Patent GB-715578-A (GB)
Title: Improvements in or relating to heating apparatus incorporating a reso-jet tube
IPC: F23C15/00
Filed: 1952-08-11
Abstract: 715,578. Generating combustion products under pressure. HEIZMOTOREN GES. Aug. 11, 1952 [Aug. 9, 1951 ; April 5, 1952], No. 20177/52. Class 51 (1). (Also in Group XI]  In a heating device in which a combustion mixture is blown into a furnace or fire-box by a reso-jet tube the reso-jet tube has an independent fuel supply and the combustion mixture is introduced into the reso-jet exhaust tube via a throttle valve at such a distance from the resojet tube combustion chamber that even during the sub-pressure phase of the pulsations in the reso-jct tube the combustion mixture is not drawn into the reso-jet tube combustion chamber. The reso-jet tube comprising a combustion chamber 2 and an exhaust tube 1 sucks, during the sub-pressure phase, combustion air through a non-return valve 3 which air is mixed with fuel at a carburetter jet 4 and resulting mixture is ignited m a passage 5 by a sparking plug 6. The resulting explosion drives a stream of hot gas through the exhaust tube 1 into a furnace or the like combustion space 7. The hot gas stream passing through the tube 1 causes a decrease in the pressure in the combustion chamber 2 so that a fresh combustible mixture is sucked into the chamber 2 and the process is repeated. After the reso-jet tube has been set in operation by initially pumping air through a pipe 13 a throttle valve 10 is opened so that air mixed with fuel from a carburetter jet 11 is sucked through a branch pipe 8 provided with a non-return valve 9 into the tube 1 but not into the combustion chamber 2 during the sub-pressure phase and the resulting combustible mixture is then blown out of the tube 1 into the furnace or the like combustible space 7 when the next explosion occurs within the chamber 2. As shown in Fig. 2 a jacket 14, 15 surrounds the reso-jet tube 1, 2 and is formed with an injector 16 at its outlet orifice. During the sub-pressure phase in the reso-jet tube. the injector 16 causes air to be sucked into the jacket 14, 15 through a filter 17, which air is heated by contact with the reso-jet tube and is mixed with fuel sprayed into the jacket space 18 from a nozzle 19. The tank 21 from which fuel is fed to the nozzle 19 through a control valve 20 is connected to the reso-jet exhaust tube 1 through a pipe 22 provided with a non-return valve which allows transfer of the peak pressures occurring in the tube 1 to the tank 21 which is thus subjected to a pressure of .5 to 1 atmospheres. In a modification shown in Fig. 3 the combustion space 2a of the reso-jet tube lies within a jacket 14a and its exhaust tube 1a is led in a spiral coil around the outside of the jacket 14a. Fuel is sprayed through a nozzle 19a into the tube 1a adjacent its exit end and is then blown through an injector 24 where it is mixed with air to form a combustible mixture which passes through a pipe 23 arranged tangentially to the jacket 14a around the space 18a, where it is heated, and then into the combustion space 7. A narrow annular exit orifice 25 formed between the chamber 2a and the jacket 14a prevents ignition of the mixture within the space 18a. The mixture entering the space 7 is ignited by a glow pot 26 formed in the end of the chamber 2a and on to which pot 26 a part of the mixture is directed through radial apertures in a sleeve 27. In a further modification shown in Fig. 5 the exit end 105 of the reso-jet exhaust tube 104 terminates in a silencer 106 to which a mixing tube 107 is connected. Fuel is fed to the tube 107 from a nozzle 108 fed from a tank 109. The combustible mixture fed to the silencer 106 passes through a mixing nozzle 116 where it is mixed with additional air in a funnel 115 whence the resulting mixture passes into an annular space 114 to be heated by the reso-jet tube combustion chamber 101 and then burnt in the combustion space 120. Additional air may enter the space 120 in the direction of arrows P. The apparatus is started by heating a sparking plug 123 and pumping air by means of a hand pump 122 connected to a non-return valve 103 and a suction silencer, which is mixed with fuel from a carburetter jet 102 into the combustion chamber 101 where the mixture is ignited by the plug 123. After a number of explosions have occurred at acoustic resonant frequency in the chamber 101 the apparatus is sufficiently heated and a fuel valve 124 leading to the nozzle 108 is opened so that a combustible mixture is fed from the silencer to the combustion space 120 where it is ignited by the heated thin wall glow pot 117. In a modification, Fig. 6 (not shown), of the apparatus described with reference to Fig. 5 and for use with fuels having a high boiling point a small mixing tube into which a spray nozzle is directed is connected into and about 10-15 centimetres from the end of the reso-jet tube which is upwardly bent within the silencer. The outlet tube extends downwardly to a point adjacent the end of the reso-jet tube and is similarly upwardly bent at its end. The fuel tanks 126, 109 the first of which supplies fuel to the carburetter jet 102 and the second to the nozzle 108 are 'kept under pressure by the peak pressures occurring in the exhaust tube 104 and transferred to the tanks through a non-return valve 111 and pipes 125, 110. In a further modification, Fig. 7, the reso-jet exhaust tube 104b opens tangentially into a conical silencer 132 and fuel is dropped from a pipe 108a into the swirling gases and then passes up a central outlet pipe 116a to a funnel 115a where it is mixed with air ; the combustible mixture then being passed to the space 114 and the combustion chamber 120 shown in Fig. 5. French Specification 949,103 is referred to.