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Transient three-dimensional multiphase flows are a characteristic feature of many industrial processes. The experimental observations and measurements of such flows are extremely difficult, and industrial process tomography has been developed over the last decade into a reliable method for investigating these complex phenomena. Gas-solids flows, such as those in pneumatic conveying systems, exhibit many interesting features and these can be successfully investigated by using electrical capacitance tomography. This paper discusses the current state of the art in this field, advantages and limitations of the technique and required future developments. Various levels of visualization and processing of tomographic data obtained in a pilot-plant-scale pneumatic conveying system are presented. A case study outlining the principles of measuring the mass flow rate of solids in a vertical channel is shown.

This paper describes the development of an experimental arrangement and the application of acetone-based Planar Laser Induced Fluorescence (PLIF) measurement techniques to study the unsteady characteristics of heat transfer processes in the parallel-plate heat exchangers of thermoacoustic devices. The experimental rig is a quarter-wavelength acoustic resonator where a standing wave imposes oscillatory flow conditions. Two mock-up heat exchangers: "hot" and "cold", have their fins kept at constant temperatures by electrical heating and water cooling, respectively. A purpose-designed acetone tracer seeding mechanism is used for PLIF temperature measurement. Acetone concentration is optimised from the viewpoint of PLIF signal intensity. Two-dimensional temperature distributions in the gas surrounding the heat exchanger plates, as a function of phase angle in the acoustic cycle, are obtained. Local and global (instantaneous and cycle-averaged) heat flux values on the fin surface are estimated and used to obtain the dependence of the space-cycle averaged Nusselt vs. Reynolds number. Measurement uncertainties are discussed.

This article describes the construction and preliminary testing of a pre-prototype thermoacoustic electricity generator to test the concept of a low-cost device for application in remote or rural areas of developing countries. A travelling-wave thermoacoustic engine with a configuration of a looped-tube resonator is designed and constructed to convert heat to acoustic power. Air at atmospheric pressure is used as the working gas, PVC tubing is utilised for the feedback pipe, while an inexpensive commercially available loudspeaker is adopted to convert the acoustic power, produced by the engine, to electricity. Preliminary experimental results are presented and discussed in detail. The results show that the approach is feasible in principle and it is possible to produce the electrical power levels in the order of 4-5 W with overall heat-to-electric efficiencies in the order of 1%. Further work towards optimising the device from the performance, manufacturing and cost point of view is outlined.