GB921748A - Improvements in devices for thawing deep-frozen substances - Google Patents

Abstract

921,748. Thawing and heating frozen food &c. PHILIPS ELECTRICAL INDUSTRIES Ltd. Oct. 14, 1959 [Oct. 16, 1958], No. 34839/59. Class 49. [Also in Groups XI and XL (c)] Apparatus for thawing deepfrozen food and other substances in a thawing chamber using hot air and high-frequency energy, has hollow waveguide supply channels 16, Fig. 2, for the supply of high-frequency energy to a plurality of positions 4 in the chamber, at or near which positions thawing of portions of deep-frozen food &c. is to be effected by way of a first series of slots 11, Fig. 4, provided in the walls of the supply channels 16 at the positions, and means for circulating hot air through a second series of slots so positioned along the waveguide supply channels as to prevent the escape of highfrequency energy; these latter slots are preferably vertical slots 9, Fig. 5 (not shown) in the side walls 10, Fig. 1, of the chamber. A rectangular hollow waveguide 7, Fig. 1, passing along the rear wall of the chamber feeds highfrequency energy from a magnetron operating e.g. at a wavelength of 12.5 cms., through slots 6 and intermediate couplings 6 to the supply channels 16. In order to avoid undesirably high energy concentrations at the slots 11 in the channels 16, the food &c. portions may be positioned in dishes on rails 12, Fig. 6, so that a substantially constant spacing is maintained. For uniform irradiation the width of the slots 11 may be 4 mm., but by the choice of the place and size of the slots the food &c. may be irradiated strongly from below whilst the top is subjected to a weaker irradiation. Reference has been directed by the Comptroller to Specification 888,518.