Refrigeration experiments of gas wave rotor based on calibration-free WMS-TDLAS method

•A calibration-free WMS-TDLAS method for short path and low temperature is proposed.•The principle of spectroscopy pairs selection is proposed.•A WMS-TDLAS system is developed and validated by thermocouple and simulation.•Low temperature induced by expansion waves in oscillation channel is successfully measured.•The refrigeration efficiency of GWR is more accurately evaluated by true gas temperature. The refrigeration efficiency is mainly dependent on the low temperature generated by gas wave dynamics in oscillation channel. In this paper, a temperature rapid monitoring method for short light path based on the calibration-free wavelength modulation spectroscopy-tunable diode laser absorption spectroscopy (WMS-TDLAS) method is proposed. The selection of absorption wavelength, measurement procedure and data processing are specifically introduced. The wave dynamics and medium temperature under different pressure ratios and rotary speeds are studied, and the energy transfer efficiency of the gas wave refrigerator is evaluated. As the pressure ratio increases, the temperature in the cold zone behind the expansion wave gradually decreases to 257.6 K and the relative humidity of the cold zone inside the channel increases, which is caused by local condensation. At the same time, the expansion refrigeration efficiency is increasing from 27.3 % to 64.9 %. The increasing rotary speed of rotor also benefit to refrigeration efficiency from 45.8 % to 75.6 % as low temperature decreases to 252.1 K, which illustrates that rotary speed has more improvement effect on refrigeration efficiency than just higher-pressure ratio.