Discontinuous Cleaning 2

The previous project “Discontinuous Cleaning” (483 ZGB) was able to show high potential of discontinuous – in particular intermittent – flow to increase the cleaning efficiency for swellable model soils on a laboratory scale. Furthermore, it could be shown that the waviness of the draining film is increases, which also increases the local heat transfer in theory. In fact, measurements of the heat transfer proof these theoretical considerations. The results, thus, support the assumption of a close correlation between heat and mass transfer in the matter of cleaning of non-immerged systems.

As the intermittend pulsing mode was found to be optimal in the previous project, the follow-up project “Discontinuous Cleaning 2” (18747 BG) will deal with the transfer of this cleaning mode and found parameters to an industrial scale (see Figure 1). This includes the increase of the test stand dimensions and the utilisation of rotatory jet heads as the largest field of application for liquid jets in cleaning processes. Scientific core of the follow-up project is the study of discontinuous jets in terms of the forces appearing at the jet impingement by location- and time-resolved stationary pressure measurement (see Figure 2), the exploration of the pulsation range and the influence of higher cleaning and wetting distances. The latter can induce jet breakup, which is why this effect on the cleaning behavior is going to be investigated in this project. For comparison there will be analogous tests with continuous jets. In addition, the link between cleaning performance and heat transfer is going to be subject of research as it was in the previous project. The goal is the development of a clear correlation, which could be used to minimise or fully replace expensive and time-consuming cleaning tests with contaminated surfaces as well as applying in-process-control by temperature measurements.

The main goal is to proof the applicability of discontinuous jets in industry scale and to demonstrate the expected improvement in efficiency. Besides, important decision making and construction tools will be developed, which include:

• a preliminary determination of the expected impact pressure
• predictions concerning the state of jet breakup at the point of impingement
• selection of cleaning systems based on the wetting and cleaning distance
• determination/validation of appropriate pulsation parameters
• establishment of a more simple method of estimating the cleaning results based on heat transfer processes

Thus, small and medium enterprises (SMEs) gain tools that allow a more time-efficient design of cleaning systems resulting in significant cost reduction during the design process. The SMEs are also stimulated to use intermittent flows leading to more efficient cleaning equipment by reduction of cleaning time and cleaning agent consumption, which creates new sales arguments.