http://web.ist.utl.pt/ist11061/leq-II/Documentos/OpUnitarias/BubbleColumnReactors(review).pdf

Bubble column reactors

On-microchip multiphase chemistry - a review of microreactor design principles and reagent contacting modes

With the dramatic increase in the international oil price, gas-to-liquid processes of Fischer -Tropsch (FT) synthesis, methanol synthesis, and dimethyl ether (DME) synthesis have become increasingly important and received much attention from both academic and industrial interests. The slurry reactor has the advantages of simple construction, excellent heat transfer performance, online catalyst addition and withdrawal, and a reasonable interphase mass transfer rate with low energy input, which make it very suitable for gas-to-liquid processes. However, its multiphase flow behaviors are very complex and the multiphase reactor has some remarkable scale-up effects; therefore, extensive studies are still needed for the development and design of a high-performance slurry reactor. This article gives a state-of-the-art review of the recent studies on the slurry reactor for gas-to-liquid processes. The influences of the superficial gas velocity, operating pressure and temperature, solid concentration, column dimensions, and gas distributor are discussed. Some recent developments in the liquid-solid separation in a slurry reactor are also summarized. The concept of using internals to intensify the mass transfer and improve the hydrodynamics is discussed based on both experimental results and theoretical analysis. Modeling and simulations of the gas -liquid and gas-liquid-solid flows are briefly reviewed, with focus on the new trend of coupling the population balance model (PBM) into the computational fluid dynamics (CFD) framework to describe the complex bubble behaviors and gas-liquid interphase interactions. The results of a 3000 ton/year pilot plant for DME synthesis are given, showing that the slurry reactor has promising applications in gas-to-liquid processes. Fast development of the world economy and increase of the international oil price have made the global energy and environmental problems increasingly serious. The supply of coal is much more abundant than that of oil; therefore, the development of coal-based technologies for producing clean fuel is very important for the sustainable development of the economy and of the energy supply for the world. Gas-to-liquid processes of Fischer-Tropsch (FT) synthesis, methanol synthesis, and dimethyl ether (DME) synthesis have become increasingly important and received much attention from both academic and industrial interests. 1-9 Besides providing clean fuel, the products of gasto-liquid processes can be further produced to many other chemical products. 10

Slurry Reactors for Gas-to-Liquid Processes: A Review

An experimental investigation was conducted to determine the thermal behavior of arrays of micro heat pipes fabricated in silicon wafers. Two types of micro heat pipe arrays were evaluated, one that utilized machined rectangular channels and the other that used an anisotropic etching process to produce triangular channels. Once fabricated, a clear pyrex cover plate was bonded to the top surface of each wafer using an ultraviolet bonding technique to form the micro heat pipe array. These micro heat pipe arrays were then evacuated and charged with a predetermined amount of methanol. Using an infrared thermal imaging unit, the temperature gradients and maximum localized temperatures were measured and an effective thermal conductivity was computed. The experimental results were compared with those obtained for a plain silicon wafer

Experimental Investigation of Micro HeatPipes Fabricated in Silicon Wafers

https://hull-repository.worktribe.com/preview/1636046/1612634.pdf

Comparative study of a concentrated photovoltaic-thermoelectric system with and without flat plate heat pipe

Interfacial area and volumetric mass transfer coefficient in a bubble reactor at elevated pressures

Thermal performance of finned heat pipe system for Central Processing Unit cooling

An experimental study is realized in order to verify the Mini Heat Pipe (MHP) concept for cooling high power dissipation electronic components and determines the potential advantages of constructing mini channels as an integrated part of a flat heat pipe. A Flat Mini Heat Pipe (FMHP) prototype including a capillary structure composed of parallel rectangular microchannels is manufactured and a filling apparatus is developed in order to charge the FMHP. The heat transfer improvement obtained by comparing the heat pipe thermal resistance to the heat conduction thermal resistance of a copper plate having the same dimensions as the tested FMHP is demonstrated for different heat input flux rates. Moreover, the heat transfer in the evaporator and condenser sections are analyzed, and heat transfer laws are proposed. In the theoretical part of this work, a detailed mathematical model of a FMHP with axial microchannels is developed in which the fluid flow is considered along with the heat and mass transfer processes during evaporation and condensation. The model is based on the equations for the mass, momentum and energy conservation, which are written for the evaporator, adiabatic, and condenser zones. The model, which permits to simulate several shapes of microchannels, can predict the maximum heat transfer capacity of FMHP, the optimal fluid mass, and the flow and thermal parameters along the FMHP. The comparison between experimental and model results shows the good ability of the numerical model to predict the axial temperature distribution along the FMHP.

/pdf/flat-miniature-heat-pipes-for-electronics-cooling-state-of-50neic82cr.pdf

Flat Miniature Heat Pipes for Electronics Cooling: State of the Art, Experimental and Theoretical Analysis

The present study deals with the pressure effects on the hydrodynamic flow and mass transfer within an agitated bubble reactor operated at pressures between 10 5 and 100x10 5 Pa. In order to clarify the flow behavior within the reactor, liquid phase residence time distributions (RTD) for different operating pressures and gas velocities ranging between 0.005 and 0.03 m/s are determined experimentally by the tracer method for which a KCl solution is used as a tracer. The result of the analysis of the liquid-phase RTD curves justifies the tank-in-series model flow for the operating pressure range. Good agreement is obtained between theoretical and experimental results assuming the reactor is operating as perfectly mixed. Two parameters characterizing the mass transfer are identified and investigated in respect to pressure: the gas-liquid interfacial area and volumetric liquid-side mass transfer coefficient. The chemical absorption method is used. For a given gas mass flow rate, the interfacial area as well as the volumetric liquid mass transfer coefficient decrease with increasing operating pressure. However, for a given pressure, a and k L a increase with increasing gas mass flow rates. The mass transfer coefficient k L is independent of pressure.

Samah Maalej

Papers

Interfacial area and volumetric mass transfer coefficient in a bubble reactor at elevated pressures

Thermal performance of finned heat pipe system for Central Processing Unit cooling

Flat Miniature Heat Pipes for Electronics Cooling: State of the Art, Experimental and Theoretical Analysis

Influence of Pressure on the Hydrodynamics and Mass Transfer Parameters of an Agitated Bubble Reactor

Numerical study of the electrohydrodynamic effects on the two-phase flow within an axially grooved flat miniature heat pipe