Encapsulation Method for Small Wireless Measurement Systems in High Temperature Environments
Abstract This paper presents an encapsulation concept that enables the construction of small wireless measurement systems that can operate in industrial environments with ambient temperatures of up to 1200°C. To maximize operational time and minimize size, a layer of thermal insulation is combined with water absorbed in a porous material in the core of the device. The simulated operating time before all of the frozen water at 0°C has transformed into steam at 100°C when the ambient temperature of the device was 1200°C is 21 minutes for a sphere with an outer radius of 4 cm. If the outer radius is increased to 10 cm the simulated operating time increases to 125 minutes. Measurements were performed to validate the design. When a sphere with a radius of 4 cm was subjected to an oven temperature of 1200°C the device held the core temperature at or below 101°C for a total of 25 minutes. The time to reach the boiling point of the water was 9 minutes. Thereafter, the temperature was held constant at 100 +/− 1°C for an additional 16 minutes whereafter a rapid rise in temperature took place once all water had evaporated.