Numerical and experimental study on intermittent spray cooling for plate-fin heat exchanger

This study develops numerical models to analyze evaporative cooling and air cooling in an intermittent spray cooling system. The impact of heat load and film thickness on evaporation time and heat transfer enhancement is investigated. Results indicate that a thinner initial liquid film improves cooling performance due to quicker heat transfer and evaporation. The average cooling performance ratio between evaporative cooling and air cooling is evaluated for different spray intervals. Experimental findings demonstrate a 20 % to 40 % enhancement in cooling performance across varying intervals, with a spraying surface ratio of 0.45. Comparison between numerical and experimental results shows that with a fixed spray period of 5 s and intervals ranging from 25 s to 45 s, the numerical inaccuracy remains within 15%. The calculation of heat transfer performance considers the effective water utilization percentage. Shorter intervals lead to increased water loss as subsequent spray droplets wash out the liquid water on the fins. For instance, with a spraying interval of 5 s, water loss reaches 32.2%, whereas it is 20% with a 25 s interval. These findings underscore the reliability of the numerical model in capturing system behavior and validating heat transfer enhancements under different operational conditions.