Impact of water temperature and structural parameters on the hydraulic labyrinth-channel emitter performance

<p>The effects of water temperature and structural parameters of a labyrinth emitter on drip irrigation hydraulic performance were investigated. The inside structural parameters of the trapezoidal labyrinth emitter include path width (<em>W</em>) and length (<em>L</em>), trapezoidal unit numbers (<em>N</em>), height (<em>H</em>), and spacing (<em>S</em>). Laboratory experiments were conducted using five different types of labyrinth-channel emitters (three non-pressure compensating and two pressure-compensating emitters) commonly used for subsurface drip irrigation systems. The water temperature effect on the hydraulic characteristics at various operating pressures was recorded and a comparison was made to identify the most effective structural parameter on emitter performance. The pressure compensating emitter flow exponent (<em>x</em>) average was 0.014, while non-pressure compensating emitter’s values average was 0.456, indicating that the sensitivity of non-pressure compensating emitters to pressure variation is an obvious characteristic (<em>p</em>&lt;0.001) of this type of emitters. The effects of water temperature on emitter flow rate were insignificant (<em>p</em>&gt;0.05) at various operating pressures, where the flow rate index values for emitters were around one. The effects of water temperature on manufacturer’s coefficient of variation (<em>CV</em>) values for all emitters were insignificant (<em>p</em>&gt;0.05). The <em>CV</em> values of the non-pressure compensating emitters were lower than those of pressure compensating emitters. This is typical for most compensating models because they are manufactured with more elements than non-compensating emitters are. The results of regression analysis indicate that N and H are the essential factors (<em>p</em>&lt;0.001) to affect the hydraulic performance.