Drop breakup can occur inside the gap of a high-pressure homogenizer – New evidence from experimental breakup visualizations

High-pressure homogenizers are used extensively in food and beverage processing. For design and operation optimization, it is vital to understand where breakup takes place. Using an experimental high-speed camera setup on a scaled model, this contribution shows that breakup events can occur inside of the gap of a homogenizer valve. This contrasts with many previous studies which only observe breakup downstream of the gap. Results show that gap breakup occurs at a substantially lower rate than outlet chamber breakup. Comparisons with computational fluid dynamics suggest that a necessary (but not sufficient) condition for gap breakup, is that the drop passes into the high-shear region close to the separation zone at the seat wall. Implications for food emulsification are discussed.