Experimental investigation of the cryogenic LN2-cooling performance for an impinging jet configuration for different inflow conditions

This work focuses on the cryogenic impingement cooling performance depending on the given inflow conditions. An experimental setup is presented which allows a detailed observation of the time depen-dent temperature distribution in a solid body via a thermal imaging camera during the cooling process. The space-and time-dependent heat transport from the solid to the impinging fluid is calculated from the gained temperature data using the so-called inverse global integration method (IGIM). This method allows an accurate determination of the heat flux density without the necessity of a precise calculation of the sensible temperature gradients. An investigation of the LN2-impingement conditions such as mass flow rates and fluid density is conducted to bridge the gap between the inflow conditions and the result-ing heat fluxes. Moreover, a variation of the working pressure and the nozzle geometry is also performed to assess the main dependencies of the cooling performance. Thus, some important conclusions regarding the heat flux and its governing physical phenomena can be drawn. In order to simplify the application of the gathered information, the corresponding heat transfer coefficients are calculated as a function of the time dependent surface temperature and the set inflow conditions. It is shown that the usage of a constant value results in a high inaccuracy because the heat flux density and the heat transfer coefficient show no trivial correlation for arbitrary impingement conditions. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This work presents an experimental setup to study cryogenic impingement cooling performance under given inflow conditions, examining the relationship between heat flux and heat transfer coefficients. Important conclusions regarding heat flux and its governing physical phenomena are drawn.