GB436467A - Improvements in or relating to the ionisation of gases, more particularly applicableto conditioning air for ventilation - Google Patents

Abstract

<PICT:0436467/III/1> Mixtures of positive and negative ions in desired proportions are obtained by supplying to one or more sharp electrodes an alternating voltage greater than 8000 volts, causing an air flow over the electrodes and varying the length of the path from the electrodes to earth whereby the rate of destruction of the negative ions relative to that of the less mobile positive ions can be varied to give the desired mixture of ions. The voltage is preferably between 10,000 and 20,000 volts. In the arrangement shown in Fig. 1, ionizing heads 20 and 22 are connected to the secondary winding 3 of a suitable step-up transformer. These heads preferably consist of brass bolts having 12 to 50 sharp needles projecting from the surface. A current of air is passed over the electrodes, to blow the positive ions away from the electrodes. One of the heads is surrounded by an earthed grid 50 of variable diameter, and the proportion of negative ions is increased with increasing diameter of the grid. The cylindrical grid may be replaced by an earthed plate, the position of which may be varied. Alternatively, both ionizing heads may be connected to one end of the secondary winding, the other end being earthed, and either or both ionising heads may be surrounded by grids. Fig. 4 illustrates the application to an air-conditioning system, an electrode 20 being mounted in the discharge duct 24 leading to an enclosure 25. The conditioner 26 is equipped with sprays 27 fed from refrigerating equipment 28 to maintain a predetermined dew-point. Control 31 may be responsive to varying water temperature and regulate the temperature of the spray water and control dampers 32 and 33. Eliminators 34 at the discharge end remove entrained moisture. Outdoor air through intake damper 32 and return air from enclosure 25 through damper 33 enter the conditioner for treatment and after conditioning may be augmented by a volume of recirculated air from the enclosure entering through damper 36. This serves to reheat the conditioned air and reduce its relative humidity. Control 38 regulates damper 36 and controls reheater 39 when required. Air ionized in the above manner may also be employed for the treatment of disease or applied to industrial processes, e.g. in the storage of tobacco to control the amount of oxidation. The Specification as open to inspection under Sect. 91 describes also the use of unidirectional current for producing mixtures of positive and negative ions. An earthed shield or grid of variable diameter may be used in this case, but the current of air over the electrodes is omitted. Examples of circuits suitable for use with unidirectional current are given. This subject-matter does not appear in the Specification as accepted.