Analysis of heterogeneous cooling of agricultural products inside bins Part I: aerodynamic study

Álvarez, G.; Flick, Denis

doi:10.1016/s0260-8774(98)00164-2

Cited by 71 publications

(35 citation statements)

References 12 publications

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“…However, strong cooling heterogeneity is created during forced-air precooling due to poor temperature management [2,3]. Commodities located behind blind walls may not be sufficiently cooled, while others exposed to higher velocities are over-cooled.…”

Section: Forced-air Precooling Processmentioning

confidence: 99%

See 1 more Smart Citation

Mathematical Modeling Procedures for Airflow, Heat and Mass Transfer During Forced Convection Cooling of Produce: A Review

2010

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The aim of this review paper is to give comprehensive and detailed mathematical modeling procedures for the airflow, heat and mass transfer occurred during forced convection cooling of produce in order to optimize the cooling process. First, a brief explanation of forced-air precooling process and its importance in improving produce market quality will be given. Then, two main modeling procedures used during the process, namely porous medium approach and direct numerical simulation, will be explored. In addition, various related models available in the literature will be critically discussed together with their capabilities and drawbacks. Finally, a case study for optimizing the process using direct numerical simulation is shown. KeywordsMathematical modeling Á Direct numerical simulation Á Porous medium approach Á Forced-air precooling List of symbols A Surface area (m 2 ) A o Volumetric or specific surface area (1/m) A fs Interfacial area between fluid and solid phases (m 2 ) c Diffusivity in element Peclet number (Pa.s or W/m K) c art Coefficient of artificial diffusion (Pa.s or W/ m K) c p,a Air specific heat capacity (J/kg K) c p,p Produce specific heat capacity (J/kg K) d Hydraulic diameter (m) or pore-level linear length scale (m) d eff Effective produce diameter (m) D Diffusivity of water vapor in air (m 2 /s) or total diffusivity (m 2 /s) D d Dispersion coefficient (m 2 /s) f and g Respiration constants h Element size (m) h sf Interstitial convection heat transfer coefficient (W/m 2 K) I Second-order identity tensor k Mass transfer coefficient (kg/m 2 .s. Pa) k air Air film mass transfer coefficient (kg/m 2 .s. Pa) k 0 air Air film mass transfer coefficient (m/s) k skin Skin mass transfer coefficient (kg/m 2 .s. Pa) k a Air thermal conductivity (W/m K) k p Produce thermal conductivity (W/m K) K 1 and K 2 Constants in Darcy-Forchheimer equation K e Effective thermal conductivity (W/m K) ' Linear length scale for representative elementary volume (m) L Latent heat of evaporation (J/kg) or system dimension (m) _ m Rate of produce moisture loss (kg/s.m 2 ) Nu d Nusselt number (dimensionless) Nu d ¼ h sf d k a P Pressure (Pa)

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Section: Forced-air Precooling Processmentioning

confidence: 99%

“…However, complete or partial losses of fresh fruits and vegetables occur as a result of poor temperature management during the process [2,3]. This is mainly due to the nonuniform nature of produce cooling [51,61], resulting in under-cooling or over-cooling of fresh produce located at different parts of ventilated packages.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Modeling Procedures for Airflow, Heat and Mass Transfer During Forced Convection Cooling of Produce: A Review

2010

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“…Recently, some researchers have proposed models that can accommodate such effects and apply the porous media assumptions to flow through packaged agricultural commodities (Alvarez and Flick, 1999;van der Sman, 2002). This type of porous media modeling requires an assumption of continuous media.…”

Section: Flow Through Porous Packagesmentioning

confidence: 99%

Commercial-Scale Forced-Air Cooling of Packaged Strawberries

Anderson¹,

Sarkar²,

Thompson³

et al. 2004

Transactions of the ASAE

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trawberries are an extremely valuable crop in the U.S., and are second only to apples in fresh market value among fruits. California produces over 635 million kg (1,400 million pounds) of strawberries per year with a value of over $800 million, accounting for over 80% of the total U.S. production. Approximately 75% of the strawberry production is harvested for the fresh market (California Strawberry Commission, 2002). Strawberries are also one of the most perishable fruits. They are very susceptible to mechanical damage, microbial decay, and water loss. One of the most important factors in maintaining quality of strawberries is rapid cooling and distribution under refrigerated conditions. Freshly picked strawberries are typically field packed and rushed to a cooling facility, where they are forced -air cooled to approximately 0°C for refrigerated distribution and storage. This process is termed "precooling" of strawberries.

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“…The forced convection cooling process is the most common technology used for this purpose [1,2]. However, it induces strong heterogeneities of the thermal treatment due to heterogeneous airflow distribution at different locations in ventilated packages [3][4][5]. Commodities located behind blind walls may not be sufficiently cooled while others exposed to higher velocities are over-cooled.…”

Section: Introductionmentioning

confidence: 99%

“…Some of the previously attempted strategies can not accurately measure or predict air velocity inside ventilated packages during the process [3,7,10]. However, recent advances in computational resources have provided powerful tools to obtain detailed aerodynamic and thermal analysis by modeling coupled airflow and heat transfer during the process.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Aerodynamic and Thermal Analysis during Cooling of Stacked Spheres inside Ventilated Packages

2008

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Aerodynamic and thermal analysis during forced convection cooling of produce was conducted by modeling coupled airflow and heat transfer. Air velocities and heterogeneity indexes were predicted for different configurations of package openings at an airflow rate of 0.022 m 3 /s. Predicted temperature profiles were compared with experimental data for model validation. Good agreement between model prediction and measured data was obtained. The results showed that airflow distribution during the process was not homogeneous. More uniform airflow distribution was obtained by increasing the vent area from 2.4 to 12.1 %. The highest cooling heterogeneity index (108 %) was recorded at 2.4 % vent area whereas the lowest heterogeneity index (0 %) was detected in a package with 12.1 % vent area. Proper package vent design is necessary to provide more uniform cooling operation during the forced convection cooling process.

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Analysis of heterogeneous cooling of agricultural products inside bins Part I: aerodynamic study

Cited by 71 publications

References 12 publications

Mathematical Modeling Procedures for Airflow, Heat and Mass Transfer During Forced Convection Cooling of Produce: A Review

Mathematical Modeling Procedures for Airflow, Heat and Mass Transfer During Forced Convection Cooling of Produce: A Review

Commercial-Scale Forced-Air Cooling of Packaged Strawberries

Simultaneous Aerodynamic and Thermal Analysis during Cooling of Stacked Spheres inside Ventilated Packages

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