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Drip Irrigation: Designing a Subsurface Inline emitter and Mechanical Soil Moisture Sensor/Actuator

Project Category: Mechanical

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About our project

The project focus is on drip irrigation. Impediments in the implementation of drip irrigation systems were reviewed and discussed with individuals in the relevant industry and then analyzed. Issues of overwatering (water conservation) and clogging of drip irrigation emitters (the components which transmit water and irrigate the crop) were chosen to be examined. Some areas of interest were the lack of affordable and practical soil moisture sensing devices, and the internal labyrinth designs of the drip irrigation emitters, respectively. 

The project scope entailed the design of a new emitter composing an anti-clogging and pressure compensating labyrinth design. CAD software was utilized to model the emitter design, while labyrinth geometries were analyzed in CFD in order to identify improvements.

Also, a mechanical soil moisture sensing system was developed (which does not require aid of any electronic components) to react to the relative soil moisture in the crop system, and stop flow proceeding from the emitter when the moisture sensor delineates that overwatering is occurring. To restrict the flow of the emitter, a hydromorphic material (a material that expands when exposed to water) was analyzed and implemented within the mechanism.

Meet our team members

Saad Warraich

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I am a fourth year Mechanical Engineering student with interests in Materials and Robotics. I worked on the material analysis and mechanism design of the project. In my spare time I enjoy boxing, working out, and watching movies.

Paul Jifon

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I am a final year Mechanical Engineering student with interests in Turbomachinery and Aerodynamics. For this project, I am responsible for the conceptual design and CFD simulations. In my free-time, I practice dancing, fitness activities and basketball.

Ricardo Parra

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I am a final year Mechanical Engineering student. My areas of interest are fluid dynamics in combination with numerical methods. For the project, I was responsible for labyrinth design and CFD simulations. In my free time, I train swimming, volunteer, read books and watch videos.

Kern Jones

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I am a fourth year Mechanical Engineering student with good mechanical aptitude and communication skills. I focused on the physical testing and design verification for our project. In my spare time I enjoy backcountry skiing and mountain biking. 

Atharv Ambhorkar

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I am a final year Mechanical Engineering student with an interest in robotics, manufacturing and product development. I worked on the design and manufacturing of the project. In my spare time I like to 3D print and bike.

Details about our design

What is drip irrigation?

An efficient form of crop irrigation that allows a small quantity of water (droplets) to slowly irrigate crops with a network of tubes. The system functions by utilizing devices inside and outside of tubing with outlet points (emitters) to water every crop. Since water is pumped through the tubing (at varying pressures), the emitters work to reduce the water pressure, allowing water to be emitted uniformly, conserving water usage.

Figure 1: Layout of Drip Irrigation [1]

What is the problem?

There are two main issues in drip irrigation systems:

  • Running water usually contain particles that over time accumulate on emitter walls which leads to reduced flow or clogging, this usually happens inside the emitter’s labyrinth which is the region where the pressure drops due to energy dissipation caused by friction.

Figure 2: Final Labyrinth Design

  • As the emitter outlet hole is always open, the plant is watered even after it has received sufficient amounts of water and leads to overwatering. Additionally, the distance between the pump and the last emitters along with differences in elevation throughout the tubes leads to an uneven distribution of water between the emitters. If the farmer decides to close the system which is usually subdivided into various parts, it would also result in time cost.
How our design addresses practical issues with Drip Irrigation?
  • The designed emitter may reduce the effects of clogging by implementing a geometry that is spatially efficient and creates enough turbulence to drop pressure, this was quantified using a turbulence coefficient, K.
  • The mechanical sensor design reduces the effects of overwatering by implementing a hydromorphic material that senses water and blocks the outlet hole after a specific time interval (4 hours in our case).
What makes our design innovative?

Emitter: Designed and analyzed an emitter labyrinth inspired from a fish ladder design which enhances turbulence.

Figure 3: Fish Ladder [2]

Sensor: Designed a purely mechanical soil moisture sensor that actuates a mechanism to block the outlet flow of the emitter by using the expansion of a hydromorphic material after it senses a certain amount of soil moisture,  specific to a crop, without the need for any electrical components.

What makes our design solution effective?

Figure 4: Integrated Final Design

The designed emitter labyrinth solution has potential to reduce clogging while maintaining an efficient pressure drop which allows for a better filtration system.

The designed mechanical soil moisture sensor allows the detection and prevention of overwatering for any specific crop and type of soil it is utilized for while also evening out the distribution of water inside the tube network.

How we validated our design solution?

Two part experiment conducted on an integrated emitter-sensor prototype.

  1. Comparing the flow rate of an existing emitter and prototype emitter while inspecting the functionality of the sensor.
  2. Compare the time taken by the two emitters to clog by intentionally mixing particles into the water. 
Feasibility of our design solution
  • The designed emitter will require the same methods of production, materials, and cost relative to drip irrigation emitters currently available around the globe.
  • The mechanical soil moisture sensor would require an external casing which can be easily added during the manufacturing process.

Partners and Mentors

We would like to thank Dr. Simon Li and Danny Wong for their support and encouragement. We would also like to thank Dr. Michelle Konschu and Murray MacKinnon for sharing their knowledge and experience about farming and drip irrigation. We would like to thank Southern irrigation for providing an emitter and Multiurethanes for the Hydrotite material. Lastly, we would like to thank Dr. Keekyoung Kim and Hitendra Kumar for letting us use the SLA printer to manufacture our prototype.

Our Photo Gallery

References

[1] Fruit, K., & *, N., First Fruits Landscaping, 6 benefits of drip irrigation, 14-July-2020,  Available: https://firstfruitslandscaping.com/landscaping/benefits-drip-irrigation/ , [Accessed: 07-Apr-2021].

[2]  “Fish Ladder,” Engineering and Architecture, 22-Apr-2020. [Online]. Available: https://engineeringandarchitecture.com/fish-ladder/ .  [Accessed: 07-Apr-2021].

Software used: MATLAB, ANSYS Fluent, SolidWorks, VEGAS PRO 18, Blender and Motion5.