The presented work analyses the design space and performance potential of microfabricated Brayton... more The presented work analyses the design space and performance potential of microfabricated Brayton cycle and Rankine cycle devices, accounting for lower component efficiencies, temperatures limited by the material properties and system implementation -constraints imposed by silicon microfabrication and miniaturization. By exploring the design space of such microsystems, their potential thermal efficiency and power density are defined. Results for both types of devices are shown graphically and design challenges and guidelines are determined and found to be different from their large-scale counterparts.
This paper presents the system-level and component design of a micro steam turbine power plant-on... more This paper presents the system-level and component design of a micro steam turbine power plant-on-a-chip which implements the Rankine cycle for micro power generation. The microfabricated device consists of a steam turbine that drives an integrated micropump and generator. Two-phase flow heat exchangers are also integrated on-chip with the rotating components to form a complete micro heat engine unit, converting heat to electricity. The system-level design includes cycle analysis and overall performance predictions, accounting for the expected performance of miniaturized components, thermal and structural integrity of the microsystem, and system-level trade-offs for optimal overall performance. Operating principles and design studies are also presented for the core component, with emphasis on a multistage, planar, radial microturbine and a spiral groove viscous pump. Design consideration for two-phase flow heat exchangers, microbearings, seals and micro-generators are also presented. Expected power levels range from 1-12 W per chip with energy conversion efficiency in the range of 1-11%. This suggests power density of up to 12 kW/kg for this technology, which is an order of magnitude greater than competing technologies, such as thermoelectrics. This study suggests the viability of a micro Rankine power plant-on-a-chip, but also identifies critical engineering challenges that must be met for practical implementation.
In this paper, the design process for multi-stage micro scale turbomachinery will be presented, a... more In this paper, the design process for multi-stage micro scale turbomachinery will be presented, along with CFD predictions of the key aerodynamic performance parameters required in this design process. This work focuses on the unique and unexplored design space defined by the small scale and planar geometries characteristic of MEMS turbopumps, compressors, gas turbines, steam turbines, or other turbomachinery-based microsystems. Correlations are proposed for the loss coefficient, based on laminar flow theory. A critical Reynolds number is also identified (Re crit =200-300), below which adjacent boundary layers merge, inducing a sharp increase in loss and deviation. This imposes practical limits on the miniaturization of such microturbomachinery.
This paper presents the experimental testing and characterization of a microscale radial outflow ... more This paper presents the experimental testing and characterization of a microscale radial outflow turbine with four concentric stages. The device is a five layer structure composed of shallow and deep reactive ion etched silicon wafers and an ultrasonically drilled Pyrex glass wafer that are assembled using anodic and fusion bonding techniques. They enclose a 4mm diameter rotor that was spun up to 330,000 rpm and produced roughly 0.1W of mechanical power from each stage totaling 0.38W with 0.75 atm differential pressure across the microturbine. Modeling of the turbine based on a mean line analysis with loss correlations extracted from CFD suggests a turbine isentropic efficiency of 35% and Re=266 at the maximum speed. The pressure distribution across the blades rows was measured and showed close agreement with the calculation results. Using the model, the microturbine is predicted to produce 3.2 watts with an isentropic efficiency of 63% at a rotor speed of 1.1 million rpm.
ABSTRACT A parametric investigation has been performed to study the different operating limits of... more ABSTRACT A parametric investigation has been performed to study the different operating limits of heat pipes employing a novel type of metal foam as wick for chip cooling applications. These foams have a unique spherical pore cluster microstructure with very high surface to volume ratio compared to traditional metal foams and exhibit higher operating limits in preliminary tests of heat pipes, suggesting high cooling rates for microelectronics. In the first part of this parametric study, widely used correlations are applied to calculate the five types of heat transfer limits (capillary, boiling, viscous, entrainment and sonic) as a function of temperature, type of foam, and porosity. Results show that the dominant limit is mostly the capillary limit, but for 50 pore-per-inch (PPI) foam, the boiling limit will be dominant. Also, 50 and 60 PPI foams have higher heat transfer limits than sintered copper powder. In the second part of this study, thermodynamic steady state modeling of a flat heat pipe has been done to study the effect of the different parameters on the dominant limit (capillary). A dimensionless number has been proposed to evaluate the balance between the pressure loss in the vapor and liquid phases as an additional design guideline to improve the capillary limit in flat heat pipes.
ABSTRACT Micro-electro-mechanical systems (MEMS) are an enabling technology that has lead to vari... more ABSTRACT Micro-electro-mechanical systems (MEMS) are an enabling technology that has lead to various miniature sensor concepts. Utilizing recent advances in silicon carbide (SiC) MEMS fabrication techniques allows for the development of a new series of sensors that leverages the high temperature capabilities of SiC. One such sensor concept is a shear stress sensor that can operate over a high dynamic range, and at very high temperatures, with an application emphasis on ground and flight testing in supersonic and hypersonic flow. The application of this fundamental sensor element and capacitance sensing design to very high temperature and very high shear environment, however, brings another set of challenges that involve the associated packaging and electrical control scheme. While this project is still a work in progress, we present an overview of our efforts to design, develop, fabricate and test a MEMS shear stress sensor for hypersonic aeropropulsion test and evaluation applications.
In a recent study, an effective means of mixing a low Reynolds number pressure-driven flow in a m... more In a recent study, an effective means of mixing a low Reynolds number pressure-driven flow in a micro-channel was reported by Stroock et al. using trenches on the lower wall that form a staggered herringbone pattern. In the present work numerical results are reported that indicate enhanced mixing using a similar herringbone pattern in the context of an electroosmotically driven flow in microchannels. Instead of trenches, all walls are flush, making microfabrication easier. The lower wall would have lithographically deposited polymer coatings that exhibit a zeta potential of a sign opposite to that at the other walls. These coatings are chosen to form a herringbone pattern.
Abstract. Resistance Temperature Detectors were used to investigate the thermal performance of th... more Abstract. Resistance Temperature Detectors were used to investigate the thermal performance of three different cell carrier structures. A carrier configuration with 0.78 mm thick C110 grade copper and 54 µm thick dielectric epoxy was chosen to fabricate five ...
This paper introduces and experimentally demonstrates the design concept of multi-stage microturb... more This paper introduces and experimentally demonstrates the design concept of multi-stage microturbomachinery, which is fabricated using silicon microfabrication technology. The design process for multi-stage micro scale turbomachinery based on meanline analysis is presented, along with CFD predictions of the key aerodynamic performance parameters required in this design process. This modeling was compared to a microturbine device with a 4mm diameter rotor and 100 micron chord blades, based on microelectromechanical system (MEMS) technology, which was spun to 330,000 RPM and produced 0.38W of mechanical power. Modeling suggests a turbine adiabatic efficiency of 35% and Re=266 at the maximum speed. The pressure distribution across the blade rows was measured and showed close agreement with the calculation results. Using the model, the microturbine is predicted to produce 3.2 watts with an adiabatic efficiency of 63% at a rotor speed of 1.1 million rpm.
This work presents the impact of integrating microfluidic channels at different locations in a 3D... more This work presents the impact of integrating microfluidic channels at different locations in a 3D stacked chip configuration to improve its thermal management. Bringing fluidic cooling within the microelectronic package can allow the use of higher power chips in limited space applications, but suitable sites for the microchannels in packaged 3D stacks must be determined. The approach uses an analytical representation of microfluidics and heat transfer at the package level to evaluate the equivalent thermal resistances. This analytical lumped-element circuit model is used to compare different microchannel cooling configurations, for 3D stacked chips. With the addition of microfluidic cooling, the allowable power level increases dramatically. The study also shows that locating the fluid cooling inside or adjacent to the chip stack reduces the thermal resistance over 6 times compared to microchannels located at the surface of the molding or the ball grid array. Within the chip stack ho...
The use of silicon microfabrication is evaluated to form micron scale electrode structures for pr... more The use of silicon microfabrication is evaluated to form micron scale electrode structures for proton exchange membrane fuel cells. The structure of the half cell consists of a perforated; electrically conductive; silicon gas diffusion layer (GDL) on one side. With an etched matrix of high aspect ratio silicon columns covered with platinum catalyst and a thin polymer electrolyte film (Nafion), acting as the electrodes on the other side. Design guidelines are defined through analytical modeling of mass transport, catalytic surface area, and internal ionic and electrical resistance. Progress in developing the microfabrication processes to create the silicon structure, the Pt layer, the Nafion layer and cell assembly are then presented. Work to date suggests that achieving high catalytic surface area and low ionic resistance in the electrodes will be challenging with the proposed approach, but will allow first order modeling and geometric optimization to potentially reduce Pt loading.
An analysis of water management in air breathing small polymer electrolyte membrane fuel cells (P... more An analysis of water management in air breathing small polymer electrolyte membrane fuel cells (PEM-FCs) is presented. Comprehensive understanding of flooding and dry-out limiting phenomena is presented through a combination of analytical modeling and experimental investigations using a small PEMFC prototype. Configurations of the fuel cell with different heat and mass transfer properties are experimentally evaluated to assess the impact of thermal resistance and mass transport resistance on water balance. Manifestation of dry-out and flooding problems, as limiting phenomena, are explained through a ratio between these two resistances. Main conclusions are that decreasing the ratio between thermal and mass transport resistance under a certain point leads to flooding problems in air breathing PEMFC. Increasing this ratio leads to dry-out of the polymer electrolyte membrane. However, too high thermal resistance or too low mass transport resistance reduces the limiting current by pushing forward the dry-out problem. This work provides a framework to achieve the proper balance between thermal rejection and mass transport to optimize the maximum current density of free convection fuel cells.
This is a report on work in progress on microelectrical and mechanical systems (MEMS)-based gas t... more This is a report on work in progress on microelectrical and mechanical systems (MEMS)-based gas turbine engines, turbogenerators, and rocket engines currently under development at MIT. Fabricated in large numbers in parallel using semiconductor manufacturing techniques, these engines are based on micro-high speed rotating machinery with the same power density as that achieved in their more familiar, full-sized brethren. The micro-gas turbine is a 1 cm diameter by 3 mm thick SiC heat engine designed to produce 10-20 W of electric power or 0.05-0.1 Nt of thrust while consuming under 10 grams/hr of H 2 . Later versions may produce up to 100 W using hydrocarbon fuels. A liquid fuel, bi-propellant rocket motor of similar size could develop over 3 lb of thrust. The rocket motor would be complete with turbopumps and control valves on the same chip. These devices may enable new concepts in propulsion, fluid control, and portable power generation.
We have developed an innovative MEMS education program that combines virtual fabrication with act... more We have developed an innovative MEMS education program that combines virtual fabrication with actual testing of classic MEMS devices. This approach is suitable both for large classes and in university environments that do not have access to large fabrication facilities. Under NSF funding, we are currently refining the curriculum tn allow the course to he easily adopted by other schools.
Abstract. Wireless sensor networks are poised to become a very significant enabling technology in... more Abstract. Wireless sensor networks are poised to become a very significant enabling technology in many sectors. Already a few very low power wireless sensor platforms have entered the marketplace. Almost all of these platforms are designed to run on batteries that have a ...
... Osvaldo Arenas1, Louis-M. Collin1 Simon Chow2, Jeffrey F. Wheeldon2, Christopher E. Valdivia2... more ... Osvaldo Arenas1, Louis-M. Collin1 Simon Chow2, Jeffrey F. Wheeldon2, Christopher E. Valdivia2, Karin Hinzer2, Luc Frechette1, Vincent Aimez1, Richard Arès1 1Centre de Recherche en Nanofabrication et en Nanocaractérisation CRN², Université de Sherbrooke, QC ...
IEEE Transactions on Components, Packaging and Manufacturing Technology, 2013
ABSTRACT Concentrated photovoltaics (CPV) focus the sunlight on a cell area smaller than the aper... more ABSTRACT Concentrated photovoltaics (CPV) focus the sunlight on a cell area smaller than the aperture area, making the use of highly efficient multijunction solar cells cost-effective. However, the high heat flux generated under concentration can raise the cell temperature and reduce the benefits of higher concentration. Low thermal resistance cell packages (receivers) associated with effective heat sinking can alleviate this problem. This paper proposes a new experimental method and characterization platform to measure the thermal performance of a solar cell receiver in a specific cooling module. The platform injects a calibrated heat flux into a test receiver to measure its contribution to the thermal resistance, demonstrating an accuracy and reproducibility of ±0.15°C/W. A metric to evaluate the heat spreading capability of the receiver is defined and extracted from experimental measurements conducted with different thermal boundary conditions. Multiple receiver configurations and materials were characterized, demonstrating that the proposed test methodology and platform can capture their impact on the heat spreading capabilities. The results also highlight the importance of thermal interfaces and the benefits of spreading the heat in metallic layers before conducting it through the dielectric layers that form the receiver. The proposed metrics and characterization platform will therefore be beneficial for the design, experimental development, and selection of CPV receivers and cooling modules.
The presented work analyses the design space and performance potential of microfabricated Brayton... more The presented work analyses the design space and performance potential of microfabricated Brayton cycle and Rankine cycle devices, accounting for lower component efficiencies, temperatures limited by the material properties and system implementation -constraints imposed by silicon microfabrication and miniaturization. By exploring the design space of such microsystems, their potential thermal efficiency and power density are defined. Results for both types of devices are shown graphically and design challenges and guidelines are determined and found to be different from their large-scale counterparts.
This paper presents the system-level and component design of a micro steam turbine power plant-on... more This paper presents the system-level and component design of a micro steam turbine power plant-on-a-chip which implements the Rankine cycle for micro power generation. The microfabricated device consists of a steam turbine that drives an integrated micropump and generator. Two-phase flow heat exchangers are also integrated on-chip with the rotating components to form a complete micro heat engine unit, converting heat to electricity. The system-level design includes cycle analysis and overall performance predictions, accounting for the expected performance of miniaturized components, thermal and structural integrity of the microsystem, and system-level trade-offs for optimal overall performance. Operating principles and design studies are also presented for the core component, with emphasis on a multistage, planar, radial microturbine and a spiral groove viscous pump. Design consideration for two-phase flow heat exchangers, microbearings, seals and micro-generators are also presented. Expected power levels range from 1-12 W per chip with energy conversion efficiency in the range of 1-11%. This suggests power density of up to 12 kW/kg for this technology, which is an order of magnitude greater than competing technologies, such as thermoelectrics. This study suggests the viability of a micro Rankine power plant-on-a-chip, but also identifies critical engineering challenges that must be met for practical implementation.
In this paper, the design process for multi-stage micro scale turbomachinery will be presented, a... more In this paper, the design process for multi-stage micro scale turbomachinery will be presented, along with CFD predictions of the key aerodynamic performance parameters required in this design process. This work focuses on the unique and unexplored design space defined by the small scale and planar geometries characteristic of MEMS turbopumps, compressors, gas turbines, steam turbines, or other turbomachinery-based microsystems. Correlations are proposed for the loss coefficient, based on laminar flow theory. A critical Reynolds number is also identified (Re crit =200-300), below which adjacent boundary layers merge, inducing a sharp increase in loss and deviation. This imposes practical limits on the miniaturization of such microturbomachinery.
This paper presents the experimental testing and characterization of a microscale radial outflow ... more This paper presents the experimental testing and characterization of a microscale radial outflow turbine with four concentric stages. The device is a five layer structure composed of shallow and deep reactive ion etched silicon wafers and an ultrasonically drilled Pyrex glass wafer that are assembled using anodic and fusion bonding techniques. They enclose a 4mm diameter rotor that was spun up to 330,000 rpm and produced roughly 0.1W of mechanical power from each stage totaling 0.38W with 0.75 atm differential pressure across the microturbine. Modeling of the turbine based on a mean line analysis with loss correlations extracted from CFD suggests a turbine isentropic efficiency of 35% and Re=266 at the maximum speed. The pressure distribution across the blades rows was measured and showed close agreement with the calculation results. Using the model, the microturbine is predicted to produce 3.2 watts with an isentropic efficiency of 63% at a rotor speed of 1.1 million rpm.
ABSTRACT A parametric investigation has been performed to study the different operating limits of... more ABSTRACT A parametric investigation has been performed to study the different operating limits of heat pipes employing a novel type of metal foam as wick for chip cooling applications. These foams have a unique spherical pore cluster microstructure with very high surface to volume ratio compared to traditional metal foams and exhibit higher operating limits in preliminary tests of heat pipes, suggesting high cooling rates for microelectronics. In the first part of this parametric study, widely used correlations are applied to calculate the five types of heat transfer limits (capillary, boiling, viscous, entrainment and sonic) as a function of temperature, type of foam, and porosity. Results show that the dominant limit is mostly the capillary limit, but for 50 pore-per-inch (PPI) foam, the boiling limit will be dominant. Also, 50 and 60 PPI foams have higher heat transfer limits than sintered copper powder. In the second part of this study, thermodynamic steady state modeling of a flat heat pipe has been done to study the effect of the different parameters on the dominant limit (capillary). A dimensionless number has been proposed to evaluate the balance between the pressure loss in the vapor and liquid phases as an additional design guideline to improve the capillary limit in flat heat pipes.
ABSTRACT Micro-electro-mechanical systems (MEMS) are an enabling technology that has lead to vari... more ABSTRACT Micro-electro-mechanical systems (MEMS) are an enabling technology that has lead to various miniature sensor concepts. Utilizing recent advances in silicon carbide (SiC) MEMS fabrication techniques allows for the development of a new series of sensors that leverages the high temperature capabilities of SiC. One such sensor concept is a shear stress sensor that can operate over a high dynamic range, and at very high temperatures, with an application emphasis on ground and flight testing in supersonic and hypersonic flow. The application of this fundamental sensor element and capacitance sensing design to very high temperature and very high shear environment, however, brings another set of challenges that involve the associated packaging and electrical control scheme. While this project is still a work in progress, we present an overview of our efforts to design, develop, fabricate and test a MEMS shear stress sensor for hypersonic aeropropulsion test and evaluation applications.
In a recent study, an effective means of mixing a low Reynolds number pressure-driven flow in a m... more In a recent study, an effective means of mixing a low Reynolds number pressure-driven flow in a micro-channel was reported by Stroock et al. using trenches on the lower wall that form a staggered herringbone pattern. In the present work numerical results are reported that indicate enhanced mixing using a similar herringbone pattern in the context of an electroosmotically driven flow in microchannels. Instead of trenches, all walls are flush, making microfabrication easier. The lower wall would have lithographically deposited polymer coatings that exhibit a zeta potential of a sign opposite to that at the other walls. These coatings are chosen to form a herringbone pattern.
Abstract. Resistance Temperature Detectors were used to investigate the thermal performance of th... more Abstract. Resistance Temperature Detectors were used to investigate the thermal performance of three different cell carrier structures. A carrier configuration with 0.78 mm thick C110 grade copper and 54 µm thick dielectric epoxy was chosen to fabricate five ...
This paper introduces and experimentally demonstrates the design concept of multi-stage microturb... more This paper introduces and experimentally demonstrates the design concept of multi-stage microturbomachinery, which is fabricated using silicon microfabrication technology. The design process for multi-stage micro scale turbomachinery based on meanline analysis is presented, along with CFD predictions of the key aerodynamic performance parameters required in this design process. This modeling was compared to a microturbine device with a 4mm diameter rotor and 100 micron chord blades, based on microelectromechanical system (MEMS) technology, which was spun to 330,000 RPM and produced 0.38W of mechanical power. Modeling suggests a turbine adiabatic efficiency of 35% and Re=266 at the maximum speed. The pressure distribution across the blade rows was measured and showed close agreement with the calculation results. Using the model, the microturbine is predicted to produce 3.2 watts with an adiabatic efficiency of 63% at a rotor speed of 1.1 million rpm.
This work presents the impact of integrating microfluidic channels at different locations in a 3D... more This work presents the impact of integrating microfluidic channels at different locations in a 3D stacked chip configuration to improve its thermal management. Bringing fluidic cooling within the microelectronic package can allow the use of higher power chips in limited space applications, but suitable sites for the microchannels in packaged 3D stacks must be determined. The approach uses an analytical representation of microfluidics and heat transfer at the package level to evaluate the equivalent thermal resistances. This analytical lumped-element circuit model is used to compare different microchannel cooling configurations, for 3D stacked chips. With the addition of microfluidic cooling, the allowable power level increases dramatically. The study also shows that locating the fluid cooling inside or adjacent to the chip stack reduces the thermal resistance over 6 times compared to microchannels located at the surface of the molding or the ball grid array. Within the chip stack ho...
The use of silicon microfabrication is evaluated to form micron scale electrode structures for pr... more The use of silicon microfabrication is evaluated to form micron scale electrode structures for proton exchange membrane fuel cells. The structure of the half cell consists of a perforated; electrically conductive; silicon gas diffusion layer (GDL) on one side. With an etched matrix of high aspect ratio silicon columns covered with platinum catalyst and a thin polymer electrolyte film (Nafion), acting as the electrodes on the other side. Design guidelines are defined through analytical modeling of mass transport, catalytic surface area, and internal ionic and electrical resistance. Progress in developing the microfabrication processes to create the silicon structure, the Pt layer, the Nafion layer and cell assembly are then presented. Work to date suggests that achieving high catalytic surface area and low ionic resistance in the electrodes will be challenging with the proposed approach, but will allow first order modeling and geometric optimization to potentially reduce Pt loading.
An analysis of water management in air breathing small polymer electrolyte membrane fuel cells (P... more An analysis of water management in air breathing small polymer electrolyte membrane fuel cells (PEM-FCs) is presented. Comprehensive understanding of flooding and dry-out limiting phenomena is presented through a combination of analytical modeling and experimental investigations using a small PEMFC prototype. Configurations of the fuel cell with different heat and mass transfer properties are experimentally evaluated to assess the impact of thermal resistance and mass transport resistance on water balance. Manifestation of dry-out and flooding problems, as limiting phenomena, are explained through a ratio between these two resistances. Main conclusions are that decreasing the ratio between thermal and mass transport resistance under a certain point leads to flooding problems in air breathing PEMFC. Increasing this ratio leads to dry-out of the polymer electrolyte membrane. However, too high thermal resistance or too low mass transport resistance reduces the limiting current by pushing forward the dry-out problem. This work provides a framework to achieve the proper balance between thermal rejection and mass transport to optimize the maximum current density of free convection fuel cells.
This is a report on work in progress on microelectrical and mechanical systems (MEMS)-based gas t... more This is a report on work in progress on microelectrical and mechanical systems (MEMS)-based gas turbine engines, turbogenerators, and rocket engines currently under development at MIT. Fabricated in large numbers in parallel using semiconductor manufacturing techniques, these engines are based on micro-high speed rotating machinery with the same power density as that achieved in their more familiar, full-sized brethren. The micro-gas turbine is a 1 cm diameter by 3 mm thick SiC heat engine designed to produce 10-20 W of electric power or 0.05-0.1 Nt of thrust while consuming under 10 grams/hr of H 2 . Later versions may produce up to 100 W using hydrocarbon fuels. A liquid fuel, bi-propellant rocket motor of similar size could develop over 3 lb of thrust. The rocket motor would be complete with turbopumps and control valves on the same chip. These devices may enable new concepts in propulsion, fluid control, and portable power generation.
We have developed an innovative MEMS education program that combines virtual fabrication with act... more We have developed an innovative MEMS education program that combines virtual fabrication with actual testing of classic MEMS devices. This approach is suitable both for large classes and in university environments that do not have access to large fabrication facilities. Under NSF funding, we are currently refining the curriculum tn allow the course to he easily adopted by other schools.
Abstract. Wireless sensor networks are poised to become a very significant enabling technology in... more Abstract. Wireless sensor networks are poised to become a very significant enabling technology in many sectors. Already a few very low power wireless sensor platforms have entered the marketplace. Almost all of these platforms are designed to run on batteries that have a ...
... Osvaldo Arenas1, Louis-M. Collin1 Simon Chow2, Jeffrey F. Wheeldon2, Christopher E. Valdivia2... more ... Osvaldo Arenas1, Louis-M. Collin1 Simon Chow2, Jeffrey F. Wheeldon2, Christopher E. Valdivia2, Karin Hinzer2, Luc Frechette1, Vincent Aimez1, Richard Arès1 1Centre de Recherche en Nanofabrication et en Nanocaractérisation CRN², Université de Sherbrooke, QC ...
IEEE Transactions on Components, Packaging and Manufacturing Technology, 2013
ABSTRACT Concentrated photovoltaics (CPV) focus the sunlight on a cell area smaller than the aper... more ABSTRACT Concentrated photovoltaics (CPV) focus the sunlight on a cell area smaller than the aperture area, making the use of highly efficient multijunction solar cells cost-effective. However, the high heat flux generated under concentration can raise the cell temperature and reduce the benefits of higher concentration. Low thermal resistance cell packages (receivers) associated with effective heat sinking can alleviate this problem. This paper proposes a new experimental method and characterization platform to measure the thermal performance of a solar cell receiver in a specific cooling module. The platform injects a calibrated heat flux into a test receiver to measure its contribution to the thermal resistance, demonstrating an accuracy and reproducibility of ±0.15°C/W. A metric to evaluate the heat spreading capability of the receiver is defined and extracted from experimental measurements conducted with different thermal boundary conditions. Multiple receiver configurations and materials were characterized, demonstrating that the proposed test methodology and platform can capture their impact on the heat spreading capabilities. The results also highlight the importance of thermal interfaces and the benefits of spreading the heat in metallic layers before conducting it through the dielectric layers that form the receiver. The proposed metrics and characterization platform will therefore be beneficial for the design, experimental development, and selection of CPV receivers and cooling modules.
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Papers by Luc Fréchette