The document discusses transonic combustion, a new combustion process that aims to improve the efficiency of internal combustion engines. It operates by injecting liquid fuels into a supercritical state before combustion in the engine chamber. This allows the fuel to burn more completely than traditional vaporization methods. The system could readily be integrated into existing engines and is claimed to achieve 100 mpg in vehicles. It presents an opportunity to further optimize engines for liquid fuels, which will likely be the dominant transportation fuel source for the next 30 years.

1. Transonic Combustion
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ABSTRACT
Advanced diesel and gasoline engines, and alternative fuels, are really at the middle of
everything. For the next 30 years, these are more ‘classical powertrains’ will dominate in
industry. The traditional four stroke Otto cycle engine piston engine only has a thermal
efficiency of 25-30 percent; there is clearly still plenty of room for improvement. While
most of the green automobile attention in recent years has been focused on electrification,
liquid fuels still have about 100 times the energy density of today’s best lithium-ion
batteries, a difference that probably won’t change significantly any time in the near future.
With that in mind, there is still plenty of effort being expended on improving the humble
internal combustion engine. These efforts range from completely different structures like
Eco Motors opposed piston opposed cylinder (OPOC) to new combustion processes such
as homogeneous charge compression ignition (HCCI). One of the most interesting
combustion related developments comes from a transonic combustion. In 2007, a
company was claiming it could get an ICE vehicle to 100 mpg.The transonic system isn’t
really a radical departure from what we have today on engines. The system has fuel
injectors, a common rail, a fuel pump, and a control system. The system could be readily
integrated in to existing engines; company anticipates production of the concept in 2015
time frame. It is a fact that liquid fuels are going to be there for a long time more and more
they’re going to be from alternative sources. That’s why we need to optimize the
propulsion system for those liquid fuels. The heart of transonic technology is a new fuel
delivery system. To get the liquid fuel into a supercritical state before injecting into the
combustion chamber. Traditionally, matter has been thought of as having three states
liquid, solid, gas and any given material can exist in one of those at any point in time
depending on the temperature and pressure. Fuels like gasoline and diesel generally only
burn after they are vaporized. . The injector may operate on a wide range of liquid fuels
including gasoline, diesel and various bio fuels. The injector fire at room pressure and up
to the practical compression limit of IC engines.

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INDEX
Sr. No. Content Page No.
Acknowledgement
Abstract
List of Figures
i.
ii.
iii.
1. Introduction 1
2. Literature Review 3
3 Construction and Working 4
3.1 Overview of IC Engines and
Thermal Losses
4
3.2 Transonic Combustion 7
3.3 Supercritical Fuel 11
3.4 Properties and Phase Diagram 13
4. Advantages 14
5. Disadvantages 15
6. Application 16
7. Conclusion 17
8. Future Scope 18
References

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LIST OF FIGURES
Fig. No. Figure Name Page No.
3.1 Brief Classification of I.C Engines 4
3.1.2 Thermal Losses in I.C Engine 6
3.2.1 Four Strokes of Transonic Combustion 8
3.2.2
A Fuel Injection System in Transonic
Combustion and Normal Combustion
10
3.3.1
Supercritical fuel and Normal Fuel Injection
System
11
3.3.2
Carbon-dioxide Pressure-Temperature Phase
Diagram
13
8.1 Gas Guzzler 18
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