Name: Leonardo Rodrigues de Araujo
Type: PhD thesis
Publication date: 29/06/2020

Namesort descending Role
José Joaquim Conceição Soares Santos Advisor *

Examining board:

Namesort descending Role
Helder Roberto de Oliveira Rocha External Examiner *
João Luiz Marcon Donatelli Co advisor *
José Joaquim Conceição Soares Santos Advisor *
Julio Augusto Mendes da Silva External Examiner *
Marcelo José Colaço External Examiner *
Marcio Ferreira Martins Internal Examiner *
Wellington Betencurte da Silva Internal Examiner *

Summary: In a world with finite resources of natural fuels, increased energy demand and increasing levels of environmental pollution, issues related to the thermal systems design, such as energy efficiency, cost estimation, design complexity, environmental awareness and optimization are becoming increasingly common. In a large internal combustion engine (ICE), Diesel and stationary, less than 45% of the fuel energy is converted into useful energy, while the remaining energy is lost, mainly by exhaust gases, cooling water and lubrication system. Thus, the implementation of waste heat recovery systems (WHRS) in ICE has been one of the main areas of research to increase power, reduce fuel consumption and pollutant emissions, which favors the improvement of this equipment. Currently, there are two important challenges regarding the use of WHRS in ICE: (i) What is the best technology or an association of them for recovering waste heat in an ICE from an economic point of view? (ii) What is the ideal configuration and the best design parameters for the most suitable thermal system? In this work, thermoeconomic optimization of superstructures for the recovery of waste heat in an ICE is carried out, which are composed of Organic Rankine Cycle (ORC), Kalina Cycle (KC) and Conventional Rankine Cycle (CRC). To that end, the economic model of each of the components of the superstructure is provided and an adequacy function is introduced based on the specific cost. Due to the complexity of the thermoeconomic optimization problem of the superstructure, the use of the response surface method (RSM) in the optimization problem can become more efficient when compared to the optimization of the original modeling. The problem of thermoeconomic optimization of the superstructure, as well as its thermodynamic and economic modeling, are formulated and solved with the EES and Octave software. For a medium-sized superstructure (384 variables - 17 decision variables), despite the high computational cost, the use of the RSM in the optimization problem is more efficient than the optimization of the original modeling. Whereas, for a large-sized superstructure (944 variables - 45 decision variables), the use of the RSM makes it possible to solve the optimization problem.
Response surface method, optimization, superstructure, commercial software, waste heat recovery systems, internal combustion engine.

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