Publications by John Richard Thome

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This paper presents a theoretical and numerical model to predict film condensation heat transfer in mini and micro-channels of different internal shapes. The model is based on a finite volume formulation of the Navier-Stokes and energy equations and it inc ...

The one-dimensional transient numerical code of JJ Cooling Innovation has been significantly improved to simulate the thermal/hydraulic performance of pulsating heat pipes (PHPs). Using a mechanistic approach, the liquid slug and vapor plug flows and their ...

Background. The small characteristic sizes (in the range of 102 - 103 μm) of Microstructured reactors (MSR) lead to very high specific interfacial area which, in turn, increases heat- and mass transfer efficiency. However, for quasi instantaneous exothermic reactions, the overall reaction kinetics in MSR is strongly influenced by mixing. The characteristic time of the latter phenomenon varies from millisecond to seconds depending on the operating conditions used. If mixing is the rate determining step for h

The present study illustrates new experimental two-phase flow pattern observations together with diabatic boiling and adiabatic two-phase frictional pressure drop results for ammonia (R7117) flowing inside a 14-mm internal diameter, smooth horizontal stain ...

Due to the increase in energy prices and spiralling consumption, there is a need to greatly reduce the cost of electricity within data centers, where it makes up 50% of the total cost of the IT infrastructure. A technological solution to this is using on-c ...

Measuring the strong local variation in heat transfer coefficients in multi-microchannel evaporators is related to the inverse heat conduction problem (IHCP). As the local flow heat transfer coefficients change greatly in magnitude from single-phase liquid ...

Extensive work on flow boiling in microchannels with the aim of cooling of electronics has been undertaken in the past 15 to 20 years. With this knowledge in hand, the next step is to develop detailed, accurate and validated simulation codes for steady-state and transient operations of (i) the entire thermal package (micro-channel evaporator, its inlet and outlet ports, the thermal interface material and the electronic chip), (ii) the flow distribution to multiple chips to be cooled in parallel, and (ii) th

A new method to predict the void fraction in annular two-phase flow in macroscale and microscale channels is presented. The underlying experimental database contains 2673 data points collected from 29 different literature studies for 8 different gas-liquid ...

Thermal designers of data centers and server manufacturers are showing a greater concern regarding the cooling of the new generation data centers, which consume considerably more electricity and dissipate much more waste heat, a situation that is creating ...

Thermal designers of data centers and server manufacturers are showing a great concern regarding the cooling of new generation data centers, which are more compact and dissipate more power than is currently possible to cool by conventional air conditioning ...

Two-phase micro-scale cooling implemented with passive, gravity-driven closed-loop thermosyphons represents a highly-reliable solution to increase heat dissipation and to maximize energy efficiency of the next-generation electronics cooling technologies. T ...

This paper presents numerical simulations of annular laminar film condensation heat transfer in microchannels 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 nonuniform heat flux not included in other models so far in the literature. The contributions of the surface tension, axial shear stresses, and gravitational forces

Two-phase, refrigerant-based cooling offers significant promise for increasing heat densities and energy efficiencies of electronic components. One barrier to wide spread adoption of two-phase cooling solutions is preserving product features deemed essenti ...

This paper presents a comprehensive and critical review of studies on nucleate pool boiling heat transfer, flow boiling heat transfer, critical heat flux (CHF), and two-phase flow phenomena with nanofluids. First, general analysis of the available studies ...

An experimental study is presented to characterize two-phase thermal and hydraulic performance of a prototype corrugated plate heat exchanger with small pressing depth. In particular, upward flow boiling of low pressure refrigerant R245fa was investigated ...

In the framework of Isothermal Compressed Air Energy Storage (CAES), a new finned piston compressor has been designed and realized at LEI laboratory in EPFL. This system comprises a series of concentric annuli’s fitting into each other compressing the air ...

A moving mesh approach is employed to simulate two-phase flow with phase change. The mathematical model is based on the Arbitrary Lagrangian-Eulerian (ALE) description of the axisymmetric Navier-Stokes equations and energy conservation. These equations are ...

On-chip two-phase cooling of parallel pseudo-CPUs integrated into a liquid pumped cooling cycle is modeled and experimentally verified versus a prototype test loop. The system's dynamic operation is studied since the heat dissipated by microprocessors is c ...

Semi-Lagrangian (SL) schemes are of utmost relevance to simulate two-phase flows where advection dominates. The combination of SL schemes with the finite element (FE) method and arbitrary Lagrangian-Eulerian (ALE) dynamic meshes yields a strong ingredient ...

Recent improvements in numerical algorithms for Eulerian-based CFD simulations of multiphase flows can now recover the exact balance between the pressure and surface tension terms within the momentum equation. This has led to the minimization of the so called "spurious velocities": unphysical flows appearing at interfaces when using implementations of the Continuum Surface Force technique to model surface tension forces. Nevertheless, non-null velocity fields are still observed in the proximity of interface

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Numerical modeling of laminar annular film condensation for different channel shapes

Simulation and experimental validation of pulsating heat pipes

Effect of hot spots in microstructured reactors on product distribution during quasi-instantaneous exothermic reactions

Ammonia two-phase flow in a horizontal smooth tube: Flow pattern observations, diabatic and adiabatic frictional pressure drops and assessment of prediction methods

Green Cooling of High Performance Micro Processors: Parametric Study between Flow Boiling and Water Cooling

A new method for reducing local heat transfer data in multimicrochannel evaporators

Recent Advances in On-Chip Cooling Systems: Experimental Evaluation and Dynamic Modeling

Void fraction prediction in annular two-phase flow

A Review of On-Chip Micro-Evaporation: Experimental Evaluation of Liquid Pumping and Vapor Compression Driven Cooling Systems and Control

Two-Phase Control of On-Chip Two-Phase Cooling Systems of Servers

General Thermosyphon Simulation Code for Electronics Cooling Applications

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

Thermal Interface Material Enablement of Off-Board Two-Phase Cooling

Fundamental Issues, Technology Development, and Challenges of Boiling Heat Transfer, Critical Heat Flux, and Two-Phase Flow Phenomena with Nanofluids

High resolution local heat transfer and pressure drop infrared measurements of two-phase flow of R245fa within a compact plate heat exchanger

Thermo-Electric Analogy Method for Computing Transient Heat Transfer in a New Reciprocating Finned Piston Compressor

Moving mesh method for direct numerical simulation of two-phase flow with phase change

Two-Phase Flow Control of Electronics Cooling With Pseudo-CPUs in Parallel Flow Circuits: Dynamic Modeling and Experimental Evaluation

One- and two-step semi-Lagrangian integrators for arbitrary Lagrangian-Eulerian-finite element two-phase flow simulations

Characterization of the velocity fields generated by flow initialization in the CFD simulation of multiphase flows