Influence of scale deposits on the temperature conditions in the channels of plate-type heat exchangers

Abstract

Introduction. At the present stage of development of the heat supply system, the transfer from shell-and-tube constructions to the plate version of heat exchange apparatus is observed. Their main advantages are compactness and efficiency.The main operational problem is the fouling of the inter-plate channels as a result of which the thermal efficiency decreases and operational costs increase. The aim of the work is to establish the dependence of fouling and individual hydraulic conditions in each channel on the temperature regime of a plate-type heat exchanger. Since this issue in the theory of heat exchange apparatuses is not well studied in and has significant assumptions, the diagnosis of fouling of channels is incorrect. Materials and methods. The theory of resistance characteristics of hydraulic systems is used to determine the hydrodynamic mode of plate-type heat exchange apparatus. The temperatures of heating and heated heat carriers at the outlet of each heat exchange channel are determined on the basis of the mass conservation law. This method made it possible to use the results of hydrodynamic calculation of resistance characteristics to calculate the temperature conditions of a plate heat exchange apparatus along the length of the plate pack, including the effect of scale deposits. The validity of the proposed methods was determined by comparing the Pearson’s and Student’s criteria with the results of computer modelling. Results. The dependence between final temperatures of the coolant at outlet of channels depending on the flow distribution of the coolant, taking into account channel impurity was found. The application of the theory of resistance characteristics to calculate the thermal-hydrodynamic mode of the plate heat exchanger and the proposed calculation of the thermal regime, including taking into account the factor of fouling, will improve the accuracy of pollution diagnosis and reduce operating losses. Conclusions. The conducted research confirms the influence of fouling of heat-exchange apparatuses and individual hydraulic conditions of inter-plate channels on the temperature regime. Results of research represent scientific and practical interest at studying and development of the intensified surfaces of heat exchange with the purpose of increase of power indicators of heat-exchange apparatuses, and also in the field of diagnostics of mode parameters of water-heating equipment in the period of its operation.