Use of Optical Distributed Sensors for Spatial Temperature Measurements in HVAC&R Research

In this paper, we will summarize the principles of operation of a distributed temperature measurement systems using fiber optics and variable frequency laser and a coherent optical frequency domain reflectometer. We will then present experimental results characterizing temperature distribution along a water tube cooled due to natural convection. These measurements are confirmed with conventional thermocouple measurements co-located within the test section. Demonstration of the viability of this technique for HVAC&R related work opens up the possibility of understanding temperature distributions in air flow, temperature glides of zeotropic mixtures, coil tube surface measurement and other applications of interest to ASHRAE.