ASSESSMENT OF INNOVATIVE COOLING METHODS OF LACTATING DAIRY COWS USING COMPUTATIONAL FLUID DYNAMICS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: TERMINATED
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1006944
• Project No.: WIS01898
• Project Start Date: Sep 1, 2015
• Project End Date: May 31, 2018

Project Director
CHOI, CH.

Recipient Organization
UNIV OF WISCONSIN
21 N PARK ST STE 6401
MADISON,WI 53715-1218

Performing Department
Biological Systems Engineering

Non Technical Summary
Heat stress is a major concern for dairy farmers everywhere across the United States. During the summer months especially, the stress brought on by excessive heat can cause a lactating cow to produce less milk, and a prolonged period of high heat poses a serious risk to the animal's health. Because dairy cows typically crowd close together in holding pens while waiting to be milked, thereby increasing the ambient air temperature and relative humidity, they will often experience acute heat stress during the warmer months. A cow's core body temperature will also rise when she lies down, especially when she does so in an enclosed area such as a stall bedded with sand and compost. With the expectation of finding a viable way to mitigate the threat that heat stress poses to cows waiting in a holding pen or reclining in stalls, we propose to examine two different systems. That is, one that uses a positive pressure tubes to entrain fresh air from outside the holding pen and blow it through uniformly spaced impinging jets at a speed that will achieve an optimum convective cooling effect, and another that uses cooling heat exchangers placed on the floor upon which the animals recline. Both systems are designed to reduce core body temperature. In the course of our study, we will use computational fluid dynamics (CFD) to develop and test a series of models that are potentially capable of assessing (i) the effectiveness of an array of air jets aimed so as to impinge directly on targeted animals and (ii) a cooling mattress that transfers a cow's body heat away from the animal by means of thermal conduction.

Animal Health Component

0%

Research Effort Categories

Basic

10%

Applied

50%

Developmental

40%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
306	3410	2020	100%

Knowledge Area
306 - Environmental Stress in Animals;

Subject Of Investigation
3410 - Dairy cattle, live animal;

Field Of Science
2020 - Engineering;

Keywords

dairy cows

heat stress

climate change

mitigation

computational fluid dynamics

Goals / Objectives
The primary objectives of this study are (i) to evaluate and improve the design of the positive pressure tubes that will be used to entrain fresh air from outside the holding pen, and (ii) to examine the viability of the conductive cooling technology being used.

Project Methods
Poly-tube Project: The computational domain for the CFD model will be considered a rigid tube with the dimensions based on an exemplary poly-tube (although the actual polyethylene tube is pliant). The model considers the flow to be turbulent and utilizes the k-e model. The boundary conditions (as well as the computational domain) for the CFD model will be carefully established: walls on the floor, ceiling, tube walls, and tube ending; the pressure outlets on the left, right, and back boundaries; the pressure inlet at the front boundary; and the fan at the beginning of the tube. The wall boundary condition restricts the flow; the pressure outlet assumes that the flow leaves the domain at a specific pressure (1 atm); the pressure inlet assumes the flow enters the domain at a specific pressure (1 atm). Interestingly, the jets do not produce a symmetrical pattern despite the symmetry of the tube, a phenomenon primarily due to the effects of the fan's counter clock-wise swirl effect. The swirl effects drastically influence the patterns produced by the first few sets of jets while the patterns produced by the last 5-6 sets are consistent (as the back-pressure eliminated the swirl effects).This study will explore the ability of CFD to accurately model the flow characteristics at a 1.5 m height, which is the height of an average standing cow. Subsequently, the CFD results will be compared with the experiment data using an ultrasonic anemometer (including 3D velocity vectors) and a hot-wire anemometer (wind speed only). The outcomes should qualify the use of the CFD tools to conduct more complex modeling efforts aimed at predicting heat and mass transfer emanating from the realistically modeled cows and also the corresponding effectiveness of the optimally designed poly-tube system.Conductive Cooling:To simulate the effectiveness of conductive-cooling heat exchangers without the need for the typical bedding materials, the computational model will be partitioned into three sections. A thin rubber section will be at the top surface, a section made up of water channels will be filled with groundwater, and a pliant foam will placed between the water channels. The velocity and temperature of the water can be imposed at the inlets, and a static pressure at the outlet. A flow rate at the inlet will be set at approximately 1LPM as per our preliminary heat and fluid flow estimations. The water will run through the channels under undeveloped laminar conditions (due to the geometry) at a relatively low Reynolds number. The three inlets will supply water to the waterbed at an even rate and a constant temperature (i.e., 10 ºC). The temperature of the top surface of the rubber mat will be maintained at 35ºC, which will match a typical cow's skin temperature. The thermal conductivity of the rubber mat will remain at 0.14W/m-K.The present CFD study will examine the key design parameters including the size and shape of the grooves, groundwater flow rate, and the rubber thickness, to name a few. The study is designed to improve the total cooling capacity through design optimization prior to large-scale field experimentation. It should be noted that this conductive cooling design is not limited to cooling dairy cows; other livestock could also benefit.

Progress 09/01/15 to 05/31/18

Outputs
Target Audience:The target audiences are the producers, practitioners, and researchers. The outcomes have been disseminated to them through refereed journals, websites, and technical meetings. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project can provide training and professional development opportunities understanding in airflow within dairy buildings for graduate students and postdoctoral fellows. They presented conference papers at international agricultural engineering meetings and published outcomes in refereed journals. How have the results been disseminated to communities of interest?A couple of trade journals for producers featured a few articles based on our research activities and outcomes. The PI and the graduate students presented the technical contents at local dairy shows and international agricultural engineering conferences. Additionally, a series in-depth refereed journal articles were published based on computational and experimental studies. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? We created and validated computational fluid dynamics (CFD) models capable of replicating the flow distribution formed by a positive pressure polyethylene tube ventilation system. The outcomes were compared with experimental data sets. We confirmed that a polytube ventilation system could effectively cool dairy cows and also the CFD could help optimize the design and predict the system's operational efficiency. Results showed that the CFD model created a flow field similar to that found in the field experiments. Testing also revealed that the first few jets in both the model and the actual setup tended to discharge air at an angle that aligned with the axis of the tube. Additionally, the swirl effect created by the inlet fan proved to be a major influence affecting the distribution patterns of the air jets. To improve the model in this regard, a special boundary condition was added, after which the CFD model was able to replicate the damping effect created by backpressure generated at the end of the tube and a nearly identical air velocity at cow level. In addition, when the rubber deflector redirected the first jet to a more perpendicular angle, the jet no longer affected the downstream jets. The study thus was able to confirm that a polytube ventilation system could effectively cool dairy cows and that CFD can help optimize the design and predict the system's operational efficiency. We also discovered that attaching a deflector proved to be an effective way to redirect these jets without affecting the downstream jets, we can conclude that, if properly designed, installed, and managed, a polytube system will effectively provide extra cooling to individual members of a confined dairy herd. We also evaluated a conductive cooling mattress (CCM) system with respect to its effectiveness when used to cool dairy cows and facilitate resting behavior in a freestall barn. The present study considered the system's design, installation, and maintenance. A group of sixteen lactating Holstein cows are considered into two equal groups for the experimental study in an effort to measure their body core temperature. The control group is allowed access to 8 sand-bedded free stalls, while the 8 cows in the treatment group has access to an unbedded conductive cooling mattress. We found that the cooling system could help alleviate heat stress on reclining cows. Results indicated that the cooling mattress was associated with a significantly lower average core body temperature (CBT), compared with those in sand-bed free stalls (SAND), dependent on the ambient temperature humidity index (THI). At a temperature humidity index of 80, average lying-bout CBT was maintained 0.31 °C lower on CCM cows compared with SAND. Meanwhile, at a THI of 72 there were no significant effects between SAND and CCM cows. In summary, the cooling bed could help alleviate heat stress in cows under high THI environments.

Publications

• Type: Journal Articles Status: Published Year Published: 2018 Citation: Drewry JL, M Mondaca, BD Luck, CY Choi (2018). A Computational Fluid Dynamics Model of Biological Heat and Gas Generation in a Dairy Holding Area. Transactions of the ASABE, 61:2, 449-460.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Drewry JL, CY Choi, JM Powell, BD Luck (2018). Computational model of methane and ammonia emissions from dairy barns: development and validation, Computers and Electronics in Agriculture, 149, 80-89.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Drewry JL, CY Choi, JM Powell. Design and calibration of chambers for the measurement of housed dairy cow gaseous emissions. Transactions of ASABE, 60:4, 1291-1300.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Mondaca M, CY Choi. A computational fluid dynamics model of a perforated polyethylene tube ventilation system for dairy operations, Transactions of the ASABE, 59:6, 1585-1594.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Mondaca M, CY Choi. An evaluation of simplifying assumptions in dairy cow computational fluid dynamics models, Transactions of the ASABE, 59:6, 1575-1584.

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:The target audiences are the producers, practitioners, and researchers. The outcomes has been disseminated to them through refereed journals, websites, and technical meetings. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The PI uses CFD based research outcomes in his upper-level classes - BSE 464: Biological Systems Heat and Mass Transfer. How have the results been disseminated to communities of interest?We presented outcomes at the international and regional conferences for agricultural engineers and pratitionors. What do you plan to do during the next reporting period to accomplish the goals?We will complete our publications in refereed journals. Based on what we have accomplished, we will further develop CFD models for large scale barns in an effort to alleviate cows' heat stress.

Impacts
What was accomplished under these goals? We evaluated the viability of a conductive cooling system to cool cows resting in a freestall barn based on an original design concept. Using the outcomes of computational fluid dynamics (CFD) simulations, a conductive cooling mattress was designed, built and tested on an initial group of 16 lactating Holstein cows divided equally into treatment and control groups. The control group was allowed access to 8 sand-bedded freestalls, while the treatment group had access to 8 un-bedded conductive cooling mattresses. The conductive cooling system used groundwater, typically at 10-13 °C as the working fluid. Each cow's lying activity and vaginal temperature, as well as the temperature and humidity levels in the barn, and the flow rate and water temperature circulating through the conductive cooling system were monitored. Results indicated that the conductive cooling system was associated with a significantly lower average core body temperature, compared with sand-bedded freestalls, dependent on the ambient temperature humidity index. At a temperature humidity index of 80, average lying-bout core body temperature was maintained 0.31 °C lower on conductive cooling system cows compared with the cows on sand-bedded freestalls. In conclusion, the conductive cooling system could help alleviate heat stress in cows under high temperature and humidity environments.

Publications

• Type: Journal Articles Status: Accepted Year Published: 2018 Citation: Mondaca M, N. Cook, CY Choi, DESIGN AND EVALUATION OF A CONDUCTIVE COOLING SYSTEM FOR ADULT DAIRY CATTLE HOUSED IN FREESTALLS, Agrociencia
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Mondaca M, CY Choi An evaluation of simplifying assumptions in dairy cow computational fluid dynamics models, Transactions of the ASABE, 59:6, 1575-1584.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Mondaca M, CY Choi A computational fluid dynamics model of a perforated polyethylene tube ventilation system for dairy operations, Transactions of the ASABE, 59:6, 1585-1594.

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Producers, design engineers, and research engineers Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?We have produced two publications in journal articles. What do you plan to do during the next reporting period to accomplish the goals?We have designed, built and testedthe new conductive cooling systemin a freestall barn under naturally occurring ambient conditions. We plan to present the effectiveness of the system in terms of its ability to cool cows resting in a freestall barn.The report will include the system's design, installation procedure and maintenance, as this is the first conduction cooling mattress system installed in a free-stall barn with 16 cows.

Impacts
What was accomplished under these goals? A polytube system was designed and installed. Precise magnitude and direction measurements, as well as their spatial locations, were recorded. Results showed that the computational fluid dynamics model created a flow field similar to that found in the field experiments. Testing also revealed that the first few jets in both the model and the actual setup tended to discharge air at an angle that aligned with the axis of the tube and in consequence failed to strike their intended targets. Additionally, the swirl effect created by the inlet fan proved to be a major influence affecting the distribution patterns of the air jets. To improve the model in this regard, a special boundary condition was added, after which the computational model was able to replicate the damping effect created by backpressure generated at the end of the tube and a nearly identical air velocity at cow level. In addition, when the rubber deflector redirected the first jet to a more perpendicular angle, the jet no longer affected the downstream jets. The study thus was able to confirm that a polytube ventilation system could effectively cool dairy cows and that computational fluid dynamics can help optimize the design and predict the system's operational efficiency. An additional computational study sought to use computational fluid dynamics to create and evaluate different cow geometries. These geometries were compared on the basis of their relative ability to replicate the effects of various different cooling and ventilation systems in operation inside a dairy barn. While all realistic geometries predicted heat transfer with nearly the same degree of accuracy (all were within 10% of each other), the test showed that key localized differences must be taken into account when selecting a particular geometry. Testing also found evidence that an animal-occupied zone should be treated as porous media when evaluating the effects that the zone will have on the rest of the computational domain. Concurrent with the development of technologies and strategies for abating the heat buildup inside dairy barns, there is greater demand for an efficient and accurate way to test their performance. Computational modeling has improved to the point that it is now feasible to create realistic representations of animals to facilitate fluid dynamic modeling. Our studies clearly demonstrated that computational modeling can be a critical tool for design optimization for animal housing.

Publications

• Type: Journal Articles Status: Published Year Published: 2016 Citation: Mondaca M, CY Choi (2016) A computational fluid dynamics model of a perforated polyethylene tube ventilation system for dairy operations, Transactions of the ASABE, 59:6, 1585-1594.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Mondaca M, CY Choi (2016) An Evaluation of Simplifying Assumptions in Dairy Cow Computational Fluid Dynamics Models, Transactions of the ASABE, 59:6, 1575-1584.

Progress 09/01/15 to 09/30/15

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project will provide training and professional development opportunities with understanding airflow within dairy buildings. How have the results been disseminated to communities of interest?We have been preparing a few summary articles for trade journals based on our literature survey. Additionally, in-depth refereed journal articles will be submitted upon completion of the computational and experimental studies. What do you plan to do during the next reporting period to accomplish the goals?We will create and validate a computational fluid dynamics (CFD) model capable of replicating the flow distribution created by a positive pressure polyethylene tube ventilation system. The outcomes will be compared with experimental data sets. We intend to confirm that a polytube ventilation system can effectively cool dairy cows and has the CFD can help optimize the design and predict the system's operational efficiency. We will evaluate a conductive cooling mattress system with respect to its effectiveness when used to cool dairy cows and facilitate resting behavior in a freestall barn. The present study will consider the system's design, installation and maintenance. A group of sixteen lactating Holstein cows are considered into two equal groups for the experimental study in an effort to measure their body core temperature. The control group is allowed access to eight sand-bedded free stalls, while the eight cows in the treatment group have access to an unbedded conductive cooling mattress. We will investigate the evidence of how the cooling system can help alleviate heat stress on reclining cows.

Impacts
What was accomplished under these goals? In the reporting period of September, we conducted a series of preliminary computational simulations and field experiments. The outcomes will be summarized, presented and submitted for publications. The data sets are currently analyzed.

Publications