Power enhancement of a turbo-charged industrial diesel engine by using of a waste heat recovery system based on inverted Brayton and organic Rankine cycles

Abstract

In this study, energy assessment is performed for an industrial turbocharged diesel engine integrated with a novel waste heat recovery (WHR) system. The exhaust energy is used in inverted Brayton cycle (IBC) for waste heat recovery purpose. Also, the heat energy from IBC heat exchanger is used as the heat source for the organic Rankine cycle (ORC) to produce extra power. The case study engine is modelled in AVL BOOST software and the model is validated against real engine performance data. For studying the performance of the proposed waste energy recovery system, IBC is added to the engine model in AVL BOOST software and the thermodynamic model of the ORC is developed in MATLAB and it is linked to AVL BOOST. Then, the model is solved, and the main engine output parameters are studied at 1800 RPM and various engine loads. The results show that employment of the proposed WHR system leads to enhancement of the system power by about 18%. However, the backpressure produced by installing the WHR system can result in increase of the BSFC up to 3% and reduction of the total thermal efficiency by almost 1% at engine full load condition. The results of this work contribute to determine the interactions between the proposed novel waste heat recovery system (IBC-ORC) and the engine. The proposed bottoming cycle based on IBC-ORC can be installed on existing industrial stationary engines for enhancement of power generation without imposing a new source of power generation.