Internal-combustion engines – Charge forming device – Heating of combustible mixture
Patent
1990-07-02
1991-08-13
Dolinar, Andrew M.
Internal-combustion engines
Charge forming device
Heating of combustible mixture
123590, 123545, 123552, 123540, 261142, F02M 3100
Patent
active
050387421
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a vaporiser nozzle and in particular relates to a vaporiser nozzle useful in evaporating liquids into gaseous streams for example liquid fuels into an air stream.
In internal combustion engines, turbines, liquid fuel fired furnaces, and the like, liquid fuel is mixed with an oxidising gas stream, for example an air stream. In a conventional fuel/air mixing device such as a carburettor the fuel discharges from a jet or metering bar in a stream which is torn apart into ligaments which progressively break up and contract into droplets of various sizes. During this process vaporisation takes place and the droplets progressively reduce in size, the finest vaporising completely. Ideally, all of the liquid droplets would be vaporised and uniformly distributed in the air stream by the time they reach the combustion zone or combustion chamber.
In practice, especially under the varying conditions which internal combustion engines in particular are subjected to, some of the droplets are incompletely vaporised and this has adverse effects on both fuel economy and the cleanliness of the exhaust gases. In most conventional devices such as carburettors complete vaporisation only occurs at some part throttle conditions. Furthermore vaporisation occurs at a substantial distance away from the point of fuel discharge which distance varies with variable fuel demands of the engine. Fuel vaporisation is improved with forced fuel injection systems where the fuel injection nozzle functions to mechanically atomise the fuel at the tip exposed to the air stream. Fuel injection has several advantages over conventional carburettors but suffers from the disadvantages of high manufacturing costs and additional complexity requiring more sophisticated servicing.
In our international patent application No. PCT/GB88/00508 (WO 89/00240) there is described a vaporising device including a nozzle which comprises a wall of porous material through which a liquid to be evaporated percolates from one side thereof in to a gas stream at the other side thereof. The porous material is a sintered metal, in particular brass, bronze, cupro-nickel or the like. Conveniently, the wall will be cylindrical in configuration and the gas stream may flow over the cylinder, in which case the liquid will be supplied internally of the cylinder, or may flow through the cylinder in which case the liquid will be supplied externally of the cylinder. The primary use of this nozzle is in mixing hydrocarbon fuels with an air stream, for use in for example an internal combustion engine.
The nozzle of our above mentioned PCT application is very efficient and thus at high rates of vaporisation it is subjected to considerable cooling. This, in turn, affects the density and viscosity of the fuel and can adversely affect fuel flow. Indeed, in our earlier patent publication it was recognised that heat may need to be supplied to help combat this effect.
We have now discovered that if heat is applied in a precisely controllable manner it may be employed actually to regulate the flow of fuel from the nozzle and thus provide a very simple and efficient engine management system.
According to the present invention there is provided a vaporising nozzle which comprises a wall of porous material through which a liquid to be evaporated percolates from one side thereof into a gas stream at the other side thereof characterised in that a thermoelectric device is located at or adjacent the wall of porous material whereby to regulate the temperature thereof.
A thermoelectric device is a solid state device operating on the Peltier effect. The latter is the discovery that the passage of an electrical current through a junction of two dissimilar conductors cools or heats the junction depending on the direction of the current. Thermoelectric devices operating on this principal are now commercially available. If a steady or pulsating DC current source is connected to such a device heat will be absorbed at one end of the device, cooling it, while heat is ejected at the other
REFERENCES:
patent: 3828736 (1974-08-01), Koch
patent: 4088104 (1978-05-01), Ibbott
patent: 4212275 (1980-07-01), Inoue
patent: 4336783 (1982-06-01), Henson
patent: 4742314 (1988-05-01), Desage
patent: 4848302 (1989-07-01), Firey
patent: 4849604 (1989-07-01), Woolcott
Dolinar Andrew M.
E-Tech Limited
Macy M.
LandOfFree
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