Heat transfer and energy consumption in the freezing of guava pulp in large containers

Reno, Marciu José; Resende, Jaime Vilela de; Peres, A. P.; Giarolla, T.M.O.; Prado, Mônica Elisabeth Torres

doi:10.1016/j.applthermaleng.2010.10.015

Cited by 8 publications

(4 citation statements)

References 14 publications

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“…The thermophysical properties for the guava pulps required for calculation of the freezing times were obtained from Reno et al (2011) and are shown in Table 1. …”

Section: Thermophysical Propertiesmentioning

confidence: 99%

“…The locations were chosen among the samples to register the transient behavior of the heat transfer during the process in the most comprehensive manner possible (Reno et al, 2011). The thermocouples and RTDs were connected to a signal conditioning system (National Instruments -Model SCXI -Hungary).…”

Section: Monitoring Of Sample and Air Temperaturesmentioning

confidence: 99%

“…The product can have a standard form and size, but this rarely occurs. The external heat transfer may be constant across the entire surface of the product; however, wide variations in the heat transfer coefficients, mainly the convective heat transfer coefficient, may occur in different positions (Pham and Willix, 1987;Reno et al, 2011;Resende et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Heat transfer analyses using computational fluid dynamics in the air blast freezing of guava pulp in large containers

Okita

Reno

Peres

et al. 2013

Braz. J. Chem. Eng.

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-Heat transfer during the freezing of guava pulp conditioned in large containers such as in stacked boxes (34 L) and buckets (20 L) and unstacked drums (200 L) is discussed. The air velocities across the crosssection of the tunnel were measured, and the values in the outlet of the evaporator were used as the initial conditions in computational fluid dynamics (CFD) simulations. The model tested was turbulent standard k-ε. The CFD-generated convective heat transfer coefficients were mapped on the surfaces for each configuration and used in procedures for the calculation of freezing-time estimates. These estimates were compared with the experimental results for validation. The results showed that CFD determined representative coefficients and produced good correlations between the predicted and experimental values when applied to the freezing-time estimates for the box and drum configurations. The errors depended on the configuration and the adopted mesh (3-D grid) construction.

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“…The thermophysical properties for the guava pulps required for calculation of the freezing times were obtained from Reno et al (2011) and are shown in Table 1. …”

Section: Thermophysical Propertiesmentioning

confidence: 99%

Section: Monitoring Of Sample and Air Temperaturesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Heat transfer analyses using computational fluid dynamics in the air blast freezing of guava pulp in large containers

Okita

Reno

Peres

et al. 2013

Braz. J. Chem. Eng.

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show abstract

“…Knowledge of thermophysical properties then becomes essential for the optimization and design of the equipment used in processes involving heat transfer (MERCALI et al, 2011). A large amount of data has been published in the literature, but for tropical fruit pulps, data are still scarce (PEREIRA et al, 2013;RENO et al, 2011;AZOUBEL et al, 2005). At low temperatures, the measurements are quite difficult to perform due to the dependence of the properties on the continual change of the content of ice in the temperature range between 0 and -40 °C and the large variations in these properties (RENAUD et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Effect of concentration and temperature on the thermal conductivity of frozen acerola pulp

et al. 2015

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The purpose of this work was the experimental determination of the thermal conductivity of acerola pulp at concentrations of 5.5, 7.5, 9.5, 11.5 and 13.5 °Brix and temperatures of 0, -5, -10, -15, -20, -25 and -30 °C. The methodology used involved a hot wire probe, and the experimental results were compared with values estimated by several theoretical models (series, parallel and Maxwell-Eucken models) to evaluate the error involved. We observed an influence both of the concentration and the temperature on the thermal conductivity of the pulp. An increase of the conductivity with a decrease in temperature and in the solids concentration was detected. We observed the greatest increases in the range of 0 to -10 °C. Linear and polynomial equations were adjusted for the direct determination of the thermal conductivity of the pulp in the range of temperature and concentration studied. Key words: Frozen acerola pulp, thermal conductivity, hot wire probe, theoretical model ResumoA finalidade deste trabalho foi a determinação experimental da condutividade térmica da polpa de acerola nas concentrações de 5.5, 7.5, 9.5, 11.5 e 13.5 °Brix e nas temperaturas de 0, -5, -10, -15, -20, -25 e -30 °C. A metodologia utilizada foi a da sonda linear de aquecimento e os resultados experimentais obtidos foram comparados com valores estimados pelos modelos teóricos em série, paralelo e Maxwell-Eucken, avaliando o erro envolvido. Observou-se uma influência tanto da concentração quanto da temperatura na condutividade térmica da polpa. Houve aumento da condutividade com a redução da temperatura e da concentração de sólidos, observando-se os maiores aumentos na faixa de 0 a -10 °C. Equações polinomiais e lineares foram ajustadas para a determinação direta da condutividade térmica da polpa de acerola na faixa de temperatura e concentração estudada. Palavras-chave: Polpa congelada de acerola, condutividade térmica, sonda de fio quente, modelo teórico

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Non-uniform Heat Transfer During Air-Blast Freezing of a Fruit Pulp Model in Multilayer Boxes

Resende

Prado

Silveira³

2011

Food Bioprocess Technol

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Heat transfer and energy consumption in the freezing of guava pulp in large containers

Cited by 8 publications

References 14 publications

Heat transfer analyses using computational fluid dynamics in the air blast freezing of guava pulp in large containers

Heat transfer analyses using computational fluid dynamics in the air blast freezing of guava pulp in large containers

Effect of concentration and temperature on the thermal conductivity of frozen acerola pulp

Non-uniform Heat Transfer During Air-Blast Freezing of a Fruit Pulp Model in Multilayer Boxes

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