Numerical investigation on effects of side curtain opening behavior on indoor climate of naturally ventilated dairy buildings

Qifeng Li,Weihong Ma,Luyu Ding,Ronghua Gao,Chuanxia Yao,Ligen Yu,Wengang Zheng

doi:10.25165/j.ijabe.20201305.5805

Abstract

The side-curtain is popular in cattle buildings to regulate indoor climates and ventilation rates by adjusting the opening ratio. It normally had three different adjusting strategies relate to the position of rollers, i.e. central roller (S1), top roller (S2) and bottom roller (S3), which result in different opening behaviors to generate the same opening ratio but different opening positions in the side wall for a full-curtain house. Numerical simulations were conducted using computational fluid dynamics (CFD) to investigate the effects of the eight potential opening behaviors of side curtains on the indoor climates and airflow rates in winter for a typical naturally ventilated dairy house in China when the opening ratio were 8.5% and 17%. Airflow patterns, wind chilled temperature (WCT) and age of air were analyzed in the animal occupied zone (AOZ) by taking reference planes. Openings at the very bottom of side walls had more efficient ventilation due to the younger air age, more effective air disturbing, more uniformly distributed indicators in AOZ. However, it will result in a lower WCT in AOZ although a lower ventilation rate was observed in this case. Openings on the very top of side wall would generate a better thermal comfort in AOZ but with very poor air quality and nonuniformly distributed airflows in the dairy house. S1 was not recommended to the practical application due to the poor indoor climate and the higher cost of the mechanical structure. Based on the comprehensive evaluations of the analytic hierarchy process, the most satisfaction opening positions were at the bottom of the side curtains and the optimized adjusting strategy is S2. Keywords: thermal comfort, age of air, ventilation rate, computational fluid dynamics, analytic hierarchy process DOI: 10.25165/j.ijabe.20201305.5805 Citation: Li Q F, Yao C X, Ding L Y, Yu L G, Ma W H, Gao R H, et al. Numerical investigation on effects of side curtain opening behavior on indoor climate of naturally ventilated dairy buildings. Int J Agric & Biol Eng, 2020; 13(5): 63–72.

Highlights

Natural ventilation with adjustable curtain sidewalls and the open ridge is popular in housing dairy and beef cattle, especially in China and the USA
3.1 Validation of computational fluid dynamics (CFD) model The performance of the CFD model was evaluated by comparing the simulation results with the field measurements of air velocity, air temperature in the summer case
For validation of the CFD simulation of air velocity, the measured and simulated horizontal air velocities were compared because the air velocity meter was placed perpendicular to the airflow to measure the dominant horizontal airflow

Summary

Introduction

Natural ventilation with adjustable curtain sidewalls and the open ridge is popular in housing dairy and beef cattle, especially in China and the USA. For a full-curtain cattle house, it only has a concrete wall around 30 cm above the ground and the sidewall curtain can be adjusted by three different strategies (Figure 1): (1) A central roller generates two openings on the top of the upper side curtain and at the bottom of the lower side curtain (S1, Figure 1a). (3) Two independently controlled curtains at the upper and lower side generate openings on the top of each curtain (S3, Figure 1c) These different adjustment strategies result in different opening behaviors to get the same opening size with different opening locations

Objectives

Methods

Results

Conclusion