Influence of the Operating Parameters of the Irrigation Heat Exchanger of a Desalinating Plant on the Efficiency of Its Operation

Abstract

A review of modern desalination technologies is conducted with an analysis of their advantages and disadvantages. The processes of heat and mass transfer in a spray heat exchanger are considered to determine the optimal operating parameters that ensure the minimum possible heat-exchange surface area. Mathematical modeling of heat and mass transfer processes in a spray heat exchanger has been performed. The influence of pressure in the irrigation chamber, the amount of salt deposits, and the flow rate of the heating coolant on the thermal and design characteristics of the desalination plant is analyzed. As a result of the numerical experiment, the dependence of the heat-transfer coefficient and heat-exchange surface area on the studied parameters was established. It was found that, with a decrease in pressure in the irrigation chamber and an increase in temperature pressure, the boiling process intensifies, which leads to an increase in the heat-transfer coefficient. This effect allows for significantly reducing the required surface area and dimensions of the irrigation heat exchanger. Based on the calculation studies, the optimal operating parameters of the heat and mass exchange apparatus were determined: the permissible thickness of the carbonate deposit layer (the content of CaCO₃ and MgCO₃ is over 50%, the thermal conductivity coefficient is approximately 1 W/(m² K)) should not exceed 0.1 mm; the pressure in the steam generation chamber is recommended to be maintained at 10 kPa; the heat-exchange surface area (required and possible) under the given design conditions (0.04 and 0.05 m internal and external pipe diameter, respectively; brass material, 29 independent circuits) is 5 m². With the specified parameters, the heat-transfer coefficient reaches 2500 W/(m² K) for the considered design of the device.