Heat transfer in turbocharger turbines under steady, pulsating and transient conditions

Abstract

a b s t r a c tHeat transfer is significant in turbochargers and a number of mathematical models have been proposed to account for the heat transfer, however these have predominantly been validated under steady flow conditions. A variable geometry turbocharger from a 2.2 L Diesel engine was studied, both on gas stand and on-engine, under steady and transient conditions. The results showed that heat transfer accounts for at least 20% of total enthalpy change in the turbine and significantly more at lower mechanical powers. A convective heat transfer correlation was derived from experimental measurements to account for heat transfer between the gases and the turbine housing and proved consistent with those published from other researchers. This relationship was subsequently shown to be consistent between engine and gas stand operation: using this correlation in a 1D gas dynamics simulation reduced the turbine outlet temperature error from 33°C to 3°C. Using the model under transient conditions highlighted the effect of housing thermal inertia. The peak transient heat flow was strongly linked to the dynamics of the turbine inlet temperature: for all increases, the peak heat flow was higher than under thermally stable conditions due to colder housing. For all decreases in gas temperature, the peak heat flow was lower and for temperature drops of more than 100°C the heat flow was reversed during the transient.

Turbocharger heat transfer and mechanical losses influence in predicting engines performance by using one-dimensional simulation codes

“…Some authors have performed experimental measurements in gas stand concluding that the effect of turbocharger heat transfer is irrelevant compared to turbocharger mechanical power at high engine loads [10]. However, more recent studies [11] show that heat transfer in the turbine always represent an important part of its enthalpy change, being 45 more relevant in the low torque region. Some authors [12] have measured turbocharger performance in an engine test bench concluding that at high engine speeds and loads the deviation between adiabatic and non-adiabatic compressor efficiency is small.…”

Exergy analysis on Turbocharger Radial Turbine with Heat Transfer

“…As for the turbine side, a large number of studies are focusing on reducing errors associated with predicting turbine outlet temperature (e.g. Burke et al, 2015).…”

“…This operating point was chosen because literature observations show that heat transfer has larger impact on the turbine performance at low speed lines (e.g. Shaaban and Seume, 2012;Burke et al, 2015). At the inlet boundary plane, uniform mass flow rateṁ in =0.058 kg/s and total temperature T t in =1173 K were imposed.…”

Modelling of heat transfer and fluid flow in the hot section of gas turbines used in power generation: A comprehensive survey

“…As mentioned in Chung et al, 6 significant water consumption can be recognised as one of the main practical concerns regarding steam injection. According to Burke et al, 7 a humid air turbine (HAT) or an integrated gasification humid air turbine is a well-known example of a gas turbine using evaporation cycles in power generation. 2 However, for power plants using steam injection or humid air cycles, the water content in exhaust gases can be higher than power plants using other recuperative systems.…”