Development of a System for Low Flow Control with a Proportional Solenoid Valve

This study presents the development and implementation of a precision faucet system capable of delivering water at a specified flow rate and temperature by mixing hot and cold water streams. The system utilises Proportional Solenoid Valves (PSVs) to control the mixing process. Initially, a thorough characterization of the PSVs was conducted to understand their behaviour. Based on this characterization, an algorithm was developed to calculate the appropriate Pulse Width Modulation (PWM) signals for both hot and cold water PSVs, determining the required flow rates for each line. However, to address the issue of non-linear behaviour of the valves, a Proportional- Integral (PI) controller was implemented. This controller generates corrected PWM signals by taking the inlet temperature and flow rate fluctuations and system non-linearities into consideration. The enhanced system demonstrates improved performance, achieving a flow rate tolerance of ±0.5 LPM and a temperature tolerance of ±2 degrees Celsius. This research contributes to the field of precision fluid control systems, offering insights into the challenges of working with non-linear valve characteristics and the effectiveness of feedback control in mitigating these issues. The developed system has potential applications in various industries requiring accurate temperature and flow control