Measurement of Temperature Distribution Using Acoustic Reflector Array

We propose an ultrasonic measurement of temperature distribution. Using the system, we aim to measure temperature distribution to be used for a sophisticated air-conditioning system. The system consists of a loudspeaker (SP), a microphone (MIC) and an acoustic reflector array. Sound velocity is dependent on air temperature along the propagation path, and is measured from the time of flight (TOF) of sound. A measurement area is partitioned into a 1×3 grid. The sound velocities in each partitioned grid square were obtained by arranging the SP, MIC and three reflectors appropriately. We created a temperature gradient in a grid square of the measurement area using an electrical heat source to confirm that the system detects an area of heat concentration. The product of area length (m) and area temperature (°C) corresponds to the amount of heat (m·°C) in that area. The amount of heat measured by the system showed good agreement with the amount of heat estimated using thermocouples, which were installed as reference. The method has the advantages of noncontact sensing, a quicker response and a simpler composition, over conventional temperature measurement systems.