Residue Cost Formation of a High Bypass Turbofan Engine

Abstract

The kinetic energy produced by a turbofan engine is inseparable from the unavoidable generation of waste heat dissipated into the environment and the chemical exergy of exhaust gases. However, exergoeconomic cost analyses of these propulsion systems have focused only on the formation process of the functional product and not the cost of residue formation. In this study, symbolic thermoeconomics was applied to evaluate the impact of residue formation on the production costs of a turbofan engine and analyze the effect of component malfunctions on the fuel impact formula for diagnosing anomalies. The GE90-115B high bypass turbofan engine under takeoff conditions and a thrust requirement of 510 kN was considered as a case study. The total exergoeconomic cost of the engine was 26,754.28 USD/h: 61.04% corresponded to external resources; 0.14% and 33.07% corresponded to waste heat dissipated from the bypass and core engine, respectively; 3.28% corresponded to the chemical exergy of the exhaust gases; 2.47% corresponded to capital and operating costs. A malfunction analysis revealed that a 1% reduction in the isentropic efficiency of the compressor reduced the total kinetic exergy by −0.77 MW, increased fuel consumption by 0.49 MW, and generated irreversibility and residue of 0.80 and 0.45 MW, respectively.

Thermoeconomic Diagnosis of the Sequential Combustion Gas Turbine ABB/Alstom GT24

“…A productive structure is a graphic representation of the distribution of internal resources and products in an energy system using a physical model as a reference [13]. The products of each productive component serve as resources for other components to form the main products, by-products, and residues [19]. The productive components are those that provide resources to other components to form the final products and residual streams of an energy system.…”

“…There is no single methodology to allocate the cost formation process of residue to the productive components of a system [15,16]. Some allocation criteria reported in the literature include the distribution cost of residues proportional to entropy generation (or negentropy) [5,17], exergy [8], distributed entropy [18], and irreversibility [19].…”

“…Valero et al [13,20] developed thermoeconomic methodologies that include the formation processes of both the functional product and the residue in the accounting of the costs of internal flows in a system, along with the costs of the product and residue, and applied the distributed exergy criterion to attribute the cost of the residue to the productive components. This contribution has been used to study the production and formation costs of residues from energy systems, with respect to combined cycles [14,18], heating and cooling systems [8], and aviation [19], among others. Likewise, Valero et al proposed an exergoeconomic methodology known as symbolic thermoeconomics, in which a productive scheme was developed from the physical structure of the study system, also known as the productive structure, while analyzing the distribution of exergy flows throughout the system and the interaction of the system with the environment [12,21].…”

“…This methodology formulates two alternative representations for the productive structure of a system: fuelproduct-residue (FPR) and product-fuel-residue (PFR). The FPR representation is mainly adopted for cost accounting, while the PFR representation is used more for thermoeconomic diagnosis [19]. The thermoeconomic diagnosis compares two operating conditions (actual and design) to quantify, with respect to additional consumption of resources, the effect generated by the malfunction of a component within a system that aims to generate the same useful product [22][23][24][25].…”

On the Allocation of Residues Cost using Conventional and Comprehensive Thermoeconomic Diagrams

“…Despite the proposed criterion reaching results in agreement with the compared criteria, it does not permit to calculate the costs of internal streams for assessing the impact of the additional fuel required to compensate component malfunctions. These same authors recently published an analysis of the waste cost formation of a high bypass turbofan engine used in aviation [67].…”