The highest increment in the efficiency of the IC engine can be achieved with the thermoelectric generators which have tremendously increased the efficiency by almost 15–20%. The concept of compounded Rankine cycle increases the combined engine and waste heat recovery efficiency almost by 10%.
The efficiency of turbo-compounding can be brought closer to 50%. The maximum efficiency achieved in turbocharging is 44.1%, which is more than the conventional engines by 9.1–14.1%. The goal of this chapter is to address the role of waste heat recovery methods such as turbocharging, turbo-compounding, organic Rankine cycle, and thermoelectric generators, to enhance the thermal efficiency of the internal combustion (IC) engine over the past few decades. In the present era, with the continuous rise in a global energy crisis and increasing ecological awareness, waste heat recovery became a common concern in various sectors of energy. The demand for more efficient engines is increasing gradually and will continue to rise in the coming decades.
