BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1. is a Schematic Drawing of the proposed CI Diesel Engine Cycle system and their relationship provide a clean high performance vehicular engine. A typical engine crossection, Reformed Diesel Engine 46, is shown with Fuel Pump 50, and Inlet Water Manifold. Air flow into the engine through a filtered air inlet to the Turbocharger 34 to increase the inlet pressure to 3 times ambient and maintains control of the temperature by passing it through an Inlet Cooler 30. The engine operates at a cycle pressure ratio of 25 to one. Exhaust from the engine is discharged into an Exhaust Heatexchanger 32 the water is heated to 1000 F (acting as a boiler). The cooled exhaust is then expanded through the Turbocharger 34 turbine to a reduced temperature of 346.5° F. and 26.3 psia pressure. Exhaust from the turbocharger enters the Water Condenser 90 to remove the heat of vaporization from the mixture of steam and exhaust products and collects the condensed water returning it to the Combined Water and Fuel Tank 94. The high pressure steam from the exhaust heatexchanger enters the Inlet Water Manifold for delivery to the cylinders with an electronic control system. The engine is designed to operate in the diesel mode and also a bottoming steam cycle mode. Power output in the diesel mode is 313.3 horsepower at a specific fuel consumption of 0.1583 lb/hp-hr. The steam engine cycle provides an additional output of 330.3 horsepower.
The engine cross-section shown is assumed to be a four cycle, six cylinder Mercedes 200D type engine with a modified Garrett Turbocharger. Analysis considered an engine with a bore of 3.710 inches and a stroke of 3.937 inches. The drawing illustrates a two valve per cylinder, but modern design would incorporate a four valve per cylinder system.
A secondary water system is shown on the schematic. The engine cooling system operates on a second water supply. Radiator 20 is a conventional air cooled radiator with an integral water tank. This system provides the cooling for the Inlet Cooler 30 and the water cooled engine system. Storage of the cooling water is in the Bottom Tank 24.
The water pump is a high pressure design that is geared to the Turbocharger 34 shaft and is capable of providing a water flow of 50 lbs/min at 2000 psi to the Exhaust Cooler (Boiler) 32 entering at 60 F and discharging at 1000 F.
FIG. 2 Psychrometric Chart of the Steam Cycle illustrates the highly efficient Rankine Cycle which is used by the electric power industry. Steam is provided at 1000 F and 2000 psia, which includes 370 F of superheat, to the prime mover driven generators. Experience has shown that a thermal efficiency of 45.7 percent is feasible. The intake valves will remain closed during scaveng portion of the cycle, allowing the steam to pressurise the cylinder and operate as a steam engine. Based on the second law of thermodynamics 330.3 horsepower will be generated with the steam available. Water enters the Exhaust Cooler 32 (Boiler) A at 60 F and 2000 psia and is discharged, as superheated steam at K 1000 F. The steam is expanded by the piston (CPR 25:1) and the turbocharger turbine to 346.5° F. and 26.3 psia at G. Passing through the Water Condenser 90 water will be condensed and removed depending on the efficiency of the ram air cooling. The condensed water is then drawn off and returned to the Combined Water And Fuel Tank 94.
FIG. 3. Shows a Duel Fuel and Water Injector with Reformer 86. This figure illustrates the mechanical design modifications introduced by the invention to make this a dual fluid injector to the reformer. An additional Water Attachment Fitting 82 has been added introducing a Water Inlet 66 line to the injector. A distribution passage through the housing will deliver the water to the Pintle 74. The Pintle 74 has a central passage and nozzle to direct a central water spray into the reformer. A glow plug, if required, is shown which does not influence the invention, but is desired to assist in the cold starting of the diesel engine. The mechanical arrangement of the reformer is illustrated.
FIG. 4. shows the Fuel Reformer 86. This figure illustrates the flow patterns as the fuel and water are injected into the reformer. Fuel is injected initially encountering a delay before combustion is started by autoignition, followed shortly by the water spray. The water flashes into steam at these temperatures, controlling the peak temperatures in the reformer and disassociating into hydrogen, oxygen and water vapor. Products of the chemical reaction pass through the radial passages in the fins and through the axial conical to the showerhead. Thereby, directed through a multitude of discharge orficies, designed to distribute the products uniformly into the cylinder cavity where it will undergo a secondary combustion of the hydrogen and carbon monoxide. This combustion will occur during the expansion stroke as long as combustible products are available.
FIG. 5 Detail Exhaust Condenser. The exhaust condenser is very important to the proposed cycle since it has been designed to reduce the exhaust temperature from 346.5 F to below 200° F. removing the heat of vaporisation and condensing the water vapor in the exhaust. The cooling is at ram velocity and at 60 F passing through the offset aluminum fins at the outer diameter of the condenser duct. The spherical aluminum plates are pierced and flanged to provide a maximum exposed surface to the exhaust products. The specific volume of the exhaust drops significantly as consensing occurs, reducing the velocity of the exhaust. The spherical shape is designed to trsp the condensate, collection it in a tube at the bottom of the duct. The concentrate will then be pumped into the dual fuel tank. The recovered water is distilled and will be recirculated indefinately. Since about ten percent of the products of combustion is water, about 9.8 pounds per hour will be added to the tank.
The drop in pressure across the condenser, as a result of the condensation of the water vapor, will increase the pressure drop across the offset cooling fins and acting as a jet pump will increase cooling air flow. The low velocity of the exhaust at the outlet will result in a very low noise level.
FIG. 6 The fuel tank is designed to store both the fuel and the water. A flexible elastomeric kevlar bellows is used to provide a variable volume for the fuel tank. As the fuel is used additional space becomes available for the 9.8 lbs/hr of water, condensed from the products of combustion, of the fuel while operating at maximum power. Water surrounds the flexible fuel storage to eliminate space for a fuel vapor to form. A major problem in vehicular accidents is the ignition of the fuel vapor, causing an explosition and fire.
A siginificant storage is required for the water of the steam engine portion of the cycle, resulting in the use of up to 49.27 lb/min at maximum power. All of the water in the steam cycle will be condensed and resuable. The water from products of combustion will be added to replace any leakage or drained at refuling time for other uses. Distilled water is sold today at about half the price per gallon of diesel fuel.
FIG. 7 Exhaust Products Variation With Exhaust Cooling. This curve shows cylinder combustion products as a perceentage of the flow, versus exhaust products temperature. This plot of the calculated combustion products in the cylinder, as a percentage of the weight of the fluid in the cylinder. The data covers the period from ignition through the completion of the expansion stroke and the opening of the exhaust valve. Engine speed was 3750 RPM, FA was equal to 0.50 and FW was equal to 1.20. of the twelve properties calculated seven were plotted, namely CO, CO2, H2O, H2, OH, NO and O2. The results of the analysis show how the NO, OH and CO are reduced drastically by the cooling in the heat exchanger. An additional reduction in gas temperature is made as the exhaust pressure is reduced as it passes through the turbocharger turbine, thereby, providing the work required to drive the compressor. At this point the temperature is near ambient, causing a portion of the water vapor to condense before entering the condenser to complete condensation and returning the condensate to the storage tank.
PREFERRED EMBODIMENT—DESCRIPTION
FIG. 1. is a Schematic Drawing of the Compression Ignition Engine Cycle. This drawing illustrates the mechanical components and their physical relationship in the operation of the engine. The radiator 20, is an assembly of the surge tank 22, cooling fins 23, and the bottom tank 24. A coolant fan 26, draws the cooling air over the cooling fins 23. Coolant from the engine enters the top of the radiator and is drawn from the bottom by the coolant water pump 28 and is directed into the inlet cooler 30, to the exhaust cooler 32 and into the internal cooling passages of the reformed diesel engine 46, and the cooled exhaust manifold 33. The engine airflow is drawn into the turbocharger 34, through an inlet air filter 40, State A and into the compressor 36. The air pressure ratio across the compressor 36, is controlled by regulating the amount of air bypassing turbine 38. The amount of this bypass air is controlled by the exhaust bypass valve 44, with the power to modulate this bypass control valve provided by the engine oil, bypass control pressure is regulated by the pressure ratio control valve 42, discharge oil from the control pressure ratio valve is returned to the engine oil tank 45. Compressed air from the turbocharger compressor, State B, is cooled by the inlet cooler 30, State C and is then delivered into the intake manifold 47. Additional compression of the air occurs during translation of the piston 45, represented by State D, of the reformed engine 46, in the manner conventional to the operation of an internal combustion engine. Fuel is introduced by means of the injector 72, supplied through a fuel inlet line 70 and a water inlet line 66, that are internally connected within the injector 72. The fuel and water are supplied at the pressure required for injecting liquids into the cylinder by the engine driven high pressure fuel and water pumps 50. Fuel is brought to the pumps from the fuel portion of the tank and water from the portion of the water tank 94, by the supply pumps 58, State E. After combustion and expansion, exhaust air leaves the engine through the cooled exhaust manifold 33 and enters the exhaust cooler 32. The cooled exhaust air, State F enters the turbocharger and a controlled portion passes through the turbocharger turbine 38, State G. The speed of the turbocharger is controlled by bypassing turbine air not required to maintain the desired pressure rise across the compressor. The remaining bypassed air is routed to the exhaust discharge. Turbine air is expanded, passing through the turbine 38 and cooled to near ambient temperature in the Condenser 90. When cooled to this lower temperature, water vapor in the exhaust will condense, forming the equivalent of rain in the discharge, State H. The water condenser 90 will be designed to remove the liquid water from the exhaust and by means of a water scavange, returning this water to the storage tank, where it is available for recycling to the engine.
FIG. 3. shows the Dual Fuel and Water Injector with Fuel Reformer. A modified water attachment fitting 82, has been added to the housing 78, of the injector 72, to provide a means of attaching the water inlet 66 line and connecting it to a passage which is provided to deliver this water to an annular distribution space around the pintle 74, to allow the water to enter the pintle through radial holes connected to a central passage in the pintle 74, this passage provides the means for delivering the water to an orfice nozzle on the center line at the tip of the pintle 74, generating the water spray entering the reformer 86. The fuel inlet 70, line introduces the fuel to a passage through the housing 78, to an annulus area surrounding the end of the pintle 74. Fuel pressure acting on the end of this pintle will retract the pintle 74, against the pintle return spring 76, allowing a conical spray of fuel to enter the reformer through the dual fuel and water nozzle 73. The glow plug 80, is shown to illustrate how it can be incorporated into the design to provide the additional heat required for cold starts of the diesel engine.
FIG. 4. shows the Fuel Reformer 86 giving a cross sectional detail of the reformer mechanical design, consisting of a two piece casting, insert 83, which has been diffusion bonded to form one integral part, the reformer 86. The outer surface has been plasma coated with a ceramic insulation (zirconium oxide) to limit the amount of heat that can be transferred to the cooled wall of the supporting structure. The water spray from the central nozzle will impinge on the end of the insert 83, and be deflected in a radial direction to contact the outer walls of the reformer 86. As fuel pressure rises the pintle 74 retracts causing an annulus orfice to open and introduce a conical spray of fuel. Initial combustion will occur on the inner and outer edge of the spray with the remaining liquid striking and traveling along the outer wall of the reformer. The high temperature within the reformer and the wall temperature accelerates the evaporation of both fuel and water. The four radial fins of insert 83, have a series of radial holes to direct the products of combustion to flow into a central conical passage, this difussing passage directs the flow to the shower head with an opening to the cylinder through a hole pattern shown in View B-B. As seen by this view, a majority of the holes are in the outer periphery of the elipsoidal shape. During the combustion period when the combustion products are being passed into the cylinder, the piston 45, will be close to the line of the cylinder head, and the majority of the flow of combustion products will be distributed uniformely into this cavity to mix with the remaining air and support the secondary combustion. The mass of the reformer is greater than ten times the mass of the combustion products, consequently the resulting high thermal inertia, the cyclic flow of the inlet and scavenge air with the combustion gases and the heat required for the vaporization of both the fuel and water are balanced to provide acceptable reformer operating temperatures.
Operation—Main Embodiment
FIG. 1. is a Schematic Drawing of the Compression Ignition Engine Cycle. This is a cycle definition used for the performance analysis of the internal combustion engine as concieved for this invention with turbocharging, intercooling, precombuster (reformer), two cycle operation, exhaust cooling with a water seperator in the exhaust followed by two cycle as a steam engine. An extensive analytical analysis of each of the components is required to arrive at a selection for the optimum engine to be used for a specific vehicular design. Many variables can be studied to understand their influence on reducing the pollutants discharged into the environment. In the example to be presented, the turbocharger compressor pressure ratio, the diesel compression ratio, intercooling, FA ratio and exhaust cooling will be discussed. The cycle analysis consists of the following eight designated state points. From ambient condition to State A, represents the predicted pressure drop across the inlet filter, which can vary considerably in some applications by the dust environmental filter requirements. Pressure and temperature changes from State A, to State B, represent the design pressure ratio and the efficiency of the turbocharger compressor. Changes of conditions from State B, to State 3, represent the amount of intercooling and the resulting pressure drop across the heat exchanger. State C, represents the conditions entering the engine and will remain constant during each analysis, while State D, will vary as a function of the crank shaft angle. The crank shaft 49, is shown with the piston in the TDC position (top dead center), or 180 degrees. The CPR (compression ratio) is the ratio of the cylinder cavity volume at BDC (bottom dead center), zero degrees by the cavity volume at TDC. This is a volume relationship, not pressure. Thermodynamic properties are determined at each degree of crank shaft rotation.
Combustion (oxidation of both carbon and hydrogen) will occur in both the reformer and the cylinder cavity, with the combustion continuing in the cylinder until the exhaust valve opens at 308 degrees. The mass flow of air is nearly doubled in passing from exhaust discharge, combined with scavenge steam from an adjacent cylinder, mixing, resulting in a mixed average temperature at State E. In moving from State E, to State F, the pressure changes because of pressure drop across the exhaust cooler and the temperature changes by the amount of cooling produced in the heat exchanger. The turbocharger pressure ratio is controlled by the operation of a bypas valve that bypasses excess air (not required to maintain the speed required to provide the desired pressure ratio across the compressor) around the turbine, discharging it into the exhaust up stream of the water seperator. As the performance of the engine is increased by the addition of water and higher FA ratios an excess of energy is available in the exhaust. Water injected radial aircraft engines and research adiabatic diesel engines have used a power recovery turbine compounded with the turbocharger to recover this energy. This invention proposes using steam generated by the exhaust cooler and enjected acting as a steam engine cycle. Moving from State G, to State H, the exhaust temperature has been reduced to 346.5° F. by the turbine work, will make it possible for the condensation of the water vapor in the exhaust. This condensate will be trapped by the water seperator and with the scavenge water pump 92, will be returned to the tank to be recycled.
Since one of the products of combustion is water (about an amount equal to about 9.8 lbs/hr of distilled water) a significant amount of pure water would be obtained. Diesel engine power has been limited by the rate of combustion which controlled the maximum engine speed. With the intimate mixing of the fuel and oxidizer of this invention and the dual combustion zones the piston speed can be increased, with efficient combustion, resulting in higher output power.
Analytical Approach
To analyze the effects of the addition of water to the diesel cycle, the chemical formula for the reaction during combustion has been modified as follows:
- FA=Fuel/Air Ratio FW=Fuel/Water Ratio MWF=Modal Weight Fuel MWW=Modal Weight Water SG=Specific Gravity Fuel
The above equation has thirteen unknowns, five more equations are obtained from the atomic balance equations of carbon, hydrogen, oxygen, nitrogen and arogon. Six dissociation equilibrium reactions are included and the thirteenth equation required is the energy equation, which for the steady flow process states that the energy of the reactants is equal to the energy of the products. With these thirteen equations defined the unknowns are determined at each degree of rotary motion of the crankshaft. The amount of heat added at each shaft rotation increment is dependant on the amount of carbon that is converted to carbon monoxide and carbon dioxide and the amount of hydrogen that has been converted to water vapor.
EXAMPLE
A modification of the Mercedes Benz 200d, with a Garrett turbocharger, was selected as an example for a CI automotive engine that could be used for the analytical study of the theroy of water injection and the introduction of a bottoming steam engine cycle on the third stroke of a four cycle engine. This modified six cylinder diesel engine with precombuster has a bore of 3.710 inches piston diameter and a stroke of 3.937 inches. Assumed turbocharger pressure ratio of 3.0:1 and an engine cycle compression ratio of 25:1. Operating speed of 3750 RPM. Diesel fuel used C10H22 with a LHV of 19,192 BTU/lb. Intake Valve Open at 48 degrees with fuel injected at 167 degrees. Shower Head Area of 0.032 square inches. Exhaust valve open at 308 degrees. The analysis was based on the assumption that the duration of the fuel injection is proportional to the fuel-air ratio. The start of water injection has been delayed by a prescribed amount to allow ignition of the fuel to start in the reformer allowing an increase in reformer gas temperature before water vaporization starts, thereby, preventing the flame from being extinguished. All of the fuel and practically all of the water has been injected by the time the crankshaft has reached 250 degrees at the fuel-air ratio of 1.00.
- Cond. 1 Engine operating at 3750 RPM with a fuel air ratio of 0.55 and no water introduced into the cycle.
- Cond. 2 Engine operating at 3750 RPM with a fuel air ratio of 0.55 and a fuel water ratio of 1.2 with water introduced into the cycle at top dead center.
- Cond. 3 Engine operating at 3750 RPM with a fuel air ratio of 0.55 and a fuel water ratio of 1.2 with water introduced at the intercooler discharge, reducing the air inlet temperature to 147.6 degrees.
- Cond. 4 Engine operating as a steam engine with steam introduced at 2000 PSI and 1000 degrees F. at top dead center.
- Cond. 5 Predicted output conditions by the addition of engine Cond. 2 and Cond. 4.
|
Cond
HPD
HPS
SFC
DME
TEFF
TMAX
TEX
|
|
|
1
230.2
.4411
46.2
30.1
3903
2765
|
2
304.0
.3301
45.7
40.2
3805
2688
|
3
313.3
.3268
46.6
40.6
4274
3159
|
4
323.7
0
46.6
45.7
2000
300
|
5
313.3
323.7
.1599
46.6
1494
|
|
HPD = Horse Power Diesel
|
HPS = Horse Power Steam
|
SFC = Specific Fuel Consumption LB/HP Hr
|
DME = Air or Steam Flow LB/Min
|
TEFF = Thermal Efficiency
|
TMAX = Maximum Cycle Temperature Degrees F.
|
Tex = Exhaust Temperature Degrees F.
|
CONCLUSIONS, RAMIFICATIONS AND SCOPE
The object of this patent is to provide an environmentally acceptable CI engine, operating on a low cost safer diesel fuel, that provides excellent vehicular operational characteristics and has eliminated undesirable pollutants, including noise and smell from the exhaust. By reforming the fuel, particulates, smoke, hydrocarbons and aldehydes which are responsible for the obnoxious smell, are eliminated from the exhaust. Exhaust cooling will allow for condensation and recycling of the water while it eliminates the carbon monoxide and nitrous oxides from the exhaust. An important ramification of this cooling is reflected in the design of the turbocharger turbine. An undesirable characteristic of a turbocharged vehicular engine is the response rate of the turbocharger, which is directly related to the mass polar moment of inertia of the turbocharger rotor. By cooling the exhaust, the requirement for a high temperature material for the turbine has been eliminated. Both turbine and compressor can be fabricated from a composite material, significantly reducing the polar moment of inertia and at the same time reducing the cost and significantly improving the response rate of the engine.
A second ramification of the proposed cycle is the possibility of designing the turbocharger with additional flow through the compressor to supply bleed air for an air cycle airconditioning system. More energy is available in the exhaust than is required for the turbocharger. To bring this air to the desired temperature level for airconditioning, it can be used to power a tip turbine driving the cooling fan and/or a generator for the electrical system.
A third ramification of the proposed design will be its ability to operate on a wide variety of fuels including kerosene, distillate fuel oils, Jet A, Jet B, JP-3, JP-4, JP-5, CITE, methanol and alcohol.
A fourth ramification will be the surplus condensed distilled water that will be available each time the tank is refilled. The water used for the steam cycle is reuseable indefinately and the additional water from the products of combustion is continually added.
While my above description contains many specificities, these should not be construed as limitations on the scope of the invention, but rather as an amplification of one perferred embodiment thereof. Many other variations are possible. For example, the military and commercial fan and jet engines are major (possibly a major) contributors to the particulates found in the air of the large metropolitan communities. A comparison of the amount of jet fuel burned will confirm this statement. The reformer principle of this invention can be directly applied to the combustion section of these engines. A large contributor to the carbon monoxide and nitrous oxides are the afterburning military jets and the commercial transport engines. The temperature of the exhaust is a direct measure of the relative amount of both carbon monoxide and nitrous oxides, and the afterburner temperatures exceed 3540° F. which is well above the temperatures where a siginificant amount of disassociation does occur.
Accordingly, the scope of the invention should be determined not by the embodiment(s) illustrated, but by the appended claims and their legal equivalents.
Patent Application
20080087017
