Optimized Vaporization in Liquid-Fed Microresistojets Using Pulsed Heating

A water-fed MEMS vaporizing liquid microthruster (VLM) has been designed and fabricated by CNR-IMM (Italy) in collaboration with the University of Salento (Italy) and with the support of KU Leuven (Belgium). Previous studies have demonstrated VLM functioning. The present work provides a preliminary experimental assessment of a pulsed heating system actively controlled by temperature using a PI-D logic and applied to the VLM. This performance assessment focuses on the power consumption evaluation in steady-state operation and dynamic response analysis of the VLM undergoing actively controlled pulsed heating using both manual and DD offline adaptive PI-D temperature controls. Concerning the steady-state operation, results have shown a promising enhancement to values above 0.9 using temperature-controlled pulsed heating, with a maximum of 94 % at a setpoint temperature of 160 °C. Concerning the dynamic response analysis, results demonstrated that operating with a single set of fixed PID parameters is not feasible: manual tuning is a trial-and-error approach that is very sensitive to the operator experience, the operating conditions, and the reference temperature profile. Furthermore, shorter rise and response times require a higher proportional gain, and the overshoot experienced when crossing the saturation temperature cannot be avoided. The data-driven adaptive controller solved these issues: the maximum settling time was reduced from about 59 s to less than 10 s, and the overshoot was not experienced thanks to the temporal modification of the PID parameters. © 2022 International Astronautical Federation, IAF. All rights reserved.