Listagem por temas:

Escolhendo um título você terá acesso ao arquivo original em Post-Script.

COB321 PROJETO RÁPIDO DE TROCADORES DE CALOR DO TIPO CASCO E TUBOS / SHORT-CUT DESIGN PROCEDURE FOR TUBE-AND-SHELL HEAT EXCHANGERS

Roger J. Zemp e Cristiane Junqueira

Departamento de Engenharia de Sistemas Químicos, Faculdade de Engenharia Química, Unicamp Caixa Postal 6066, CEP 13083-970 Campinas SP, email: zemp@desq.feq.unicamp.br

A new short-cut procedure for the design of tube and shell heat exchangers is presented. Departing from the energy balances, fluid properties and tube diameters/layout, the algorithm computes the main exchanger variables (pressure drops / area), and therefore can be used for the economic optimisation of the exchanger. The advantage of the procedure is that no detailed design is required, so that it can be used in projects where quick designs are required, like synthesis and design of pressure-drop constrained heat exchanger networks. A procedure to obtain a complete exchanger design, fully meeting the heat transfer requirements, based on the optimised conditions, is also proposed. Available pressure drops are fully utilised, leading to cost effective exchanger designs. The procedure makes use of the Bell-Delaware design method.

Keywords: Projeto rápido de trocadores de calor, perda de carga em trocadores de calor / short-cut heat exchanger design, pressure drop in heat exchangers.

COB325 Trocadores de Calor Alimentados por Hidrogênio / Oxigênio Eletrolítico - Uma Análise Comparativa / HEAT EXCHANGERS POWERED BY HYDROGEN/OXYGEN ELETROLYTIC - A COMPARATIVE ANALYSIS

Maurício Alves da Motta Sobrinho ¹, Júlio Goldfarb ², Kepler Borges França ²

¹ Universidade Federal de Pernambuco, Departamento de Engenharia Química, Av Prof. Arthur de Sá, s/n, Cidade Universitária, CEP : 50.740-080, Recife, Pernambuco, Brasil, Tel. : (081) 271-8238, Fax : (081) 271-0095, E-Mail: mottas@npd.ufpe.br

² Universidade Federal da Paraíba, Departamento de Engenharia Química, Campina Grande, Paraíba, Brasil, Fax.: (083) 310-1011.

The environmental care and the search for alternative energy sources are some of the main problem for the governments. Solar and wind energy and hydrogen can de solution. This work shows results of a research run by the Hydrogen Group of UFPB for the development of heat exchangers. The performance of two heat exchangers were compared, a tubular and a convective heat exchanger, through the analysis of the internal and external environmental variation, the gas and the electricity consumption. As a result, the convective exchanger showed a better suitability, suggesting that its efficacy can increase after some alterations to be made, mainly at the gas outlet.

Keywords: Trocador de Calor, Aquecimento de Ambientes, Hidrogênio Eletrolítico, Energia Alternativa.

Heat-Exchanger, Environmental Heating, Eletrolytic Hydrogen, Alternative Energy.

COB528 AN INVESTIGATION ON THE HEAT TRANSFER IN AN INDUSTRIAL FLUIDIZED BED HEAT EXCHANGER

Paulo Roberto Tardin Jr. and Leonardo Goldstein Jr.

Department of Thermal and Fluids Engineering, College of Mechanical Engineering - UNICAMP

Zip Code 13083-970 Campinas, Brazil - E-mail: tardin@fem.unicamp.br

Luis Carlos Casavechia

Superintendência da Industrialização do Xisto - SIX, PETROBRAS S/A, Zip Code 83900-000 São Mateus do Sul, Brazil

An industrial size fluidized bed heat exchanger was tested and the results were applied to check the available correlations for the bed-to-tube heat transfer coefficient. The heat exchanger was designed to recover the heat content of the ashes produced in a 1 MW circulating fluidized bed boiler pilot plant burning oil shale, with an horizontal tube immersed in the bed. The solids inlet temperature was about 375 ^oC and the superficial velocity 0.10 m/s. About 75% of the total heat transfer rate from the ash was transferred to the water and the balance to the air stream. The Molerus correlation (1995) has shown the best agreement with the data, with less than 20% deviation.

Keywords: Heat exchanger, Fluidized bed, Heat recovery, Bed-to-tube heat transfer coefficient.

COB1130 Estudo numérico de um trocador de calor compacto com aletas recortadas e uma fileira de tubos / Numerical study of a compact heat exchanger with offsets and one tube row

Jurandir Itizo Yanagihara, Paulo Eduardo Batista de Mello

Departamento de Engenharia Mecânica, Escola Politécnica - Universidade de São Paulo

Av. Prof. Mello Moraes, 2231 - São Paulo - SP - CEP 05508-900 - Brasil - E-Mail: jiyanagi@usp.br

Heat transfer and flow loss characteristics of a fin-tube compact heat exchanger were obtained numerically. The heat exchanger model has one tube row and utilises the heat transfer enhancement technique known as "offsets", that promotes successive boundary layer break-ups. The heat conduction effect in the fin was taken into account (conjugate heat transfer) and so the cyclic characteristic of the flow in the perpendicular direction, generated by the interruptions that the "offsets" promote over the fin. The influence of the thermal conductivity parameter over the heat transfer was verified. This paper presents correlations for the Colburn factor and friction factor, both function of Reynolds number, for the laminar regime. With the objective of evaluating the heat transfer enhancement obtained with the "offsets", one model with the same dimensions but with plain fins was simulated numerically. With the results, important aspects were discussed, such as enhancement obtained with "offsets", flow loss increase, influence of the thermal conductivity of the fin and indications for a better design.

Keywords: compact heat exchanger, offset, tube-fin / trocadores de calor compactos, tubo-aleta

COB1132 CONJUGATE HEAT TRANSFER AND FLOW LOSSES IN COMPACT HEAT EXCHANGER WITH SMOOTH FINS AND TWO ROWS OF TUBES

Rogério Rodrigues Jr. & Jurandir Itizo Yanagihara

Department of Mechanical Engineering, Polytechnic School of University of São Paulo

Av. Prof. Mello Moraes, 2231 - São Paulo - CEP 05508 - 900 - E-mail: jiyanagi@usp.br

The present work refers to a numerical analysis of the local and global heat transfer and fluid flow characteristics of a fin-tube heat exchanger with smooth fins. These investigations aim to provide basic information for the development of heat transfer enhancement techniques applied to evaporator/condenser of domestic air-conditioning systems. Momentum and energy conservation equations were solved by the finite volume method with a boundary fitted coordinate system. The computational model consists of a compact heat exchanger with two rows of round tubes in a staggered arrangement using smooth fins. The numerical simulations were carried out for a steady-state thermally and hydrodynamically developing laminar flow. The influence of channel parameters such as transverse and longitudinal tube spacing on the heat transfer and flow losses were analyzed. The results allow to identify situations in which the fin effectiveness decreases, providing useful information for the application of heat transfer enhancement techniques to this kind of geometry.

Keywords: compact heat exchangers; fin-tube channels; smooth fins; conjugate heat transfer; finite volume method

COB1402 OTIMIZAÇÃO DO PROJETO TERMO-HIDRAULICO DE TROCADORES DE CALOR DE PLACAS/OPTIMIZATION OF THERMAL-HYDRAULIC DESIGN OF PLATE HEAT EXCHANGERS

Oscar M. H. Rodrigues, Arlindo de Matos, Rigoberto E. M. Morales e Leonardo Goldstein Jr.

Faculdade de Engenharia Mecânica - FEM; Universidade Estadual de Campinas - UNICAMP.

CEP-13083-970. Campinas - SP - Brasil - E-Mail: oscarmh@fem.unicamp.br

This work presents a methodology for the thermal-hydraulic design optimization of Plate Heat Exchangers. It is also presented the results of the application to a typical case.

Keywords: Plate Heat Exchangers, Thermal-hydraulic Design, Optimization. / Trocadores de Calor de Placas, Projeto Termo-hidráulico, Otimização

COB1484 Estudos Preliminares de um Trocador de Calor Tubular alimentado por Hidrogênio Eletrolítico/ preliminaRy studies of A HEAT EXCHANGE POWERED BY ELETROLITIC HYDROGEN

Maurício Alves da Motta Sobrinho ¹, Mirian C.C. Amorin ², Júlio Goldfarb ², Kepler Borges França ²

¹ Universidade Federal de Pernambuco, Departamento de Engenharia Química, Av Prof. Arthur de Sá, s/n, Cidade Universitária, CEP : 50.740-080, Recife, Pernambuco, Brasil, Tel. : (081) 271-8238, Fax : (081) 271-0095, E-Mail: mottas@npd.ufpe.br

² Companhia Pernambucana de Água e Saneamento (COMPESA), Escritório de Petrolina, Pernambuco.

³ Universidade Federal da Paraíba, Departamento de Engenharia Química, Campina Grande, Paraíba, Brasil, Fax.: (083) 310-1011.

An environmental heating system fueled by electrolytic hydrogen has been developed by the Hydrogen Group at the Chemical Engineering Department of the Paraíba Federal University . This system purposes to replace the heating obtained by pollutant carbonic fuels and can be integrated with fotovoltaic collectors or aero-generators to improve the utilized energy.

The first tests realized with this heat exchange, developed and projected by this group, are presented besides with the system flow chart. The temperature input and the output of the heater dissipation unit using water and Dowtherm* G synthetic organic oil and the room temperature has been analyzed, as a function of the time. Results shown a higher performance when using the organic oil.

Keywords: Trocador de Calor, Hidrogênio, Eletrólise, Aquecimento de Ambientes / Heat Exchanger, Hydrogen, Electrolyse, Environmental Heating

.