Design of a heat pipe thermostat and stability analysis of temperature field for a speed of sound apparatus

Abstract

Thermophysical properties of working fluids are the basis for thermodynamic cycle design and optimization. The speed of sound is an important thermodynamic property that can be accurately measured. An apparatus, based on the pulse-echo technique, was developed to measure the speed of sound in compressed fluid for temperatures from 313 K to 453 K with pressures up to 100 MPa. A heat pipe thermostat was designed to provide a stable and uniform temperature field for the speed of sound measurement. The temperature field in the thermostat was simulated by COMSOL Multiphysics software. The temperature stability and uniformity of the sample in the pressure vessel were estimated to be less than 3 mK and the overall uncertainty in the temperature measurement was estimated to be within 5 mK.