INFLUENCE OF MATERIAL STRUCTURE ON THE MAGNETOSTRICTIVE PROPERTIES OF A RADIATOR FOR DEFROSTING HEAT EXCHANGERS OF VENTILATION EQUIPMENT
The article deals with the properties of ferromagnetics and their behaviour in an external magnetic field. The conditions under which magnetism occurs in materials are shown and the choice of material for a magne-tostrictive emitter is justified. The composition and properties of permendur as the most suitable material for the manufacture of magnetostrictive radiators are presented. It is shown that for the manufacture of the magnetostrictor it is feasible to use electro-erosion equipment for cutting packages from permendur compared to the costly and cumbersome method of stamping in a matrix of a particular shape. Tests were carried out on a duralumin heat exchanger with artificial frostbite. The evaporator was fed with refrigerant at 0.22 MPa, which corresponds to the boiling point of R 410a refrigerant at 35°C, by means of a refrigerant line made of aluminium pipes. Frostbite was then produced by applying moist air using an ultrasonic steam generator. Frost on the evaporator surface is discharged by means of a magnetostrictor mounted on the heat exchanger. The proposed method allows for the most effective cleaning of the surfaces of heat exchangers of ventilation equipment from scale, fouling and other mechanical deposits by means of mechanical vibrations.