Facts About Waste Heat Recovery for IC Engines


Last month we hosted a webinar on waste heat recovery for internal combustion engines and beyond. You can view the webinar here.

This is becoming an increasingly popular topic in our industry and we’re seeing more information being posted from other industry professionals, so we thought this would be a great time to explain some basics about this energy efficient technology.

The situation:
A large part of the energy produced in an IC engine is lost to the surroundings but the waste heat from the engine exhaust and coolant is still an attractive energy source that reaches around 60% of the total energy converted from fuel.

The facts:
Only 10.4% of fuel energy is converted to useful work. The thermal energy lost through exhaust gas is about 27.7%. Energy analysis show that only about 9.7% of fuel energy is converted to brake power and exhaust to about 8.4%. As much as 34% fuel savings can be achieved by installing a heat exchanger to recover exhaust energy of the engine.
It was predicted that if 6% of the heat contained in the exhaust gases were converted to electric power, 10% reduction of fuel consumption can be achieved. The research result shows that engine thermal efficiency could improve by 5.4% through exhaust heat recovery and to obtain the degree of recovery of about 13 %.

The technologies (Positive and Negative):
Thermo Electric Power Generators
++ No moving parts,  low maintenance
– – Poor efficiency (~10%)  very long payback periods
++Promising technology under development
++ Recover exhaust energy and boost inlet pressure,  increase power output, better efficiency
++Implemented in almost all categories of IC engines from smallest (TATA NANO-800cc)  to large trucks, marine engines, helicopter engines
Organic Rankine Cycles
++Organic Fluids with low boiling point
++Ideal for use in low temperature regions
++Modular construction
++Higher Efficiency

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