Name: Bruno Muniz de Freitas Miotto
Type: MSc dissertation
Publication date: 27/02/2021

Namesort ascending Role
José Joaquim Conceição Soares Santos Advisor *

Examining board:

Namesort ascending Role
Osvaldo José Venturini External Examiner *
Leonardo Rodrigues de Araujo External Examiner *
José Joaquim Conceição Soares Santos Advisor *
João Luiz Marcon Donatelli Co advisor *

Summary: This work aims to analyse, size and compare two configurations of a waste heat recovery (WHR) thermal system for intake air conditioning purposes of a large ICE, with an economic feasibility study for each configuration based on real commercial proposals. A turbocharged internal combustion engine, model Wärtsilä 20V34SG, with 9MW rated shaft power, installed at the Thermoelectric Power Plant Luiz Oscar Rodrigues de Melo (UTE LORM), in Linhares, Espírito Santo, is used as case study. The first thermal system configuration uses water from a cooling tower to provide further cooling to the engine cooling system, while the second configuration uses chilled water. A modelling of the thermal system integrated with engine is developed in Python, based on energy balance from Wärtsilä brochure and on a transient model developed separately in the GT-Power software, which also defines the maximum allowed engine’s power output. Absorption chiller, heat exchangers, cooling coil and cooling tower sizing is based on distinct weather conditions for a period of 26 months which are extracted from a weather station’s record near the thermoelectric plant. With the exception of the auxiliary heat exchanger, every equipment from the thermal system with chilled water to aid the radiator is bigger than the alternative configuration, and the most expensive equipment, the absorption chiller, requires a capacity of 550 RT to attend chilled water demand in 99,52% of the historic environment data, while 185 RT are required for the other configuration. After sizing every equipment, an economic feasibility study is performed based on investment values for commercial proposals of each configuration. Results show that the configuration using cooling tower water to aid the radiator is the best investment in this case, with initial investment cost of R$2.530.000,00, a Net Present Value (NPL) of R$12.618.534,53, a payback period of 1,23 years and Initial Rate of Return (IRR) equal to 95,66%. Meanwhile, the second thermal system has initial investment cost of R$4.059.300,00, a Net Present Value (NPL) of R$10.165.334,56, a payback period of 2,24 years and Initial Rate of Return (IRR) of 55,98%. The thermal system with cooling tower water in the auxiliary heat exchanger is the best financial investment by all economic indicators, and even though the other alternative is economically worse, colder fluid stream in the heat exchanger aids the engine in a wider range of environmental temperatures, while also allowing the engine to operate farther from its safety limits.

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