| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 647086 | Applied Thermal Engineering | 2012 | 11 Pages |
This paper examines the temperature profiles and flow characteristics of thin liquid films on a rotating surface by means of an Infrared (IR) thermal imaging camera. The challenges of obtaining accurate temperature measurements using thermographic techniques, in particular for thin liquid films of varying thicknesses, are outlined in this study. The temperature profiles obtained by the Infrared camera are compared to those estimated by a theoretical model of disc/film heat transfer. It is found that the theoretical model based on the disc average film heat transfer coefficient, h, estimated by the Nusselt theory overestimates the exit process liquid temperature measured by the thermal imaging camera by up to 67% for water as the process fluid. Better agreement is generally obtained when Therminol SP oil is used as the process fluid. The reasons for the deviation between the theoretical and measured temperature profiles are attributed to a variety of factors such as significantly overestimated h values which affect the theoretical model and incorrect emissivity values which affect the IR temperature measurements. In spite of these limitations in the quantitative analysis, the use of the thermal imaging camera provides an excellent platform for qualitative analysis of liquid film flow in highly accelerated centrifugal fields whereby the flow path and wave characteristics on a rotating disc are visually observed to change significantly as the disc speed, fluid flowrate and viscosity are varied. The effects of increased disc speed and reduced feed flowrate on improving the heat transfer efficiency are also clearly visible on the thermograms.
► We examined the temperature profiles and flow characteristics of thin liquid films. ► The work provides a visual insight into the heat transfer mechanism involved. ► Also an excellent platform for qualitative analysis of heating thin liquid films. ► The temperature profiles are compared to those estimated by a theoretical model.
