New approach to reduce analysis time of thermal response test: Active thermal response test using linear heat optical fiber sensor

This study introduces an innovative approach to reduce the analysis time of thermal response tests (TRTs) by employing an active TRT using a linear heat optical fiber sensor. Conventional TRTs require prolonged heating periods, making them time-consuming and resource-intensive. This research focuses on comparing conventional and active TRTs using computational fluid dynamics (CFD) simulations to validate the accuracy and efficiency of the proposed method. The active TRT method demonstrated the potential to shorten heating time while maintaining accurate thermal conductivity measurements. The findings reveal that the difference in thermal conductivity estimation between 15 and 48 h is only 0.03 W/(m∙K), indicating stable results with shorter testing times compared to the conventional TRT. Although stable results were obtained, uncertainties persist due to field conditions and measurement errors. To address this, an approximate equation was proposed for estimating thermal conductivity using the Relaxation Time of Temperature (RTT) method, which has been validated in previous studies through ground recovery temperatures. Future work will involve conducting field Active TRT to verify the accuracy of this method in reducing TRT duration.