Numerical evaluation on spray cooling to mitigate heat stress in cattle using computational fluid dynamics

Ruimin Yang; Wenqi Zhang; Christopher Y. Choi; Li Rong; Guoqiang Zhang; Kai Liu; Xiaoshuai Wang

doi:10.1016/j.compag.2024.109775

Numerical evaluation on spray cooling to mitigate heat stress in cattle using computational fluid dynamics

Ruimin Yang, Wenqi Zhang, Christopher Y. Choi, Li Rong, Guoqiang Zhang, Kai Liu, Xiaoshuai Wang^*

^*Corresponding author for this work

Department of Civil and Architectural Engineering - Building Science

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

1 Citation (Scopus)

Abstract

Many dairy farms use the combined sprinkler-fan cooling system to mitigate the heat stress in dairy cows by enhancing evaporative heat transfer. Effectively controlling the system depends on key parameters such as the time period for water to completely evaporate (hereafter drying time), heat transfer rate, and the strategy for regulating spraying duration. Developing an effective control strategy can not only enhance cooling efficiency but also save water. The heat transfer rate and drying time are influenced by several determining parameters, such as the hair coat's initial water content, air temperature, relative humidity (RH), and air velocity. However, the correlation between drying time, heat transfer rate, and the aforementioned determining parameters has not been thoroughly analysed. Consequently, this study aimed to propose models that use computational fluid-dynamics (CFD) simulations to predict drying time and total heat flux, and then propose an improved spray cooling strategy. The simulation results indicated that the total heat flux (W m⁻²) released via evaporation and convection from the skin surface of a cow can be 162 % higher than the value of pure convection under conditions of air temperature in 30 °C, relative humidity of 70 %, air velocity of 2 m s⁻¹, with an initial water content in the hair coat of 0.07 kg m⁻². The size of the wetted skin surface area did not significantly affect the heat flux (W m⁻²) and drying time but a larger wetting area will increase the total heat transfer (W). The drying time increased with higher RH and initial water content but decreased with higher air velocity. The drying time initially decreased and then increased as the air temperature rose. The total heat flux increased as the air velocity and initial water content increased and decreased as air temperature and RH increased. The results indicated that the sprinklers should be opened before the total heat flux from the wetted area falls below the minimum requirements to ensure the cooling efficiency while saving the water consumption because an increase of 19 % in average heat loss from the wetted area was obtained when relative humidity was 70 %, air temperature was 40 °C, air velocity was 2.0 m s⁻¹, and initial water content was 0.05 kg m⁻².

Original language	English
Article number	109775
Journal	Computers and Electronics in Agriculture
Volume	229
ISSN	0168-1699
DOIs	https://doi.org/10.1016/j.compag.2024.109775
Publication status	Published - Feb 2025

Keywords

Dairy cow
Heat stress
Mass and heat transfer
Spraying strategy
Sprinkler-fan cooling system

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10.1016/j.compag.2024.109775

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@article{d77955783f5746bd9536e7df05f64c50,

title = "Numerical evaluation on spray cooling to mitigate heat stress in cattle using computational fluid dynamics",

abstract = "Many dairy farms use the combined sprinkler-fan cooling system to mitigate the heat stress in dairy cows by enhancing evaporative heat transfer. Effectively controlling the system depends on key parameters such as the time period for water to completely evaporate (hereafter drying time), heat transfer rate, and the strategy for regulating spraying duration. Developing an effective control strategy can not only enhance cooling efficiency but also save water. The heat transfer rate and drying time are influenced by several determining parameters, such as the hair coat's initial water content, air temperature, relative humidity (RH), and air velocity. However, the correlation between drying time, heat transfer rate, and the aforementioned determining parameters has not been thoroughly analysed. Consequently, this study aimed to propose models that use computational fluid-dynamics (CFD) simulations to predict drying time and total heat flux, and then propose an improved spray cooling strategy. The simulation results indicated that the total heat flux (W m−2) released via evaporation and convection from the skin surface of a cow can be 162 \% higher than the value of pure convection under conditions of air temperature in 30 °C, relative humidity of 70 \%, air velocity of 2 m s−1, with an initial water content in the hair coat of 0.07 kg m−2. The size of the wetted skin surface area did not significantly affect the heat flux (W m−2) and drying time but a larger wetting area will increase the total heat transfer (W). The drying time increased with higher RH and initial water content but decreased with higher air velocity. The drying time initially decreased and then increased as the air temperature rose. The total heat flux increased as the air velocity and initial water content increased and decreased as air temperature and RH increased. The results indicated that the sprinklers should be opened before the total heat flux from the wetted area falls below the minimum requirements to ensure the cooling efficiency while saving the water consumption because an increase of 19 \% in average heat loss from the wetted area was obtained when relative humidity was 70 \%, air temperature was 40 °C, air velocity was 2.0 m s−1, and initial water content was 0.05 kg m−2.",

keywords = "Dairy cow, Heat stress, Mass and heat transfer, Spraying strategy, Sprinkler-fan cooling system",

author = "Ruimin Yang and Wenqi Zhang and Choi, \{Christopher Y.\} and Li Rong and Guoqiang Zhang and Kai Liu and Xiaoshuai Wang",

note = "Publisher Copyright: {\textcopyright} 2024 Elsevier B.V.",

year = "2025",

month = feb,

doi = "10.1016/j.compag.2024.109775",

language = "English",

volume = "229",

journal = "Computers and Electronics in Agriculture",

issn = "0168-1699",

publisher = "Elsevier B.V.",

}

Numerical evaluation on spray cooling to mitigate heat stress in cattle using computational fluid dynamics. / Yang, Ruimin; Zhang, Wenqi; Choi, Christopher Y. et al.
In: Computers and Electronics in Agriculture, Vol. 229, 109775, 02.2025.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

TY - JOUR

T1 - Numerical evaluation on spray cooling to mitigate heat stress in cattle using computational fluid dynamics

AU - Yang, Ruimin

AU - Zhang, Wenqi

AU - Choi, Christopher Y.

AU - Rong, Li

AU - Zhang, Guoqiang

AU - Liu, Kai

AU - Wang, Xiaoshuai

PY - 2025/2

Y1 - 2025/2

N2 - Many dairy farms use the combined sprinkler-fan cooling system to mitigate the heat stress in dairy cows by enhancing evaporative heat transfer. Effectively controlling the system depends on key parameters such as the time period for water to completely evaporate (hereafter drying time), heat transfer rate, and the strategy for regulating spraying duration. Developing an effective control strategy can not only enhance cooling efficiency but also save water. The heat transfer rate and drying time are influenced by several determining parameters, such as the hair coat's initial water content, air temperature, relative humidity (RH), and air velocity. However, the correlation between drying time, heat transfer rate, and the aforementioned determining parameters has not been thoroughly analysed. Consequently, this study aimed to propose models that use computational fluid-dynamics (CFD) simulations to predict drying time and total heat flux, and then propose an improved spray cooling strategy. The simulation results indicated that the total heat flux (W m−2) released via evaporation and convection from the skin surface of a cow can be 162 % higher than the value of pure convection under conditions of air temperature in 30 °C, relative humidity of 70 %, air velocity of 2 m s−1, with an initial water content in the hair coat of 0.07 kg m−2. The size of the wetted skin surface area did not significantly affect the heat flux (W m−2) and drying time but a larger wetting area will increase the total heat transfer (W). The drying time increased with higher RH and initial water content but decreased with higher air velocity. The drying time initially decreased and then increased as the air temperature rose. The total heat flux increased as the air velocity and initial water content increased and decreased as air temperature and RH increased. The results indicated that the sprinklers should be opened before the total heat flux from the wetted area falls below the minimum requirements to ensure the cooling efficiency while saving the water consumption because an increase of 19 % in average heat loss from the wetted area was obtained when relative humidity was 70 %, air temperature was 40 °C, air velocity was 2.0 m s−1, and initial water content was 0.05 kg m−2.

AB - Many dairy farms use the combined sprinkler-fan cooling system to mitigate the heat stress in dairy cows by enhancing evaporative heat transfer. Effectively controlling the system depends on key parameters such as the time period for water to completely evaporate (hereafter drying time), heat transfer rate, and the strategy for regulating spraying duration. Developing an effective control strategy can not only enhance cooling efficiency but also save water. The heat transfer rate and drying time are influenced by several determining parameters, such as the hair coat's initial water content, air temperature, relative humidity (RH), and air velocity. However, the correlation between drying time, heat transfer rate, and the aforementioned determining parameters has not been thoroughly analysed. Consequently, this study aimed to propose models that use computational fluid-dynamics (CFD) simulations to predict drying time and total heat flux, and then propose an improved spray cooling strategy. The simulation results indicated that the total heat flux (W m−2) released via evaporation and convection from the skin surface of a cow can be 162 % higher than the value of pure convection under conditions of air temperature in 30 °C, relative humidity of 70 %, air velocity of 2 m s−1, with an initial water content in the hair coat of 0.07 kg m−2. The size of the wetted skin surface area did not significantly affect the heat flux (W m−2) and drying time but a larger wetting area will increase the total heat transfer (W). The drying time increased with higher RH and initial water content but decreased with higher air velocity. The drying time initially decreased and then increased as the air temperature rose. The total heat flux increased as the air velocity and initial water content increased and decreased as air temperature and RH increased. The results indicated that the sprinklers should be opened before the total heat flux from the wetted area falls below the minimum requirements to ensure the cooling efficiency while saving the water consumption because an increase of 19 % in average heat loss from the wetted area was obtained when relative humidity was 70 %, air temperature was 40 °C, air velocity was 2.0 m s−1, and initial water content was 0.05 kg m−2.

KW - Dairy cow

KW - Heat stress

KW - Mass and heat transfer

KW - Spraying strategy

KW - Sprinkler-fan cooling system

UR - https://www.scopus.com/pages/publications/85212320079

U2 - 10.1016/j.compag.2024.109775

DO - 10.1016/j.compag.2024.109775

M3 - Journal article

AN - SCOPUS:85212320079

SN - 0168-1699

VL - 229

JO - Computers and Electronics in Agriculture

JF - Computers and Electronics in Agriculture

M1 - 109775

ER -

Numerical evaluation on spray cooling to mitigate heat stress in cattle using computational fluid dynamics

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Keywords

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