This invention relates to a novel fuel-conditioning-method and coupled-combustion process applicable to piston engines and rotary engines. Liquid fuel is first thermally conditioned inside a gasification chamber comprised inside a piston or inside a rotor and then it is transferred into a combustion chamber when combustion needs to be initiated.
Most popular internal combustion engines (ICEs), specifically the Otto cycle or spark ignition (SI) engine, the Diesel cycle or compression ignition (CI) engine and the homogeneous charge compression ignition (HCCI) engine release polluting exhaust requiring a complex and costly after-treatment system in order to comply with government emission standard regulations. The individual combustion processes employed by these engines are responsible for different levels and variety of raw exhaust contaminants.
Decades of ongoing ICE research and development, testing and refinement has yielded impressive improvement in tailpipe exhaust cleaning. However, an alternative combustion processes that would require less costly, simpler and more durable after-treatment devices is needed. Furthermore, feasibility of running an ICE with fuel requiring less refining processes and without additives would be desirable.
Air polluting emissions are caused by incomplete fuel combustion and undesired oxidation reactions intrinsic to the combustion process particular to each ICE. The contaminants affected by emission standards are carbon monoxide (CO), soot or particulate matter (PM), nitrogen oxides (NOX), non-methane organic gases (NMOG) and formaldehyde (HCHO).
In sum, prior art has accomplished enormous progress in reducing ICE tailpipe exhaust pollutants via intricate fuel management, sophisticated combustion chamber designs, special fuel formulation and adequate fuel additives as well as a variety of complex and costly devices for after-treatment of raw exhaust.
The herein disclosed fuel-conditioning-method and coupled-combustion (F-C-M & C-C) process allows to minimize the raw exhaust contaminants from an ICE when compared to actual prior art levels. In addition, application of this invention will yield better fuel economy.
This invention is suitable for incorporation into reciprocating piston engines, free piston engines and rotary engines.
It is believed that the F-C-M & C-C process will provide a cost-effective alternative for air pollution control from ICEs as well as an improved fuel economy.
When this inventor realized the need to create a more efficient combustion process than the processes employed by prior art ICEs, the purposes of this invention were inspired, leading him to the conception and the accomplishment of this invention.
This invention provides manufacturers of automobiles, trucks, power plants, marine propulsion, rail locomotives, mines clean energy sources, etceteras with a new, safe, reliable, useful and less costly F-C-M & C-C process for ICEs that permits to substantially abate air pollution contamination when comparing to prior art engines.
The advantages of disclosed F-C-M & C-C process are: (1) a gasification chamber comprised inside a piston allows thermal conditioning (i.e. vaporization and gasification) of the fuel prior to combustion, (2) hot gaseous-fuel ignition delay is negligible, (3) the combustion is controlled by a gaseous mass-diffusion flame, (4) a rich-burn follow by lean-burn mode minimize pollutant formation, (5) fuel is not required to be rated for neither octane or cetane number, (6) improvement of engine fuel economy and (7) permits switching among different liquid fuels.
An important mechanical advantage is that the gasification chamber comprised inside a piston has no valves or moving parts for its closing and opening thus resulting in cost savings, less complexity and more reliability.
Further advantages of the invention will become apparent upon consideration of the following drawings and descriptions.
Underlined numerals designate an assembly. The parts cited in the following description are:
The following acronyms are used throughout the specification and the abstract:
BDC (bottom dead center),
BDCL (left piston bottom dead center),
BDCR (right piston bottom dead center),
CI (compression ignition),
CO (carbon monoxide),
F-C-M & C-C (fuel-conditioning-method and coupled-combustion),
HCCI (homogeneous charge compression ignition),
HCHO (formaldehyde),
ICE (internal combustion engine),
NMOG (non-methane organic gases),
NOX (nitrogen oxides),
PM (soot or particulate matter),
SI (spark ignition),
TDC (top dead center),
TDCL (left piston top dead center) and
TDCR (right piston top dead center).
Before proceeding to describe the entire embodiments in the next section, it is important to understand the essential hardware required to implement the disclosed F-C-M & C-C process as well as its operational mode.
In operation, referring to
During the down stroke of piston 12 when gasification chamber inlet 34 over pass the bottom edge 36 pertaining to transfer port 18 the hot combustion gases are shut close inside gasification chamber 10 by the inner wall of cylinder 20. As piston 12 continues traveling toward the BDC hot combustion products remain entrapped inside gasification chamber 10. While approaching the BDC position, see
As piston 12 travels towards the TDC there is sufficient residence time for liquid fuel droplets to vaporize and then to reach gaseous phase state. When gasification chamber inlet 34 meets the bottom edge 36 pertaining to port 18, see
Since entrapped combustion products contain insignificant amount of oxygen, when fuel spray 32 is injected no significant combustion occurs inside gasification chamber 10 thus causing a subsequent pressure and temperature decrease as fuel droplets absorb heat to vaporize and to finally reach a gaseous phase state.
The residence time available for fuel droplets vaporization/gasification can be increased by placing fuel injector 24 near the bottom edge 36 pertaining to transfer port 18 and injecting fuel during the piston down stroke. This approach if required, imply the utilization of a more costly fuel injection system that needs to inject at a higher discharge rate and the injector tip is exposed to combustion products, a undesirable hot environ that might cause the overheat of the nozzle tip of fuel injector 24 enough to cause fuel coking thus shortening injector life. The preferred location of fuel injector 24 shown in
The average droplets size of a fuel spray injected into prior art ICEs plays a central role in the production of harmful emissions and fuel economy. Smaller droplets are desirable, that requires a more sophisticated and more costly fuel injection system. The F-C-M & C-C process is nearly independent of average droplets size of the injected fuel spray 32 since inside gasification chamber 10 fuel droplets vaporize reaching a gaseous phase. Consequently, a less costly and more rugged fuel injection system is suitable.
Since the combustion products entrapped inside gasification chamber 10 contain insignificant amount of oxygen, NOX formation is negligible during the vaporization/gasification phase.
Referring again to
The initial combustion is of the rich-burn mode type, either by (1) hot gasified fuel jetting into a hot air charge contained inside combustion chamber 22, or by (2) hot air jetting into a hot gasified fuel contained inside gasification chamber 10. Since for both cases the flame zone is controlled by the mixing rate between hot gaseous-fuel species and hot air, either inside the combustion chamber 22 or inside gasification chamber 10, there is not a propagating flame front like occurs inside SI or HCCI engines as a result eliminating possibility for the occurrence of detonation. Unlike Diesel engines there is not fuel droplets transferred into combustion chamber 22. Consequently the fuel suitable to operate the F-C-M & C-C process is not required to be rated neither for octane nor for cetane numbers.
This feature is extremely important since allows to exploit cheap petroleum derived fuels, biodiesel, bioalcohol, vegetable oils, biomass liquid fuel, coal-oil-slurry and coal-water-slurry. Inclusion of the vast supply of coal to supply large-low-speed engines is possible when utilizing the disclosed F-C-M & C-C process. Achieving this goal could result on an immense saving on crude petroleum demand.
Because of the initial rich-burn mode just described a temperature level much lower than that corresponding to stoichiometric combustion is achieved and, due to the relative lack of oxygen around the flame zone the formation of NOX is minimized. Additionally, since both air and gaseous-fuel are at relatively high temperature, ignition delay is negligible and chemical reaction rates are very fast compared to prior art ICEs. Consequently it allows for efficient combustion even while the engine is running at relatively high speed.
Furthermore, the intrinsic fast gas-phase initial combustion described above tied to a relatively prolonged final lean-burn stage (that develops at the reacting mixing interface after gasification chamber 10 is shut close) assures full oxidation of diverse hydrocarbon species. Accordingly, formation of PM, NMOG and HCHO is minimized when compared to prior art ICEs.
The above described combustion process is qualitative only. A quantitative evaluation requires a state-of-the-art computational modeling and simulation for each particular engine-fuel combination. Two separate modeling are required, (1) the vaporization/gasification process inside gasification chamber 10 while accounting for heat losses into gasification chamber 10 and cylinder 20 walls as well as heat transferred into fuel droplets, fuel distillation, chemical breakdown and (2) accurate mixing and chemistry formulation to account from the initial rich-burn thru the final lean-burn stages including heat losses into engine walls. Ultimately experimental measurements are indispensable to fine tune a prototype.
Summarizing, disclosed F-C-M & C-C when applied to ICEs offers: (1) substantial abatement of raw exhaust contaminants affected by emission standards regulation and (2) improved fuel economy when compared to SI, CI and HCCI type engines.
Gasification chamber inlet 34, see
Starting the ICE depicted by
The ICE depicted by
Notice that the distance “D” between the bottom edge 36 of transfer port 18 and the TDC determines combustion timing. Nevertheless, factors such as transfer port 18 geometrical dimension, direction of flow direction arrow 26 and initial magnitude of the pressure differential prevailing between combustion chamber 22 and gasification chamber 10 also affect effective combustion initiation timing. As engine speed increases combustion initiation timing needs to occur earlier and vice versa.
A multiplicity of gasification chambers 10s could be incorporated into piston 12 each with matching transfer ports 18 of different distance between their bottom edges 36s and the TDC. This approach could be desirable in order to optimize the overall combustion process within a wide range of load and speed.
The reader will realize that application of the F-C-M & C-C process is also suitable for incorporation into a uniflow scavenged 2-stroke engine as shown in
Notice that a fixed geometry transfer port 18 is not suitable for application into a 4-strokes engine since during the end of the exhaust stroke and the beginning of the intake stroke the combustion products entrapped into gasification chamber 10 will transfer into combustion chamber 22 defeating the object of the invention. Nevertheless, this obstacle could be circumvented by adding a cyclical shutoff mechanism onto transfer port 18.
Referring specifically to the entirety of this invention, another preferred embodiment is shown in
In operation, referring to
The remainder of the cycle is identical to the above description related to
Another preferred embodiment is shown in
Operation of each power module 50 is identical to that of the 2-stroke engine described by
In the prior art there are different design arrangements and applications of the free piston engine concept. Nevertheless, incorporation of a F-C-M & C-C process is directly applicable into all of those free piston engines.
Another preferred embodiment is shown in
For easy visualization of the 4-strokes cycle that evolves inside the Wankel type rotary engine and to understand the accomplishment of the F-C-P & AC process,
Location of transfer port 18 cannot be arbitrarily choose, see Section A-A and Detail C in
Notice that location of fuel injectors 24, see Section B-B in
It is important to realize that the volume of squeezed gas 70 located near the trailing end of rotor-flank 60, near one apex 56, is air reach thus the exhaust is not burden with unburned fuel and CO as tends to occur with prior art Wankel type rotary engines. Inside those prior art engines the relatively elongated squeezed gas 70 volume prevents the flame front from reaching the trailing edge of moving combustion chamber 64.
Still another preferred embodiment is shown in
During engine running at high speed fuel is injected mainly into gasification chamber 10 whose gasification chamber inlet 34 first reaches a leading edge 68, while at low speed and idle fuel is injected mainly into the other gasification chamber 10, the one whose gasification chamber inlet 34 last reaches a leading edge 68. During part load operation the fuel could be simultaneously injected into both gasification chambers 10-10.
Given the above descriptions, the reader can appreciate the non-obvious novelty disclosed.
A strenuous effort is taking place worldwide to conceive and develop improved ICEs. Decades of ongoing research and development, testing and refinement has yielded impressive improvement in tailpipe exhaust cleaning by use of intricate micro-computer controlled fuel management, sophisticated combustion chamber designs, special fuel formulation and adequate fuel additives as well as a variety of complex and costly devices for after-treatment of raw exhaust.
The herein disclosed F-C-M & C-C process allows to minimize raw exhaust contaminants from ICEs when compared to actual prior art levels. Raw emissions could be low enough to eliminate the need for tail pipe after-treatment systems. In addition, application of this invention yields better fuel economy.
Accordingly, the reader will see that the F-C-M & C-C process disclosed provides manufacturers of specific engines applicable to automobiles, trucks, small airplanes, small helicopters, military vehicles, power plants, marine propulsion, rail locomotives, mine's clean energy sources, etceteras with new, safe, reliable, useful and less costly strategic means that will permit (1) to substantially abate air pollution contamination, (2) to improved fuel economy and (3) to allow utilization of diverse liquid fuels when comparing to prior art engines.
One or more embodiments of this invention may offer one or more of the following advantages when compared to prior art engines:
The above description contains many specificities; these should not be construed as limiting the scope of the invention, but rather as merely providing illustrations of some of the presently envisioned embodiments of this invention. Any replacement of parts that are functionally equivalent is within the scope of this invention. Indeed, from the foregoing description, various other variations and changes will become apparent to those skilled in the art without departing from the spirit and scope of this invention.
The reader will find that the embodiments illustrated by
The scope of this invention should be determined by the appended claims and their legal equivalents, rather than by the embodiments illustrated.