Publications de John Richard Thome

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The reliable prediction of pressure drop in two-phase flow is an important prerequisite to accurate optimization of thermal systems. Because of the complexity of these types of flow, empirical or semiempirical relationships are only of limited reliability ...

A novel visualization method was developed and implemented in a refrigerant-flooded evaporator tube bundle. Specifically, a method to visualize the two-phase flow inside plain tube bundles was developed using a dummy tube with a tubular glass section for v ...

Experimental condensation heat transfer data for the new refrigerant R1234ze(E), trans-1,3,3,3-tetrafluoropropene, are presented and compared with refrigerants R134a and R236fa for a vertically aligned, aluminum multi-port tube. Local condensation heat tra ...

A new type of flow structure has been observed in cocurrent adiabatic vertically downward air-water flow and is described here. Membranes, in the form of thin liquid films spanning the channel cross-section and horizontally dividing the gas core were visua ...

A new model for numerical simulations of condensing annular flows in microchannels was previously developed by Nebuloni and Thome [14]. Presently, their condensation model has been extended by including turbulent liquid films and evaporating annular flows. In particular, the treatment of dry patch formation in the evaporating thin film of the annular flow is carried out. As such, the model is able to predict heat transfer and fluid flow characteristics in a large portion of the flow pattern map for microcha

This paper presents numerical simulations of annular laminar film condensation heat transfer in micro-channels of different internal shapes. The model, which is based on a finite volume formulation of the Navier-Stokes and energy equations for the liquid phase only, importantly accounts for the effects of axial and peripheral wall conduction and non-uniform heat flux not included in other models so far in the literature. The contributions of the surface tension, axial shear stresses and gravitational forces

Efficient, small, state-of-the-art passive cooling two-phase systems, i.e. advanced micro-thermosyphon cooling systems, are viable solutions for high performance datacenter servers and power electronics cooling applications. The objective of this study is ...

This paper advances the state-of-the-art in novel passive two-phase systems for more efficient cooling of datacenters and telecom central offices compared to the traditional air-based cooling solutions (e.g. aisle-based containment systems). The proposed p ...

Three-dimensional (3D) stacking of integrated-circuit (IC) dies increases system density and package functionality by vertically integrating two or more dies with area-array through-silicon-vias (TSVs). This reduces the length of global interconnects and t ...

This paper is the third part of the present study on two-phase mini-thermosyphon cooling systems. As mentioned in the first two parts, gravity-driven cooling systems using microchannel flow boiling are a very promising long-term viable solution for electro ...

The fluid mechanics of elongated bubbles in confined gas-liquid flows in micro-geometries is important in pore-scale flow processes for enhanced oil recovery and mobilization of colloids in unsaturated soil. The efficiency of such processes is traditionall ...

A flow visualisation study of flow boiling of R245fa in silicon multi-microchannels at low mass flux and moderate heat flux has been carried out with a high speed digital camera. The micro-evaporator had 67 channels of length 20 mm, width 223 mu m, and hei ...

Cooling of datacenters is estimated to have an annual electricity cost of 1.4 billion dollars in the United States and 3.6 billion dollars worldwide. Currently, refrigerated air is the most widely used means of cooling datacenter’s servers, which typically ...

This paper introduces a numerical model developed based upon the arbitrary Lagrangian-Eulerian/finite element scheme to analyze bubble plumes in a periodic domain. A spherical air bubble is immersed into a large pool of quiescent water to act as an unconfi ...

To better understand the underlying two-phase phenomena and thus better predict transitions between the various two-phase flow patterns, it is necessary to update our way of thinking from one-of-a-kind flow pattern maps of limited applicability to a genera ...

Next-generation High-Performance Computing (HPC) systems need to provide outstanding performance with unprecedented energy efficiency while maintaining servers at safe thermal conditions. Air cooling presents important limitations when employed in HPC infr ...

Experimental test results for flow boiling of pure ammonia inside horizontal tubes were obtained for a plain stainless steel tube. Tests were run at a nominal saturation temperature of 4°C, nine mass velocities from 20- 140 kg/m2s, vapor qualities from 1-99% and heat fluxes from 5-58 kW/m2. Two-phase flow observations showed that the current test data covered the following regimes: fully stratified, stratified-wavy, intermittent, annular and annular with partial dryout. The Kattan-Thome-Favrat flow boiling

A heat transfer assembly for transferring heat from a heat generating device (5) to a circulating fluid, said heat transfer assembly comprising - an evaporator device (3) having at least one microchannel (1) formed therein, in thermally conductive contact ...

Intube evaporation tests for R-407C and R-407C/oil are reported for a plain copper tube. The tests were run at a nominal inlet pressure of 6.45 bar (93.5 psia) at mass velocities of 100, 200 and 300 kg/m2s (73581, 147162 and 220743 lb/h ft2) over nearly the entire vapor quality range. Pure R-407C performed very similar to pure R-134a run previously in similar tests at all three mass velocities, differing only at high vapor qualities where the peaks in href vs. x were shifted slightly. For local vapor qualit

Multiphase CFD simulations are presently employed to investigate the flow boiling of multiple sequential elongated bubbles in a horizontal microchannel. Most of the computational studies published so far explored the features of boiling flows within microc ...

John Richard Thome

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Flow pattern based two-phase frictional pressure drop model for horizontal tubes. Part I: Diabatic and adiabatic experimental study

Boiling on a Tube Bundle: Part I-Flow Visualization and Onset of Dryout

Experimental study on condensation heat transfer in vertical minichannels for new refrigerant R1234ze(E) versus R134a and R236fa

A new type of flow structure in cocurrent adiabatic vertically downward air-water flow: Membrane flow

Numerical Simulation of Condensing and Evaporating Annular Flows in Microchannels with Laminar and Turbulent Liquid Films

Numerical Modeling of the Conjugate Heat Transfer Problem for Annular Laminar Film Condensation in Microchannels

Two-Phase Mini-Thermosyphon Electronics Cooling, Part 1: Experimental Investigation

Operational Map And Thermal Performance Of A Thermosyphon Cooling System For Compact Servers

Modeling of Two-Phase Evaporative Heat Transfer in Three-Dimensional Multicavity High Performance Microprocessor Chip Stacks

Two-Phase Mini-Thermosyphon Electronics Cooling, Part 3: Transient Modeling and Experimental Validation

Pore-scale analysis of the minimum liquid film thickness around elongated bubbles in confined gas-liquid flows

A novel time strip flow visualisation technique for investigation of intermittent dewetting and dryout in elongated bubble flow in a microchannel evaporator

On-chip two-phase cooling of datacenters: Cooling system and energy recovery evaluation

ALE/finite element modeling of an unconfined bubble plume in periodic domain: bubble shape and oscillation analysis

Unified mechanistic multiscale mapping of two-phase flow patterns in microchannels

Design of a Two-Phase Gravity-Driven Micro-Scale Thermosyphon Cooling System for High-Performance Computing Data Centers

Evaporation of Ammonia in a Smooth Horizontal Tube : Heat Transfer Measurements and Predictions

Heat transfer assembly

Intube Flow Boiling of R-407C and R-407C/Oil Mixtures. Part 2: Plain Tube Results and Predictions

Numerical investigation of the influence of leading and sequential bubbles on slug flow boiling within a microchannel