Patent Application
20110108000
The invention relates to the structure and mode of operation of internal combustion engines, and more particularly to the injection of a non-fuel fluid such as water into the combustion chamber.
The increased power and gains in fuel economy obtained by the injection of water or other non-fuel fluid into the cylinders of an internal combustion engine have long been known. Water, added during the compression cycle has been shown to reduce the engine NOx.
“ISO conditions” are used when specifying power to account for changes in ambient temperature, pressure and humidity, and are 59° F. (15° C.), atmospheric pressure at sea level (14.54378 psi or 1.01325 bar) and 60% relative humidity, respectively. The predominant mass operating within the cylinder to provide motive power with either the Diesel or Otto cycle is provided by atmospheric air, heated by the fuel added to the engine. Since the density of air is a function of its temperature, pressure, and humidity, the mass within the cylinders and hence the resulting power of the engine can be reduced under certain atmospheric conditions that deviate from the standardized ISO conditions.
Van Dal U.S. Pat. No. 4,589,377 describes the injection of water or other non-fuel material into an Otto cycle internal combustion engine, the amount of non-fuel material being injected and the time of injection being governed by such factors as mass of fuel induced, compression ratio of the engine, quality of the fuel and pre-selected peak temperature of combustion.
Nakayama U.S. Pat. No. 6,112,705 describes the injection of water into a compression ignited (i.e., Diesel cycle) internal combustion engine to lower NOx emission. Zur Loye et al. U.S. Patent Publication No. 2002/0026926 also describe the injection of water into a compression ignited internal combustion engine.
Singh U.S. Pat. Nos. 6,311,651, 6,571,749 and 7,021,272 describe computer controlled internal combustion engines employing the injection of water into each cylinder of the engine, particularly during or after combustion has been initiated in the cylinder. Each cylinder of the internal combustion engine is provided with a pressure sensor and a temperature sensor for measuring the pressure and temperature in the cylinder. These sensors are connected to a computer for controlling the rate and duration of water injected into the cylinder based on the “energy content” of the cylinder determined by signals received from the sensors.
Hobbs U.S. Pat. No. 5,125,366 describes the introduction of water into an internal combustion engine in which a pressurized source of water is utilized. A computer and various engine sensors are employed to control the introduction of water to the cylinders of the engine. Binion U.S. Pat. Nos. 5,718,194 and 5,937,799 describe in-cylinder water injection systems for internal combustion engines. The water is injected at a high pressure, low temperature. Miller U.S. Pat. No. 4,448,153 describes a water injection system for an internal combustion engine that injects water into the cylinders of the engine in response to engine temperature. U.S. Patent Publication No. 2006/0037563, Connor U.S. Pat. No. 5,148,776, and Lee U.S. Pat. No. 6,892,680 all disclose water injection for internal combustion engines in which the injection of water is controlled by a computer in response to one or more sensed engine/cylinder parameters.
The disclosures of the foregoing U.S. Pat. Nos. 4,448,153, 4,589,377, 5,125,366, 5,148,776, 5,718,194, 5,937,799, 6,311,651, 6,571,749, 6,892,680 and 7,021,272, and U.S. Patent Publication Nos. 2002/0026926 and 2006/0037563 are hereby incorporated by reference herein.
While the benefits and gains in fuel economy by the injection of water (or other non-combustible fluid) into the cylinders of an internal combustion engine have long been known, some or all of the following features are believed to be particularly characteristic of various embodiments of the present invention, both separately and in combination:
(a) a correction in the injected quantity of water (or other non-combustible fluid) injected in response to any change in external air density (pressure and temperature) and/or water content (humidity) in the fuel air mixture;
(b) an ability to adjust the amount of water added to the cylinders in the water injection control system to enable the engine to produce its rated capacity at ISO conditions, independent of current atmospheric conditions;
(c) a high energy ignition system capable of igniting leaner engine mixtures;
(d) an in-cylinder pressure measurement system capable of outputting absolute (ISO) engine pressures;
(e) a pre-chamber design capable of having its flame pattern modified to be compatible with different engine geometrics;
(f) a water injector design capable of having its spray pattern modified to be compatible with different engine geometries and flame patterns of the pre-chamber igniter for Otto cycle engines, or with the Diesel injector spray pattern of a compression ignited engine;
(g) an oil/water separator to remove water from the engine oil;
(h) an exhaust heat exchanger used to preheat the water being injected into the engine to thereby reduce the viscosity of the water used for in-cylinder injection and otherwise promote process efficiency;
(i) a secondary condensing heat exchanger to recover water from the exhaust of the engine;
(j) an organic Rankine variable phase turbine and condenser to extract added energy from the condensing heat exchanger and exhaust; and
(k) supplementing a first injection of water prior to control combustion during the compression stroke with a second injection of water at a higher temperature during the expansion stroke.
Certain embodiments of the present invention provide an internal combustion operating system that enables the engine to operate at internal combustion conditions (such as the pressure and temperature inside the combustion chamber) emulating those occurring at the standard ISO rated atmospheric conditions and thus able to deliver its ISO rated output regardless of atmospheric conditions. A water injector is preferably provided having a plug end fitting to a combustion chamber of an internal combustion engine of the spark ignition or compression ignition type, though which a quantity of water or other non-fuel fluid is injected into the combustion chamber; a nozzle is fitted to the plug end of the water injector containing a plurality of openings to provide the water or other non-fuel fluid to the combustion chamber in a predetermined spatial spray pattern. In those embodiments, the temperature and combustion pressure of each engine chamber as well as the temperature, pressure and humidity of the atmosphere are preferably monitored and used to control the water injected into the combustion chambers. This can not only compensate for lower working fluid mass within the cylinder due to the air's atmospheric characteristics, by the addition of mass from the water injected into the cylinder during the compression and expansion cycles when operating at full rated power under other than standard ISO conditions, but can also improve overall engine efficiency when operating at less than full rated power. In particular, maximum rated power under non-ISO conditions may be achieved when the water is pressurized, preheated, and injected into the cylinder after top dead center whereupon it vaporizes during the expansion stroke.
In accordance with certain characteristic features of other embodiments, water injection may be utilized to increase the engine's power to its rated conditions when atmospheric conditions have reduced the density of air such as to reduce available horse power (de-rate the engine). This can compensate for lower working fluid mass within the cylinder due to the air's atmospheric characteristics, by the addition of mass from the water injected into the cylinder during the compression and expansion cycles. This is believed to be the result of the added mass and therefore the increased pressure inside the combustion chamber. Each engine cylinder's pressure is preferably monitored during each cycle to obtain a gage pressure relative to current actual atmospheric conditions, and the differences in temperature, pressure and humidity between current atmospheric conditions and the ISO rating conditions are then used to convert the measured gage pressure to a corresponding ISO absolute internal pressure at standard ISO rating conditions. By comparing this measured ISO absolute internal pressure with the known absolute internal pressures that are actually produced when operating at maximum rated output at those same ISO rating conditions, water injection can be controlled to return the engine to its rated output regardless of atmospheric conditions.
Water injection into the combustion chamber is preferably controlled by measuring the ambient air's temperature, pressure, and humidity, the water in the fuel, and the water injected in the compression cycle, as well as the engine operational parameters within the combustion chamber such as pressure and temperature, with the sensor for measuring cylinder pressure preferably being integrated with the water injector component. This applies to both Otto cycle (spark-ignited) and Diesel cycle (compression ignited) engines, as well as modifications of these cycles (such as Miller, Split Chamber, and Compressed Charge Ignition engines). The resultant new controlled water injection combustion cycle not only improves engine efficiency (the degree of improvement being affected by the temperature, timing and spray pattern of the injected water) but also permits the production of the maximum rated power measured at ISO conditions under all atmospheric conditions by means of the time controlled, spatially patterned addition of water (or other appropriate non-fuel fluid) directly into the combustion chamber.
Another characteristic feature of certain embodiments of the invention is the introduction of a non-fuel fluid such as water into all cylinder chambers with a unique spray pattern designed for each engine with its unique cylinder and piston geometry, preferably controlling both the spatial pattern of the injected water into the cylinder, as well as the spatial pattern of the fuel's ignition source within the cylinder.
The injectors, igniters, and/or pressure sensors are preferably combined into a single hydrometer device for each cylinder, having a nozzle arrangement at its plug end that intrudes into the combustion chamber and is preferably designed to be secured in place using the standard thread specifications for spark plugs and/or Diesel injectors, or in an alternative embodiment by means of conventional Diesel injector holding clamps. This enables both used and new equipment to be conveniently upgraded in the field to take advantage of many benefits of the various water injection technologies herein described. For spark-ignited engines, a high energy pre-chamber igniter is preferably integrated with the water injector to form a “pyrohydrometer” igniter-injector which independently controls both ignition of the compressed fuel air mixture within the combustion chamber and the injection of water at the appropriate time (or times) during the compression/expansion cycle. For diesel and other compression ignited engines, the water and fuel are preferably independently injected into the combustion chamber by means of a “diesel hydrometer” injector equipped with two sets of nozzle jets, with the water jets having a spatial spray pattern that complements that of the diesel jets.
In accordance with yet another important characteristic of certain other preferred embodiments, a pre-combustion chamber may be incorporated into the water injector design such that a higher energy ignition source exists permitting leaner combustion chamber mixtures (such as would occur with water injection during compression) to be ignited. The pre-combustion chamber can also be used for special fuel addition, such as hydrogen gas, for purposes of better pre-combustion with higher velocity jets going into the combustion chamber, as well as providing lower overall engine emissions with extremely lean fuel mixtures as can occur with large quantities of water injection. The non-fuel fluid can be modified by the addition of peroxide, or urea, or other additives or lubricants to modify the NOx, CO, characteristics of the engine exhaust or the lubricity of the cylinder walls. These additives can also be a function of the measured atmospheric parameters as well as external exhaust measurements.
For diesel engines, liquefied natural gas (LNG) or compressed natural gas (CNG) is preferably substituted for a substantial portion (preferably from about 60% to 98%) of the normal diesel fuel by means of an added fuel input (either CNG or LNG) to the diesel hydrometer, preferably including additional injector outlets in the injector nozzle for the LNG or CNG substitute fuels. Similarly, by injecting a low volatility fuel (such as hydrogen or an oxygen hydrogen mixture (Rhodes' gas or Brown's gas)) that will be ignited only after it has entered the main combustion chamber (preferably by means of additional passageways through the hydrometer), NOx can be reduced in the engine exhaust. This is believed to be due to the high velocity flame's ability to ignite extremely lean fuel mixtures as can occur with high quantities of water injection. Addition of these high velocity flame fuels into the combustion chamber is believed to concentrate the ignition closer to top dead center, thus reducing compression pumping losses and further improving engine efficiencies.
An engine controller, with appropriate sensor inputs, is preferably utilized to monitor all of the engine's internal operating parameters, external air temperature, pressure and humidity, water injection temperature, water content in fuel and other fuel parameters. These input parameters are then used by the controller to control the timing of water injection as well as the amount and temperature of water injected into each cylinder with each engine cycle as well as the timing of the ignition system for each cylinder. Especially when combined with an optimal water injection spray pattern inside the combustion chamber, this results in improved engine efficiency when operating at or less than full rated power. Since multiple parameters are input into the controller from different sensor in different cylinders, the water injection/ignition timing controller preferably also evaluates whether each individual sensor is operating properly.
The injection water can have its viscosity modified prior to injection by using the exhaust heat to raise its temperature. A heat exchanger by-pass system permits a full range of water temperatures. This change in viscosity can reduce the water pumping load required for injection, as well as have an effect on the spray pattern within the combustion chamber. The cycle efficiency can also be improved by recovering otherwise wasted heat from the engine exhaust to preheat the water before it is injected into the cylinder.
For turbo-charged Otto cycle engines, water injection can be applied by either (a) misting after the turbo charger, (b) misting prior to each cylinder intake, or (c) direct injection into the combustion chamber during the intake or compression stroke or any combination of the above. The water injection can be used to further increase engine efficiency by removing the heat of compression of the turbo charger (instead of using an inner cooler) as well as to control engine knock (engine pre-ignition or detonation). The efficiency of the Otto cycle can be improved by increasing the pressure ratio and avoiding engine knock by cooling the engine air with water injection to below a temperature inducing engine knock. An engine knock sensor is preferably added to ensure that engine knock will not occur due to cylinder temperature rise prior to ignition.
A water/oil separator is preferably included in the water injection system to remove the water from the engine oil. During engine operation, the engine's combusted gasses mix with the engine oil due to gaps in the piston rings and piston ring clearance, creating the potential for water to be mixed with the engine oil.
In accordance with another important characteristic of certain preferred embodiments, the engine exhaust can be further used to produce energy and recover a major portion of the injected water by installing a condensing heat exchanger and/or a turbo generator. The heat exchanger can either be made from acid-resistant metals or Teflon-coated metal to resist attack from the slightly acidic exhaust gases. An organic Rankine turbine employing a variable phase turbine or trilateral cycle with R245fa (1,1,1,3,3-pentafluoropropane) and condenser can be used to extract energy from the condensing heat exchanger and condense water for injector reuse. Atmospheric air can be blended into the engine exhaust gas to provide the proper temperature conditions for the organic turbine's working fluid within the heat exchanger.
This invention finds utility in a wide range of technical applications, including transportation and power generation, and will typically result in an increase in power and efficiency over what has heretofore been feasible. For use on locomotives and ships, a turbo generator responsive to the exhaust gasses may provide additional power; the required injection water can be transported by the locomotive or can be produced aboard ship by reverse osmosis. For landfill gas (LFG) and other biofuels having a high water content, the water in the fuel performs a similar mass enhancing function as the water being directly injected into the combustion chamber, so rather than being a contaminant that should be filtered out, it is simply measured and provided as an input to the water injection controller.
For a more complete understanding of the present invention, reference is now made to the following detailed descriptions of a few representative presently preferred embodiments and to the accompanying drawings.
For ease of reading, the following description will generally refer to the use of water as the non-fuel fluid, but it will be understood that other non-fuel fluids can be used. Thus, while water is an obvious choice as the non-fuel fluid to be injected into the combustion chamber as the added mass, other suitable fluids can be used, including inert gases such as argon, nitrogen, carbon dioxide, and ammonia, as well as oxygenated water combinations.
Referring to
Processed water (with or without additives) is supplied to a high pressure regulated pump 14. The pump provides high pressure water to each cylinder 16 of the engine 10. The water first passes through an exhaust heat exchanger 18 which raises the temperature of the water. The water is used in both the engine's compression cycle to prevent knock, as well as the engine's expansion cycle to provide added power and improve cycle efficiency. During the initial compression cycle, the water can be either (a) directly injected into the cylinder, or (b) injected into the compressor exhaust of the turbo charger, or (c) injected into the intake valve, or (d) any combination of the above.
Each cylinder 16 is instrumented with a knock sensor 20, a temperature sensor 22, and a pressure sensor 24 (shown in
Referring additionally to
Oil-purification system 42 is designed to remove any entrapped water in the oil system. The oil is then returned to the crankcase for engine lubrication.
As shown in
As shown in
Referring to
Referring to
Referring to
Referring to
The diesel hydrometer in
Tables 1 through 4 show numerical results obtained from a computerized thermodynamic model of a typical reciprocating engine (in this case, a CAT G3516C) modified and operated in accordance with various embodiments of the present invention, after calibration with its data sheet efficiency ratings both at maximum power at standard ISO 3046/1 conditions and as derated at non-ISO conditions generator efficiency of 96.7% was assumed and constant turbocharger compressor and expander efficiencies were assumed. Also, the combustion inlet air flow rate along with the cylinder geometry and compression ratio was used to calculate the required turbocharger pressure ratio at ISO (due to lack of a compressor map, the turbocharger pressure ratio was kept constant in the model). The constructed model was mapped through altitude (0 to 12,000 ft), temperature (50 to 130° F.), and humidity (0% to 100%). The off-design performance was determined and tabulated. Using the datasheet, the thermodynamic model was calibrated (for efficiencies of the turbocharger, compression, and expansion).
The Table 1 data was then generated by adding water injection to the model at top-dead center and then matching the resultant calculated flame temperature to that of the ISO reference model without any water injection (this was achieved by varying the fuel flow rate). The amount of water determined the power increase that could be achieved and this process was iterated until the power and flame temperature were brought up to ISO conditions. In particular, it will be seen from Table 1 that the amount of injection water required to maintain full rated output increases at higher altitudes (lower pressures), experiencing a noticeable peak at about 100° F. (38° C.). Table 1 assumes a 60% relative humidity, the same procedure can be repeated for other ambient humidities, so that the required injection water flow rate for a given ambient atmospheric temperature and pressure can be adjusted to take into account the actual humidity, and also to take into account any water already present in the fuel.
A more refined version of that thermodynamic model with more variables (Table 2) was then enhanced (Table 3) to include the benefits of other embodiments of the invention. In particular, varying quantities of water were injected at two different times at two different temperatures during the compression/decompression cycle, not only to increase power, but also to increase efficiency. By injecting a small amount of water at a relatively low temperature (100° F.) before the fuel ignition it was possible to increase the compression ratio from 11.3 to 14 without auto-ignition because the temperature inside the combustion chamber is thereby reduced. In addition to the increased power and efficiency resulting from the increased compression ratio, the water injection is also beneficial in reducing losses two-fold. By reducing the peak temperature, dissociation is reduced, improving combustion efficiency, and losses due to jacket water and heat radiation are also lowered. It was found that the optimum injection point for such efficiency improvements is before the compression, with no water injection during the stroke. This can be accomplished with standard inlet fogging after the aftercooler.
Further calculations using other modifications to the model also suggested that the optimal time for injecting water to enhance power was not at top dead center (as was assumed for Table 1), since that apparently resulted in the water being vaporized when mixed with the combustion gases, thereby quenching the expansion that would otherwise have occurred and producing an immediate drop in the pressure and temperature inside the compression chamber and a resultant reduction in expansion performance. However, if the power enhancing water injection occurs later, preferably once the gases have expanded by a factor of four, then any quenching effect is outweighed by the improvements to both efficiency and power attributable to reduced heat losses in the engine as well as the expansion of the water. Additionally, if the pressurized water for the later occurring injection during the expansion stage is first preheated to a substantially higher temperature (preferably to about 650° F.) using the engine exhaust and the high temperature water is then squirted onto the piston head and walls to both cool the metal surfaces and vaporize, there is a further increase in overall efficiency, as reflected in Table 3 (ISO conditions) and in Table 4 (reduced atmospheric pressure and elevated temperature).
Although the present invention has been described in connection with the preferred embodiments, it is to be understood that modifications and variations may be utilized without departing from the principles and scope of the invention, as those skilled in the art will readily understand. Accordingly, such modifications may be practiced within the scope of the appended claims.
This application claims benefit of and priority from U.S. provisional application 61/133,176, filed on 28 Jun. 2008.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US09/48882 | 6/26/2009 | WO | 00 | 12/23/2010 |
| Number | Date | Country | |
|---|---|---|---|
| 61133176 | Jun 2008 | US |
