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The ozone behavior on heated catalytic probe surfaces is examined in gas flow downstream of atmospheric-pressure dielectric barrier discharge ozonizers. Negative and positive variations in the probe voltage as a function of probe heating current enable one to discriminate catalytic dissociation of ozone at low temperatures and catalytic recombination of oxygen radicals at high temperatures, respectively, on the probe surface. The loss coefficient of ozone on the probe surface derived from the amount of heat removed by catalytic dissociation is of the order of $10^{-4}$ , which increases with increasing probe temperature. The probe temperature decrease per ozone concentration by catalytic dissociation of ozone as a measure of measurement sensitivity increases with probe temperature and is measured typically in the range of 0.5–0.8 Kg $^{-1}\text{m}^{3}$ at ozone concentrations of 10 and 17 gm $^{-3}$ , respectively, showing the applicability of a catalytic probe to a simple sensor body. [ABSTRACT FROM AUTHOR]

DC or pulsed-type high-electric field plasma (HEFP) is investigated. Here, HEFP means that no discharges take place in atmospheric environment, and strong electric field less than about $3 \times 10^{6}$ v/m is produced to accelerate free electrons to high energy for decomposition of chemicals, water vapor, or killing bacteria. In order to produce HEFP, two types of high-voltage exciter such as: 1) short rise time pulsed-type high voltages or 2) dc high voltages are used. The phenomena observed are slightly different between two types of high voltages in addition to the consumed electric power. The main purposes of the present studies are to show the typical characteristics of HEFP, including trapping of microdust particles with diameter $0.3~\mu \text{m}$ or larger, in addition to decomposition of chemicals and sterilization. The dust particles are perfectly trapped by adding HEFP with dc voltages, while in the case of pulsed HEFP, 100% trapping of dust particles was not observed at present. The decomposition of chemicals and bacteria sterilization is confirmed in both HEFP structures. These phenomena are applied to make new type of air cleaner working in the rooms such as private small rooms or hospitals with many patients staying at the same time or in the moving vehicles. [ABSTRACT FROM AUTHOR]

A simple heat flow model is established for numerical analysis of the effect of catalytic dissociation of ozone on electrode surface temperature in a coaxial cylindrical-type dielectric barrier discharge ozonizer. The amount of heat consumed by the ozone decomposition at the electrode surface is determined from the balance of heat flow among the discharge gas, electrode, and cooling water. Our calculation using the experimental data shows that the ozone decomposition by 1.6% in total ozone reaching the electrode surface is required to explain the observed temperature decrease from about 20 °C to 8 °C for a stainless steel electrode, while that by 4.5% is needed to explain the temperature decrease from about 20 °C to 19 °C for a copper electrode. The decomposition rates calculated in the discharge are about two orders of magnitude higher than those measured in gas flow downstream of a similar discharge. [ABSTRACT FROM PUBLISHER]

Temperature variation of a catalytic metal surface exposed to ozone produced in an atmospheric-pressure dielectric barrier discharge is examined by using a very thin thermocouple. The metal sheet is heated initially to a certain temperature ( T1) using a resistive heater and, then, the ozone concentration is increased with the heater current unchanged. When T1 is room temperature, the temperature of the metal sheet remains almost constant independent of ozone concentration. When T1 is increased up to 80 °C, the temperature of the metal sheet decreases clearly with increasing ozone concentration due to enhanced catalytic dissociation of ozone at the metal surface. The rate of decrease in temperature for a stainless steel sheet is increased from nearly 0% to $\sim 5.7$ % with increasing T1 from room temperature to 80 °C, while that for a platinum sheet is increased further to $\sim 17.5$ % at 80 °C due to stronger catalytic activity of platinum. The results confirm that the sensitivity for ozone is improved with a stronger catalytic metal heated to a higher temperature as the sensor body. [ABSTRACT FROM PUBLISHER]