Innovative photoacoustic instrument for fast and accurate detection and localization of R-134a leaks in refrigeration systems

Abstract

Refrigerant leaks are a common issue that can seriously impact both the performance of refrigeration systems and the environment. The need for reliable and sensitive leak detection has become increasingly critical due to regulatory bans on refrigerants with a high global warming potential. A new potential option for detecting possible leaks in refrigeration installations is the development of a highly sensitive photoacoustic (PA) instrument, which allows for more accurate, faster and easier detection of leakage points in refrigeration equipment than currently commercially available equipment. This article reports on the development of a highly sensitive photoacoustic instrument for the detection and localization of R-134a leaks to identify leaks at rates as low as 1.2 g/year in refrigeration systems. The developed system includes a quantum cascade laser that operates around 10.3 µm with a maximum output power of 84 mW. It features a stainless steel photoacoustic cell with two 40 mm resonator tubes, each with a 3.5 mm inner diameter. This setup ensures the accurate detection of R-134a refrigerant leaks by targeting specific absorption lines. The fast response time, wide dynamic concentration range, and high sensitivity of the PA instrument make it a promising tool for refrigerant leak detection. The paper also discusses spectral interference from other environmental and refrigerant gases, such as water vapor, carbon dioxide, ammonia, methane, propane, and R-32. A detailed finite element model has been developed and implemented in COMSOL Multiphysics 6.2. The simulation results matched the experimental data, validating the accuracy of the PA system.