Monitoring and assessment of the thermomechanical performance of a concrete layer section of a thermocline tank

Abstract

In previous research, a hybrid steel-concrete tank section for Thermal Energy Storage (TES) was built and operated as a thermocline tank, indicating that the concrete section demonstrated its suitability and good thermal response under repetitive thermal fatigue cycles. In this investigation, the effect of the high temperature in the Calcium Aluminate Cement concrete (CAC) layer has been analysed in detail for the preconditioning, commissioning, during thermal fatigue operation and after the thermal cycling. For that purpose, 2 different types of instrumentation were used for the monitoring of thermal and mechanical response: conventional thermocouples and innovative Fiber Bragg Grating (FBG) sensors to measure both temperature and strain at high temperatures continuously. Besides, a protocol for monitoring the commissioning and operation of the concrete tank the electrical resistance (ER) of the CAC layer at high temperatures was measured to control the drying process. Moreover, some visual and physicochemical tests were carried out after the thermal performance to evaluate the effect of the heat across the concrete layer. The findings showed that the used of CAC concrete withstands the heating and cooling cycles between 200 and 500 °C and the appropriateness of using FBG sensors has been fully demonstrated. The measure of the ER is a useful tool for following the drying process and temperature cycling operation.