High salinity seawater boiling point elevation: Experimental verification

Abstract

Boiling point elevation (BPE) for high salinity solutions is a crucial parameter that significantly affects the overall thermal efficiency of desalination, water treatment, and many other industrial processing systems, especially when minimum or zero liquid discharge is a key requirement. This paper addresses the discrepancies among the empirical correlations reported in the literature that were commonly used to determine BPE for seawater solutions. An evaluation of these correlations developed for solutions with low salinity reveals that they cannot be applied to determine the BPE at high salinity (X > 140 g/kg). There are large discrepancies among the different correlations when used to determine the BPE for high salinity seawater. As a result of limited availability of experimental data of BPE for X > 140 g/kg and the need to eliminate the discrepancies, an experimental setup was built, which can produce reliable and repeatable BPE data for any solution salinity. Boiling points were obtained experimentally for seawater solutions with a wide range of salinity (X between 20 and 280g/kg) and brine solution temperature (tb between 20 and 80°C). The experimental results of BPEs for seawater are further compared with the experimental data and analytical results reported in the literature. The newly obtained experimental results show that the minimum and maximum BPE values for the brine solutions tested are 0.175 °C at tb = 20 °C and X = 20 g/kg, and 11.6 °C at tb = 80 °C and X = 280 g/kg, respectively. Furthermore, the measured BPE data for seawater salinity over 80 g/kg are fitted and presented using an appropriate fitting model. The new correlation can accurately predict the BPE for high salinity seawater brines and thus should be very helpful in the design of high-energy-efficient evaporation systems.