Abstract

Internal combustion (IC) engines, widely used in automotive, marine, and industrial applications, are inherently inefficient due to significant thermal energy losses. A substantial portion of the energy generated from fuel combustion is expelled as waste heat through the exhaust system and cooling fluids. With increasing emphasis on energy efficiency and environmental sustainability, Waste Heat Recovery (WHR) technologies have garnered considerable attention for their potential to enhance overall engine performance and reduce fuel consumption and emissions. Among the various WHR methods, Thermoelectric Generators (TEGs) and Organic Rankine Cycle (ORC) systems have emerged as leading solutions due to their adaptability and effectiveness in different thermal regimes. This review provides a comparative analysis of TEG and ORC systems for IC engine waste heat recovery. TEGs are solid-state devices that convert thermal gradients directly into electrical energy using the Seebeck effect. Their advantages include compactness, absence of moving parts, and silent operation, although they suffer from low conversion efficiency and material limitations. In contrast, ORC systems use organic working fluids to generate mechanical power via an expansion process, making them more efficient at converting medium-grade heat but at the cost of increased complexity, size, and maintenance. The paper explores the fundamental working principles, recent advancements in materials and system architectures, integration strategies with IC engines, and the performance metrics of each technology. A detailed comparison highlights their respective benefits and trade-offs in terms of efficiency, scalability, cost, and system complexity. Emerging trends, such as hybrid systems and smart control technologies are also discussed, offering insights into future integration prospects.

Keywords:Waste heat recovery, internal combustion engines, thermoelectric generators, organic Rankine cycle, energy conversion efficiency, thermal energy utilization

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Abstract

Internal combustion (IC) engines, widely used in automotive, marine, and industrial applications, are inherently inefficient due to significant thermal energy losses. A substantial portion of the energy generated from fuel combustion is expelled as waste heat through the exhaust system and cooling fluids. With increasing emphasis on energy efficiency and environmental sustainability, Waste Heat Recovery (WHR) technologies have garnered considerable attention for their potential to enhance overall engine performance and reduce fuel consumption and emissions. Among the various WHR methods, Thermoelectric Generators (TEGs) and Organic Rankine Cycle (ORC) systems have emerged as leading solutions due to their adaptability and effectiveness in different thermal regimes. This review provides a comparative analysis of TEG and ORC systems for IC engine waste heat recovery. TEGs are solid-state devices that convert thermal gradients directly into electrical energy using the Seebeck effect. Their advantages include compactness, absence of moving parts, and silent operation, although they suffer from low conversion efficiency and material limitations. In contrast, ORC systems use organic working fluids to generate mechanical power via an expansion process, making them more efficient at converting medium-grade heat but at the cost of increased complexity, size, and maintenance. The paper explores the fundamental working principles, recent advancements in materials and system architectures, integration strategies with IC engines, and the performance metrics of each technology. A detailed comparison highlights their respective benefits and trade-offs in terms of efficiency, scalability, cost, and system complexity. Emerging trends, such as hybrid systems and smart control technologies are also discussed, offering insights into future integration prospects.

Keywords:Waste heat recovery, internal combustion engines, thermoelectric generators, organic Rankine cycle, energy conversion efficiency, thermal energy utilization

🔒 This is a subscription article

Full text is available to subscribers and institutional members. Please choose an option below to access it.