Acoustic measurement of temperature distribution in a room using a small number of transducers

We propose a method for noncontact measurement of room temperature distribution using a small number of acoustic transducers. The sound propagation velocity is dependent on the air temperature; and it is acquired from the time of flight of sound. The mean temperature parallel to the sound probe is acquired using an acoustic delay line consisting of a pair of transducers. The measured object is a room of size 4,000 mm (D) x 4,200 mm (W) partitioned into a 3 x 3 grid, with 9 unit cells. By at-ranging a certain geometrical property of the sound propagation path, we can formulate an expression for the temperature distribution as a matrix function of the sound velocity. Twelve transducers are installed in contact with the four walls. We create a temperature gradient throughout the room using an electrical heat source. Experimental reconstruction results of the room temperature distribution were in agreement with the distributions estimated from the temperature profiles of the heat sources. This technique has the advantages of noncontact sensing, quicker response time and simpler calculation of room temperature distribution, in comparison with conventional temperature measurement systems.