Design of a Thermal Measurement System with Vandal Protection Used for the Characterization of New Asphalt Pavements through Discriminated Dimensionless Analysis

Abstract

This work focuses on the protection of measurement sensors against accidents, vandalism, or theft and on the improvement of the data collected due to the interference produced by these protections. These sensors are part of a larger study, within the framework of a LIFE Heatland project, carried out in a Spanish city, Murcia, with the fundamental objective of minimizing the urban heat island effect using pavements with lower solar energy storage than traditional ones. The study presented here has been carried out through the implementation of aluminum tubes that protect the sensors installed in the street. Once the problem of sensor protection had been solved, the problem of thermal interference in the measurements due to overheating inside the tubes had to be overcome by means of discriminated dimensionless analysis techniques, focusing on heat transfer by convection of the air flow in the inner part of the tube, by finding the most suitable size and materials to complement the outer aluminum coating. In particular, the search for the critical radius of the tubes was essential since it allowed the insulator size to be optimized. Derived from the study carried out to avoid the overheating of the tube, a small part was covered with a dark material and holes were made to improve air circulation inside the tube, allowing adequate measurement results to be obtained. Finally, the results showed that the designed device was suitable for temperature measurement, since small variations were observed with respect to the control device.