Session 9: Equipment, Process, and Energy Systems

Chairs:

José Carlos Charamba Dutra

Nisio de Carvalho Lobo Brum
Programa de Engenharia Mecânica - UFRJ

Silvia Azucena Nebra
DE/FEM/ UNICAMP









s09p02

A TWO-PARAMETER PRELIMINARY OPTIMIZATION STUDY FOR A FLUIDIZED-BED BOILER THROUGH A COMPREHENSIVE MATHEMATICAL SIMULATOR

José A. Rabi - [email protected]
Márcio L. de Souza-Santos - [email protected]
UNICAMP - State University at Campinas, Faculty of Mechanical Engineering, Department of Energy, Cx. P. 6122 - 13083-970 - Campinas, SP, Brazil

Modeling and simulation of fluidized-bed equipment have demonstrated their importance as a tool for design and optimization of industrial equipment. Accordingly, this work carries on an optimization study of a fluidized-bed boiler with the aid of a comprehensive mathematical simulator. The configuration data of the boiler are based on a particular Babcock & Wilcox Co. (USA) test unit. Due to their importance, the number of tubes in the bed section and the air excess are chosen as the parameters upon which the optimization study is based. On their turn, the fixed-carbon conversion factor and the boiler efficiency are chosen as two distinct optimization objectives. The results from both preliminary searches are compared. The present work is intended to be just a study on possible routes for future optimization of larger boilers. Nonetheless, the present discussion might give some insight on the equipment behavior.

Keywords: Fluidized-bed boiler, Simulation, Modeling, Optimization
 
 



s09p04

ANALYSIS FLOW IN STEAM NETWORK

Oliveira, P.A.P. - [email protected]
Silva, M.G. - [email protected]
Ebinuma, C.D. - [email protected]
Luz Silveira, J. - [email protected] br
Departamento de Energia - UNESP - Campus de Guaratinguetá
Avenida Dr. Ariberto Pereira da Cunha, 333 - 12.516-410 Guaratinguetá-SP

In steam distribution systems, the consumers are production sector that are located in strategic points of the factory, with differently distance of the steam generators. The steam distribution is a direct function of the geometry of each pipeline and also of the accessories that it is composed, causing values different of the mass of the condensed for a same line extension. The different values obtained for the condensed attributed to the each customer raise administrative subjects that say respect to the calculation of the costs that will be collected of these consumers that share extensions in the production section. The purpose of this paper is to develop a methodology of analysis of the flow field in the distribution net, through computations methods, which makes possible the alternative enterprising for energy analysis and establishment of costs in steam distribution lines.

Keywords: Steam, pipe network, applied numerical methods, Plant Design.
 
 



s09p07

EXERGETIC ANALYSIS OF A GAS TURBINE PLANT WITH CHEMICAL RECUPERATION

Mario G. Sánchez Prieto - email: [email protected]
Silvia Azucena Nebra - email: [email protected]
Waldir L. Ribeiro Gallo - email: [email protected]
Universidade Estadual de Campinas, Departamento de Energia, FEM, Faculdade de Engenharia Mecânica. Cidade Universitária Zeferino Vaz. CP 6122, Campinas SP 13083-970. Brasil.

One of the proposals that has been more recently analyzed with growing interest in Gas Turbine cycles, with the purpose of obtaining gains in the power output and thermal efficiency, is the Chemically Recuperated Gas Turbine Cycle, (CRGT). Such systems are equipped of chemical heat recovery components in which the waste heat in the turbine exhaust is used to convert a methane-steam mixture into a hydrogen-rich fuel in a methane steam reformer. One additional aspect of these cycles that represents a potential benefit is explained by the ultra-low NOx emission levels, even less than those system which use steam injection This paper, with the aid of the concepts emanated from the Second Thermodynamic Law, is presenting an evaluation of the exergetic performance of one installation of this type. Exergetic efficiencies are evaluated according to the relation fuel-product, considering one control volume for each component of the system.

Keywords: exergy, chemical recuperation, fuel, turbine.
 
 



s09p08

THERMAL AND ECONOMIC ANALYSIS OF AIR/WATER HEAT EXCHANGERS IN CABINETS FOR PACKING ELECTRONIC EQUIPMENT UNDER VARIABLE ENVIROMENTAL CONDITIONS

J. V. C. Vargas - [email protected]
M. C. Campos - [email protected]
M. R. Errera - [email protected]
Universidade Federal do Paraná, Departamento de Engenharia Mecânica
Cx. P. 19011 - 81531-990 - Curitiba, PR, Brasil

In this work, a comparative study is conducted experimentally, between two heat exchanger systems, air/air and air/water, mounted in a reference experimental cabinet that houses several internal elements that generate heat. The function of the heat exchangers is to extract heat from the cabinet internal ambient, such that the electronic equipment may operate below a pre-specified maximum temperature level. The study consists of introducing a novel system of air/water heat exchangers, a thermal and economic analysis, a comparison between the experimental results obtained with the proposed system and a conventional air/air system, and an analysis of the monthly consumption of energy and water of the tested equipment. In general, the reference cabinet operating with the new system showed a steady-state internal average temperature significantly lower than the same cabinet operating with the traditional air/air system. Another positive aspect is that, differently from the air/air system, the new air/water system is independent of the external environmental conditions, since the performance depends only on the local supplying water temperature.

Keywords. Temperature measurements, Thermal conductance
 
 



s09p10

SUGARCANE EXERGY CALCULATION

Maria I. Fernandez P.
Silvia A Nebra P.
universidade Estadual de Campinas, Fac. de Engenharia Mecânica
Arnaldo Martinez R.
Universidade de Oriente - Santiago de Cuba

This paper presents a sugarcane exergy calculation, carried out considering the material as constituted by dry fiber and juice, being the last one that includes all the sucrose and water present in sugarcane. The variation intervals of sugarcane chemical composition and consequently the chemical composition of fibre and juice were obtained from a bibliograph research. the finals results show that, the fibre exergy, as was considered totally dry and without sucrose, is a function of it chemical composition only. The quotient between the exergy and low calorific value has a middle value of 1,14 and the middle value of it exergy was 2329 kJ/kg of cane. Based on the enviromental reference proposed by Szargut for the sugarcane juice exergy determination, it was obtained that the mixture component of the juice exeergy has no pratical influence in the total exergy juice value, being the value of the reactive exergy component the determining of a middle value of sugarcane juice exergy of 2814,25 kJ/kg of juice and 2380Kj/Kg of cane. The sugarcane exergy value obtained for 8-18% of fiber, 75-82% of water and 14.5-22% of sucrose was 4709Kj/kg of cane.

Keywords: Sugarcane exergy, Exergy, Sugar cane, Sugar-cane
 
 



s09p11

CAPACITY DEGRADATION OF FINNED-TUBE HEAT EXCHANGERS DUE TO TUBE-TO-TUBE HEAT TRANSFER

José L. Lage - [email protected]
Mechanical Engineering Department
Southern Methodist University
Dallas, TX 75275-0337

A simplified mathematical model allows the simulation of the heat transfer process of air flowing in between two parallel fins of a finned-tube heat exchanger. The model is based on the assumption of fully developed flow, being conservative in the sense that it does not account for the increased heat transfer coefficient achieved by the developing flow within the entrance length. The heat transfer from the air to the fin surfaces is modeled via a volumetric heat generation term dependent on the heat transfer coefficient between air and fin surface, and on the air-to-fin local temperature difference. Numerical results from simulating the heat transfer process of a general 4 ×3 finned-tube, air-water heat exchanger, indicate the existence of strong tube-to-tube heat transfer along the fin surface. This effect accounts for 20 % of the heat exchanger capacity and it is stronger among neighboring tubes presenting very different temperatures. Thin adiabatic layers placed along the fin surface are shown to be very efficient in interrupting the tube-to-tube heat transfer. A preliminary simplified analysis to estimate the tube-to-tube heat transfer effect, suggested as a design tool, is satisfactorily tested against the numerical results.

Keywords: finned-tube heat exchanger, capacity degradation, air-cooling/dehumidifying, zeotropic mixture
 
 



s09p12

CARBON DIOXIDE RECOVERY FROM GAS-FIRED POWER PLANTS

Ricardo Salgado Martins - [email protected]
João Roberto Barbosa - [email protected]
Instituto Tecnológico de Aeronáutica - ITA, Departamento de Energia
12228-900 - São José dos Campos, SP, Brasil

Eduardo Lanari Prado - [email protected]
Rice University - Jones Graduate School of Business
6100 - Main Street - Houston, Texas, USA

Adriana de Moura Vieira - [email protected]
Instituto Brasileiro de Mercado de Capitais - IBMEC, Departamento de Finanças
Av. Rio Branco, 108 - 4o andar - 200040-001 - Rio de Janeiro, RJ, Brasil

Since 1996 the Brazilian electric sector has undergone a major restructuring. The aim of such change is to reduce the State's participation in the sector, and to induce the growth of private investments. In particular, this event created several opportunities for thermal power plant projects, leading to competition at the generation level. In this scenario of increased competition, the power plant efficiency becomes a key element for determining the feasibility and profitability of the project. Moreover, the utilization of the plant's own effluents as feedstock or as a source of additional revenue will impact positively in its economics. As an example, long-term additional revenues could be created by the sale of CO2 extracted from the combustion products of thermal power plants. The production of CO2 also contributes to mitigate the environmental impacts of the power plant project by significantly reducing its airborne emissions. This paper shows how a gas-fired power plant can extract and utilize CO2 to generate additional revenue, contributing to a more competitive power plant.

Keywords: Combustion, Environmental Engineering, and Process & Energy Systems.
 
 



s09p13

COMPUTATIONAL SIMULATION OF DIRECT EXPANSION EVAPORATORS

Jorge A. Gatica S.- [email protected]
Nisio C.L. Brum - [email protected] serv.com.ufrj.br
Universidade Federal do Rio de Janeiro, Departamento de Engenharia Mecânica
Cx. P. 68503 - 21945-970 - Rio de Janeiro, RJ, Brasil

This work presents a model to simulate the performance of a typical refrigeration equipment, the direct expansion evaporator. The resultant code is capable to predict the evaporator thermal capacity, the influence of the several overall tube layouts, the importance of all geometrical variables, the dehumidification process and the frost formation. Also some results are presented in order to show the influence of the heat exchanger compactness. The analysis for the different refrigerants used nowadays is performed by the software REFPROP 6.0, which was included in this code. With the tube-by-tube algorithm used, it was possible to study the performance of the relative flow between the air and the refrigerant.

Keywords: Evaporator, Heat Exchanger, Refrigeration.
 
 



s09p15

EXERGY ANALYSIS OF THE FIGUEIRA THERMAL POWER PLANT OPERATION

George Stanescu - [email protected]
João E. Lima - [email protected]
Federal University of Paraná - UFPR, Mechanical Engineering
Department, 81531-990 Curitiba, PR - BRAZIL

Carlos de Andrade - [email protected]
FIGUEIRA Thermal Power Plant, Dr. Fajardo Street 245, 84285-000
Figueira, PR - BRAZIL

Exergy analysis is a powerful tool to evaluate, design and improve the thermal systems. The method of exergy analysis or availability analysis is well suited for furthering the goal of increasing the efficiency of existing power generation systems, and the capability of more effective energy resource use. Exergy analysis of the FIGUEIRA thermal power plant is presented. Exergy losses occurring in various components are considered and the exergy balance is shown in tabular form. Results clearly reveal that the steam generator is the principal site of thermodynamic losses, while the condenser is relatively unimportant.

Keywords: Exergy Analysis, Rankine Cycle, Thermodynamic Optimization
 
 



s09p18

MODELAGEM DA CURVA DE CARGA DAS FAIXAS DE CONSUMO DE ENERGIA ELÉTRICA RESIDENCIAL A PARTIR DA APLICAÇÃO DE UM PROGRAMA DE GERENCIAMENTO DE ENERGIA PELO LADO DA DEMANDA

Prof. Eng. Sérgio Barbosa Rahde, MSc. - [email protected]
PUCRS - Pontifícia Universidade Católica do Rio Grande do Sul
FENG/Departamento de Engenharia Mecânica e Mecatrônica
Av. Ipiranga, 6681 - Porto Alegre - Brasil CEP: 90.619-900

Prof. Eng. José Wagner Kaehler, Dr. - [email protected]
PUCRS - Pontifícia Universidade Católica do Rio Grande do Sul
Faculdade de Engenharia
Av. Ipiranga, 6681 - Porto Alegre - Brasil CEP: 90.619-900

The dissertation aims to offer a current vision on the use of electrical energy inside CEEE`s newly defined area of operation. It also intends to propose different alternatives to set up a Demand Side Management (DSM) project to be carried out on the same market segment, through a Residential Load Management program. Starting from studies developed by DNAEE (the Brazilian federal govemment(tm)s agency for electrical energy), to establish the load curve characteristics, as well as from a research on electrical equipment ownership and electricity consumption habits, along with the contribution supplied by other utilities, especially in the US, na evaluation is offered, concerning severalapproaches to residential energy management, setting up conditions that simulate the residential segment(tm)s scenarios and their influence on the genaral system(tm)s load.

Keywords: DSM, Demand Side Management, Energy Conservation, End Use
 
 



s09p22

OPTIMATION OF THE COOLING PROCESS OF ALUMINUM COIL

Pedro Magalhães Sobrinho - [email protected]
Paulo Magalhães Filho - [email protected]
UNESP- Universidade Estadual Paulista, Departamento de Energia
Cx. Postal 205 - 12516-470 - Guaratinguetá, SP, Brasil

In this paper the cooling process an aluminum coil of about 9 ton is evaluated. The cooling is a stage of production process that depends on the way it is performed and it could be a long term process. In this study alternatives to reduce in 50 % the total process time used in this stage is proposed. Solutions obtained based on experiments on a 1:8 scale model permited to find out the behavior of the real coil. Comparative results of the coil thermal behavior under different coolling conditions are presented and their possible use under ambient conditions are discussed. The relationship between power supply and mass flow rate for each case is also showed.

Keywords: Aluminum, Heat Transfer, Cooling
 
 



s09p25

COMPLEMENTARY COLD WATER PRODUCTION FOR A DAIRY INDUSTRY: THE USE OF BIOGAS GENERATED IN THE EFFLUENT TREATMENT STATION

Villela, I. A. C. - [email protected]
Departamento de Matemática Aplicada
Faculdade de Engenharia Química de Lorena

Napoleão, D. A. S. - [email protected]
Silveira, J. L. - [email protected]
Departamento de Energia - UNESP - Universidade Estadual Paulista
Avenida Dr. Ariberto Pereira da Cunha, 333 - 12.516-410 Guaratinguetá - SP

In this paper is analysed the possibilit y energet ic ut ilizat ion of biogas in the effluent treat ment st at ion of a medium dairy indust ry locat ed in São Paulo state. In this station are produced about 80 Nm 3 /h of biogas, with a molar composit ion of 62,5% of CH4, 13,4% of N2, 5% of CO, 2,4% of CO2, 2,4% of steam H2O e 14,1% of H2S. The generated biogas is today burning in a flair, according the national rule, with evident losses of energetic utilization potential.. The purpose of this paper is the direct utilization of this biogas to run an absorpt ion refrigerat ion syst em ut ilizing H2O + NH3 mixt ure. The level of H2S in the biogas permits the energy recovery of the available heatin minimum temperature level up to 230º C, according to the pinch point proceding.This pot ent ial of energy recovery permits a complement at ion of the cold wat er product ion (7,3 kg/s) at 1ºC. So, is made the energet ic analysis of the proposed inst allat ion showning the tecnical feasibilit y of the actual use of the generated biogas, to produce usefull energy.

Keywords: Refrigeration, biogas, absorption machine.
 
 



s09p31

AIR CONDITIONING DESIGN TEMPERATURE - A NEW PROPOSAL

José R. Camargo  -  [email protected]
Sebastião Cardoso  -  [email protected]
Universidade de Taubaté - Departamento de Engenharia Mecânica
Rua Daniel Danelli, s/n. - Jardim Morumbí
12060-440 - Taubaté - SP

Jerônimo S. Travelho  -  [email protected]
INPE - Instituto Nacional de Pesquisas Espaciais
Av. dos Astronautas, 1758
12201-970 - São José dos Campos - SP

ABNT - Associação Brasileira de Normas Técnicas (Brazilian Association for Technical Standards) - establishes, in NBR-6401, Table 1 (Interior Design Conditions), the dry-bulb summer temperature and the relative humidity to be used in air conditioning design. In thermal comfort plant for residences, hotels, offices and schools these values are, respectively, 23 oC to 25 oC and 40% to 60% rh. These data are in accordance with what is recommended by ASHRAE, which was established as a model for North America. This paper presents a new proposal to air conditioning design temperature that takes into consideration Brazilian climatological conditions. The method, named "effective temperature distribution", compares the maximum recommended effective temperature for each region with dry-bulb temperatures and effective temperatures plotted in a single diagram. This diagram may be used in energetic planning to mininize the use of electric energy for air conditioning. It concludes that the method allows an accuracy analysis about both the temperature levels and the periods of utilization of the air conditioning systems.

Key-words: Air conditioning, thermal comfort, effective temperature.
 
 



s09p32

TEMPERATURE AND ENERGY CONSUMPTION FOR CLOTHING DRYER

Jefferson Almeida Ribeiro - [email protected]
Paulo Magalhães Filho - [email protected]
Universidade Estadual Paulista-Unesp, Faculdade de Engenharia, Departamento de Energia
Cx. P. 205 - 12516-410, Guaratinguetá, SP, Brasil

The cloth dehumidification is done by hot air circulation through it in dryers. The air circulation is done by a fan, run by an electrical motor, and the air temperature raise, which goes through the cloths aiming their moisture dragging, is gotten by the heat dissipation from electrical resistance. This work shows the results of an experimental modeling, examining the behavior of several kinds of cloth in a vertical suspense-type dryer, such as: polyester, cotton-spandex, flannel, blue-jeans and viscose rayon. It was analyzed the behavior of the moisture content in these cloths related to controlled-temperature-air flows, determining the needed heat to reach the required drying standards. The drying device fans were tested for the determination of their flow rate and energy consumption, establishing a flow rate versus consumption relationship. Comparative results among the various kinds of cloths are presented.

Keywords: Clothing dryer, Drying temperature, Energy consumption
 
 



s09p34

UMA FERRAMENTA COMPUTACIONAL PARA O PROJETO DE FORNOS DE PROCESSAMENTO TÉRMICO RÁPIDO

Edgar Alexander - [email protected]
Antônio José da Silva Neto * - [email protected]
Instituto Politécnico, Universidade do Estado do Rio de Janeiro, CP 97282, CEP 28601-970,
Nova Friburgo, RJ, Brasil.

In this work is presented a rapid thermal processing furnace simulator developed with object oriented programming, were the user can define the geometry from the furnace, perform the simulation and watch the results through user friendly graphical interfaces. In this way the designer have a computational tool that allows the testing of several furnaces configurations. A comparison of the results obtained with other simulators is presented for a rapid thermal processing furnace configuration. We also examine some aspects of parallel processing adopted in the module of radiative heat transfer computation.

Keywords: Rapid Thermal Processing, Integrated circuit, Computational simulator, Conduction heat transfer, Radiative heat transfer