Variable-rate drip irrigation emitter with weber number-based precision droplet control

Overview

This technology addresses a critical gap in precision agriculture: the lack of widely available, variable-rate drip irrigation solutions. While advances in big data and AI enable high-granularity prescriptions for farm management, the hardware to execute those prescriptions at the individual emitter level has been missing. This innovation delivers affordable, emitter-by-emitter control of water and chemical application, unlocking the full potential of data-driven irrigation management.

The core insight is that by manipulating the Weber Number of the emitter device, the pressure within the pipe has a vanishingly small impact on flow. Surface tension forces, combined with geometric features of the emitter, create water droplets of constant volume. These droplets are counted via a simple electronic switch, and micro-solenoids coupled with a printed circuit board form a feedback control system. This enables precise drip-level control at every emitter in a field, as well as active modulation of chemical application rates such as fertilizers admixed directly within the dripline.

Technical specifications

Key features:

• Pressure-independent droplet formation achieved through Weber Number manipulation, eliminating flow variability caused by pipe pressure fluctuations
• Geometric emitter design controls droplet size, enabling tunable output through physical modification of the emitter
• Simple electronic droplet counting via a low-cost switch for real-time flow verification
• Micro-solenoid and printed circuit board integration creating a closed-loop feedback control system at each emitter
• Electrical conductivity measurement of each droplet, allowing calibration to chemical concentration for precise fertigation and chemical application
• Pulsed chemical additive admixing capability within the dripline for variable-rate fertilizer delivery

How it works:

The emitter leverages surface tension forces and specific geometric parameters to produce droplets of consistent volume regardless of internal pipe pressure. A droplet counting switch registers each emitted drop, while micro-solenoids regulate flow based on feedback signals. When chemical additives are introduced, conductivity measurements of individual droplets provide real-time concentration data, enabling accurate titration and reporting of applied chemical amounts.

Technology readiness level

The technology is at an advanced prototype stage. Laboratory testing has confirmed that droplet size is independent of pressure and can be manipulated by varying emitter geometry. The system is patent pending. Field trials are scheduled for the 2021 growing season at a vineyard and an ornamental tree nursery, each employing a 12x8 randomized complete block design with fully automated control across multiple deficit irrigation levels. Dependent variables under measurement include water productivity and crop quality. Additional laboratory validation is planned to confirm the emitter's ability to admix pulsed chemical additives within the dripline and to record titrated chemical amounts via conductivity-based calibration.