Thermal energy recovery via integrated small scale boiler and superheater

Thapa, Suvhashis; Borquist, Eric; Weiss, Leland

doi:10.1016/j.energy.2017.10.063

Cited by 5 publications

(4 citation statements)

References 16 publications

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“…This allows formal concentration on the FPE operating cycle. Future efforts and experiment will consider phase change effects of working fluids already under investigation through experimental boiler development [19]. These are generally 'dry' fluids with a negative slope to the saturation curve.…”

Section: Resultsmentioning

confidence: 99%

“…To evaluate the suitability of FPE at miniature scales and to optimize FPEs, one needs to identify their important design and operating parameters. Prior efforts recorded in literature have made progress on design and operation of thermal harvesters on several fronts -different working fluids (steam, helium, and air) have been considered [14,15,17,18] -different boiler and superheater designs for miniature length scales have been proposed [19,20] -new lumped parameter-based and numerical-based models of the free piston expander (FPE) have been developed [16,21]. Many efforts are specific to low temperature waste-heat harvesting and multiple have resulted in real prototypes across different length scales [22,23,14,15,16,18].…”

Section: Introductionmentioning

confidence: 99%

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Design and performance of a miniature free piston expander

Burugupally

Weiss

2019

Energy

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The availability of free thermal energy provide an opportunity for power generation at miniature length scales (millimeter). Though free piston based expanders at macro length scales (centimeter and above) are found to be suitable for heat energy harvesting, their implementation at miniature scales are plagued by significant parasitic losses, yielding low thermal efficiencies. Through physics-based models we investigate the behavior and performance of a miniature free piston expander that operates on an open cycle. Here, we explore the design space of the free piston expander with an objective to achieve an efficiency of at least 15%. Three observations are reported that contribute to higher efficiency operation: (1) a higher injection pressure;(2) an optimum nondimensionalized duration of injection time of 1.5; and (3) softer springs, lower loads, and heavier pistons. A sample calculation showed that a centimeter-sized expander can generate an output power of 2.24 W at 18% efficiency. We observe that both the performance parameters of the expander, namely efficiency and output power are sensitive to injection pressure of the working fluid compared to the time duration of the working fluid injection. Our study reveals that the miniature free piston expander is promising for low temperature waste-heat harvesting.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Design and performance of a miniature free piston expander

Burugupally

Weiss

2019

Energy

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“…The common MEMS fabrication technology of a boiler was combined with capillary channels with the 3D printing of a superheater. While the boiler alone could capture 2/3 of the incoming thermal energy, the addition of the superheater increased this value by 10%, in this way increasing thermal energy scavenging [56].…”

Section: Combining 3d Printing With Other Technologiesmentioning

confidence: 99%

3D Printed MEMS Technology—Recent Developments and Applications

Błachowicz

Ehrmann

2020

Micromachines

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Microelectromechanical systems (MEMS) are of high interest for recent electronic applications. Their applications range from medicine to measurement technology, from microfluidics to the Internet of Things (IoT). In many cases, MEMS elements serve as sensors or actuators, e.g., in recent mobile phones, but also in future autonomously driving cars. Most MEMS elements are based on silicon, which is not deformed plastically under a load, as opposed to metals. While highly sophisticated solutions were already found for diverse MEMS sensors, actuators, and other elements, MEMS fabrication is less standardized than pure microelectronics, which sometimes blocks new ideas. One of the possibilities to overcome this problem may be the 3D printing approach. While most 3D printing technologies do not offer sufficient resolution for MEMS production, and many of the common 3D printing materials cannot be used for this application, there are still niches in which the 3D printing of MEMS enables producing new structures and thus creating elements for new applications, or the faster and less expensive production of common systems. Here, we give an overview of the most recent developments and applications in 3D printing of MEMS.

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“…The constructed prototype showed improvement in sealing and piston motion length through low viscous fluids (HFE 7100), allowing the expander to operate at a natural frequency of about 33 Hz. Other work has investigated design of individual components namely, boiler, superheater, and heat exchangers that are required for a fully functional millimeter scale expander system [52][53][54].…”

Section: External Heat Based Fpe Devices: Expandersmentioning

confidence: 99%

Power Generation via Small Length Scale Thermo-Mechanical Systems: Current Status and Challenges, a Review

Burugupally

Weiss

2018

Energies

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There has been significant interest and work toward the development of small length scale (micrometer to centimeter) energy conversion systems—heat engines and thermal energy harvesters—that operate on different thermal sources. Small combustion driven heat engines offer high power densities and longer operating durations, and present an opportunity to replace large and heavy chemical batteries. Thermal energy harvesters provide a great opportunity to harness the freely available thermal energy: solar, geothermal, and human body heat. These systems can contribute to significant energy savings when coupled to an existing, larger power generation system (e.g., vehicles and diesel generators) for the purpose of energy recovery. In this review, we discuss technological challenges, opportunities, and recent progress in small length scale energy conversion systems with special focus on free piston devices (engines and expanders) and phase-change driven devices. We discuss in detail four important design considerations that can have significant effect on small length scale device performance.

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Thermal energy recovery via integrated small scale boiler and superheater

Cited by 5 publications

References 16 publications

Design and performance of a miniature free piston expander

Design and performance of a miniature free piston expander

3D Printed MEMS Technology—Recent Developments and Applications

Power Generation via Small Length Scale Thermo-Mechanical Systems: Current Status and Challenges, a Review

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