30,093 research outputs found
Nanoplasmon-enabled macroscopic thermal management
In numerous applications of energy harvesting via transformation of light
into heat the focus recently shifted towards highly absorptive materials
featuring nanoplasmons. It is currently established that noble metals-based
absorptive plasmonic platforms deliver significant light-capturing capability
and can be viewed as super-absorbers of optical radiation. However, direct
experimental evidence of plasmon-enabled macroscopic temperature increase that
would result from these efficient absorptive properties is scarce. Here we
derive a general quantitative method of characterizing light-capturing
properties of a given heat-generating absorptive layer by macroscopic thermal
imaging. We further monitor macroscopic areas that are homogeneously heated by
several degrees with plasmon nanostructures that occupy a mere 8% of the
surface, leaving it essentially transparent and evidencing significant heat
generation capability of nanoplasmon-enabled light capture. This has a direct
bearing to thermophotovoltaics and other applications where thermal management
is crucial
Thermal analysis of lithium ion battery-equipped smartphone explosions
Thermal management of mobile electronics has been carried out because performance of the application processor has increased and power dissipation in miniaturized devices is proportional to its functionalities. There have been various studies on thermal analyses related to mobile electronics with the objectives of improving analysis methodologies and cooling strategies to guarantee device safety. Despite these efforts, failure to control thermal energy, especially in smartphones, has resulted in explosions, because thermal behaviors in the device under various operating conditions have not been sufficiently conducted. Therefore, several scenarios that caused the failure in thermal management of smartphone was analyzed to provide improved insight into thermal design deducing the parameters, that affect the thermal management of device. Overcurrent in battery due to malfunction of battery management system or immoderate addition of functionalities to the application processor are considered as reliable causes leading to the recent thermal runaways and explosions. From the analyses, it was also confirmed that the heat generation of the battery, which have not been considered importantly in previous literature, has significant effect on thermal management, and heat spreading could be suppressed according to arrangement of AP and battery. The heat pipe, which is utilized as a cooling device in mobile electronics, was also included in the thermal analyses. Although the heat pipes have been expected to improve the thermal management in mobile electronics, it showed limited heat transfer capacity due to its operating conditions and miniaturization. The demonstrated results of our analysis warn against vulnerabilities of smartphones in terms of safety in design
Understanding the thermal implications of multicore architectures
Multicore architectures are becoming the main design paradigm for current and future processors. The main reason is that multicore designs provide an effective way of overcoming instruction-level parallelism (ILP) limitations by exploiting thread-level parallelism (TLP). In addition, it is a power and complexity-effective way of taking advantage of the huge number of transistors that can be integrated on a chip. On the other hand, today's higher than ever power densities have made temperature one of the main limitations of microprocessor evolution. Thermal management in multicore architectures is a fairly new area. Some works have addressed dynamic thermal management in bi/quad-core architectures. This work provides insight and explores different alternatives for thermal management in multicore architectures with 16 cores. Schemes employing both energy reduction and activity migration are explored and improvements for thread migration schemes are proposed.Peer ReviewedPostprint (published version
Integrated electroplated heat spreaders for high power semiconductor lasers
Thermal management of high power semiconductor lasers is challenging due to the low thermal conductivity of the laser substrate and the active device layers. In this work, we demonstrate the use of a microfabricated laser test device to study the thermal management of edge emitting semiconductor lasers. In this device, metallic heat spreaders of high thermal conductivity are directly electroplated on structures that mimic edge-emitting semiconductor lasers. The effects of various structural parameters of the heat spreader on the reduction of the thermal resistance of the laser test device are demonstrated both experimentally and theoretically. Without resolving to computational costive simulations, we developed two independent analytical models to verify the experimental data and further utilized them to identify the dominant thermal resistance under different laser mounting configurations. We believe our approach here of using microfabricated devices to mimic thermal characteristics of lasers as well as the developed analytical models for calculating the laser thermal resistance under different mounting configurations can potentially become valuable tools for thermal management of high power semiconductor lasers
Nonlinear model predictive control for thermal management in plug-in hybrid electric vehicles
© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.A nonlinear model predictive control (NMPC) for the thermal management (TM) of Plug-in Hybrid Electric Vehicles (PHEVs) is presented. TM in PHEVs is crucial to ensure good components performance and durability in all possible climate scenarios. A drawback of accurate TM solutions is the higher electrical consumption due to the increasing number of low voltage (LV) actuators used in the cooling circuits. Hence, more complex control strategies are needed for minimizing components thermal stress and at the same time electrical consumption. In this context, NMPC arises as a powerful method for achieving multiple objectives in Multiple input- Multiple output systems. This paper proposes an NMPC for the TM of the High Voltage (HV) battery and the power electronics (PE) cooling circuit in a PHEV. It distinguishes itself from the previously NMPC reported methods in the automotive sector by the complexity of its controlled plant which is highly nonlinear and controlled by numerous variables. The implemented model of the plant, which is based on experimental data and multi- domain physical equations, has been validated using six different driving cycles logged in a real vehicle, obtaining a maximum error, in comparison with the real temperatures, of 2C. For one of the six cycles, an NMPC software-in-the loop (SIL) is presented, where the models inside the controller and for the controlled plant are the same. This simulation is compared to the finite-state machine-based strategy performed in the real vehicle. The results show that NMPC keeps the battery at healthier temperatures and in addition reduces the cooling electrical consumption by more than 5%. In terms of the objective function, an accumulated and weighted sum of the two goals, this improvement amounts 30%. Finally, the online SIL presented in this paper, suggests that the used optimizer is fast enough for a future implementation in the vehicle.Accepted versio
Thermal management in microfluidics using micro-Peltier junctions
We report refrigeration and heating of nanoliter fluid volumes with micro-Peltier junctions. The temperature of small liquid reservoirs can be rapidly changed and controlled within a range between -3 degrees C to over 120 degrees C with good long-term stability. These thermal management systems enable the fabrication of complex chip-based chemical and biochemical reaction systems in which the temperature of many processes can be controlled independently
Effective thermal management of multiple electronic components
[[abstract]]The objective of this paper is to provide an effective and accurate analytical solution to compute the spreading thermal resistance of a vapor chamber thermal module, as well as the surface temperatures and the heat flux distributions at the heating surface. The analytical solutions are expressed in a reduced unit system with the governing parameters of the corresponding distance between heat sources, dimensionless plate thickness of the vapor chamber. This paper also presents vapor chamber temperature distribution, and it is correlation to heat source sizes, hence, spreading thermal resistance decreases with the increasing lateral length. There is the obvious difference between spreading thermal and conductive thermal resistance as lateral length is disproportion to heating area. Therefore, spreading thermal resistance is an important factor when design the thermal solution of a high density chipset power, and it caused high temperature in heat sources by embedded a thinner heat sink base. According to Fourier conductivity theorem, spreading thermal resistance is disproportion to sink base, then thermal resistance is not only parameter for vapor chamber module design, it needs to consider spreading resistance of vapor chamber and fin performance for cooling LEDs array, in order to prevent mismatch on numerical analysis and mathematical calculation. Thermal simulation is used as a design tool, and it is close to experimental data. The difference is within 5.9%, and it presents a precise result.[[conferencetype]]國際[[conferencedate]]20101020~20101022[[iscallforpapers]]Y[[conferencelocation]]Taipei, Taiwa
Atom Interferometry in Space: Thermal Management and Magnetic Shielding
Atom interferometry is an exciting tool to probe fundamental physics. It is
considered especially apt to test the universality of free fall by using two
different sorts of atoms. The increasing sensitivity required for this kind of
experiment sets severe requirements on its environments, instrument control,
and systematic effects. This can partially be mitigated by going to space as
was proposed, for example, in the Spacetime Explorer and Quantum Equivalence
Principle Space Test (STE-QUEST) mission. However, the requirements on the
instrument are still very challenging. For example, the specifications of the
STE-QUEST mission imply that the Feshbach coils of the atom interferometer are
allowed to change their radius only by about 260 nm or 2.6E-4% due to thermal
expansion although they consume an average power of 22 W. Also Earth's magnetic
field has to be suppressed by a factor of 10E5. We show in this article that
with the right design such thermal and magnetic requirements can indeed be met
and that these are not an impediment for the exciting physics possible with
atom interferometers in space.Comment: v2: minor changes to agree with published version; 8 pages, 6 figure
Using MCD-DVS for dynamic thermal management performance improvement
With chip temperature being a major hurdle in microprocessor design, techniques to recover the performance loss due to thermal emergency mechanisms are crucial in order to sustain performance growth. Many techniques for power reduction in the past and some on thermal management more recently have contributed to alleviate this problem. Probably the most important thermal control technique is dynamic voltage and frequency scaling (DVS) which allows for almost cubic reduction in power with worst-case performance penalty only linear. So far, DVS techniques for temperature control have been studied at the chip level. Finer grain DVS is feasible if a globally-asynchronous locally-synchronous (GALS) design style is employed. GALS, also known as multiple-clock domain (MCD), allows for an independent voltage and frequency control for each one of the clock domains that are part of the chip. There are several studies on DVS for GALS that aim to improve energy and power efficiency but not temperature. This paper proposes and analyses the usage of DVS at the domain level to control temperature in a clustered MCD microarchitecture with the goal of improving the performance of applications that do not meet the thermal constraints imposed by the designers.Peer ReviewedPostprint (published version
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