Aerosol particles suspended in hot fluids tend to deposit on the cold walls of piping in chemical plants, so that it is important to estimate the degree of scaling or fouling caused by the deposition of aerosol particles. The study was undertaken to obtain information on the thermophoretic deposition of aerosol particles In a heat-exchanger pipe. The experiments were made to determine the deposition of aerosol on the pipe walls of a heat exchanger in a temperature gradient along its length, as a function of velocity range from laminar to turbulent. The degree of thermophoretic deposition of aerosol agrees relatively well with Its analysis, connecting thermal repulsive force acting on particles with parameters of the heat exchanger, such as mean temperature difference, velocity, and temperature gradient between hot fluid and coolant.

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Time lags to breakdown in n-hexane have been measured in high over-voltages, using approximately 100 ns width rectangular pulses. At a constant field, the time lags are divided into two types, N and B, at a 'critical distance' d. Above dc, Laue plots have almost similar kinked-line characteristics; below dc, a straight line is obtained. From the prebreakdown current estimated from the voltage waveforms, the ionisation coefficient, which increases with increasing applied fields, is estimated to be 6.4*103 cm-1 at 3.5 MV cm-1, provided a single-electron avalanche is occurring.

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