ENCIT2012-017 THERMOECONOMIC ASSESSMENT OF COMBINED CYCLE PLANT PERFORMANCE - PDF
Felipe Raúl Ponce Arrieta, Mario David Mateus Herrera, Paulino Tiago de Freitas, PUC-Minas, Brazil
Abstract: The purpose of this paper is carry out the thermoeconomic assessement of a combined cycle cogeneration plant under different operating conditions. A termodynamic simulation model of the plant thermal scheme was developed using the Gate CycleTM software, to execute out the mass, energy, entropy and exergy balances. The structural theory of thermoeconomic was used to compute the unit exergetic cost and the exergoeconomic cost of the internal flows and the products (electricity and heat) of the combined cycle cogeneration plant. In order to the minimum plant products unit exergetic cost evaluates the influence of some plant equipment design variables variation were also assessed. The results of the assessment indicates that it is more convenient and inexpensive the production of electric power by injecting the fuel into the gas turbine combustion chamber than in the HRSG's duct burner, mainly because the exergoeconomic cost of electric power generated in the gas turbine is less than in the steam turbine.
Keywords:Thermoeconomic assessment; Combined Cycle Cogeneration; Performance.
Presentation Schedule: Wednesday, 14:20-14:40. Session: ETS4. Presenter: Felipe Raúl Ponce Arrieta.
ENCIT2012-023 MODELING OF THE TRANSIENT THERMAL ANALYSIS OF THE HEATING OF WATER IN WASHING MACHINES - PDF
Ana Cristine Meinicke, UFSC, Brazil
Fernando Antonio Ribas Jr., Whirlpool Latin America, Brazil
Abstract: The reduction of energy consumption and water usage for washing machines has become more and more important. Based on that scenario, good numerical models that are capable to predict the energy and thermal dynamics of those machines are becoming more necessary. Most of the horizontal axis machines sold in the USA and Europe apply a heater to heat up the water, in order to maximize the washing performance. This heat rise process is the main responsible for the appliance energy consumption. In this sense, this study aims to develop a thermal model, using Modelica language, that predicts the water heat rise and energy consumption during the washing process. With that, it is possible to study and optimize the energy consumption of the washing machine. Experiments have been performed in order to validate the thermal model. When the numerical and experimental results are compared, it has been observed a good agreement, making the model suitable for energy and thermal studies.
Keywords:washing machine; energy consumption; water heating; Modelica.
Presentation Schedule: Wednesday, 14:40-15:00. Session: ETS4. Presenter: Ana Cristine Meinicke.
ENCIT2012-271 ANALYSIS OF AVOIDABLE AND UNAVOIDABLE EXERGY DESTRUCTION IN A COMBINED CYCLE PLANT\&\#8207; - PDF
Dimas José Rúa Orozco, José Carlos Escobar Palacio, Osvaldo José Venturini, FEI, Brazil
Abstract: Thermoeconomic diagnosis of thermal systems for power generation is proposed for searching which of the elements of a power cycle (turbines, compressors, heat exchangers, etc.) have abnormal behavior that cause fuel over-consumption for the same level of production. Furthermore, those anomalies (also called malfunctions) have not only economical, but most often, environmental implications. Such malfunctions are expressed as irreversibilities of the system, that are quantified through the exergetic analysis. Thus, the purpose of thermoeconomic diagnosis is to identify and act over those components that are destroying exergy (due to a malfunction) and to return them to their optimal operational state after maintenance. However, not all the exergy destruction can be avoided, so that we can divide the exergy destroyed in two types: the unavoidable and avoidable exergy destruction. Only on the latter kind of exergy destruction are valid serious efforts to achieve savings in fuel consumption. This paper presents an analysis of a combined cycle to identify and quantify the avoidable exergy destruction, and how this type of exergy is affected by the presence of malfunctions associated with each equipment and malfunctions induced by the other components of the cycle.
Keywords:Thermoeconomic diagnosis; Avoidable exergy destruction; Malfunction.
Presentation Schedule: Wednesday, 15:40-16:00. Session: ETS4. Presenter: Dimas Jose Rua Orozco.
ENCIT2012-060 REPLACEMENT OF DIESEL GENERATOR SETS IN ISOLATED COMMUNITIES WITH MORE EFFICIENT BIOMASS COMBUSTION PROCESS - PDF
Civinelli de Almeida Victor Bicalho, Marco Aurélio da Cunha Alves, UFJF, Brazil
Abstract: Electrical power supply to communities isolated from urban areas is typically complex and expensive. Their geographical situation and the lack of infrastructure and qualified workforce impede the provision of electricity. Many are the sources of energy available, but few are appropriate or sustainable. Combustion of diesel fuel is a good technical solution; however, it is neither economic nor environmentally tenable. This paper presents the advantages of using biomass as an energy source, along with its potential increase in efficiency when steam is generated in specific circumstances of temperature and pressure.
Keywords:biomass; direct combustion; electrification; isolated communities; steam engine.
Presentation Schedule: Wednesday, 15:20-15:40. Session: ETS4. Presenter: Victor Bicalho.
ENCIT2012-131 THERMODYNAMIC DIAGNOSIS TECHNIQUES TO ASSESSMENT THE BEHAVIOR OF VAPOUR COMPRESSION REFRIGERATION SYSTEMS - PDF
Tiago Mendes, Osvaldo José Venturini, Marcelo José Pirani, FEI, Brazil
Abstract: Nowadays, there is an extensive use of the chilling or freezing processes in the food industry by means of the mechanical refrigeration, either during production or storage of manufactures food. Thus, it is of extreme importance to have a close control over the equipment used in these facilities, in order to make them able to operate at maximum efficiency under all conditions. Considering that the refrigeration and air conditioning systems are huge consumers of electricity, it is clear that this practice allows for a significant reduction in energy consumption at global level. Considering this scenario, mathematical models of refrigeration and air conditioning systems have been used to analyze their operation under various working conditions, predicting the system operation and of their components. Considering this context, the aim of this work is to develop a method for thermodynamic diagnosis of refrigeration systems, considering the thermo economic concepts for to evaluate the degradation of the refrigeration system components, and also the influence of the individual components degradations in the efficiency and power consumption of the system. Through this analysis, it is expected to obtain a prognosis of the system behavior, which can be used for maintenance scheduling, as well as a complete analysis of the whole system and of each one of its component.
Keywords:thermo economic diagnosis; refrigeration system; energy consumption; computer modeling.
Presentation Schedule: Wednesday, 16:00-16:20. Session: ETS4. Presenter: Tiago Mendes.
ENCIT2012-319 APPLICATION OF AN ALTERNATIVE THERMOECONOMIC APPROACH TO TWO BENCHMARK REFRIGERATION CYCLES - PDF
Atilio Barbosa Lourenço, José Joaquim Conceição Soares Santos, João Luiz Marcon Donatelli, UFES, Brazil
Abstract: In any energy system, in the same manner that there are productive components, there also exist dissipative components. Although there has been an advance in the development of thermoeconomic criteria for dissipative components allocation, this problem is still open. The introduction of the negentropy in thermoeconomics represented a great advance, since this magnitude allows quantifying the condenser product. However, negentropy itself does not allow defining the product of valves. To overcome such a limitation, the UFS Model was proposed. This approach is based on the disaggregation of the physical exergy into three terms, namely, internal energy, flow work and syntropy. In this paper, the UFS Model is applied to the Carnot refrigeration cycle and also to the simple vapor compression refrigeration cycle. The application to the former cycle is done to show the consistency of the UFS Model and the application to the latter one is done as a case study. Results show that the exergetic unit costs of productive flows are greater than or equal to one and product-resource ratio of each productive unit are less than or equal to one, depending on the situation, i.e., when considering the simple vapor compression cycle or the Carnot cycle, respectively.
Keywords:Exergy Disaggregation; Refrigeration Cycle; Thermoeconomics; Valves Isolation.
Presentation Schedule: Wednesday, 15:00-15:20. Session: ETS4. Presenter: Atilio B. Lourenço.