A review of heat transfer in turbochargers

Abstract

The conventional powertrain has seen a continuous wave of energy optimization, focusing heavily on boosting and engine downsizing. This trend is pushing OEMs to consider turbocharging as a premium solution for exhaust energy recovery. Turbocharger is an established, economically viable solution which recovers waste energy from the exhaust gasses, and in the process providing higher pressure and mass of air to the engine. However, a turbocharger has to be carefully matched to the engine. The process of matching a turbocharger to an engine is implemented in the early stages of design, through air system simulations. In these simulations, a turbocharger component is represented largely by performance maps and it serves as a boundary condition to the engine. The thermodynamic parameters of a turbocharger are calculated through the performance maps which are usually generated experimentally in gas test stands and used as look-up table in the engine models. Thus, the operational of the engine is dictated by the air flow thermodynamic parameters (pressure, temperature and mass flow) from the turbocharger compressor; this in turn will determine the thermodynamic parameters for the exhaust gas entering the turbocharger turbine. The importance and its sensitivity dictate that any heat transfer affecting the experiments to acquire the performance maps will cause errors in the characterization of a turbocharger. This will consequently lead to inaccurate predictions from the engine model if the heat transfer effects are not properly accounted for. The current paper provides a comprehensive review on how the industry and academics are addressing the heat transfer issue through advancing researches. The review begins by defining the main issues related with heat transfer in turbochargers and the stateof-the-art research looking into it. The paper also provides some inputs and recommendations on the research areas which should be further investigated in the years to come.

Dynamic Behaviour Analysis of Turbocharger Rotor-Shaft System in Thermal Environment Based on Finite Element Method

“…e CHT simulation method [16][17][18][19][20][21][22] is used to obtain the temperature distribution of the rotor, and the node temperature is provided for the modal simulation part.…”

Thermal management of an internal combustion engine focused on vehicle performance maximization: A numerical assessment

“…However, in this case, for the same power required, an increased crankshaft speed would result in a lower torque output, greater fuel consumption and engine temperature. 14,15 To avoid a possible ICE overheat and consequent performance losses or even a durability compromise, the correct design of the cooling system becomes a fundamental aspect, especially concerning the airflow through the heat exchangers and its distribution through the inlet surface. 16 These factors depend directly on the grille opening in the bumper and the air resistance through the engine compartment.…”

“…However, in this case, for the same power required, an increased crankshaft speed would result in a lower torque output, greater fuel consumption and engine temperature. 14,15…”

Nonstationary gas-dynamics and local heat transfer in the output channel of the turbocharger compressor

“…Therefore, the mutual agreement of the thermomechanical characteristics of gas flows between the ICE and TC pipelines is an actual topic in the development of engine building. Today, the receipt of new data on the features of gas-dynamics and heat transfer in gas-air tracts of turbocharged engines is an important task, since the efficiency of power machines based on ICEs depends on the perfection of these processes [1][2][3]. Modern research in this field is devoted to the study of the parameters of gas flows at the inlet and outlet of the TC turbine [4][5][6], heat transfer inside the compressor [7], the thermal effect of the turbine on the compressor in the composition of the TC [8] and ways to improve the efficiency of the turbocharger [9,10].…”