Air velocity in an insulated box

Published: 19 April 2022| Version 1 | DOI: 10.17632/ggmkzk634h.1
Contributors:
Tanathep Leungtongkum,
,
, Alain Denis,

Description

The detailed description of data can be found in Experimental conditions.docx The data was categorized by - Measurement position: middle plane and lateral plane - Box configuration: Horizontal and Vertical - Phase Change Material (PCM) position: on a side wall and at the top - Ambient temperature: 10°C, 20°C and 30°C - Product initial temperature: 4°C and 10°C - Space beneath the product: 20 mm and 0 mm For example: C01 Air velocity X-250 mm Horizontal Side Empty.xlsx: Air velocity component, its magnitude and uncertainty on middle plane (X = 250 mm) in a horizontal box with PCM at side wall (empty box). C01 Air velocity X-15 mm Horizontal Side Empty.xlsx: Air velocity component, its magnitude and uncertainty on lateral plane (X = 15 mm) in a horizontal box with PCM at side wall (empty box) C02 Air velocity X-250 mm Horizontal Top Empty.xlsx: Air velocity component, its magnitude and uncertainty on middle plane (X = 250 mm) in a horizontal box with PCM at top (empty box) C03 Air velocity X-150 mm Vertical Side Empty.xlsx: Air velocity component, its magnitude and uncertainty on middle plane (X = 150 mm) in a vertical box with PCM at side wall (empty box) C04 Air velocity X-250 mm Horizontal Side 20CAmb 4CInitial 20mmGap.xlsx: Air velocity component, its magnitude and uncertainty on middle plane (X = 250 mm) in a loaded horizontal box with PCM at side wall under 20°C ambient, product initial temperature = 4°C with 20 mm gap below. C07 Air velocity X-250 mm Horizontal Side 30CAmb 4CInitial 20mmGap.xlsx: Air velocity component, its magnitude and uncertainty on middle plane (X = 250 mm) in a loaded horizontal box with PCM at side wall under 30°C ambient, product initial temperature = 4°C with 20 mm gap below. C10 Air velocity X-250 mm Horizontal Side 20CAmb 10CInitial 20mmGap.xlsx: Air velocity component, its magnitude and uncertainty on middle plane (X = 250 mm) in a loaded horizontal box with PCM at side wall under 10°C ambient, product initial temperature = 4°C with 20 mm gap below. C12 Air velocity X-250 mm Horizontal Side 20CAmb 4CInitial noGap.xlsx: Air velocity component, its magnitude and uncertainty on middle plane (X = 250 mm) in a loaded horizontal box with PCM at side wall under 20°C ambient, product initial temperature = 4°C with no gap below.

Files

Steps to reproduce

Air velocity data was collected by Particle Imagery Velocimetry (PIV) under stable conditions: after 90 min. for empty boxes, and after 4 hours for loaded boxes. Then, PIV measurement was undertaken for a duration of 30 min. The tracer was oil-based smoke tracer (mean diameter 0.3 μm). It was precooled from about 50°C to around 10°C by PCM slabs. By the aid of a small fan, smoke was introduced to the box through a connecting duct, while its flow rate was regulated by a valve. A 2D-PIV system (LaVision, FlowMaster 2D) included three main components: a double-pulsed Nd:YLF laser (527 nm wavelength, 10 mJ pulse energy), a high speed 12-bit CMOS video camera (Photron, FASTCAM SA3; 1024 ×1024 pixels in resolution) attached with a lens (Sigma; 105 mm, f/1:2.8) and a programmable timing unit (PTU-X) for the synchronization of laser and camera. The image acquisition and post-processing to obtain air velocity field were achieved using the software, DaVis 10.0.5. Based on the image calibration using a ruler and this software, a magnification factor of 0.108 mm/pixel was defined and the image size was 115.5 mm × 115.5 mm. Several measured windows with partial overlapping between them were used to cover the whole area of the plane. For each measured window, 500 pairs of images were recorded every 20 ms with a time interval of 900 μs between two images of the same pair, in other words between two pulsed laser illuminations. The total duration of measurement was 10 s. A multi-pass correlation algorithm was applied in order to calculate the instantaneous airflow vector. The cross-correlation between each image in the pair was accomplished by using decreasing interrogation window sizes: 64 × 64 pixels with 50% overlap for the first pass and 32 × 32 pixels with 75% overlap for the 3 following passes. In each pass, all interrogation windows at the same position on the paired images were cross-correlated and independently produced a single displacement vector, then were later merged to produce a 2D vector field of the whole image. After 500 instantaneous vector fields had been attained, the mean velocity field of each measured window was calculated.

Institutions

Paris-Saclay Food and Bioproduct Engineering Research Unit

Categories

Cold Chain Food Storage, Airflow

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