Thermoeconomic Modelling and Parametric Study of a Simple ORC for the Recovery of Waste Heat in a 2 MW Gas Engine under Different Working Fluids

Abstract

This paper presents a thermo-economic analysis of a simple organic Rankine cycle (SORC) as a waste heat recovery (WHR) systems of a 2 MW stationary gas engine evaluating different working fluids. Initially, a systematic methodology was implemented to select three organic fluids according to environmental and safety criteria, as well as critical system operational conditions. Then, thermodynamic, exergy, and exergo-economic models of the system were developed under certain defined considerations, and a set of parametric studies are presented considering key variables of the system such as pump efficiency, turbine efficiency, pinch point condenser, and evaporator. The results show the influence of these variables on the combined power of the system (gas engine plus ORC), ORC exergetic efficiency, specific fuel consumption (∆BSFC), and exergo indicators such as the payback period (PBP), levelized cost of energy (LCOE), and the specific investment cost (SIC). The results revealed that heat transfer equipment had the highest exergy destruction cost rates representing 81.25% of the total system cost. On the other hand, sensitivity analyses showed that acetone presented better energetic and exergetic performance when the efficiency of the turbine, evaporator, and condenser pinch point was increased. However, toluene was the fluid with the best results when pump efficiency was increased. In terms of the cost of exergy destroyed by equipment, the results revealed that acetone was the working fluid that positively impacted cost reduction when pump efficiency was improved; and toluene, when turbine efficiency was increased. Finally, the evaporator and condenser pinch point increased all the economic indicators of the system. In this sense, the working fluid with the best performance in economic terms was acetone, when the efficiency of the turbine, pinch condenser, and pinch evaporator was enhanced.

Exergy, Economic, and Life-Cycle Assessment of ORC System for Waste Heat Recovery in a Natural Gas Internal Combustion Engine

“…Among the benefits of proposing sustainable waste heat recovery systems is that they demand less consumption of resources for energy production [31]. They make it possible to achieve a sustainable energy supply by adopting environmentally-friendly organic fluids, in terms of low ozone depletion potential and global warming potential [30,32]. This allows the amount of reusable material to be increased at the end of the product life cycle, which significantly reduces environmental impacts throughout the life of the thermal system [33].…”

Advance Exergo-Economic Analysis of a Waste Heat Recovery System Using ORC for a Bottoming Natural Gas Engine

“…Thus, the energy recovery of the exhaust line of the natural gas generation engines is one of the alternatives to increase the thermal efficiency of these systems [27]. However, this issue has been approached from different approaches but not articulated with alternative generation systems, which leads to an enormous scientific impact since if it is true that different ORC configurations have been studied, these have not been studied from an advanced exergetic point of view and integrated with thermo-economic modeling in real contexts of operation of stationary high-power natural gas turbocharged engines as a means of heat recovery, in order to obtain technically and economically viable solutions that allow their commercial application [28].…”

A comparative study of the energy, exergetic and thermo-economic performance of a novelty combined Brayton S-CO2-ORC configurations as bottoming cycles

“…Also, the main opportunities for improvement with the help of advance exergo-economic analysis had been evaluated [ 20 ], revealing promising results when this system will be evaluated integrated as bottoming cycle from a Brayton, and also optimized. In addition, parametric study of the integrated system considering the main operational variables are not widely reported in literature, where the monetary value is allocated to the exergy flow to calculate the cost of the exergetic inefficiency these systems [ 21 ].…”