Abstract: The disclosure is related to a coolant replenishment device, a cooling circulation system and an electronic device. The electronic device includes a heat source, a circulation pipe, a pump, a heat exchanger and a coolant replenishment device. The circulation pipe has a circulation channel configured to accommodate a first coolant. The pump is disposed on the circulation pipe. The heat exchanger disposed on the circulation pipe. The coolant replenishment device includes a liquid storage tank, a push plate and a driving member. The liquid storage tank has an accommodating space configured to accommodate a second coolant. The push plate is movable toward or away from the liquid outlet. The driving member is disposed in the liquid storage tank and constantly apply a force on the push plate to push the second coolant from the accommodating place into the circulation channel through the liquid outlet.

Abstract: An expansion tank which comprises a tank having a predetermined volume capacity; an expandable elastomeric bladder in the tank, partitioning tank volume into a liquid-containing portion for holding liquid and a gas-containing portion for holding a gas under a pressure that defines a normal pressurized gas volume when the liquid-containing portion holds a predetermined liquid volume; and a proximity sensor mounted to the tank at the gas-containing portion thereof and adapted to emit an alarm signal when volume of the gas-containing portion is reduced.

Abstract: The present invention relates to a method of controlling pressure maintenance equipment for a cooling and heating system. More particularly, the present invention relates to a method of operating and controlling, under optimum conditions, pressure maintenance equipment with multiple sensors so as to check for irregularities in the sensors which measure the same physical parameter. In the present invention, measurement values of two or more sensors are used to detect whether an abnormality has occurred in any sensor. If a sensor is determined to be abnormal, a measurement value of the abnormal sensor is excluded when determining a reference control value. Thereby, the pressure can be precisely and reliably controlled in response to actual conditions of the system.

Abstract: A high-speed flat panel display having a long lifetime. Thin film transistors in a pixel portion having a plurality of pixels are contacted differently from thin film transistors in driving circuit portions for driving the pixels, thereby enhancing luminance uniformity and reducing power consumption. The thin film transistors each have a channel region and a body contact region for applying a predetermined voltage to the channel region. At least one thin film transistor in the pixel portion is a source-body contact thin film transistor having the body contact region connected to one of source and drain electrodes so that the predetermined voltage can be provided to the channel region. Each thin film transistor in the driving circuit portion is a gate-body contact thin film transistor having the body contact region connected to the gate electrode so that a predetermined voltage can be provided to the channel region.

Abstract: An expansion tank is fastened to a support using a bracket with a U-shaped cross-section formed by a back and two sidewalls. The edges of the sidewalls each have a notch mating with a weld bead on the tank. Fasteners hold the back of the bracket to the support. First and second hose clamps pass through the sidewalls by the back to encircle the tank and clamp it to the edges of the sidewall when the hose clamps are tightened.

Abstract: A valve assembly including a body having a first end, a second end, a passageway extending between the first and the second ends, and four ports defined by the body and connected to the passageway. The assembly also has a first valve member received in the passageway at an intersection of the passageway and the first port, the valve member including a tee shaped passage such that in a first position the valve member opens the passageway and the first port, in a second position closes the passageway and connects the first end to the first port, in a third position closes the passageway and connects the first port to the second end, and in a fourth position opens the passageway and closes the first port. The assembly also includes a second valve member for opening and closing the third port.

Abstract: The heat pump hydronic heater of the invention includes a heat pump circuit and a hot water tank circuit, the heat pump circuit and the hot water tank circuit are accommodated in one casing 50, and a hermetic expansion tank 37 is connected to a hot water tank 7 and the heat pump hydronic heater can absorb expansion of water in a circulation path when hot water in a hot water tank 7 is circulated through heat a floor or supply hot water.

Abstract: A hot-water supply heat exchanger having a mixing valve and a mixing valve integrated adopter are provided to facilitate control of hot water temperature with a simplified pipe structure. A hot-water supply heat exchanger comprises a heat exchange part (100), a heating water inlet (212), a heating water outlet (214), a cold water inlet (222), a hot water outlet (224), and a mixing valve (230). The heat exchange part allows heat exchange between hot water provided from a main heat exchanger (20) with cold water. The heating water inlet draws hot water into the heat exchanger. The to heating water outlet discharges the hot water heat-exchanged by the heat exchanger. The cold water inlet draws the cold water into the heat exchange part. The hot water outlet discharges the cold water that is heat-exchanged with heating water in the heat exchange part. The mixing valve mixes the hot water discharged through the hot water outlet with cold water provided from the cold water inlet.

Abstract: A fluid containment and transfer vessel having a chamber defining a fluid inlet for receiving fluid from a primary heater and a separate fluid outlet for delivery of fluid at least to be circulated via a circulated fluid central heating system, the chamber adapted to contain fluid in use to such a level as to define a header region surmounting the fluid therein, wherein the inlet is provided into the header region, the outlet is provided at a base portion of the chamber, and a conduit is provided within the chamber open at either end and with a first end in the vicinity of and generally above the outlet and a second end venting out of the vessel at a higher point thereto in use.

Abstract: An expansion tank comprising a bladder style water storage tank and method of use. The expansion tank includes an alarm module to sense a flooded tank condition. The system also has the ability to sense a bladder over-extended condition. The expansion tank use includes a sonic alarm and/or a visual alarm and is used in combination with a boiler or related hot water system. Method steps using the described design are also included. The hydro-pneumatic expansion tank has important utility in HVAC, boiler and potable water systems.

Abstract: A tank for use with a liquid heating vessel of a hydronic radiant heating system to assist in the simultaneous sealing and venting of air from the system where the heating vessel has a flue for release of exhaust, the tank including a liquid holder that is exposed to the atmosphere and an aperture defined in the holder such that the flue of the vessel may extend upward through the aperture of the tank.

Abstract: A non-pressurized hydronic space heating system for circulating heated fluid through coils placed within a dwelling or structure. The system includes a heat tank for heating liquid, and piping connected to the heat tank for receiving the heated liquid and circulating the liquid throughout coils and back to the heat tank. The heat tank is positioned above the coils. The system includes a releasing means for releasing air contained within the piping. The releasing means or auxiliary fluid isolation ballast allows for the release of air within the piping so that continued circulation of the liquid throughout the system may occur and so that the fluid within the system is isolated from the atmosphere to seal the system from introduction of air bubbles.

Abstract: Method and apparatus for operating a closed hot water installation provided with a pipe system, a boiler, heat exchangers, an expansion tank, a water make-up provision and a de-aerator, the method including the steps of opening a non-return valve to allow air to escape, detecting a water level in the de-aerator, feeding water to the closed installation when the level falls below a predetermined level, blocking opening of the non-return valve until the water level has fallen to a first level and starting the feed of water when a second lower level is reached.

Abstract: A method for expansion control in a closed fluid circulation system with varying temperature, in which system air is drawn from the circulating fluid through the formation of an air head wherein air to be withdrawn is collected and from which air can be blown off, controlled by a valve, to the environment or a receiving space, while further off, measures are taken for taking up, when the temperature varies, an attendant expansion and shrinking of the fluid within the closed system, and measures for enabling adding fluid to the system, which fluid is withdrawn from an external stock of fluid under pressure, and the air head volume is measured and when a predetermined value is exceeded, a fluid valve is opened through which fluid is introduced into the air head until the volume of the air head is substantially equal to the predetermined value and the fluid valve is closed.

Abstract: Expansion tank (10) for receiving volume changes caused by temperature fluctuations in service and heating water systems (28, 29), comprising a tank (11, 11a) divided by a diaphragm (16, 22) into a pressurized gas compartment (19, 24) and a water compartment (18, 23). Water compartment (18, 23) communicates through ports (14, 27) with a water system (28, 29). Service water compartment (18) and heating water compartment (23) are integrated in a common tank (11, 11a).

Abstract: The invention relates to a heating installation comprising a closed liquid circuit which is under pressure during operation, in which are incorporated a heating boiler in which heat is supplied to a liquid circulating in the circuit and heat-generating means such as radiators and/or convectors, further comprising a pressureless liquid reservoir connectable by valve means to the circuit, which valve means are mechanical valve means controlled by the pressure in the circuit.

Abstract: An improved closed loop variable volume water heating or cooling system having one or more work units for supplying heated or cooling water to a heating or cooling system which includes a dual purpose water mixing and air separator vessel. This vessel includes two inlets and one outlet port disposed in predetermined locations in the side walls of said vessel to receive and mix return water from the system and water bypassed from the work units prior to communicating this mixture to the supply inlet of the work units. The inlet ports are offset from the centerline of the vessel to cause entrained air to separate from the water streams and rise to exit the vessel through an air vent disposed in an upper portion of the vessel.

Abstract: An improved closed loop variable volume water heating or cooling system having one or more work units for supplying heated or cooling water to a heating or cooling system which includes a dual purpose water mixing and air separator vessel. This vessel includes two inlets and one outlet port disposed in predetermined locations in the side walls of said vessel to receive and mix return water from the system and water bypassed from the work units prior to communicating this mixture to the supply inlet of the work units. The inlet ports are offset from the centerline of the vessel to cause entrained air to separate from the water streams and rise to exit the vessel through an air vent disposed in an upper portion of the vessel.

Abstract: An automatic fluid-supply apparatus for a boiler system automatically controls an amount of fluid being supplied to a fluid tank of the boiler system. The automatic fluid-supply apparatus is provided with a flux detecting portion which comprises a rotor assembly disposed inside a fluid-supply pipe to rotate in proportion to the flux of the fluid flowing from a fluid-supply source to the fluid tank and a HALL sensor disposed close to the rotor assembly at an outer surface of the fluid tank. The HALL sensor is intermittently turned ON/OFF in response to permanent magnets provided to the rotor assembly. A controller compares the ON/OFF frequency with a preset ON/OFF frequency range and transmits an ON/OFF signal to a solenoid valve.

Abstract: A method and device for maintaining a fluid at a working pressure in a substantially closed fluid circulation system wherein the temperature of the fluid can vary and which is preferably deaerated continuously. The maintenance of a working pressure is realized by keeping the system filled automatically by connecting said system, by means of a closable connection, to a stock of fluid which is under atmospheric pressure, the fluid circulation system and the stock of fluid being connected directly, which connection is opened at and below atmospheric pressure at the location of the connection and, when the working pressure rises, is automatically closed at atmospheric pressure at the location of the connection. If so desired, replenishment of the stock of fluid, which is preferably disposed in the vicinity of the highest point of the system and may serve as expansion possibility for the system, may be effected automatically.

Abstract: A method for purging water from flooded expansion tanks without necessitating the complete drainage and subsequent refilling of the systems allows for a stabilized hydronic water system in much less time with less effort and expense.

Abstract: A closed loop, pressurized system for a ground source heat pump and a pressure/liquid source module therefore. The pressure/liquid source module has a liquid tank having a predetermined liquid level and an inlet pipe extending downwardly within the tank from adjacent the top of the tank to a distal end which is below the liquid level. The inlet pipe is adapted to be connected to the loop of the closed loop, pressurized system of the heat pump. The liquid tank has an outlet adjacent the bottom of the tank, the outlet being connected to the heat pump through a check valve and a liquid pump. The valve is between the tank and the pump.

Abstract: Device for expansion transfer in liquid cycle systems, in particular for heating installations, comprising a heating boiler (1), a liquid line (2, 2'), radiators (3) and an expansion vessel (4) at atmospheric pressure. The expansion vessel (4) is connected to the liquid line (2) of the heating installation through an inlet line (5), an outlet line (6), an overflow valve (7) which can be adjusted according to the operating pressure of the installation, and a continuously operating circulating pump (9).

Abstract: An interface assembly between a heat pump and an elongated ground heat exchanger. First and second valve means are connected to opposed end portions of the ground heat exchanger. A conduit of a coolant-to-heat transfer liquid heat exchanger in the heat pump, a tank column, and pump means between the second valve means and the first valve means are connected in series between the first and second valve means.

Abstract: A method and apparatus for supplying a heated fluid to a heat consumption circuit, such as an injection mold. The apparatus comprises a heat exchanger, for heating the fluid, a pump for pumping the heated fluid to the heat consumption circuit, a reservoir for storing the fluid, and a degasifier for degasifying the fluid that returns from the heat consumption circuit to the apparatus. The heat exchanger, and the pump comprise one compact integral assembly. In addition, the connection between the degasifier and the reservoir is in the form of a siphon which acts as a thermal barrier to prevent the heat from the heated fluid from heating the fluid in the reservoir. As a result of this arrangement, the total volume of fluid used is much smaller than in prior art devices, thereby substantially decreasing the heat losses from the fluid to the environment.

Abstract: A fill valve for a water heating system. An expansion tank is provided with a flexible diaphragm which divides the tank into a water chamber and a closed gas chamber. A fill valve assembly is mounted within an opening in the tank and includes a valve body having an axial passage and a radial passage connects the axial passage to a water inlet. One end of the axial passage communicates with the water chamber of the expansion tank, while the opposite end of the axial passage communicates with the water heating system. The central portion of the axial passage defines a valve seat and a hollow valve member is mounted for sliding movement in the axial passage, and the inner end of the valve member extends into the tank in position to be contacted by the diaphragm. Mounted on the valve member is an annular valve which is biased to engage the valve seat. A plurality of ports extends laterally of the valve member and provides communication between the inlet and the interior of the valve member.

Abstract: A ventilating device for a closed conduit system comprising a housing (7) with a liquid throughflow conduit (11) extending through end walls (8,9) of the housing. The throughflow conduit (11) has a liquid permeable part (13) which is directed towards an upper air vent (23) and the end edges of which are spaced from the end walls, and the side edges of which part (13) adjoining the end edges are preferably provided with wing-like elements (21,22) whose free edges form gaps with the inner wall of the housing. Liquid flows out beneath the conduit through those gaps (D,E) located between the end walls and the end edges of the wing-like element, and small air bubbles enclosed in the liquid form larger air bubbles which rise up between the wing-like element and the inner wall of the housing and depart through the vents (23).

Abstract: The liquid flowing through a heat circulation system including a boiler can be maintained in an air absorbing condition even at the highest elevation in the circulation system. The air absorbing condition is attained by alternately subjecting the liquid in the boiler to the high pressure of the circulating system and at least to atmospheric pressure and effecting deaeration while the liquid is at atmospheric pressure. During deaeration the liquid is blocked from flowing from the boiler into the circulation system. Following deaeration, the liquid is brought up to the high pressure of the system before it is directed back into the system.

Abstract: Disclosed is a heating device of assembled cast panel construction with flanges joined together and whose front, side, back and top walls and bottom grates define a combustion chamber. The angled side walls define an obtuse interior angle and the side and top walls define an obtuse interior angle. An embodiment of the heating device is a boiler incorporated by operatively connected expansion tank, holding tank and a coil of water tubes disposed in the combustion chamber's top area. Another embodiment of the heating device is a hot-air furnace incorporated by a plenum chamber, cold-air return and blower fan with such blower fan directing cold air from the cold-air return to and through the plenum chamber where it is heated. A still further embodiment combines the boiler and hot-air furnace with such heating device.

Abstract: A system for generating, storing and releasing heat comprises a tank surrounding a reservoir for holding a heat transfer fluid, heat releasing means in fluid communication with the reservoir for controllably releasing heat from the fluid to an object or space to be heated, and means for regulating flow of the fluid between the reservoir and the heat releasing means. A heat conductive fire chamber is disposed within and substantially surrounded by the reservoir, the system also comprising an air supply means for carrying combustion air to the fire chamber, and a heat conductive exhaust means for carrying hot exhaust gases through the reservoir. Access passageways are provided for fuel insertion and ash removal. Boiler tubes supporting the fuel as well as collecting heat from the fire chamber communicate with fluid in the reservoir. Shaker bars interspersed between the boiler tubes supporting the fuel may be actuated to agitate and more completely combust the fuel.

Abstract: A closed-loop, incompressible-liquid circulating, hydronic heating system, for instance, a hot water heating system, which utilizes a Venturi-type control device to effect communication between the circulating hydronic heating system and a storage tank. The storage tank, which is maintained at ambient atmospheric pressure, is connected to the throat of the Venturi. The inlet and outlet of the Venturi are connected to the pump outlet and inlet, respectively, in parallel with the main circulating loop. The Venturi control device automatically controls the pressure in the circulating system by means of controlling the flow of incompressible-liquid between the storage tank and the incompressible-liquid circulating system. The Venturi control device responds automatically to changes of pressure in the circulating system. The pressure differential between the Venturi throat and the Venturi inlet remains constant.

Abstract: In a closed circulation system containing a constant amount of liquid, a force is generated for driving the liquid through the system. A branch line extends from the circulation line of the system at a point adjacent to and closely downstream from the location at which the force generating circulation is effected. A collecting chamber is provided in the branch line spaced from the circulation line. Gases dissolved in the liquid are released at the location of the force generation and the gases are removed through the branch line and the collecting chamber. Downstream from the branch line the liquid is either cooled or returned at least to normal pressure for its continued circulation so that it is able to absorb air from the air accumulations within the system with which the liquid comes into contact.

Abstract: A flue gas heat recovery system for use in conjunction with a forced hot air furnace, such system having two conventional heat exchangers, one located in the flue leading from the combustion chamber of the furnace to the chimney, and the other in the cold air chamber of the furnace adjacent the blower fan. Such heat exchangers each have a core connected into a hydraulic circuit which contains an electrically driven circulating pump controlled by a thermal device having a heat actuated switch located in the upper portion of the heat plenum in the furnace.Such switch is connected into an electric circuit adapted to activate the blower fan and circulating pump simultaneously. The core of the heat exchanger located in the flue of the furnace absorbs a substantial portion of the heat in the exhaust gases which would otherwise be lost to the atmosphere, and utilizes such heat to increase the temperature of the air supplied to the intake of the blower fan in the cold air chamber of the furnace.

Abstract: A boiler tank (1) for a hot-water heating system comprises first (2) and second (7) partitions, defining first (4), second (9), and third (10) chambers. Inlet (6) and outlet (6') pipes communicate with the second chamber, a transfer conduit (3) intercommunicates the first and second chambers, and an opening (8) intercommunicates the second and third chambers.

Abstract: A pipe connecting the equipment to be protected with a vessel is locally divided in two paths, a pump and a one-way valve being mounted in one path and an electro-magnetic valve in the other path. Pump and electric valve are controlled by a contact manometer so to fill or to empty the vessel depending on the pressure in the equipment.The liquid body in the vessel moves a diaphragm between a position above the pipe connection but below a discharge opening and a position above this opening, in which latter position liquid is discharged through a siphon provided on the opening.The diaphragm divides the vessel in two spaces and is the bottom of a bag secured to the vessel.A float in a container connected to the vessel opens a feeding valve when the liquid level in this vessel is beneath a determined value.

Abstract: A process for preventing freezing of solar collectors by automatic drainage of the water or liquid working fluid contained within the collectors the working fluid is drained from the collector, but remains within the closed solar collector circuit. Apparatus responsive to the pressure exerted on the collector circuit fluid by an external source of pressurized fluid acts to drain and refill the collectors. The pressure is transmitted through a moving transmissio means, which may be a deformable or movable wall, and which prevents transfer of the collector circuit fluid into the external source of pressurized fluid. The apparatus provides two storage tanks, one of which is provided with an auxiliary heater, the thermal yield being substantially improved by arranging one of the two tanks inside the other.

Abstract: A heat distribution system is disclosed for transferring heat, such as is generated by a burner device of conventional construction, to a remote location, with circulation away from the burner in a horizontal or downward direction. The distribution system of the invention is particularly useful whenever a building heating arrangement requires the furnace or other equivalent heating means to be located above or level with the point at which heat is to be withdrawn from a circulating fluid.

Abstract: A water heating and dispensing device includes a tank which forms the main hot water container, a heating device in the tank which is thermostatically controlled in order to maintain the temperature of the water at the desired level, inlet and outlet conduits associated with the tank and a valve associated with the inlet conduit for controlling water flow into the tank and dispensing of water from the outlet conduit. A separate reservoir is connected to the inlet conduit between the valve and the tank through a venturi nozzle which permits water to flow into and out of the reservoir. The reservoir has collapsible wall portions which collapse to provide for a decrease in volume in the reservoir as water is drawn from it through the venturi nozzle during dispensing of water, and which is expandable to an expanded maximum completely filled condition after dispensing has ceased, as a result of water flowing back from the main hot water container through the venturi nozzle.

Abstract: This invention relates to self-priming devices for indirect domestic water heating systems which device acts as expansion and contraction chambers for primary and secondary water in the system. The device consists of a closed housing divided internally by a wall intermediate its ends to form axially disposed first and second chambers. A open ended tubular member extends from the wall into the second chamber to provide communication between the chambers and an inlet and outlet is provided in the second chamber adjacent the wall. At least one inlet is provided in the first chamber at the end remote from the wall. The first chamber is connected to a primary water circuit and the second chamber is connected to the secondary water circuit to separate the water in one circuit from the water in the other circuit. The volume of the first chamber is substantially 4 to 4.

Abstract: A heat exchange system in which sensible and/or latent heat is exchanged between a stream of incoming air into an enclosure and a stream of air leaving the enclosure, comprising a heat exchanger for the incoming air and a heat exchanger for the leaving air, each of said exchangers comprising a group of passages through which the incoming air stream and the leaving air stream, respectively, flow in heat exchange relationship with a liquid passing through a separate group of passages. The liquid is circulated in a closed circuit between the two exchangers in a duct leading from the heat exchanger for the incoming air to the heat exchanger for the leaving air, and, upon heat exchange with the leaving air, recirculated in a separate duct to the heat exchanger for the incoming air.

Abstract: A system for recovering the waste heat normally exhausted into the atmosphere by chemical or other processing plants. The invented system comprises a heat exchange apparatus located in the exhaust stack or flue passage, heat transfer means for carrying the waste heat absorbed from the exhaust gases to a location remote therefrom, and a second heat exchange apparatus for releasing the transferred waste heat for beneficial use at said remote location. The present invention also includes temperature and pressure control means which enhance the safety and efficiency of the system's operation. The heat transfer means disclosed in this invention is a high temperature liquid (and associated pumping and piping means) capable of withstanding temperature up to 900 F. without flashing, changing state, or corroding the heat exchange apparatuses.

Abstract: Disclosed are suitably structured storage tanks which substantially eliminate blending problems in thermal storage systems. More particularly is disclosed floatable baffle and flexible diaphragm means for preventing blending of different temperatures of water in a storage tank. Also disclosed is a thermal storage system wherein the tanks are at the base of a building and which includes the use of energy conserving turbines to further enhance the benefits of thermal storage. Direct pumping entry of the storage water at a low pressure is permitted into the load circuit which is at a substantially higher pressure and the turbine conserves energy required in the pumping.

Abstract: A make-up tank is provided for two separate heat exchanger circuits operating at different temperatures, the tank having three compartments, a first compartment acting as a make-up tank for the first circuit, a third compartment as a make-up tank for the second circuit and a second or stagnant buffer compartment to separate the first and third compartments. A water level monitor and supply system is provided in one of the compartments only and the compartments are in restricted communication with each other.

Abstract: An expansion tank is connected to a heating system by feed and drain pipes whereby the flow of water into and out of expansion tank is regulated by a valve and a pump. In the expansion tank there is a bellow which is in contact with the outer air.

Abstract: A system for solar heating of water in combination with a domestic hot water system having a hot water storage tank having an inlet and an outlet, and a controllable heater arranged for heating water for storage within said storage tank.A solar heat collector has a surface which absorbs sunlight to produce heat, and a heat exchange passage for water in heat conductive relation. Piping and pump means are provided for circulating water from said tank outlet through said collector heat exchange passage to said tank inlet.An inflatable elastic member extends substantially the entire length of said collector passage.Means are provided to maintain air within said inflatable member at a higher hydrostatic air pressure than the static hydrostatic water pressure in said passage whereby the collector is rendered tolerant to freezing.

Abstract: A thermal distribution system for distributing heated or cooled fluid from respective fluid generators to thermal exchangers. The system comprises a regulating-reversing device for selectively controlling and distributing the fluid from and towards the hot fluid generator and the cold fluid generator, and regulating the flow thereof from and towards the thermal exchangers. A degasifying device is connected to the regulating-reversing device for distributing said fluid to the exchangers and for collecting the same from said exchangers. A pumping means is mounted between said degasifying device and said regulating-reversing device for pumping the fluid from the latter to the former.

Abstract: A modular boiler having a cylindrical combustion chamber made of three modules and a module comprising a cover and a module comprising an expansion vessel mounted coaxially on the boiler adjacent the combustion chamber at opposite ends thereof. The cover has a frustro-conical configuration with the inner walls thereof diverging from an opening in the cover toward the interior of the combustion chamber at an angle of between 30.degree. and 110.degree.. The combustion chamber is formed of three castings that define the cylindrical combustion chamber and six axial hot gas flow paths spaced circumferentially from each other and disposed axially of and radially of the combustion chamber. Hot gases from the downstream end of the combustion chamber are recirculated to the upstream end of the combustion chamber to improve the combustion.