GB899361A - Conversion of thermal energy into electrical energy - Google Patents

Abstract

899,361. Thermionic converters. THERMO ELECTRON ENGINEERING CORPORATION. Nov. 14, 1958, No. 36753/58. Class 39(1). In a process of converting thermal energy into electrical energy, one of two electronemissive surfaces 10, 12, Fig. I, maintained in closely-spaced side-by-side relation, under a vacuum of at least 10<SP>-5</SP> mm. of Hg, e.g. in steel container 17, is heated to a temperature of at least 600‹C. while the other is maintained at a temperature at least 300‹C. below, so that under the influence of crossed magnetic and electrostatic fields, set up by use of magnet 22. and an anode 16 parallel to the emissive surfaces, electrons flow from heated surface 10 to surface 12. A small portion of the power output of the device, obtained across load 26, may be used to create both the electrostatic and magnetic fields. In a further embodiment a plurality of hot plates 31-33, Fig. 2, of increasing width are arranged adjacent cold plates 36-38 of decreasing width. Associated with each plate is an anode of corresponding dimensions, positive potentials of increasing magnitude being applied to anodes of increasing width. Any number of hot plates and an equal number of cold plates may be used, depending on the power output required. Heat may be obtained from nuclear or solar sources or by burning oil, coal or natural gas or from A.C. or D.C. current. Suitable electron emissive materials are oxides of barium, strontium, calcium or lanthanum; thoriated tungsten thoria; a mixture of barium and strontium oxides covered by a sintered tungsten layer; pure tungsten; a molybdenum housing filled with granules of a fused barium oxide and aluminium oxide mixture; or a perforated molybdenum housing containing sintered thorium oxide. The hot plates are maintained at temperatures between 600‹C. and 1600‹C. depending on the materials used. The anodes may be of steel, copper or silver. To eliminate end-loss anode current due to electrons collected by anode 48 hot plates 171-176, Fig. 5, and cold plates 181-186 may be arranged in a circle, corresponding anodes 177, 188 being arranged concentrically therewith. The circuit connections are similar to those shown in Fig. 2. As shown in Fig. 5, three banks A, B, C of electrodes are arranged between heat insulators 191 within a cylindrical housing 161. Two groups of heat conducting rods 187, traversing the hot and cold plates respectively, communicate with headers at the ends of the housing, heating and cooling fluids being circulated through the respective headers. A coil 192 surrounds the housing to provide an axial magnetic field. In a further modification the hot and cold plates are in the form of cylinders surrounded by their associated anodes.