which implies that the negative effect of the amplitude decrease dominates over the increase in frequency. A fourfold decrease was also observed in the net evaporation rate (from 1027 to 242 µg/s), which explains why the amplitude decreases with the evaporator length. The research findings contribute to the design of both SOFHEs and pulsating heat pipes by suggesting that a longer heated zone improves the performance.

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A Heat-Driven Micro Jet Pump Using a Self-Oscillating Fluidic Heat Engine (SOFHE): First Demonstration

Karami,

Léveillé,

Amnache

et al. 2023

2023 IEEE 22nd International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (Po

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Microfabricated Self-Oscillating Fluidic Heat Engine (SOFHE) With Enhanced Phase Change Through Corner Capillaries

Cited by 3 publications

References 19 publications

Capillary enhanced phase change in a microfabricated self-oscillating fluidic heat engine (SOFHE)

Capillary enhanced phase change in a microfabricated self-oscillating fluidic heat engine (SOFHE)

Effect of evaporator length on the performance of a self-oscillating fluidic heat engine (SOFHE)

A Heat-Driven Micro Jet Pump Using a Self-Oscillating Fluidic Heat Engine (SOFHE): First Demonstration

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