Dynamic temperature measurements in stirling cycle machines using two-thermocouple technique

The dynamic temperature fluctuations in Stirling machines are very important and any documentation of such measurements would contribute to their design optimizations and improvement of their performance prediction codes. However, to date, there have been only a few reports of such dynamic temperature measurements. In this study, the two-thermocouple technique is utilized in order to measure temperature fluctuation in a Stirling cycle machine. First, numerical simulations were conducted to evaluate this technique. The results showed that this technique has potentials to estimate time constants of the thermocouples and to give accurate compensated temperature fluctuation at the frequency range of Stirling engine operation. Secondly, dynamic temperature measurements have been conducted in the CSU-SLRE (Cleveland State University - Stirling Laboratory Research Engine). The effectiveness of this measurement technique was confirmed by using various pairs of thermocouples having different diameters under the simulated operational conditions of the Stirling cycle machines. The paper describes the experimental results and the limitations of the two-thermocouple probe technique in the Stirling cycle machines.