Computational fluid dynamics (CFD) simulations of temperature distribution in traditional and automated dairy buildings under changing climate

Jiang, Li

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https://hdl.handle.net/2142/132796 Copy

Description

Title

Computational fluid dynamics (CFD) simulations of temperature distribution in traditional and automated dairy buildings under changing climate

Author(s)

Jiang, Li

Issue Date

2025-12-05

Director of Research (if dissertation) or Advisor (if thesis)

Akdeniz, Neslihan

Doctoral Committee Chair(s)

Akdeniz, Neslihan

Committee Member(s)

• Maghirang, Ronaldo
• Cardoso, Felipr
• de Oliveira, Luciano Alves

Department of Study

Engineering Administration

Discipline

Agricultural & Biological Engr

Degree Granting Institution

University of Illinois Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

CFD, dairy, heat stress, cold stress

Abstract

Changing weather patterns increase heat stress in modern dairy systems, driving higher ventilation demands and enhanced energy consumption. While free stall barns often rely on mechanical ventilation to ensure cow comfort, calf housing systems often lack an effective ventilation system, exposing young animals to severe environmental fluctuations. This study applied validated computational fluid dynamics (CFD) modeling to develop and evaluate energy-efficient ventilation and cooling strategies across three primary dairy housing systems: cross and tunnel-ventilated free-stall barns, dairy buildings equipped with automated milking systems (AMS), and outdoor calf hutches. In Chapter 3, CFD models were developed and validated for a full-scale cross-ventilated free stall barn supplemented with a ground-source heat pump (conductive/convective cooling). Supplemental cooling reduced the average airflow from 1.03 ± 0.34 to 0.71 ± 0.29 m/s, decreasing ventilation-related greenhouse gas emissions by 14.7–25.5% while maintaining a temperature increase across the barn of less than 2 °C. The average temperature at cow resting height decreased from 29.3 ± 0.80 °C to 28.1 ± 0.15 °C, reducing the areas exceeding 30 °C. Convective cooling reduced cow-level temperature by 1.2 °C, achieving the same temperature profile while reducing ventilation-related gas emissions by 17.0–27.7%. This study was published in Computers and Electronics in Agriculture (doi.org/10.1016/j.compag.2023.108480). In Chapter 4, CFD models were developed for a 252-cow tunnel-ventilated barn with ridge openings and circulation fans. Supplemental tube and floor cooling using a ground-source heat pump enabled a 30–65% reduction in fan operating air speed, decreasing stall-level air velocity from 1.40 ± 0.32 m/s (control) to 1.02 ± 0.41 m/s (floor cooling) and 0.69 ± 0.21 m/s (tube cooling) (p = 0.043). Despite reduced airflow, tube cooling achieved the lowest resting-height temperature (27.9 ± 0.21 °C) compared with the control (28.6 ± 0.36 °C) and floor cooling (28.3 ± 0.14 °C) (p = 0.021). For the entire barn during summer, electricity consumption was 40,590 kWh for the control, 30,683–36,181 kWh for floor cooling, and 15,879–21,378 kWh for tube cooling, showing substantial operational savings. This study was published in Smart Agricultural Technology (doi.org/10.1016/j.atech.2024.100576). In Chapter 5, CFD models were developed for two full-scale dairy barns with automated milking systems (AMS) to evaluate airflow restrictions associated with the AMS layout. Farm 1 was a tunnel-ventilated building with 218 cows and six milking robots, while Farm 2 was a cross-ventilated building with 424 cows and eight milking robots. In Farm 1, adding baffles reduced temperatures in the commitment pen by up to 4.25% and increased air velocity at cow resting height from 0.33 ± 0.20 to 0.77 ± 0.30 m s⁻¹ (p = 0.005). Replacing supply fans with an air inlet showed no improvement in airflow or temperature at either 0.5 m or 1.5 m heights. In Farm 2, removing AMS units along the side wall resulted in negligible differences in temperature (≤ 0.2 °C) and velocity (≤ 0.08 m s⁻¹), indicating that strategic AMS placement prevents airflow restriction. Although supply fans improved airflow at 1.5 m, velocity at 0.5 m remained low (0.98 ± 0.10 m s⁻¹), indicating limited benefit at the animal-occupied zone. This chapter was published in Computers and Electronics in Agriculture (doi.org/10.1016/j.compag.2025.110904). In Chapter 6, seasonal ventilation strategies for outdoor calf hutches were evaluated. CFD results were validated using reduced-scale experimental measurements. Under cold-weather conditions, adding a low airflow rate fan, achieving 4 air exchanges per hour (ACH), improved airflow uniformity and increased comprehensive climate index (CCI) values, indicating reduced cold stress. Under warm-weather conditions, increasing ventilation rates to 20 ACH reduced hutch temperature by 1.0–1.5 °C and decreased CCI by 10–15%, improving air exchange without overcooling. Under hot-weather conditions in summer, combining mechanical ventilation (40 ACH) with an aluminum reflective cover (ARC) produced the greatest benefit: internal temperature decreased by 3–5 °C, CCI/THI decreased by 6–16%, and air velocity increased by 120–140%. Overall, this dissertation suggested that CFD-based ventilation design can significantly improve heat and cold stress conditions in dairy and calf housing while reducing ventilation-related energy consumption (and associated greenhouse gas emissions). Future studies can include CFD simulations to assess the impact of the developed ventilation strategies on air quality and human health.

Graduation Semester

2025-12

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/132796

Copyright and License Information

Copyright 2025 Li Jiang

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