A numerical study on forced convective heat transfer of a chicken (model) in horizontal airflow

摘要

Under hot climatic conditions, heat stress of the animal is a general concern in livestock farming. To reduce the heat stress, an important approach is ensuring a suitable air speed in the animal occupied zone (AOZ) to increase convective heat removal for animals. Therefore, the relationship between convective heat transfer and air speed is essential to understand the effects of the airflow speed manipulation, and consequently, the optimal design and control of a ventilation system. In this study, computational fluid dynamics (CFD) was employed to study the convective heat transfer coefficient for a chicken. Simulated results were compared with the experimental data found in the literature. SST k-omega model was evaluated on a sphere model first by comparing it to a semi-experimental equation of the convective heat transfer coefficient. Good agreement was found and therefore this numerical method was adopted for further modelling with a more realistic geometric model of a chicken. Three different angles between the chicken trunk axis and airflow direction: 0 degrees, 45 degrees, and 90 degrees were studied as well as various chicken weights of the model. The study results revealed that the angle at which the airflow struck the chicken model was not significant. By testing chicken models at different weights (bird mass of 0.2 kg, 0.9 kg, and 2 kg), larger specific surface (the ratio of surface area to the weight) led to a higher convective heat transfer coefficient. In addition, a correlation of the predicted convective heat transfer coefficients was found between a sphere and the chicken models used, indicating that a chicken can be simplified as spherical model in future studies. (C) 2016 IAgrE. Published by Elsevier Ltd. All rights reserved.