Investigation of the residence time distribution in a plate heat exchanger with series and parallel arrangements using a non-ideal tracer detection technique

• Published in: Applied thermal engineering 2011-07, Vol.31 (10), p.1725-1733
• Main Authors: Gutierrez, Carola G.C.C., Dias, Eduardo F.T.S., Gut, Jorge A.W.
• Format: Article
• Language: English
• Subjects: Applied sciences; Computational fluid dynamics; Devices using thermal energy; Dispersions; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Flow distribution; Fluid flow; Heat exchanger; Heat exchangers (included heat transformers, condensers, cooling towers); Heat transfer; Hydrodynamics; Plate heat exchangers; Residence time distribution; Theoretical studies. Data and constants. Metering; Tracers; Turbulence; Turbulent flow
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2011.02.015

The objective was to study the flow pattern in a plate heat exchanger (PHE) through residence time distribution (RTD) experiments. The tested PHE had flat plates and it was part of a laboratory scale pasteurization unit. Series flow and parallel flow configurations were tested with a variable number of passes and channels per pass. Owing to the small scale of the equipment and the short residence times, it was necessary to take into account the influence of the tracer detection unit on the RTD data. Four theoretical RTD models were adjusted: combined, series combined, generalized convection and axial dispersion. The combined model provided the best fit and it was useful to quantify the active and dead space volumes of the PHE and their dependence on its configuration. Results suggest that the axial dispersion model would present good results for a larger number of passes because of the turbulence associated with the changes of pass. This type of study can be useful to compare the hydraulic performance of different plates or to provide data for the evaluation of heat-induced changes that occur in the processing of heat-sensitive products. [Display omitted] ► Active volume of exchanger was determined and correlated with pass arrangement. ► Combined PFR + CSTR model provided the best fit to RTD data. ► Numerical convolution used to correct signal distortion from tracer detection unit. ► Results useful to flow distribution diagnostics and hydrodynamics modeling.