Skin cooling and other challenges in future mobile form factor computing devices

Mongia, Rajiv; Bhattacharya, Anandaroop; Pokharna, Himanshu

doi:10.1016/j.mejo.2007.11.021

Cited by 16 publications

(6 citation statements)

References 9 publications

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“…Isothermal properties may, however, not always be present in embedded systems. Figure 1b shows an example of the thermal image of an unnamed thin and light notebook [21]. In this example, it is evident that the thermal profile can less likely be deemed isothermal within the thermal operating range of an embedded system.…”

Section: On the Isothermal Assumptionmentioning

confidence: 99%

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Theoretical Analysis of Radiative Cooling for Mobile and Embedded Systems

De Vogeleer,

Memmi,

Jouvelot

et al. 2014

Preprint

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A new global analytical model of the heat dissipation process that occurs in passively-cooled embedded systems is introduced, and we explicit under what circumstances the traditional assumption that exponential cooling laws apply in such context is valid. Since the power consumption and reliability of microprocessors are highly dependent on temperature, management units need accurate thermal models. Exponential cooling models are justified for actively-cooled systems. Here, we analyze the tractability of the cooling law for a passively cooled body, subject to radiative and convective cooling, including internal heat generation. Focusing then on embedded system-like objects, we compare the performance difference between our new passive cooling law and the conventionally-used exponential one. We show that, for quasi isothermal cooling surfaces of the order of 1 dm 2 or greater, the radiative cooling effect may become comparable to the convective cooling one. In other words, radiation becomes non-negligible for systems with a cooling surface larger than about 1 dm 2 . Otherwise for surfaces below 1 dm 2 , we show that the differences between the exact solution and the exponential cooling law becomes negligible. In the absence of accurate temperature measurements, an exponential cooling model is shown to be accurate enough for systems, such as small-sized SoCs, that require low processing overhead.

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Section: On the Isothermal Assumptionmentioning

confidence: 99%

“…Fig.1. Experimental thermal imaging of the skin temperature of (a) an Apple iPad[20] and (b) an unnamed thin notebook[21]. The iPad exemplifies the quasi-isothermal surface of an embedded system.…”

mentioning

confidence: 99%

Theoretical Analysis of Radiative Cooling for Mobile and Embedded Systems

De Vogeleer,

Memmi,

Jouvelot

et al. 2014

Preprint

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“…Several studies have focused on the cooling challenges of hand-held devices; Brown et al [2], Lee et al [5], Mongia et al [6], Huh et al [4], and Gurrum et al [3].…”

Section: Performance Expectationsmentioning

confidence: 99%

Thermal management challenges in the passive cooling of handheld devices

Wagner¹,

Maltz²

2013

19th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)

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This study explores the limits of cooling for handheld devices based on both testing and simulation under various conditions and provides guidelines for maximizing the amount of power that can be dissipated in these small form-factor devices. The factors affecting the maximum possible power dissipation are the available surface area and surface finishes, selection of the outer shell materials, thermal interface materials, heat spreaders and air gaps. In most cases, the limiting factor in the thermal design of these devices is not the temperatures of the internal components but the temperature of the external surfaces since these are in direct contact with the skin of the user. There have been studies that address the maximum allowable comfortable touch temperature of a handheld device. This study presents methods for maximizing the internal power dissipation of these devices while limiting the touch temperatures to the maximum comfortable limits.

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“…The streamwise self-similar flow profiles ( experiments 4 . A recent application of laminar wall jets is found in cooling devices of laptop computer processors 5 . According to linear stability theory (LST), laminar plane wall jets become unstable beyond a critical Reynolds number of Re c = 57 (Ref.…”

Section: Introductionmentioning

confidence: 99%

Spatial linear disturbances in a plane wall jet

2012

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A two-dimensional direct numerical simulation study of the linear instability in a laminar plane wall jet is presented. The evolution of the wall jet disturbances is in reasonable agreement with predictions by spatial linear stability theory only with regard to the wavelength and the amplitude shape of the disturbance, whereas significant differences in the linear growth rate are noticed. As a consequence, the "stable island" on the instability map based on linear stability theory turns out to be connected with the outer stable region in the simulations, thus taking the form of a "stable peninsula". The failure of the theory is attributed to the rapid streamwise spread and decay of the wall jet, which is incompatible with the assumption of parallel flow. We also assess the maximum possible transient linear amplification of two-dimensional disturbances in the plane wall jet, using the concept of optimal initial disturbances. The transient energy growth relies on the Orr mechanism, and the upper bound of the disturbance energy increases linearly in time for the present flow configuration. The optimal disturbances exhibit local maxima near the edge of the jet and close to the wall, where sites of effective receptivity are hence expected. We find that the outer region of the plane wall jet is more receptive to time periodic forcing than the inner region.

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Skin cooling and other challenges in future mobile form factor computing devices

Cited by 16 publications

References 9 publications

Theoretical Analysis of Radiative Cooling for Mobile and Embedded Systems

Theoretical Analysis of Radiative Cooling for Mobile and Embedded Systems

Thermal management challenges in the passive cooling of handheld devices

Spatial linear disturbances in a plane wall jet

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