CFD simulations to improve air distribution inside cold climate broiler houses involving heat exchangers

Abstract

While chicken meat production is less polluting than other meats, it remains a problem, given a target of 1 ton CO2-eq per capita in 2050. Most of the emissions are associated with feed production, but cold climate requires an additional energy input for space heating. This input is usually provided by propane gas. Since 2014, energy efficiency has sparked in the world of broiler production. Heat recuperation through heat exchanger can reduce significantly the heating requirement, by preheating fresh air inlet with stale air outlet. While there have been many studies on the improvement of direct ventilation in both hot and cold climate, little attention has been given to heat exchangers in broiler houses. It is therefore unknown how best to integrate this equipment in a broiler house to provide homogenous housing conditions (air temperature, humidity, contaminants). This thesis studies the integration of heat exchangers (HX) in a commercial broiler house located in a cold climate (Sainte-Melanie, Canada). The goal is to improve the housing conditions of a rectangular 1760 m3 broiler house equipped with two ductless air-to-air heat exchangers (0.38 m3s-1). Computational fluid dynamics (CFD) software OpenFOAM was used to create a 3D steady-state buoyant simulation with RNG k-e turbulence model. CFD model was validated with experimental data collected at the participating broiler house. In the original configuration (C0), the two heat exchangers are parallel, on the same longitudinal wall. Three alternative configurations (C1, C2, and C3) were studied to improve housing conditions at chick height (0.1 m): C1 consists of increasing the distance between the HX, C1 consists of a 30° rotation of the HX, and C3 consists of positioning one HX on each end wall. Air velocity, air temperature and age of air were used as performance criteria. All configurations behaved and performed differently. The configuration with the best overall performance was C2. It showed a 45% improvement in age of air distribution and 24% in velocity distribution. Temperature distribution also improved, but it was not reflected in the coefficient of variation.