Experimental determination of the cooling performance of liquid nitrogen for machining conditions

Abstract This paper presents an experimental investigation of cryogenic cooling with liquid nitrogen. A thermal imaging camera is used to measure the temperature distribution of a pre-heated titanium alloy (Ti-6Al-4V) specimen interacting with a flow of liquid nitrogen. The main objective of this work is to determine the surface heat transfer in a robust way. A new method, the so-called inverse global integration method (IGIM), is introduced which allows the calculation of the heat transfer from a solid body to the cryogenic medium using all available pixel points of a thermogram. Reproducible and accurate results could be achieved by ensuring well-defined initial and boundary conditions during the execution of the experiment. The parameters with the highest impact on the heat transfer are the surface temperature, nozzle distance, as well as the working pressure in the nitrogen tank. The work is completed by performing curve fitting on the experimental results in order to compare the cooling performance and to simplify the technical application.