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This paper assesses the use of variable conductance heat pipes (VCHPs) for reduced-power precision temperature control of photonics components. When subambient cooling is not required we consider only a VCHP and where it is required we consider a VCHP-thermoelectric module (TEM) assembly. In the former case, the setpoint of the component mounted to the VCHP is 70^\circC and a range of heat loads (0 to 12 W) and ambient temperatures (-5^\circC to 65^\circC), representative of a photonics component in a telecommunications environment, are imposed on the system. In passive operation, the VCHP provided good temperature control for varying heat load, but not for varying ambient temperature. In active operation, i.e., when the reservoir of noncondensable gas on the VCHP is heated, good temperature control is achieved for ambient temperatures from 10^\circC to 65^\circC. The experimental measurements are compared with the theoretical predictions of the flat front model. For the TEM-VCHP assembly experiments, the component is maintained at a representative setpoint temperature, 63\pm 1^\circC, for heat loads from 2 to 7 W and ambient temperatures from 0^\circC to 60^\circC, such that a TEM is essential. The TEM-VCHP assembly power consumption is quantified and compared with a TEM-constant conductance heat pipe assembly. The maximum TEM power consumption for the TEM-VCHP assembly is over 40% lower. [ABSTRACT FROM PUBLISHER]

Due to ever increasing consumer demand, today's marketplace is full of portable computing devices such as notebook computers, gaming machines, personal digital assistants, and smart phones. In each of these technologies, processing power and functionality levels are continuing to increase, resulting in increased thermal management issues. The former of these technologies already use an active cooling solution with a profile of 10-15mm while the latter two are quickly approaching the limits of passive cooling. Since a common characteristic in each of these technologies is the desire to reduce profile height, there exists a need to develop low profile cooling solutions that are capable of supporting this growing market. However, a prerequisite to developing such solutions is an accurate understanding of how the noise level characteristics of the driving fans scale with height. This paper experimentally addresses the acoustic scaling of low profile fans. The rotor heights range from 0.5mm to 15mm with diameters from 15mm to 32mm, giving an aspect ratio of height relative to diameter of 0.03-0.6. The results can be used as a foundation for the development of active cooling in mobile devices where both correlations for noise levels and basic design criteria are identified. [ABSTRACT FROM AUTHOR]

Abstract: The increasing heat flux densities from portable electronics are leading to new methodologies being implemented to provide thermal management within such devices. Many technologies are under development to transport heat within electronic equipment to allow it to be dissipated into the surroundings via conduction, natural convection and radiation. Few have considered the approach of implementing a forced convection cooling solution in such devices. This work addresses the potential of low profile integrated fan and heat sink solutions to electronics thermal management issues of the future, particularly focusing upon possible solutions in low profile portable electronics. We investigate two heat sink designs with mini-channel features, applicable to low profile applications. The thermal performance of the integrated fan and heat sinks is seen to differ by approximately 40% and highlights the importance of designing an integrated thermal management solution at this scale rather than fan or heat sink in isolation. [Copyright &y& Elsevier]