This thesis employs computational and experimental methods to explore hotspot cooling and high heat flux removal from a 3-D stacked chip using thermoelectric and microfluidic devices. Stacked chips are expected to improve microelectronics performance, but present severe thermal management challenges. The thesis provides an assessment of both thermoelectric and microfluidic technologies and provides guidance for their implementation in the 3-D stacked chips. A detailed 3-D thermal model of a stacked electronic package with two dies and four ultrathin integrated TECs is developed to investigate the efficacy of TECs in hotspot cooling for 3-D technology. The numerical analysis suggests that TECs can be used for on demand cooling of hotspots in 3-D stacked chip architecture. A strong vertical coupling is observed between the top and bottom TECs and it is found that the bottom TECs can detrimentally heat the top hotspots. As a result, TECs need to be carefully placed inside the package to avoid such undesired heating. Thermal contact resistances between dies, inside the TEC module, and between the TEC and heat spreader are shown to significantly affect TEC performance. TECs are most effective for cooling localized hotspots, but microchannels are advantageous for cooling large background heat fluxes. In the present work, the results of heat transfer and pressure drop experiments in the microchannels with water as the working fluid are presented and compared to the previous microchannel experiments and CFD simulations. Heat removal rates of greater than 100 W/cm2 are demonstrated with these microchannels, with a pressure drop of 75 kPa or less. A novel empirical correlation modeling method is proposed, which uses finite element modeling to model conduction in the channel walls and substrate, coupled with an empirical correlation to determine the convection coefficient. This empirical correlation modeling method is compared to resistor network and CFD modeling. The proposed modeling method produced more accurate results than resistor network modeling, while solving 60% faster than a conjugate heat transfer model using CFD. The results of this work demonstrate that microchannels have the ability to remove high heat fluxes from microelectronic packages using water as a working fluid. Additionally, TECs can locally cool hotspots, but must be carefully placed to avoid undesired heating. Future work should focus on overcoming practical challenges including fabrication, cost, and reliability which are preventing these technologies from being fully leveraged.

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Detta examensarbete handlar om utvecklingen av kylare med inriktning på nyutveckling. Det relevanta behovet av patent för kylare, att undersöka vad kunden behöver vid sida av hur integration ska ske samt kombinationen av market pull och technology push är de fyra huvudområden som behandlas i studien. Bortsett från inkrementella förbättringar, har mycket lite utveckling gjorts inom kylare på senare tid, vilket återspeglas i några nämnvärda förändringar. Dessutom har lite tidigare arbete utförts på utvecklingen av kylare, vilket förklarar varför en utforskande metod har använts. Kvalitativa data har samlats in från åtta olika kunder med målet att fastställa behoven och de huvudsakliga tendenserna på marknaden, en studie användes som ett exempel för att stödja de olika resonemangen. En grundlig litteraturstudie och analys av marknaden har genomförts för att bättre förstå syftet för utveckling av kylare. Patent har visat sig vara relevanta för kylare, eftersom patenterade inkrementella innovationer ger produktdifferentiering i en starkt konkurrensutsatt marknad. Däremot kan kostnaderna bli ett problem för genomförandet. Faktumet att kunderna vill kylare med ett lägre pris och en förbättrad kylkapacitet är den viktigaste slutsatsen av de utförda intervjuerna. Komplexiteten i strukturen som förbinder företaget och dess kunder, och det faktum att marknaden inte är helt medveten om sina behov resulterar i en obetydlig marknadshänsyn inom utvecklingsprocessen. Bristen på marknadsintegration tillsammans med insikten att avsaknaden av grundlig nyutveckling kan försämra utvecklingen av kylare vilket har lett till en ny ram av utveckling. Baserat på integrationen av marknadens pull and technology push, är målet att utveckla mer nyutveklade kylare. / Air-oil coolers are hydraulic products whose purpose is to cool down the temperature of oil in a hydraulic system. This thesis project deals with their development with an emphasis on innovation. Apart from incremental improvements, very little innovation has been developed for coolers in recent times, which is reflected in few notable changes. Additionally, very little previous work has been conducted on the development of coolers, which explains why an explorative method was implemented. Qualitative data was collected from eight different customers with the purpose of determining the needs and the main tendencies, and a case study was used as an example to support the various reasonings. A thorough literature review and the market analysis have been carried out to better understand the context in which coolers are developed. The relevance of patents for coolers, the uncovering of the customer needs along with their integration as well as the combination of market pull and technology push concepts have been addressed. Thus, patents are proven to be relevant for coolers, because the patented innovations provide product differentiation in the highly competitive environment. However, their low added value can be an impediment to their exploitation. The fact that customers want coolers with a lower price and an improved cooling capacity is the major finding of the performed interviews. The complexity of the structure connecting the company and its customers, and the fact that the market is not completely aware of its needs, result in market considerations insubstantially integrated in the development process. Finally, the deficiency of market integration, in addition to the lack of radical innovation led to a suggested framework. Based on the integration of market pull and technology push approaches, it pursues the objective of fostering innovation in the development of coolers.

<p>The study of Surface Air Cooled Oil Coolers (SACOC) is motivated by the need for new cooling concepts for compact machinery designs with high thermal load. Installing finned heat exchangers in the bypass duct of a turbofan engine provides an additional cooling source having transonic flow as a heat sink. The characterization of the heat transfer and the aerodynamics of the design are essential to minimize the impact on the overall efficiency of the engine. In the present study, the SACOC is studied numerically and experimentally. Two geometries are tested in a high-speed linear wind tunnel where measurements are taken with multiple sensors and optical techniques. For the heat transfer characterization, an Inverse Heat Conduction Methodology (IHCM) based on a Levenberg-Marquardt Algorithm is developed. The experimental results are matched to numerical simulations using a Reynolds Averaged Navier-Stokes (RANS) solver. Finally, a multi-objective optimization algorithm is coupled <a>with the RANS solver</a> to explore new geometries that maximize the heat transfer and minimize the pressure drop across the studied domain. The 400 profiles generated allow for the identification of the features that have a higher influence on the performance of the fins and six profiles that present large improvements are chosen for further analysis.</p>