The Union Home Minister on November 7, 2019, launched the first Winter-grade Diesel Sales Centre for Ladakh region with a view to solve the problems of people related to the use of diesel fuel during winter season as diesel reaches freezing point every year during extreme winters.
In India, Indian Oil produced a winter-grade diesel for the first time as per the requirements of the country. Panipat Oil Refinery made its first delivery. It meets Bureau of Indian Standards (BIS) specification of BS-VI grade.
It makes the transportation and travel smooth during the peak tourist season in extreme cold in the region. It is likely to give a boost to tourism and enhances the supply needs of the people of the region besides helping in the overall economic development of the area.
Winter-grade Diesel
Winter-grade diesel (also known as winter diesel, alpine diesel, or winterised diesel) is a special fuel that does not freeze in cold weather compared to standard diesel fuel, which freezes on -20 to -30 degrees. Motorists in high-altitude areas face the problem of freezing of diesel in their vehicles when winter temperatures drop to as low as -30 degrees Celsius. So, some additives are mixed with it, which prevent the winter-grade diesel from developing wax particles. It does not lose its fluidity at even -33 degrees Celsius, unlike normal grade diesel, which is difficult to be used in sub-zero temperatures.
Bharat Stage (BS) Grade
Emission control standards meant to keep a check on air pollution, based on the European regulations (Euro norms), are known as Bharat stage (BS) norms. These standards set limits for the release of air pollutants from equipment using internal combustion engines, including vehicles. A higher stage means more stringent norms. BS VI key shows improvement in fuel quality over BS IV, and includes lower sulphur content, 10 parts per million (ppm) and harmful hydrocarbon, produced due to incomplete combustion of fuel.
Freezing of Diesel Fuel
Diesel fuel gets solidified into a partially crystalline state in cold weather, giving it a cloudy appearance. The presence of waxes thickens the oil and clogs fuel filters and injectors in engines until the engine is starved of fuel, and causes it to stop running.
Based on a standardised test, the cold filter plugging point (CFPP) indicates the rate at which diesel fuel flows through a standardised filtration device in a specified length of time when cooled under certain conditions. Likewise, the ‘low temperature flow test’ (LTFT) indicates the winter performance of diesel with improver additives. Both the CFPP and LTFT temperature is some degrees above the pour point temperature, i.e., -33 degrees Celcius. Different solutions available allow diesel engines to continue to operate in cold weather conditions. Once started, the diesel motor engine may continue to operate at temperatures below the CFPP because most engines have a spill return system, by which any excess fuel from the injector pump and injectors is returned to the fuel tank. Once the engine is warmed up, it prevents gelling or waxing in the tank.
Additives
To lower the CFPP of diesel oil, there are certain additives, which are mixed well with the diesel oil (ideally at the gas station) when the fuel is still warm from the storage tanks. These additives do not prevent the diesel from developing wax particles, but are hindered from melding together to form larger wax flakes that can clog up the fuel filter. They are cheaper in comparison with blending diesel fuel with lighter fuel having a lower CFPP. That is why gas stations in cold regions offer diesel fuel with additives at no extra cost. So, no additives should be added to winterised diesel as the fluid characteristics may go down due to incompatible additives leading to the reversal of the CFPP enhancement.
Preheating the Fuel
Another solution is installing low-output electric heaters in fuel tanks and around fuel lines to extend the fluid characteristics of diesel fuel. A standard equipment in vehicles, this is mostly used with vehicles that operate in arctic weather conditions.
Most diesel motor cars are equipped with a filter heater because of the fuel filter being the first point to become clogged up. This allows summer diesel with a CFPP of -7 degrees Celcius to be operated safely in -20 degrees Celcius weather conditions. Therefore, a diesel type CFPP -15 degrees Celcius can be operated safely in -24 degrees Celcius weather conditions. Notably, a filter heater cannot melt wax particles in the feed system and so the fuel supply can be problematic at cold start.