Summary of Turbocharging as a Waste Heat Recovery System for a Variable Altitude Internal Combustion Engine

Abstract

The increase in altitude causes the decrease in internal combustion engine power and the increase in pollutant emission. Converting waste heat into more useful forms of energy through the recovery of waste heat from internal combustion engines is the most promising mechanism for improving both of these goals. This paper comprehensively reviews the development and research of waste heat recovery technology of an internal combustion engine in a variable altitude environment. It is found that exhaust gas turbocharging is the most promising waste heat recovery technology to restore high-altitude internal combustion engine power. Turbochargers are affected by low temperature and low pressure at high altitudes, resulting in poor environmental adaptability, inadequate supercharging ratios, and decreased supercharging efficiency. Therefore, it is very important to select the high pressurization system facing the plateau area and its reasonable matching characteristics. The quality of exhaust energy determines how much waste heat a turbine can recover, and only the exergy part of exhaust energy can realize heat/work conversion. The main disadvantage of turbocharging technology applied in the plateau area is that the speed ratio deviates from the design value, leading to the increase of flow loss inside the supercharger. Therefore, optimizing the internal flow field of a high-altitude supercharger is a key problem to improve the efficiency of energy recovery. The conclusion drawn from this Review is that a two-stage turbocharging system will be a key technology to improve the thermal efficiency and reduce the fuel consumption of high-altitude internal combustion engines in the coming decades. In addition, the efficient utilization of the exhaust energy of the two-stage turbine and the influence of the variable compression process of the two-stage compressor on the working medium in the cylinder will be the focus of future research.

Perspectives and Outlook of E-fuels: Production, Cost Effectiveness, and Applications

“…Currently, ICE has reached a mature stage of development, but it faces numerous challenges, including but not limited to the following categories: exhaust emissions, fuel types and sources, clean combustion, and energy consumption. − Andrius Garbaras et al have pointed out that the currently widely used fuels are diesel and gasoline. According to the statistics on the power sources of transportation vehicles in Europe, diesel engines account for 42%, while gasoline engines account for approximately 53% .…”

Role of Altitude in Influencing the Spray Combustion Characteristics of a Heavy-Duty Diesel Engine in a Constant Volume Combustion Chamber. Part II: Impinging Diesel Jet

“…Thus, a deeper understanding of the complex physical and chemical mechanisms for various stages of combustion is still required to design more powerful and efficient engines. It is considered that diesel engines, as a common type of CI engines, provide a primary solution for various economic activities and road transportation especially in plateau regions. , The inevitable reduction in atmospheric pressure with increasing altitude reduces the density of air inhaled into the cylinder. This affects the propagation and entrainment of the diesel spray, as well as the subsequent mixing-controlled combustion process, all of which have adverse effects on diesel engines .…”

A Review of Thermoelectric Generators in Automobile Waste Heat Recovery Systems for Improving Energy Utilization

“…It is broadly categorized into two classes based on the power output mode. Organic Ranking cycles [8][9][10], vapor absorption refrigeration cycles [11][12][13], turbocharging [14,15], turbo-compounding [16,17], and Stirling engines [18,19] are the existing waste recovery systems which consume waste heat as input and create mechanical torque. On the other hand, thermionic generators [20] directly convert the heat energy into an electrical current.…”