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Air blast freezing of fruit pulp models in commercial boxes: evaluation of the time-variability of product heat load.

Author(s) : RESENDE J. V. de, SILVEIRA V. Jr

Type of article: Article

Summary

The experimental values for dynamic heat load of fruit pulps models were obtained using the principle of the flow calorimeter. A group of thermocouples in arrays coupled in series was placed before and after the product in the air stream, and the temperature differential measured. Three plastic boxes of the type used in industry, were filled with arrays of 7, 5 and 3 layers of polyethylene bags (0.100 kg) containing model solutions of fruit pulps, and frozen using different air temperatures and velocities. The air velocities were established according to the number of product layers inside the boxes. A method based on the resolution of differential equations and the records of experimental temperatures of the product, was used to determine the heat load profiles of cooling. The results were compared with the data measured and that obtained from the air temperature differential. The analysis of the percentage of heat removal showed that in the configuration with the greater amount of product, practically 50% of all the heat necessary to reduce its temperature to the desired level occurred during the first two hours of processing. The theoretical amount of heat removed during the first two hours, as calculated, was 16.6% lower than the experimental values. The application of the methods of measurement and the experimental results of the evaluations are in situations that allow for a visualization of the cooling conditions of the product, creating the possibility of designing strategies to control the refrigeration system.

Details

  • Original title: Air blast freezing of fruit pulp models in commercial boxes: evaluation of the time-variability of product heat load.
  • Record ID : 2008-0734
  • Languages: English
  • Source: Braz. J. Food Technol. - vol. 5 - n. 95
  • Publication date: 2002

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