An analysis of different operating points during the evaporation of a subcooled feed in a wiped film evaporator (WFE) allows a conceptual segmental assessment, distinction and quantification of various wetting behaviors and heat transfer situations during the liquid film flow. In detail, single-phase heating, evaporation from a fully covered surface and evaporation from a partly covered surface may be distinguished. For each section the wetting situation is extracted. This knowledge is essential for operating wiped film evaporators within a suitable and appropriate range to prevent e.g. product damage. The experiments were conducted at a stainless steel and steam-heated wiped film evaporator with a spring-loaded, inclined comb wiper system and monoethylene glycole as evaporation fluid. Process pressure, wiper type and rotational velocity were kept constant. Variations of feed rate and driving temperature difference mark out the characteristic operating points. In case of sufficient wetting of the evaporation surface, overall heat transfer coefficients of 1800 W/(m²·K) are reached. By decreasing feed rate and assessing the achieved distillate rate minimum sump loads can be derived for a given driving temperature difference. This quantifies the position of film break-up leading to a partly covered heat transfer surface. Active heat transfer areas are extracted from the experimental data and quantified to get a more precise view on suitable process conditions of WFE and its principal operation.

在刮膜蒸发器（WFE）中过冷进料的蒸发过程中，通过对不同工作点的分析，可以对液膜流动期间各种润湿行为和传热情况进行概念上的分段评估，区分和量化。详细地，可以区分单相加热，从完全覆盖的表面蒸发和从部分覆盖的表面蒸发。对于每个部分，提取润湿情况。该知识对于在合适的范围内操作刮膜蒸发器至关重要，以防止例如产品损坏。实验是在不锈钢和蒸汽加热的刮膜蒸发器上进行的，该蒸发器具有弹簧加载的倾斜梳形刮水器系统和单乙二醇作为蒸发液。工艺压力 刮水器类型和转速保持恒定。进给速度和驱动温度差的变化表明了特征工作点。在充分润湿蒸发表面的情况下，总传热系数达到1800 W /（m²·K）。通过降低进料速率并评估所达到的馏出速率，可以得出给定驱动温差下的最低油底壳负荷。这量化了导致部分覆盖的传热表面的薄膜破裂的位置。从实验数据中提取有效的传热面积并进行量化，以更准确地了解WFE的合适工艺条件及其主要操作。在充分润湿蒸发表面的情况下，总传热系数达到1800 W /（m²·K）。通过降低进料速率并评估所达到的馏出速率，可以得出给定驱动温差下的最低油底壳负荷。这量化了导致部分覆盖的传热表面的薄膜破裂的位置。从实验数据中提取有效的传热面积并进行量化，以更准确地了解WFE的合适工艺条件及其主要操作。在充分润湿蒸发表面的情况下，总传热系数达到1800 W /（m²·K）。通过降低进料速率并评估所达到的馏出速率，可以得出给定驱动温度差下的最低油底壳负荷。这量化了导致部分覆盖的传热表面的薄膜破裂的位置。从实验数据中提取有效的传热面积并进行量化，以更准确地了解WFE的合适工艺条件及其主要操作。这量化了导致部分覆盖的传热表面的薄膜破裂的位置。从实验数据中提取有效的传热面积并进行量化，以更准确地了解WFE的合适工艺条件及其主要操作。这量化了导致部分覆盖的传热表面的薄膜破裂的位置。从实验数据中提取有效的传热面积并进行量化，以更准确地了解WFE的合适工艺条件及其主要操作。