Experimental investigation in an insulated box (Air velocity)

Published: 7 July 2022| Version 1 | DOI: 10.17632/yjbpwtx3c4.1


The detailed description of data can be found in Experimental condition.docx The data was categorized by - Measurement position - Phase Change Material (PCM) position: on a side wall and at the top - Loading condition: empty, extruded polystyrene (XPS) and test product (TP) For example C01 Air velocity X-250mm Side Empty.xlsx: at X = 250 mm in a box with PCM on a side wall (empty) C01 Air velocity Y-145mm Side Empty.xlsx: at Y = 145 mm in a box with PCM on a side wall (empty) C02 Ait velocity X-250mm Top Empty.xlsx: at X = 250 mm in a box with PCM at the top (empty) C03 Air velocity X-250 mm Side XPS: at X = 250 mm in a box with PCM on a side wall (XPS) C05 Air velocity X-250 mm Side TP: at X = 250 mm in a box with PCM on a side wall (TP)


Steps to reproduce

Air velocity data was collected by Particle Imagery Velocimetry (PIV) under stable conditions: after 90 min. 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.


Paris-Saclay Food and Bioproduct Engineering Research Unit


Cold Chain Food Storage, Airflow