With increasing awareness of climate change, governments and organizations have made it their mission to see a greener future. Countries like Norway, South Korea, and Canada have promised to ban internal combustion engines (ICE) by 2025-2035. Growing demand for cleaner modes of travel have taken over the market, causing everyone to look at electric vehicles for the solution. Tesla’s revenue has tripled in the past five years, 15 new electric car manufacturer shave joined, and almost all big-name ICE companies have started producing electric/hybrid cars. As the number of electric vehicles increases, a solution to long charging times will be needed to keep up with the high-power-density fuel used in ICE. Charging stations are increasing in power ratings as Tesla introduces their 250-kW supercharger and EVBox with their 350-kW Ultronig stations. These stations are comprised of power modules that stack together to reach the desired power rating. Designing, testing, and implementing power modules for electric vehicles can be a complex process due to thermal efficiency and packaging challenges. To address these issues, it is essential to establish a design methodology for power modules that takes into account validation and packaging considerations. This thesis presents a design methodology for heat exchangers that allows for rapid prototyping with sufficient accuracy, approximately below 10%. The study includes numerical simulations, reduced modeling, and experimental validation, which can increase confidence during the design phase and reduce design times. Using reduced models for quick calculations instead of relying solely on numerical models can further expedite the process. A reliable and adaptable analytical methodology for heat exchanger design is crucial for successful optimization setup. / Thesis / Master of Applied Science (MASc)

Yes / In recent times, the subject of effective cooling have become an interesting research topic for electronic and mechanical engineers due to the increased miniaturization trend in modern electronic systems. However, fins are useful for cooling various low and high power electronic systems. For improved thermal management of electronic systems, porous fins of functionally graded materials (FGM) have been identified as a viable candidate to enhance cooling. The present study presents an analysis of a convective–radiative porous fin of FGM. For theoretical investigations, the thermal property of the functionally graded material is assumed to follow linear and power-law functions. In this study, we investigated the effects of inhomogeneity index of FGM, convective and radiative variables on the thermal performance of the porous heatsink. The results of the present study show that an increase in the inhomogeneity index of FGM, convective and radiative parameter improves fin efficiency. Moreover, the rate of heat transfer in longitudinal FGM fin increases as b increases. The temperature prediction using the Adomian decomposition method is in excellent agreement with other analytical and method.

The efficacy, reliability and versatility of the light emitting diode (LED) can outcompete most established light source technologies. However, they are particularly sensitive to high temperatures, which compromises their efficacy and reliability, undermining some of the technology s key benefits. Consequently, effective thermal management is essential to exploit the technology to its full potential. Thermal management is a well-established subject but its application in the relatively new LED lighting industry, with its specific constraints, is currently poorly defined. The question this thesis aims to answer is how can LED thermal management be achieved most effectively? This thesis starts with a review of the current state of the art, relevant thermal management technologies and market trends. This establishes current and future thermal management constraints in a commercial context. Methods to test and evaluate the thermal management performance of a luminaire system follow. The defined test methods, simulation benchmarks and operational constraints provide the foundation to develop effective thermal management strategies. Finally this work explores how the findings can be implemented in the development and comparison of multiple thermal management designs. These are optimised to assess the potential performance enhancement available when applied to a typical commercial system. The outcomes of this research showed that thermal management of LEDs can be expected to remain a key requirement but there are hints it is becoming less critical. The impacts of some common operating environments were studied, but appeared to have no significant effect on the thermal behaviour of a typical system. There are some active thermal management devices that warrant further attention, but passive systems are inherently well suited to LED luminaires and are readily adopted so were selected as the focus of this research. Using the techniques discussed in this thesis the performance of a commercially available component was evaluated. By optimising its geometry, a 5 % decrease in absolute thermal resistance or a 20 % increase in average heat transfer coefficient and 10 % reduction in heatsink mass can potentially be achieved . While greater lifecycle energy consumption savings were offered by minimising heatsink thermal resistance the most effective design was considered to be one optimised for maximum average heat transfer coefficient. Some more radical concepts were also considered. While these demonstrate the feasibility of passively manipulating fluid flow they had a detrimental impact on performance. Further analysis would be needed to conclusively dismiss these concepts but this work indicates there is very little potential in pursuing them further.

Experimental measurements and numerical simulations have been performed on copper and aluminum microchannel heatsinks of 300, 420, 500, and 900 &amp / #956 / m channel widths. The heatsinks have been designed specifically for use with T/R (transmit/receive) module cooling applications of military phased array radars. An analytical calculation was also performed to aid in the design methodology. Distilled water was used as the coolant with flow rates ranging from 0.50 lpm (liters per minute) to 1.00 lpm. Local heat fluxes as high as 100 W/cm2 were tested. Upon completion of the experiments, the thermally best performing specimen, the 300 &amp / #956 / m copper specimen, yielded a maximum temperature rise of 26.1 &deg / C between the heat load and coolant inlet, at a coolant flow rate of 1.00 lpm and local heat flux of 100 W/cm2, leading to a thermal resistance of 0.63 &deg / C/W. The pressure drop measured across the heatsink under these conditions was 0.030 bar. Numerical simulations were carried out using the commercial Computational Fluid Dynamics (CFD) software FLUENT&reg / . Effects of thermal interface layers and heat spreading due to the localized heat load were investigated. Simulation results for temperature were seen to agree fairly well with experimental data as long as thermal interface layers were accounted for. The study showed that the T/R modules of military phased array radars, dissipating as high as 100 W/cm2 locally, could be cooled within the limits of the harsh environmental conditions required of military applications with moderate pressure drops.

The Internet of Things (IoT) is an infrastructure of physical objects connected via the Internet that can exchange data to achieve efficient resource management. Billions of devices must be self-powered and low-cost considering the massive scale of the IoT. Thus, there is a need for low-cost ambient energy harvesters to power IoT devices. It is a challenging task since ambient energy might be unpredictable, intermittent and insufficient. For example, solar energy has limitations such as intermittence and unpredictability despite utilizing the highest power availability and relatively mature technology. Designing a multi-source energy harvester (MSEH) based on continuous and ubiquitous ambient energy sources might alleviate these issues by providing versatility and robustness of power supply. However, combining several energy harvesters into one module must be done synergistically to ensure miniaturization, compactness and more collected energy. Also, additive manufacturing techniques must be used to achieve low-cost harvesters and mass manufacturability. This dissertation presents two different kind of ambient energy harvesters, namely radio frequency energy harvester (RFEH) and thermal energy harvester (TEH). Each harvester is individually optimized and then synergistically combined into a MSEH. First, RFEH is designed for triple-band harvesting (GSM900, GSM1800, 3G2100) using the antenna-on-package concept and fabricated through 3D and screen printing. TEH collects energy from temperature fluctuations of ambient environment through a combination of thermoelectric generators and phase change materials. It is adapted specifically for the desert conditions of Saudi Arabia. Later, TEH and RFEH are combined to realize MSEH. Smart integration is achieved by designing a dual-function component, heatsink antenna, that serves as a receiving antenna of RFEH and a heatsink of TEH. The heatsink antenna has been optimized for both antenna radiation performance and heat transfer performance. Field tests showed that the MSEH can collect 3680μWh energy per day and the outputs of TEH and RFEH have increased 4 and 3 times compared to the independent TEH and RFEH respectively. To validate the utility of the MSEH, a temperature/humidity sensor has been successfully powered by the MSEH. Overall, sensor’s data can be wirelessly transmitted with time intervals of 3.5s, highlighting the effectiveness of the synergistic MSEH.

No description available.

Yes / The ever-increasing demand for high-processing electronic systems has unequivocally called for improved microprocessor performance. However, increasing microprocessor performance requires increasing power and on-chip power density, both of which are associated with increased heat dissipation. Electronic cooling using fins have been identified as a reliable cooling approach. However, an investigation into the thermal behaviour of fin would help in the design of miniaturized, effective heatsinks for reliable microprocessor cooling. The aim of this paper is to investigates the simultaneous effects of surface roughness, porosity and magnetic field on the performance of a porous micro-fin under a convective-radiative heat transfer mechanism. The developed thermal model considers variable thermal properties according to linear, exponential and power laws, and are solved using Chebychev spectral collocation method. Parametric studies are carried using the numerical solutions to establish the influences of porosity, surface roughness, and magnetic field on the microfin thermal behaviour. Following the results of the simulation, it is established that the thermal efficiency of the micro-fin is significantly affected by the porosity, magnetic field, geometric ratio, nonlinear thermal conductivity parameter, thermogeometric parameter and the surface roughness of the micro-fin. However, the performance of the micro-fin decreases when it operates only in a convective environment. In addition, we establish that the fin efficiency ratio which is the ratio of the efficiency of the rough fin to the efficiency of the smooth fin is found to be greater than unity when the rough and smooth fins of equal geometrical, physical, thermal and material properties are subjected to the same operating condition. The investigation establishes that improved thermal management of electronic systems would be achieved using rough surface fins with porosity under the influences of the magnetic field. / Supported in part by the Tertiary Education Trust Fund of Federal Government of Nigeria, and the European Union’s Horizon 2020 research and innovation programme under grant agreement H2020-MSCA-ITN- 2016SECRET-722424.

This thesis is an investigation of the current status of additive manufacturing (AM) regarding different technologies, the level of implementation in industry and the future obstacles for further implementation. As a secondary objective, an existing heatsink for electronic equipment was redesigned, adapted to and improved using the design advantages of AM, and was later manufactured through 3D-printing in aluminium (AlSi10Mg). The thesis resulted in a summarized roadmap of recommended actions for Saab Surveillance in Järfälla in the near future. And a redesigned heatsink, which was tested to hold a static pressure of 30 bar, and simulated to achieve the same pressure drop in the channel and withstand the same vibration load as the old heatsink. At the same time, the new design reduced the total weight by 20% and increased the heat transferring surface area of the channel by 100%, potentially doubling the heat transfer capability. / Detta examensarbete har undersökt den nuvarande statusen hos additiv tillverkning (AM) vad gäller olika teknologier, hur långt implementeringen i industrin kommit och framtida hinder som måste lösas för vidare implementering. Som sekundärt mål för projektet har en existerande elektronikkylare designats om och förbättrats med hjälp av designfördelarna hos AM, och tillverkades sedan genom 3D-printning i aluminium (AlSi10Mg). Arbetet har resulterat i en sammanfattad ’roadmap’ med rekommendationer för vad Saab Surveillance i Järfälla bör göra inom AM den närmaste tiden, samt en ny kylare som framgångsrikt trycktestades upp till 30 bar. Genom simuleringar visades den uppnå samma tryckfall och klara samma vibrationer som den tidigare kylaren, samtidigt som den väger 20% mindre och har en 100% ökning av kylkanalens våta area vilket potentiellt innebär en dubblering av kylförmågan.

Yes / The ever-increasing demand for high performance electronic and computer systems has unequivocally called for increased microprocessor performance. However, increasing microprocessor performance requires increasing the power and on-chip power density of the microprocessor, both of which are associated with increased heat dissipation. In recent times, thermal management of electronic systems has gained intense research attention due to increased miniaturization trend in the electronics industry. In the paper, we present a numerical study on the performance of a convective-radiative porous heat sink with functionally graded material for improved cooling of various consumer electronics. For the theoretical investigation, the thermal property of the functionally graded material is assumed as a linear and power-law function. We solved the developed thermal models using the Chebyshev spectral collocation method. The effects of inhomogeneity index of FGM, convective and radiative parameters on the thermal behaviour of the porous heat sink are investigated. The present study shows that increase in the inhomogeneity index of FGM, convective and radiative parameter improves the thermal efficiency of the porous fin heat sink. Moreover, for all values of Nc and Rd, the temperature gradient along the fin of FGM is negligible compared to HM fin in both linear and power-law functions. For comparison, the thermal predictions made in the present study using Chebyshev spectral collocation method agrees excellently with the established results of Runge-Kutta with shooting and homotopy analytical method. / Supported in part from PhD sponsorship of the first author by the Tertiary Education Trust Fund of the Federal Government of Nigeria.

This work deals with the issue of emissivity and its impact on the heat dissipation.The first part describes the basics of thermal management, the issue of emissivity and its measurement. In the second, experimental part, are dedicated the emissivity values of examined specimens. These values are then used as initial conditions for the thermal simulation. In the last part are compared the measured results and the simulated results and is evaluated the impact of emissivity for the heat dissipation.