Browsing by Author "Carneiro, Rui"
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- 3D and transient numerical modeling of door opening and closing processes and its influence on thermal performance of cold roomsPublication . Carneiro, Rui; Gaspar, Pedro Dinis; Silva, Pedro Dinho daThis paper presents the comparison of three-dimensional and transient CFD modelling of the opening and closing processes of hinged and sliding doors and its influence on the thermal performance of cold rooms. A species transport model is used to model a tracer gas. The air infiltration through the door opening is determined by the tracer gas concentration decay technique. The prediction of air temperature and velocity fields in the cold room as function of external air temperature allows quantifying the increase of the air infiltration rate and consequently of the average air temperature inside the cold room. When the hinged door is used, the formation of vortices during the opening movement promotes a larger and faster thermal interaction between the two contiguous air masses. The air infiltration during the sliding door opening/closing is 20% lower than for a hinged door. Consequently, the average air temperature inside the cold room is 17% lower. The air infiltration rate was numerically predicted and compared with analytical models’ results. The numerical model predicts closely the air infiltration rate for each door type. Moreover, the transient CFD modelling extends the results of the analytical models allowing the analysis of the influence of door opening and closing processes on the air temperature and velocity fields.
- 3D transient CFD modeling of sliding door operation and its influence on the thermal performance of cold roomsPublication . Carneiro, Rui; Gaspar, Pedro Dinis; Silva, Pedro Dinho daThe need of rationalize energy consumption in agrifood industry has fasten the development of methodologies to improve the thermal and energy performances of cold rooms. This paper presents a 3D transient Computational Fluid Dynamics (CFD) modelling of a cold room to evaluate the air infiltration rate through sliding doors. A species transport model is used for modelling the tracer concentration decay technique. Numerical predictions indicate that air temperature difference between spaces affects the air infiltration. For this case study, the infiltration rate increases 0.012 m3 s-1 per K of air temperature difference. The knowledge about the evolution of air infiltration during door opening/closing times allows to draw some conclusions about its influence on the air conditions inside the cold room, as well as to suggest best practices and simple technical improvements that can minimize air infiltration, and consequently improve thermal performance and energy consumption rationalization.
- Computational modelling and simulation to assist the improvement of thermal performance and energy efficiency in industrial engineering systemsPublication . Gaspar, Pedro Dinis; Silva, Pedro Dinho da; Gonçalves, João Pedro Marques; Carneiro, RuiComputational modelling is nowadays a powerful tool for project and design of engineering systems, anticipating and/or correcting problems that may lead to inefficiencies. This chapter describes three distinct computational tools with different mathematical and numerical models. The computational tools are used with the purpose of improving the thermal and energy performance of cold stores. All tools are applied to the same agrifood company. First, Computational Fluid Dynamics is used to optimize velocity and temperature fields for the interior a cold room. Afterwards, an energy analysis and thermal load simulation is performed to the cold store facility to reduce its thermal loads. Finally, a statistical prediction model based on empirical correlations is used to predict the energy performance of the cold store and compare it to an average behaviour. The numerical results indicate the improvement of the thermal performance and consequently of food safety, as well as considerable energy savings that can be achieved in cold stores by the combined use of different modelling techniques.