Boiling and condensation in a liquid-filled enclosure,

Modular liquid cooling of electronic assemblies

Abstract: An electronic system includes an array of electronic assemblies at a first location within a system. An array of liquid cooling assemblies is placed at a second location within the system. Hoses or other liquid transport pathways connect the cooling assemblies to the electronic assemblies, for cooling the electronic assemblies. As more electronic assemblies are added to the system, additional cooling assemblies may be provided to manage the increased thermal demands.

Thermal Design of Immersion Cooling Modules for Electronic Components

Abstract: Direct immersion of electronic components in low-boiling point, dielectric fluids can provide a benign local ambience and accommodate substantial spatial and temporal power variations while minimizing component temperature excursions and failure rates. Following a review of possible immersion cooling configurations and the thermal mechanisms active in vapor-space and submerged condenser modules, attention is focused on the operational limits and relations for predicting submerged condenser performance. Finally, descriptions of three likely applications of submerged condenser technology are presented.

Immersion Cooling of Digital Computers

Abstract: The present work reviews the theory and practice of direct liquid cooling of microelectronic components. A morphological analysis is suggested for the classification of liquid-cooling concepts. While both immersion and microgroove cooling of chips are discussed, the emphasis is on immersion cooling. The performance of individual chips and liquid incapsulated modules, including the submerged condenser, is reviewed in detail, with data presented. Flow-through modules and falling-film techniques are also discussed. Finally, figures-of-merit for coolants are noted.

Passive decay heat removal in advanced LWR concepts

Abstract: This paper explores the possibilities of developing a passive LWR design concept which could ensure sufficient decay heat removal in the absence of emergency primary coolant supply without exceeding the safe temperature limit on cladding, and which could achieve large nominal operating power output in the range 600–1000 MWe. Various possibilities of passive decay heat removal in LWR concepts are assessed and choke points limiting the heat transfer from the fuel to the ultimate heat sink are identified. To eliminate these choke points, new core configurations are studied. The most promising concept appears to be a pressure tube reactor with fueled solid matrix and a separate moderator as a heat sink.

Experimental Investigation of a Direct Liquid Immersion Cooled Prototype for High Performance Electronic Systems

Abstract: As the demand grows for electronics to become faster and more compact, the expectation for tomorrow’s data center is no different. Like many of the current high performance data center installations, design considerations on all scales must be taken into account. The proposed solution does just this by looking at the entire cooling approach from the chip level all the way to the plenum level. The solution’s enclosure, where all the heated elements are immersed in either FC-72 or Novec 649, has dimensions of $150~{\rm mm} \times 300~{\rm mm} \times 38$ mm ( $H \times L \times W$ ). The design is versatile allowing for either flow or pool boiling heat transfer. Under pool boiling conditions, heat transfer coefficients as high as 11.5 kW/ $\text{m}^{2}\,\cdot \,\text{K}$ were achieved with surface enhancements and maximum power dissipations as high as 320 W were yielded as chip temperatures were roughly 58 °C, well below typical operating conditions. With the introduction of dielectric fluid flow within the enclosure, maximum power dissipations achieved increased substantially, reaching 605 W, which corresponds to a volumetric power dissipation of 0.354 W/cm3.

The mechanism of heat transfer in nucleate pool boiling—Part I: Bubble initiaton, growth and departure

Abstract: A criterion is developed for bubble initiation from a gas filled cavity on a surface in contact with a superheated layer of liquid. It is found that the temperature of bubble initiation on a given surface is a function of the temperature conditions in the liquid surrounding the cavity as well as the surface properties themselves. It is also found that the delay time between bubbles is a function of the bulk liquid temperature and the wall superheat, and is not constant for a given surface. By consideration of the transient conduction into a layer of liquid on the surface, a thermal layer thickness is obtained. With this thickness and a critical wall superheat relation for the cavity, a bubble growth rate is obtained. Bubble departure is considered and it is found that the Jakob and Fritz relation works as long as the true (non-equilibrium) bubble contact angle is used. At one gravity the primary effect of bubble growth velocity on bubble departure size is found to be due to contact angle changes.

On the stability of boiling heat transfer

Abstract: Boiling heat transfer in the nucleate region is reviewed The transition film-boiling region is analyzed by considering the stability of a plane vortex sheet separating two inviscid fluids Using the classical results of Helmholtz Kelvan and Rayleigh expressions have been derived that predict the maximum and minimum heat-transfer rates in the nucleate and the film-boiling regimes, respectively The model exhibits the essential features of the phenomenon and shows good agreement with experimental data (auth)