A Novel State of Charge Sensor Concept for Thermochemical Heat Storage

A functional prototype of a state of charge sensor for a solid sorption thermochemical heat storage was developed. The sensor concept is based on detecting the relative change of permittivity when water vapour adsorbs on the surface of the sorptive material. This is done by measuring the capacitance of a capacitor where the sorptive material is utilized as dielectric. We were considering Zeolite and Silica gel in the experimental validation of the sensor concept. The experiments showed a strong correlation between the measured capacity and the weight of the material which indicates the saturation with water, both in the adsorption and in the desorption stage. Several consecutive experiments proved the repeatability of the measurements which subsequently could be used to identify a sensor calibration function in order to relate the capacitance with the state of charge.