Numerical investigation of boiling heat transfer in a quenching process of jet impingement considering solid temperature distribution
Boiling jet impingements are being widely used in various industries. Hence, a quenching jet impingement is simulated numerically. A solver code based on volume of fluid method was modified to analyze the effects of conjugation and mass transfer, and validated against an experimental study. Then, optimized cooling factor (OCF) was defined to involve temperature uniformity of the block and the cooling rate simultaneously. Subsequently, in laminar two-jet configurations, the effects of velocity inlet function, jet-to-surface and jet-to-jet spacing on standard temperature uniformity index (STUI) and OCF in a highly heated block were investigated. Heaviside function of time for the inlet velocity and periods of pulse between 0 and 0.2 were considered. Some remarkable results are achieved by the proposed configurations. In all cases with pulsating jets, improvements in STUI and OCF relative to pulse-free ones were observed; when V = 0.4 m s−1, OCF peaked at 2 in P = 0.06, which was almost eight times greater than OCF of pulse-free configuration (OCF = 0.24). As velocity decreased, the temperature uniformity improved; however, OCF showed the highest value at higher velocities occurring for lower periods of pulses. This happens because of more uniform temperature distribution in both plate sides and continual destroying film boiling layers generated on the surface. Also, in a jet-to-jet spacing of about one-third of the block length, for all plate lengths, optimal temperature uniformity with maximum OCF was obtained, due to formation of two stagnation points having the highest heat transfer rate by positioning in an ideal distance from each other.
Publisher URL: https://link.springer.com/article/10.1007/s10973-018-7900-9