Home Interviews “SCR better BS VI tech for trucks”

“SCR better BS VI tech for trucks”

“SCR better BS VI tech for trucks”

Recently, Mahindra Trucks and Buses Division announced a slew of guarantees to their customers on its Blazo models. Some of these guarantees include fuel efficiency and lower engine oil changes, which are beneficial to fleet owners in terms of cost of ownership. In conversation with APF, Vinod Sahay, CEO, MTBD talks about the growing use of technology to make trucks fuel efficient which can result in lower downtimes and engine overhauling, reducing TCO for fleet managers.

The government has tightened the deadline to BS VI transition. Will the industry keep up?

We don’t really have a choice in this matter. We all have to be ready and invest in R&D and new technologies. As for now, everything is in control right and Mahindra is keeping in mind the current timelines. All we can do, in this case, is wait for the end of the planning process. It would be too early to deliver any judgment or comment as during the planning phase, things have a way of not going accordingly.

Speaking of BS IV, you use SCR technology only. What is the reason for that?

In our trucks we use the SCR instead of EGR. Most of the time the preferred solution is EGR as it is a cheaper solution.

If the engine runs at a high temperature then the NOx generation is higher. In an EGR process, part of the gases that are burnt will be put back into the engine. In any engine, each cylinder has a hundred per cent of fuel mixture (fresh air and diesel). If the exhaust gases are recirculated through the cylinders, 10 to 15 per cent of the cylinders get occupied with it. Due to this, combustion takes place at only 85 per cent capacity as exhaust gases cannot be burnt again. The engine temperature in turn, doesn’t go very high due to lower burning. As a result of this NOx production is lessened. EGR artificially restricts NOx generation generation because of which no additional filter is needed outside the engine. In an SCR engine, there is no tampering with the engine. It runs normally and produces more NOx than an EGR engine. However, there is an Ad Blue dosing done before exhaust which will reduce NOx by converting it to water. This partly restricts it resulting in clean fuel emissions. In the Blazo trucks, we guarantee a smart way of fuel efficiency where truck can switch between three modes: light, heavy and turbo. This has a host of benefits in terms of lowering highway congestion on hilly terrains and increased fuel efficiency as there is no need to increase engine rpm or fuel flow.

What are the disadvantages of an EGR engine?

The disadvantage of EGR in a truck is that it leads to lower power generation and fuel efficiency. Because the power generation is lesser than what is needed in a truck, the driver has to increase the speed, fuel delivery and the engine rpm. If that is not done, the vehicle will not be able to deliver resulting in customer dissatisfaction. This leads to a further compromise on fuel efficiency. Because the vehicle is running on higher rpm the engine is doing more of a job in the same time compared to an SCR engine. The issue with this is that it takes place from the first day: the brand new EGR engine has lower efficiency than the brand new SCR engine.

For a truck owner, engine overhaul, oil and lubricant changes are matters of concern. Engines go through overhauling and oil changes due to soot accumulation and impurities. The deposition of soot increases in an EGR engine due to the burnt exhaust gas getting recirculated in the cylinders. Due to the high RPM it starts damaging the engine in terms of high engine oil consumption, which leads to faster deterioration. However, every engine overhaul of a truck will set the owner back by at least Rs 100,000. So buying an EGR truck is cheaper but its TCO will be damaging to the truck owner’s business.

Why is EGR still the most preferred technology then?

EGR method is beneficial for passenger vehicles. These vehicles don’t cover as much distance in one year as a fleet truck does in six months. The duty cycle of a passenger car is different. The biggest advantage of EGR is that it is a cheaper tech than SCR. Everyone has the temptation of fitting an EGR engine, but it serves well in a specific type of application. A passenger car doesn’t even cover 100,000 km in its lifetime. In truck applications, customers have done that distance in a span of six months to a year. It is not feasible for them to have to do an engine overhaul every six months.

What are some of the constraints you will face during this transition?

The constraints won’t really be on our end. It is the vendors we buy from that will be under pressure to develop technology that will be compliant. If the vendors’ technology will be used in BS VI, they will view this transition as a challenge and continue to innovate. But there are vendors whose product will not be used and for them to cater to a sudden huge demand can cause problems, and they will be that much more resistant. Therefore, we have to find ways and means to tackle that.

Right now demand is not a big issue. When the demand rises, we will automatically be able to scale up.

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