COBEM99

SR27 Transferência de Calor e Massa

Title:

COOLING CURVES FOR ORANGE VALENCIA BY EXPERIMENTAL AND NUMERICAL MODEL.

Summary :

COOLING CURVES FOR ORANGE VALENCIA BY EXPERIMENTAL AND NUMERICAL MODEL. ABSTRACT. THIS PAPER TREATS ABOUT THE COOLING CURVES FOR ORANGE (VARIETY VALENCIA) USING PARAMETERS SUCH AS THE HALF-COOLING TIME AND THE COOLING RATE. THE PRODUCT WAS PRECOOLING (AT 1ºC, RH=89%, AND AIR SPEED OF APPROXIMATELY 1 M/S) THROUGH FORCED-AIR COOLING TUNNEL SYSTEM. TWO TYPES OF PACKAGE WERE USED, WITH DIFFERENT VALUE OF THE OPENING AREA, (PLASTIC BOXES AND OF CARTONS, WITH 40% AND 3,5% OF OPENING EFFECTIVE AREA, RESPECTIVELY). A BIDIMENSIONAL MATHEMATICAL MODEL WAS APPLIED, ASSUMING PROLATE SPHEROID COORDINATES, TO CHARACTERIZE THE TRANSIENT HEAT TRANSFER PROCESS INSIDE THE FRUITS, ASSUMING CONVECTIVE PROFILE CONDITIONS ON THE OUTSIDE SURFACE, DURING FORCED AIR COOLING. THE GENERATED EQUATIONS WERE NUMERICALLY SOLVED BY FINITE VOLUMES METHOD, TO OBTAIN THE HEAT TRANSFER AND THERMAL DIFFUSION COEFFICIENTS. THE COMPARATIVE ANALYSIS OF THE THEORETICAL AND EXPERIMENTAL CURVES OBTAINED, PRESENTED A SATISFACTORY AGREEMENT WITH THE OF THE COOLING CURVES WITH THE NUMERIC METHOD, BEING PROVEN THAT THE MATHEMATICAL MODEL IS CONSISTENT AND ADAPTED TO DESCRIBE THE EXPERIMENT. A HIGHLY SIGNIFICANT DIFFERENCE WAS VERIFIED IN THE HALF-COOLING TIME OF THE PRODUCTS, FOR THE TWO PACKING USED IN THE EXPERIMENTS, WHAT DEMONSTRATES THAT THE AREA OF OPENING OF THE BOXES IS ONE OF THE FACTORS THAT INFLUENCES IN A PREDOMINANT WAY ON THE EFFICIENCY OF THE PROCESS OF TRANSFER OF HEAT DURING THE COOLING. KEY- WORDS: FORCED-AIR PRECOOLING, ORANGES, EXPERIMENTAL, NUMERICAL.

Author :

Cortez, Luís Augusto Barbosa
de Lima, Antônio Gilson Barbosa
Leal, Paulo Martin
Mederos, Bárbara Janet Teruel

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