Abstract
In this study the influence of utilization of two Waste Heat Recovery (WHR) strategies, namely organic Rankine cycle (ORC) and turbocompounding, have been investigated based on the performance of a heavy-duty diesel engine using 1-D simulation engine code (GT-Power) in terms of Brake Specific Fuel Consumptions (BSFC) at various engine speeds and Brake Mean Effective Pressures (BMEP). The model of a 6-cylinder turbocharged engine (Holset HDX55V) was calibrated using an experimental BSFC map to predict engine exhaust thermodynamic conditions such as exhaust mass flow rate and exhaust temperature under various operating conditions. These engine exhaust conditions were then utilized to feed the inlet conditions for both the ORC and turbocompounding models, evaluating the available exhaust energy to be recovered by each technology. Firstly the ORC system model was simulated to obtain the power that can be generated from the system. Having this additional power converted to useful work, the BSFC was observed to reduce around 2–5% depending upon engine’s speed and BMEP. The initial model of the engine was then modified by considering a second turbine representing turbocompounding heat recovery system. The BSFC was increased due to the back-pressure from the second turbine, but the energy generated from the turbine was sufficient to reduce the BSFC further. However, by application of turbocompounding no improvement in BSFC was achieved at low engine’s speeds. It is concluded that ORC heat recovery system produces a satisfactory results at low engine speeds with both low and high loads whereas at medium and high engine speeds turbocompounding heat recovery system causes higher BSFC reduction.
Highlights
The growing demand for advanced internal combustion engines (ICEs) in automobiles, caused by several reasons, such as fuel economy, better performance, lower emissions, etc., has paved the way for the introduction of technologies such as turbochargers and superchargers [1,2,3,4,5]
This study aims to investigate the effect of utilizing of organic Rankine cycle (ORC) heat recovery system and turbocompounding on the performance of a turbocharged diesel engine using a detailed simulation study in GT-Power software and to discuss about advantages and disadvantages of operating the engine with both the technologies at different operating regions
The exhaust temperature and exhaust mass flow rates obtained as a result of the simulations of the engine model, are used as inputs to the ORC heat recovery system to study the recovery of the energy to improve the efficiency and fuel economy of the engine
Summary
The growing demand for advanced internal combustion engines (ICEs) in automobiles, caused by several reasons, such as fuel economy, better performance, lower emissions, etc., has paved the way for the introduction of technologies such as turbochargers and superchargers [1,2,3,4,5]. The organic Rankine cycle (ORC) system uses a series of devices in order to supply additional energy to the engine and improve its thermal efficiency. The implementation of a heat exchanger in the exhaust manifold increases backpressure, but compared to the turbocompounding technology this increment is approximately one order of magnitude lower [38]. Both turbocompounding and ORC WHR systems have been investigated in many studies in the past, literature comparing these two technologies is limited [8,9,13,17,18,21,32,34,36,37,38]. This study aims to investigate the effect of utilizing of ORC heat recovery system and turbocompounding on the performance of a turbocharged diesel engine using a detailed simulation study in GT-Power software and to discuss about advantages and disadvantages of operating the engine with both the technologies at different operating regions (e.g., engine speed and BMEP)
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