Browsing by Author "Ge, Xiao"
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- CFD parametric study of ambient air velocity magnitude influence in thermal behaviour of open refrigerated display cabinetsPublication . Gaspar, Pedro Dinis; Gonçalves, Luís Carlos Carrilho; Ge, XiaoThe thermal behaviour of open refrigerated display cabinets depends of ambient air condition variations such as air temperature, relative humidity and velocity magnitude and orientation. The location of air conditioning system discharge grilles, mass flows originated by pressure differences due to openings to surroundings, and air flow perturbation due to consumers’ passage nearby the frontal opening of the display cabinet, among others, affect the re-circulated air curtain behaviour and consequently the equipment’s overall thermal performance. This study presents a three-dimensional (3D) Computational Fluid Dynamics (CFD) modelling of the physical-mathematical phenomena occurring in an open refrigerated display cabinet, and particularly concerns the aerothermodynamics system of recirculated air curtain, under different magnitude values of the ambient air velocity (according to EN-ISO Standard 23953 and doubled one). A parametric study is undertaken for the air flow and heat transfer numerical predictions to determine the open refrigerated display cabinet’s thermal behaviour and of the re-circulated air curtain, taking into account the ambient air velocity’s magnitude. Results from experimental tests following EN-ISO Standard 23953 for climatic class n.er 3 (Tamb = 25 ºC, amb = 60%) are used to characterize the phenomena near inlets, outlets and physical borders. To prescribe boundary conditions as well as to validate numerical predictions of temperature and velocity distributions, the experimental results are applied.
- Influence of ambient air velocity orientation in thermal behaviour of open refrigerated display cabinetsPublication . Gaspar, Pedro Dinis; Gonçalves, Luís Carlos Carrilho; Ge, XiaoOpen refrigerated display cabinets (ORDCs) suffer alterations of their thermal behaviour and of its performance due to variations of ambient air conditions (air temperature, relative humidity and velocity magnitude and orientation). Some factors interfere and affect the re-circulated air curtain behaviour and thus the equipment’s overall thermal performance. Examples of these factors are the location of air conditioning system discharge grilles, air mass flows originated by pressure differences due to openings to surroundings, and ambient air flow instabilities due to consumers’ passage nearby the frontal opening of the display cabinet, among others. This work performs a three-dimensional (3D) Computational Fluid Dynamics (CFD) modelling of air flow and heat transfer in an ORDC. The influence of ambient air velocity orientation in performance of the re-circulated air curtain is evaluated. A CFD parametric study is developed considering the ambient air orientation parallel, oblique and perpendicular to the frontal opening plane of the equipment. The 3D effects of ambient air velocity orientation are determined through the analysis of air temperature and velocity inside the equipment as well as along and across the air curtain. The longitudinal air flow oscillations and length extremity effects are analyzed, having a considerable influence in the overall thermal performance of the equipment.