The cooling of electronic systems is a crucial issue in the light of the fast-growing heat flux removal demand. Three technologies are presented here: miniaturised vapour compression refrigeration system using a micro-channel heat sink, thermoelectric cooling and synthetic jet.
Dramatic increase in human dependence on electronic gadgets and components has resulted in rapid advancements in Very-Large-Scale Integration (VLSI) technology. This, in turn, led to an exponential rise in high-power, high-density, and high-speed microchips following Moore’s law. The flawless functioning of these electronic systems may get affected by some factors such as thermal overstressing, humidity, dust, noise, vibration and so on. Nevertheless, out of all these factors, system reliability is strongly dependent on the ambient temperature.1
Nearly 50% of failures in the internal parts of the electronic components are credited to overheating or thermal failure. The heat generated during the operation of the electronics should be effectively dissipated within a specific time limit for the proper functioning of the devices. Hence, it is desired to have an efficient thermal management system, which can efficiently remove the extra heat with simultaneous local temperature distribution control for improving reliability and avoid premature failure of these components.1
Several cooling techniques have been developed in the past for extracting the excess heat. These are classified into two categories: active cooling techniques and passive cooling techniques. Active cooling technologies need an external source of energy. Jet impingement, fan, air cooling, water cooling, vapour compression, thermoelectric coolers, synthetic jet (SJ), etc. are some of the active cooling devices. Passive cooling techniques remove heat by conduction, convection, and radiation without any additional energy source e.g. heat pipes, convective heat sinks, heat spreaders and thermal interface materials, etc. However, since electronic device processors produce more and more heat, the passive cooling technique may not be sufficient for cooling.1
. Researchers from Thailand2 have designed a miniature vapour compression refrigeration system using a micro-channel heat sink as an evaporator, in order to add more heat transfer area than in cold-plated and mini-channel heat sinks. They conclude that this system could be used for electronics cooling with the most suitable conditions at heating power of 200 W. The maximum COP (9.069) was reached at compressor speed of 3000 RPM.
. Chinese researchers3 have performed a comprehensive survey of thermoelectric cooling technology (TECT) applications in electronics cooling. They stress that with the advent of high heat flux electronic devices, conventional cooling system is no longer adequate to remove the heat fluxes at a sufficiently high rate and that TECT is one of the possible ways of solving the current heat dissipation issue. They present two analytical methodologies – a method of thermal resistance network and a method of effectiveness-number of transfer units – in order to evaluate TECT performance. They consider that low efficiency - the main drawback of TECT systems - will be improved thanks to the development of advanced thermoelectric materials and further technology.
. According to a paper from New Zealand researchers1, there is not even a single technology which can cope reliably with fast-growing heat flux removal demands. However, in the last decade, the research on Synthetic Jet (SJ) heat transfer application has been geared up because of its low cost, simple structure, light weight and facile installing making it more promising compared to other technologies in use. SJ is a fluidic device that acts as a Helmholtz resonator. It consists of an actuated cavity bounded by a periodically moving diaphragm/membrane under the influence of fluctuating voltage and a narrow opening (orifice/slot). Their paper presents a brief review of thermal enhancement using SJ along with the various parameters that influence its flow-field and cooling performance. In addition, it provides deep insights into the effect of parameters such as optimum jet-heated surface separation distance, dimensionless stroke-length, excitation frequency, number of jets and geometrical parameters on the heat transfer performance of the SJ. Finally, a list of potential gaps and challenges are presented for laying down the foundation for future research.
1 Krishan G. et al. Synthetic jet impingement heat transfer enhancement – A review, Applied Thermal Engineering, Volume 149 (2019) 1305–1323,
2 Poachaiyapoom A. et al. Miniature vapor compression refrigeration system for electronics cooling, Case Studies in Thermal Engineering (open access)
3 Cai Y. et al. Thermoelectric cooling technology applied in the field of electronic devices: Updated review on the parametric investigations and model developments, Applied Thermal Engineering, Volume 148, 5 February 2019, Pages 238-255