Combined Diesel-Petrol Engine – The Hindu BusinessLine
The problem with internal combustion engines is that if you increase the load (like vehicle weight), you need more fuel to run the engine, which leads to higher emissions. How can you increase engine efficiency at higher loads, while keeping emissions low? Research at IIT Madras could point to a way forward.
Researchers V Pradeep and Dr. Anand Krishnasamy from the Department of Mechanical Engineering studied “Premixed Charge Compression Ignition (PCCI)” and achieved notable success. PCCI is known to improve fuel efficiency and reduce emissions, but it operates at low load, up to 40% of full engine capacity. But the researchers were able to increase the motor load up to 80 percent of full load, according to a paper in IIT Madras’ internal publication. Let’s talk technology.
The researchers did this by replacing diesel with a diesel-petrol mixture in a 70:30 ratio and adding water vapor to the exhaust gas recirculation (EGR) system. The high specific heat capacity of water vapor and the low reactivity of gasoline in the fuel mixture allowed the proper combustion phasing and load extension to be achieved using smaller amounts of EGR at higher loads than what is usually required, the article says.
The purpose of the experiment was to address the load range limitation of the PCCI combustion mode in a small bore light duty diesel engine used in agricultural water pumping applications; the researchers have achieved notable success, although they add a caveat that further research is needed to perfect the technology.
TIFR Solar Battery
A scientist from the Hyderabad laboratory of the Tata Institute of Fundamental Research (TIFR) has developed a lithium-ion battery with photosensitive materials that can be directly recharged by solar energy. Typically, solar-powered battery charging requires photovoltaic cells placed in sunlight and connected to the battery. This arrangement leads to a loss of energy.
To avoid energy loss, researchers are exploring the use of photosensitive components inside a battery itself. There have been substantial advances in these efforts, leading to more compact solar batteries. Although improved in their design, existing solar batteries still have drawbacks: reduced ability to harness enough solar energy; use of organic electrolyte liable to corrode the photosensitive organic component inside a battery; and the formation of by-products that impede sustained battery performance over the long term.
TIFR’s Amar Kumar decided to explore new photosensitive materials that can also incorporate lithium to build a solar battery that can be waterproof and work efficiently in ambient conditions. Solar batteries that have two electrodes typically contain a photosensitive dye in one of the electrodes which is mixed with a stabilizing component to help drive the flow of electrons through the battery.
Kumar created a heterostructure of photosensitive molybdenum disulfide and molybdenum oxide to function as a single electrode. Being a heterostructure where molybdenum disulfide and molybdenum oxide are fused by a chemical vapor deposition technique, this electrode offers more surface area to absorb solar energy. When light rays strike the electrode, the light-sensitive molybdenum disulfide generates electrons. This solar battery, which was assembled from scratch, was found to work well when exposed to simulated sunlight, says a TIFR press release.
Drill millions of holes
The German Fraunhofer Institute reported that its scientists produced a microfilter by drilling 59 million holes, each 10 microns in diameter, in a filter sheet. The filter can be used, for example, to remove tiny microplastics from wastewater.
Researchers from the Fraunhofer Institute of Laser Technology and experts from a company called LaserJob GmbH used “ultra-short pulse” laser technology to drill the holes.
“Basically, our challenge was to drill as many holes as possible, as small as possible, in a sheet of steel in the shortest possible time,” explains Andrea Lanfermann, project manager at Fraunhofer ILT.
Drilling millions of holes one after another takes time, but can be done faster with the multi-beam process, in which an array of identical beams is generated from a laser beam through a special optical system. Fraunhofer ILT used this process with an ultra-short pulse laser to punch holes simultaneously with 144 beams.
April 10, 2022