A novel investigation of waste heat recovery from a stationary diesel engine using a dual-loop organic Rankine cycle

To make full use of the dissipated energy of internal combustion engines (ICEs), it is necessary to recover all the waste heat contained in the intake air, exhaust gases, and the coolant streams. This investigation proposed a dual-loop ORC (DORC) system for waste heat recovery (WHR) of a 12-cylinder stationary heavy-duty Diesel (HDD) engine. The numerical model of the 1000 kW diesel engine is developed 1-dimensionally and validated by experimental data. Regression equation models of output responses are formulated via response surface methodology (RSM). The multi-objective optimization is applied to optimize the responses of the system based on the desirability function approach. A comprehensive sensitivity analysis (SA) by means of RSM is accomplished to discover sensitivity of the start of injection (SOI), engine speed ( N ), higher pressure of the high-temperature loop (HPHT), and higher pressure of the low-temperature loop (HPLT) on output responses. The SA reveals that total produced power increases by increasing the SOI, N, and HPHT. The engine variables are not affecting the thermal efficiency and exergy destruction rate. Moreover, increasing the HPHT and HPLT boosts the exergy efficiency of the system. The dominant parameter affecting all outputs is the HPLT. Furthermore, the optimized output responses of the system are as follows: the net produced power of 304 kW, the thermal efficiency of 9.75%, the exergy efficiency of 45.84%, and the exergy destruction rate of 361 kW.