Thermal characteristics of flashing spray of volatile R134A cryogens

This paper presents an experimental investigation of thermal behavior of flashing spray of refrigerant R134a. A high-speed camera up to 1000 frames per second is used to visualize the shape and size of the spray and an infrared thermograph is employed to visualize the temperature variation of the spray. The temperature field within the spray is measured by a small thermocouple whose position can be systematically adjusted to cover the entire spray. The high-speed photo images of sprays revealed an explosive spray formation near the exit of nozzle and the formation of a hot core region near the nozzle. The measurements found that the hot core region was quickly dissipated, followed by a cold region of almost uniform temperature that is far below the saturation point of R134a at the ambient pressure. The measurements provide detailed quantitative information of both radial and axial temperature distributions of droplets within the spray. These results provide insight into the formation of flashing spray of volatile liquids.