Comparison of airflow homogeneity in Compost Dairy Barns with different ventilation systems using the CFD model

B. Fagundes¹, F.A. Damasceno²*, R.R. Andrade³, J.A.O. Saraz⁴, M. Barbari⁵, F.A.O. Vega⁴ and J.AC. Nascimento²

¹Professional Faculty, Department of Climatization Engineering, Porto Alegre, Tocantins Street, 937, n. 8, BR91.540.420 Porto Alegre, Brazil
²Federal University of Lavras, Department of Engineering, BR37200-000 Lavras, Minas Gerais, Brazil
³Federal University of Viçosa, Department of Agricultural Engineering, Av. Peter Henry Rolfs, s/n Campus University of Viçosa, BR36570-900, Viçosa, Minas Gerais, Brazil
⁴Univeridad Nacional de Colombia, Agrarian Faculty, Department of Agricultural and Food Engineering, Carrera 65 n. 59A – 110, Bloque 14 - Oficina 430, Medellin, Colombia
⁵University of Florence, Department of Agriculture, Food, Environment and Forestry, Via San Bonaventura, 13, IT50145 Firenze, Italy
*Correspondence: flavio.damasceno@ufla.br

Abstract:

In the pursuit of high milk productivity, producers are using confinement systems in order to improve performance and animal welfare. Among the housing systems, the Compost bedded-pack barns (CBP) stand out. In these barns a bedding area is provided inside, where cows move freely. Generally this area is covered with carbon source material (such as sawdust or fine dry wood shavings) which together with manure, thanks a regular mechanically stirring, ensures the aerobic composting process. The ventilation in these facilities has the function of dehumidifying the air, improving the air quality, drying the bedding, improving the thermal comfort conditions of the confined animals. This work aimed at validating a computational model using Computational Fluid Dynamics (CFD) to determine the best homogeneity of airflows generated by different forced ventilation systems used in CBP barns. Two CBP barns were compared with different ventilation systems: high volume low speed (HVLS) and low volume high-speed (LVHS) fans. The results showed that the proposed model was satisfactory to predict the flows generated by both types of fans. It was concluded that the use of HVLS fans produced a more homogeneous airflow when compared to LVHS fans. The use of mechanical ventilation in tropical conditions is necessary for the proper functioning of the system. In this study, the systems used promoted the increase in air speed to levels close to adequate.

Key words:

airflow, animal housing, compost-bedded pack barn, dairy cows

Alternative form to obtain the black globe temperature from environmental variables

H.H.R. Zanetoni¹*, I.F.F. Tinôco¹, M. Barbari²*, L. Conti², G. Rossi², F.C. Baêta¹, M.O. Vilela¹, C.G.S. Teles Junior¹ and R.R. Andrade¹

¹Federal University of Viçosa, Department of Agricultural Engineering, Av. Peter Henry Rolfs, s/n Campus University of Viçosa CEP: 36570-900, Viçosa, Minas Gerais, Brazil
²University of Florence, Department of Agricultural, Food, Environmental and Forestry Science, Via San Bonaventura, 13, IT50145 Firenze, Italy
*Correspondence: matteo.barbari@unifi.it; hiago.zanetoni@ufv.br

Abstract:

Reaching thermal comfort conditions of animals is essential to improve well-being and to obtain good productive performance. For that reason, farmers require tools to monitor the microclimatic situation inside the barn. Black Globe-Humidity Index (BGHI) acts as a producer management tool, assisting in the management of the thermal environment and in decision making how protect animals from heat stress. The objective of this work was to develop a mathematical model to estimate the black globe temperature starting from air temperature, relative humidity and air velocity. To reach this goal, data of air temperature and humidity were collected, with the aid of recording sensors. The black globe temperature was measured with a black copper globe thermometer and the air velocity was monitored with a hot wire anemometer. Data were analysed using a regression model to predict the black globe temperature as a function of the other variables monitored. The model was evaluated, based on the significance of the regression and the regression parameters, and the coefficient of determination (R²). The model proved to be adequate for the estimation of the black globe temperature with R² = 0.9166 and the regression and its parameters being significant (p < 0.05). The percentage error of the model was low (approximately 2.2%). In conclusion, a high relation between the data estimated by the model with the data obtained by the standard black globe thermometer was demonstrated.

Key words: