Generalised semi-empirical correlation for heat transfer in channels of plate heat exchanger

The analogy of heat and momentum transfer in turbulent flow modified for channels of Plate Heat Exchanger (PHE) is proposed. The effects of channel geometry, flow velocity and fluid properties on heat transfer are accounted in the resulting equation, which permits the calculation of film heat transfer coefficients using the generalized correlation for friction factor at the main corrugated field of the interplate channel. The results of calculations are compared with data from experimental study. The good accuracy of film heat transfer coefficients prediction is shown. In the case when the corrugations direction is parallel to the flow direction, the calculations results are quite close to the predicted by the Equation published in the literature for straight pipes. The Prandtl number influence on heat transfer is discussed and semi-empirical Equation for its evaluation is proposed. The comparison with experimental data available in the literature confirmed the accuracy of the heat transfer prediction. The proposed Equation is recommended to be used for optimization of PHEs channels geometry for different conditions in the process industries. It can be employed also for optimizing PHEs heat exchange networks and also to determine PHEs heat transfer area targets when process integration methodology is employed

The Modified Analogy of Heat and Momentum Transfers for Turbulent Flows in Channels of Plate Heat Exchangers

The modification of Von Karman analogy for turbulent flow in channels of Plate Heat Exchangers (PHEs) is proposed. The resulting equation enables to calculate film heat transfer coefficients in PHE channel on a data of hydraulic resistance of the channel main heat transfer field, accounting for the influence of channel geometry, flow velocity and fluid properties. The comparison with experimental data for water flow in models of PHE channels main corrugated fields is presented. It is shown the good accuracy of prediction for film heat transfer coefficients. In the limiting case, where corrugations are parallel to plate axis, the results of calculations by proposed Equation are in excellent agreement with Equation published for straight tubes and channels by Gnielinski in 1975. The analysis of the Prandtl number influence on heat transfer is performed. It explains the difference of Pr powers, which varies from 0.6 to 0.3 at correlations reported in different experimental papers on heat transfer. The proposed Equation can be used for modelling of PHEs heat transfer performance in a wide range of different applications in process industries

Mathematical modelling of the thermal and hydraulic behaviour of plate heat exchanger in the fouling conditions

The mathematical model of Plate Heat Exchanger (PHE) subjected to fouling is proposed. It is represented by the system of ordinary differential equations. The model is accounting for the distribution of process parameters along the PHE channel that allows predicting fouling development in time at different locations along the channel length. The development of the fouling deposit is accounted with the fouling model presented by the equation in dimensionless form. The relative influence of different terms is characterized by empirical coefficients which can be identified with the data of monitoring the PHE thermal and hydraulic performance. The model allows also the prediction of pressure drop variation in PHE with the development of fouling deposition layer and respective reduction in channels cross-section area. The application of the model and its accuracy is demonstrated with two case studies considering the monitoring of PHEs thermal and hydraulic performance in the industry at sugar factory and in District Heating system

Mathematical model of plate heat exchanger for utilisation of waste heat from condensable gaseous streams

The mathematical model of vapour condensation from the mixture with noncondensing gas in Plate Heat Exchanger (PHE) channels is presented. The model accounts for the change of process parameters along the heat transfer surface and local features of heat and mass transfer processes in PHEs channels with plates of different corrugations geometry. It consists of the system of ordinary differential equations with considerably nonlinear right parts. The software for its solution by finite difference method is developed. The validity of the model is confirmed by comparison with the experiment for steam-air mixture condensation in a PHE channel sample