When looking at both systems, Thomas Built decided that SCR was the more reliable and fuel-efficient option. The charts below outline the differences of In-cylinder Exhaust Gas Recirculation (EGR) and SCR technology.
SCR
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Advantages of SCR
- Lowers need for EGR
- Permits engine to operate under optimized combustion conditions, including increased temperature, increased pressure and excess oxygen
- Less heat rejection
- Cleaner available tailpipe emissions
- Proven technology across the globe
- Mainstream choice for 2010 solution
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Customer Benefits
- Better fuel efficiency
- Less component stress
- Fewer regenerations relative to In-cylinder EGR
- Improved durability
- Expected lower total cost, which includes maintenance and fuel
- End emission products are nitrogen, water and carbon dioxide
- Decreased CO2 emissions
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In-cylinder EGR
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Disadvantages of In-cylinder EGR
- Less efficient combustion process requires lower temperatures
- Increased heat rejection causes the engine to produce more heat
- Higher injection pressures
- Decreased power density with same displacement size
- Increased diesel particulate matter (soot)
- Increased air flow and cooling capacity
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Customer Impact
- Decreased fuel efficiency
- Increase in regenerations and fuel burned
- Increased complexity in turbo chargers, vehicle coolers, pistons and injectors
- Decreased engine durability
- Oil degradation
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