Introduction to Fuel-Air Injection Engine. (A discrete structured IC engine) KansLab

Transcription

1 Introduction to Fuel-Air Injection Engine (A discrete structured IC engine) KansLab 1

2 Fig. 1: A Fuel-Air Injection (FAI) Engine is: 1) A two-stroke engine with fuel and air injections. 2) A hybrid engine with an air motor built in the cylinder. 3) A high thermal efficiency pulsating rocket engine with piston and crankshaft as its output. 4) A clean combustion machine with gas expansion precisely controlled by digital fuel and air injections. Fuel Tank Fuel Injection Air Reservoir Air Injection External Air Supply Pneumatic System A two-stroke gas expander with no air compression cycle. Computer Controlled Clutch Filter & Air Compressor (Self Generated Air Supply) Work 2

3 Fig. 2: Piston return stroke has no load; FAI is actually a single stroke engine. Piston ring is contracted during return stroke to reduce frictional losses. S S S S F A F A F A F A Piston at the TDC. Fuel-Air injections start. Grower ignites the mixture Piston down to BDC, exhaust discharged from exhaust ports. Piston moves up. Exhaust escape through the gap. Piston slide valves contracted and the gap opened. F = Fuel Injection S = Spark/Grower A = Air Injection TDC = Top Dead Center BDC = Bottom Dead Center Piston moves to TDC. Piston slide valves expanded and the gap sealed. 3

4 Inefficiency of Conventional Piston Engines Conventional piston engines are subject to energy inefficiency and oxygen deficient combustion. Hence their fundamentals are being challenged: 1. Thermal Inefficiency - Thermal efficiency is compromised mainly due to time sharing of the cylinder. Air compression and gas expansion are two distinct processes; each has its own efficiency criteria. Since these two processes sequentially time sharing the same cylinder, both efficiencies are limited for optimization. 2. Oxygen deficient combustion 80% of air content is nitrogen, intake nitrogen into cylinder not only impedes combustion but also creates harmful NO x emission. 3. Frictional losses Severe frictional losses associated with piston rings, valves and valve-train. Cylinder sharing also causes other drawbacks such as, heat to be concentrated in the cylinder and complicated engine structure. To optimize efficiency of both air compression and gas expansion, it is essential to remove the air compression function out of the gas expander in a piston engine. 4

5 Main Advantages of FAI Engine Dedicated gas expander with higher thermal efficiency, low noises due to controlled combustion and low exhaust pressure (Fig. 1). Hybrid power mode can be activated by off loading the air compressor with the computer controlled clutch disconnected (Fig. 1). Conventional poppet valves and valve-trains are eliminated and hence their associated heat and frictional losses (Fig. 2). Contracted piston slide valves reduce 50% frictional losses during piston upward strokes (Fig. 2). With Whitworth quick return mechanism (1), thermal efficiency and power duty cycle can be further increased (Fig. 3). FAI engine may use Compressed Air Energy Storage (2) (CAES) for external air supply or even with Oxygen Enriched CAES (OE-CAES) to better achieve its goal in higher oxygen/energy density, thermal efficiency, complete combustion and NO x reduction (Fig. 4). Independent injections allow alternate fuels with various fuel-air ratios and hence the combustion is independent of fuel type/property (Fig. 5). Complete combustion is further ensured with the extended air injection during peak power periods (Fig. 6). (1): (2): 5

6 Fig. 3: FAI engine with extended Power Stroke 1.5 TDC BDC % 50% Power Stroke Conventional Piston Engine Stroke Return Stroke with frictional loss degree Sample design with Quick Return Ratio (QRR) = 2:1 TDC BDC Frictionless Quick Return Stroke % 33.3% Extended Power Stroke degree 6

7 Fig. 4: Air supply with OE-CAES for FAI Nitrogen, Argon Production Air Filtering Process Oxygen Enriched Compressed Air (OECA) Clean & High Efficiency FAI engine OE-CAES e-fuel production, Water or Building Heating Heat Oxygen Enriched Air High Pressure Compression Underutilized Grid or Renewable Power Transportation vehicles, trucks, trains, etc. 7

8 Fig. 5: Fuel Injection Comparison Conventional fuel injection with constant Fuel-Air ratio. Fuel-Air ratio Fuel-Air ratio Fuel-Air injections with variable Fuel-Air ratio. TDC TDC -10 o 0 o 10 o Piston position -10 o 0 o 10 o Piston position Fuel injection amount must meet stoichiometric ratio in order for stable combustion. Incomplete combustion is a major concern. Individual controlled fuel-air injections start with rich fuel-air ratio for high temperature flame. It tails with lean burn to ensure clean emission and energy efficiency. 8

9 Fig. 6: P-V Chart - Diesel vs. FAI engine Peak power periods often require extended fuel injection (red area WX), which results in soot emission and fuel inefficiency. Extended air injection not only provides extra power (green area WE) but also supplies oxygen for complete combustion. P WD = Work done by Diesel cycle P WD = Work done by Diesel cycle P2 WX WD WX = Extra work done by extended fuel injection P2 WD WE WE = Extra work done by pneumatic power WP = Work done by pneumatic power WP P1 P1 V1 V2 V V1 V2 V Diesel Cycle FAI Cycle 9

10 Additional Advantages of FAI Engine Reduced engine heat FAI engine doesn t generate heat due to air compression. Also, air expansion absorbs partial combustion generated heat. Unidirectional gas flow reduces losses due to turbulence. Engine starts with compressed air, no need for starter or heavy battery. Vehicle kinetic energy can be recovered with the air compressor. Low system expansion cost - Increasing air tank capacity does not significantly increase weight or cost to the system. FAI engine is operational under water. FAI engine requires no special manufacturing process or rare material. KansLab 10

11 Comparison between FAI and Conventional Engines FAI engine Pre-compressed oxygen enriched air Dedicated gas expander Wide output range (Hybrid Mode) Reduced Frictional Losses Emission is treated within the combustion chamber Flexible Fuels Doubled power ratio Conventional engines Real-time compressed air Shared Cylinder Narrow output range Severe Frictional Losses Emission is treated after combustion in exhaust system Fuel type/property dependent Poor power ratio KansLab 11

12 FAI Engine Reference Design 1. Spark/Grower Plug 7. Fuel (Air) Injectors 13. Low Pressure Fuel In 2. Air Controller 3. High Pressure Air Pump 4. Over Write Air Valve 5. High Pressure Fuel Pump 8. Pre-Combustion Chamber 9. Cylinder/Gas Expander 10. Piston 11. Low Pressure Air In 14. High Pressure Air Out 15. High Pressure Fuel Out 16. Exhaust Port 17. Piston Valve Control 6. Fuel Controller 12. High Pressure Air In 12

13 Potential FAI Engine Application - Samples Power-train for land transportation vehicles and trains. Range extender/battery charger for electric vehicles (EV). Power-train for marine vessels, aviation or vertical takeoff. Farming, construction machines or hand power tools. Shaft drive for pump, compressor, generator, construction, farming machines or various heavy equipments. Power source for pneumatic field robots or exoskeleton. Air Independent Propulsion (AIP) for under water vehicles. OE- CAES can be an oxygen source for life support. kanslab@yahoo.com KansLab 13