Effects of Temperature Changes on Emitter Discharge

Abstract

Working on the assumption that temperature affects water viscosity and emitter geometry, the writers have developed a dimensional analysis approach to the potential pressure-discharge relationship to estimate discharge sensitivity to temperature. Its accuracy was validated by experimental data. Flow rates were measured under controlled conditions on samples of six commercial emitters. Pressures of 100, 150, and 200 kPa were applied. Water temperature was modified alternating heating-cooling temperatures from 20 to 40°C. A factorial analysis of variance was performed on the observed data with the results presented as coefficients of variation. Emitter discharge was found to be insensitive to the alternation of heating-cooling temperatures. Discharge of the helical long-path emitter increased with increasing temperature at a maximum rate of 0.7%/°C. In contrast, it decreased in the vortex emitter at a maximum rate of 0.4%/°C. The dependence of orifice-type emitter discharge on temperature was less significant. Discharge of compensating emitters was affected as much by the operating time of each test as by the time elapsed between consecutive tests, and was not dependent on temperature change.