Bidirectional temperature control with thermochemical reactions

Kurzfassung

Precise and reliable temperature control is crucial for many industrial processes and components. Common active temperature control systems require parasitic power while passive temperature control cannot be adjusted to different temperature set points and disturbances. A new approach is a temperature control based on a thermochemical thermal capacitor, which controls the temperature actively and does not use parasitic power, but potential energy to drive the process. In this study, such a thermal capacitor is introduced and investigated. The concept is based on a reversible thermochemical reaction which is characterized by a temperature pressure correlation, and thus enables the pressure as actuating variable. As exemplary material, LaNi5 has been used. First, a 0D-model of the metal hydride reactor was developed and experimentally validated to optimize a PID controller for the thermochemical system. Resulting experiments with the thermal capacitor and controller prove the active and bidirectional temperature control of the system for temperature disturbances of 1.5 K. Additionally, the 0D-model was extended with an inverted 0D-model functioning as controller to show the characteristics of such a thermal capacitor using generic sinusoidal temperature disturbances. The simulative results indicate two major technical features of the presented system: the set temperature can easily be adjusted during operation and the dynamics of the thermal capacitor can be adapted to follow disturbances with various frequencies and amplitudes. Besides that, the underlying model presented in this work can be used for the improvement of thermochemical batch reactors under transient load as well as to optimize controllers and connecting reactors for applications.