A Novel Bio-Inspired Pressure Compensating Emitter for Low-Cost Drip Irrigation Systems

One of the major issues that prevent a large-scale dissemination of drip irrigation system is the requirement of high pumping pressure, which incurs a high cost of pumping and power systems. The high pressure is used to maintain the working condition of pressure-compensate emitters, which are installed at the outlets of drip irrigation system to compensate pressure loss and evenly distribute flows to each crop. A new architecture of the pressure-compensate emitter is proposed using a flexible tube enclosed in a pressurized chamber similar to the design of a medical instrument called "starling resistor." This design enables the external pressure of the tube to correlate with the driving pressure, such that a higher driving pressure leads to a higher external pressure and consequently collapses the tube. The desirable feature that the flow rate is independent of the upstream pressure variation (also called "flow limitation") can be achieved with this new design at a lower driving pressure. A series of experiments have been conducted to prove the feasibility of the concept. The lengths, wall thicknesses and inner diameters of the tube were varied to investigate the non-linear fluid-structure interaction. A theoretical model was built to predict the design performance, which was used to optimize the combination of the parameters to meet various design requirements. In addition to the low-power demand, the new architecture also allows a high flow rate and potentially is able to anti-clog compared to the traditional pressure-compensating emitters.