From the labs. Diesel-petrol combo engine

The problem with internal combustion engines is that if you increase the load (such as the weight of the vehicle), you need more fuel to keep the engine running, which results in higher emissions. How can you increase the engine efficiency at higher loads, while also keeping emissions low? Research at IIT Madras might cue a way.

Researchers V Pradeep and Dr Anand Krishnasamy of the Department of Mechanical Engineering investigated ‘premixed charge compression ignition (PCCI)’ and have achieved notable success. PCCI is known to improve fuel efficiency and reduce emissions, but it operates at low loads, of up to 40 per cent of the engine’s full capacity. But the researchers were able to increase the engine’s load up to 80 per cent of full load, according to an article in IIT Madras’ in-house publication Tech Talk.

The researchers did this by replacing diesel with a diesel-petrol mix in a 70:30 ratio and adding water vapour to the exhaust gas recirculation (EGR) system. The high specific heat capacity of water vapour and the low reactivity of gasoline in the fuel blend helped obtain the proper combustion phasing and load extension using smaller quantities of EGR at high loads than is typically required, the article says.

The aim of the experiment was to address the load range limitation of the PCCI mode of combustion in a light-duty small-bore diesel engine used in agricultural water pumping applications; the researchers have achieved notable success, though they add a caveat that further research is required to perfect the technology.

Solar battery from TIFR

A scientist at the Hyderabad lab of Tata Institute of Fundamental Research (TIFR) has developed a lithium-ion battery with photosensitive materials that can be directly recharged through solar energy. Typically, charging batteries with solar energy requires photovoltaic cells placed in sunlight and connected to the battery. This arrangement results in energy loss.

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To prevent energy loss, researchers are exploring the use of photosensitive components inside a battery itself. There has been substantial progress in these efforts, leading to more compact solar batteries. Though improved in design, existing solar batteries still have drawbacks: decreased ability to harness enough solar energy; use of organic electrolyte that may corrode the photosensitive organic component inside a battery; and formation of side products that hinder the sustained performance of a battery in the long term.

Amar Kumar of TIFR decided to explore new photosensitive materials that can also incorporate lithium to build a solar battery that can be leak-proof and operate efficiently in ambient conditions. Solar batteries that have two electrodes usually contain a photosensitive dye in one of the electrodes that is mixed with a stabilizing component to help drive the flow of electrons through the battery.

Kumar created a heterostructure of photosensitive molybdenum disulphide and molybdenum oxide to function as a single electrode. Being a heterostructure where the molybdenum disulphide and molybdenum oxide are fused through a chemical vapour deposition technique, this electrode offers more surface area to absorb solar energy. When light rays hit the electrode, the photosensitive molybdenum disulphide generates electrons. This solar battery, which was assembled from scratch, was found to operate well when exposed to simulated solar light, says a TIFR press release.

Drilling millions of holes

The German Fraunhofer Institute has reported that its scientists have produced a micro filter by drilling 59 million holes, each of 10 micron diameter, in a filter sheet. The filter can be used, for example, to remove tiny microplastics from wastewater.

Researchers at the Fraunhofer Institute for Laser Technology and experts from a company called LaserJob GmbH used ‘ultra-short pulse’ laser technology to drill the holes.

“At its core, our challenge was to drill as many holes as possible, as small as possible, in a steel foil in the shortest time possible,” explains Andrea Lanfermann, project manager at Fraunhofer ILT.

Drilling millions of holes one after the other takes time, but can be done faster with the multibeam process, in which a matrix of identical beams is generated from a laser beam via a special optical system. Fraunhofer ILT used this process with an ultra-short pulse laser to drill holes simultaneously with 144 beams.

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