The picture shows the CyroPower six-cylinder engine technology, which consists of two compression cylinders and four powered expansion cylinders.
As the transportation industry begins to enter the era of new power sources, consumers have more new options in power systems. At present, this industry, which has been dominated by gasoline spark ignition and diesel compression ignition engines, has begun to produce a wide range of new power systems, including power, natural gas, hydrogen fuel cells and bioenergy power systems. However, due to the high mileage and load requirements of heavy-duty long-haul trucks, these emerging power systems may not all be suitable for heavy-duty long-haul trucks.
Ricardo, a global engineering and environmental consulting firm, has developed a new engine concept called CryoPower. The company believes that CryoPower's new concept engine can significantly reduce current diesel power system emissions levels and fuel costs. At present, after 10 years of research and development, this engine is ready to enter the complete system demonstration and follow-up pilot application verification. To better move to the next stage, Ricardo has divested CryoPower technology and related assets from the company and established an independent company called Dolphin N2 Ltd.
To reduce emissions and fuel consumption levels, the CryoPower engine combines two unique combustion technologies, liquid nitrogen and fractional combustion. Ricardo claims that the engine's CO2 emissions and operating fuel costs will fall by 30% and 20%, respectively, and long-haul trucks and stationary generators will be the first beneficiaries of these new technologies.
“Our goal is the heavy-duty engine market,†Neville Jackson, chief technology and innovation officer at Ricardo, told Truck and Off-Highway magazine. “The key to picking a large engine is the total cost of the entire lifecycle. Our strength lies in Fuel costs can be reduced, and fuel costs account for a significant proportion of the total cost of the vehicle's life cycle, making our solution very attractive."
In the future, CryoPower technology may be used in the next step for constant power equipment and train engines. However, the company also realized that CryoPower alternative solutions are not available in all markets. “Electrification does offer some very powerful benefits for light-duty or short-haul vehicle applications,†Jackson said. “However, when your load or cruising range increases to a certain level, such as 500 or 1000 miles, The energy density of the battery cannot meet this level of demand."
Liquid nitrogen and fractional combustion process
The combustion process of CryoPower began to be no different from most engines, but the difference soon followed. Air enters the cylinder during the intake stroke. Liquid nitrogen is injected into the cylinder during the combustion stroke after the intake valve is closed. Subsequently, as the pressure continues to increase, these liquid nitrogen vaporizes and evaporates, and the inflowing air is cooled. Near the TDC (top dead center), the exhaust valve opens and the high pressure air in the cylinder is released into the heat exchanger.
Once in the heat exchanger, this part of the gas will be heated by the exhaust. Subsequently, the intake mixture releases a short crank near the top dead center into the second cylinder. The fuel is then injected into this high pressure and high temperature environment to achieve ignition and expansion without the need for mixing and turning processes of conventional engines. After the power stroke, the combustion gases will be released from the expansion cylinder through the exhaust valve and returned through the heat exchanger. This design can be used with or without an EGR (exhaust gas recirculation) system.
“Our engines are more efficient, not because of the split-cycle technology itself, but because of the fractional cycle, which allows us to have more room for technology applications,†explains Jackson. “Our main innovations fall into three main areas: First, when we compress gas or cooling gas in a compression cylinder, the compression power of this engine is 15% to 20% less than that of a conventional engine with the same compression pressure level. Second, we recover the heat of the exhaust gas and deliver it to Some high temperature parts of the cycle, such as regenerative gas turbines; finally, we designed two cylinders with different scavenging volumes for the engine, that is, our compressed cylinders have a lower scavenging volume than the expansion cylinders, so real Miller can be realized. cycle."
The system requires only a small number of components, including liquid nitrogen storage tanks, injectors, and heat exchangers between the compression and expansion cylinders, which are the “reheaters†in Ricardo's mouth. The application schematic for the CryoPower engine shows the six-cylinder configuration of the engine, including two compression cylinders and four expansion cylinders. In this design, since the expansion cylinder has a duty cycle of 2 strokes, 4 power strokes can be achieved per rotation of the crank.
Ten years of research and development
Over the past 10 years, Ricardo has been working on the development of CryoPower technology, focusing on the independent optimization of the various components before integrating the powertrain into a complete system. At present, after Ricardo's test, the performance of liquid nitrogen during injection and evaporation can be guaranteed. In fact, the company has also tested other gases, but as a stable inert gas, nitrogen stands out with good evaporation performance. In addition, the engine's valves are specifically designed to handle fractional combustion processes.
However, we have encountered a serious challenge in research and development. “The combustion system is a key part of what we have been trying to overcome,†Jackson told Truck and Off-Highway Engineering. “We have recently made great strides in enabling and optimizing the performance of combustion systems, which is what we achieved in fractional cycles. Breakthrough."
At this stage, Ricardo also cooperates with local universities in the UK to complete some research and development. For example, the University of Brighton and the University of Southampton also assisted in the completion of some of the simulations to verify the feasibility of the new combustion technology. Although Ricardo has always been the main force in the development of CryoPower, the assistance of these universities has made it possible to conduct more experimental explorations and jointly promote the progress in the field of combustion.
Follow-up: Demonstration and continued improvement
As these technologies continue to mature, it is time to apply them to demonstration and pilot projects. In order to do a better job, Ricardo has separated CryoPower technology and assets and established an independent company, Dolphin N2. Although Ricardo will still be the main member of Dolphin N2, it is time for other partners to join R&D.
“Now, all of our subsystems are in maturity,†said Simon Brewster, CEO of Dolphin N2, who told Trucks and Off-Highway Engineering. “It’s time to bring these subsystems together and demonstrate a multi-cylinder engine as a whole. Performance. This new engine is identical in appearance to a normal engine and can be mounted directly to a vehicle or generator set."
In the future, the next phase of Dolphin N2's mission, the cost of putting CryoPower technology into production vehicles, will far exceed the level that a company can afford. In this context, Dolphin N2 is now in the venture capital arena and may receive investment from more than one company. Ricardo has evaluated the possibility of bringing this engine to market with only one customer, but ultimately believes that CryoPower technology still needs to continue to develop, and it may be difficult to have a company in a short period of time.
Dolphin N2 understands that the long-haul truck and power generation industries urgently need to improve fuel efficiency and reduce emissions to meet future regulations and consumer needs. Over the past 10 years, the CryoPower system has undergone long-term research, and the current market is ready for these alternative power technologies. Liquid nitrogen and fractional combustion technology allow us to continue to optimize the engine without changing the current infrastructure as much as possible.
In the near future, we will usher in this new powertrain solution.
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