Microstructure devices for water evaporation

Abstract

Evaporation of liquids is of major interest for many topics in process engineering. One of these is chemical process engineering, where evaporation of liquids and generation of superheated steam is mandatory for numerous processes. Generally, this is performed by use of classical pool boiling and evaporation process equipment, providing relatively limited performance, or by other systems like fallingfilm evaporators. Due to the advantages of microstructure devices especially in chemical process engineering the interest in microstructure evaporators and steam generators have been increased through the last decade. In this publication different microstructure devices used for evaporation and generation of steam will be described. Starting with simple liquid-heated devices, different types of electrically powered devices containing micro channels as well as non-channel microstructures will be shown. While evaporation of liquids in crossflow and counterflow or co-current flow micro channel devices is possible, it is, in many cases, not possible to obtain superheated steam due to certain boundary conditions. Thus, a new design was proposed to obtain complete evaporation and superheating of the generated steam.

Numerical Investigation of Vapor Bubble Growth in a Rectangular Microchannel

“…This phenomena is accompanied by pulsating pressure, reversed flow or blockage of the microchannel-array. The current investigation is inspired by a series of experiments previously carried out at the Institute for Micro Process Engineering at KIT in Karlsruhe, Germany [6][7][8], which provide the necessary key data for the numerical setup. In order to gain a better physical understanding of the governing parameters of the boiling flow in the experimentally investigated microchannels we investigate the effects of the prescribed flow velocity, temperature distribution and initial position on the growth and motion of the vapor bubble using numerical simulation.…”

Heat transfer and pressure drop characterization of a tubular evaporator using manifold on the microgrooved surfaces

“…Microchannel technology has gained wide popularity in the last decade due to its orderof-magnitude higher heat transfer coefficients and the resulting substantial weight/volume saving of the heat exchanger. Several innovative concepts [3][4][5][6][7][8][9][10][11] have been successfully tested at the laboratory scale, including test runs of small refrigeration cycles with a modest coefficient of performance. But pressure drop has always been a deterring factor for the technology's widespread inclusion in industrial designs.…”

A New Microstructure Device for Efficient Evaporation of Liquids

“…One possibility is the use of concentric circular or elliptic blanks, providing circular or elliptically shaped ring walls which are arranged concentrically around a feed hole [27]. Each of the ring walls show two or more overflow openings, which act as expansion nozzles.…”