CFD Study of a Tunnel-Ventilated Compost-Bedded Pack Barn Integrating an Evaporative Pad Cooling System

Abstract

Evaporative cooling is one of the most efficient techniques to reduce heat stress in cows in agricultural facilities. Additionally, compost-bedded pack barn has been shown to improve the welfare and production of cows. Two techniques were combined and analysed by developing a computational fluid dynamics (CFD) model of a tunnel-ventilated compost-bedded packed barn that integrated the heat and airflow dynamics of an evaporative pad cooling system. This allowed us to study the distribution of dry-bulb temperature, relative humidity and airflow velocity inside the barn based on the external environmental conditions, thickness of the pad, water temperature and specific manufacturer characteristics of the pad, providing optimal cooling pad location, size and operating conditions in the barn. Employing experimental data the CFD model was validated showing good agreement. The Equivalent Temperature Index for dairy Cattle (ETIC) was used to determine the level of stress of the cows considering the airflow velocity. It was found a moderate stress due to high relative humidity and low airflow velocity. From the predicted results, it was recommended to increase the airflow velocity above 3 m s−1 when simultaneously the external dry-bulb temperature and relative humidity exceed 30 °C and 55%, respectively, simultaneously. Additionally, installation of baffles at the pad outlet to drive the airflow to the floor was suggested to improve the drying of the compost-bedded closed to the pads, where a low airflow velocity region was established.

Understanding Compost-Bedded Pack Barn Systems in Tropical Climate Regions: A Review of the Current State-of-the-Art

“…Vega et al [59] reported a first approach to modeling and simulating the thermal distribution inside a tunnel-ventilated CBP facility with an evaporative cooling system located in a tropical environment, using computational fluid dynamics (CFD). They observed that the average difference in dry-bulb temperature between the external and internal conditions was 2.1 to 5.8 °C.…”

Understanding Compost-Bedded Pack Barn Systems in Regions with a Tropical Climate: A Review of the Current State of the Art

“…Vega et al [ 53 ] reported a first approach to modeling and simulating the thermal distribution inside a tunnel-ventilated CBP facility located in a tropical environment with an evaporative cooling system using computational fluid dynamics (CFD). They observed that the average difference in the dry-bulb temperature between the external and internal conditions was from 2.1 to 5.8 °C.…”

“…Vega et al [53] reported a first approach to modeling and simulating the thermal distribution inside a tunnel-ventilated CBP facility located in a tropical environment with an evaporative cooling system using computational fluid dynamics (CFD). They observed that the average difference in the dry-bulb temperature between the external and internal con-ditions was from 2.1 to 5.8 • C. They recommended increasing the airflow velocity to above 3 m•s −1 when the external dry-bulb temperature and the relative humidity simultaneously exceed 30 • C and 55%, respectively.…”

Analysis of Heat and Mass Transfer in Compost-Bedded Pack Barns for Dairy Cows Using Computational Fluid Dynamics: A Review

“…Usually, the software used for CFD simulations is commercial. Among these, for modeling animal facilities can be highlighted the Ansys ® CFX [28,29,36,[40][41][42][43], Ansys ® Fluent [15,16,19,20,31,35,39,[44][45][46], and the Simcenter STAR-CCM+ [13,47].…”

“…Due to its versatility, the CFD technique has been increasingly applied for modeling airflow and moisture conditions in agricultural facilities, being considered an ideal complement for field measurements [27]. In dairy cattle facilities, particularly the use of CFD for heat and mass transfer modeling has been widely used to evaluate and understand the behavior of thermal environmental conditions [14][15][16]19,20,26,[28][29][30][31]. The expressive majority of CFD modeling studies in dairy cattle facilities were carried out on typical conditions of collective housing systems in individual stalls (Free Stall).…”