Entransy performance analysis of the sulfuric acid wastewater treatment process using a vacuum membrane distillation system

Industrial sulfuric acid wastewater treatment using vacuum membrane distillation (VMD) technology has attracted worldwide attention. However, high energy loss and low membrane flux seriously hinder the industrialization of VMD technology. This paper novelly introduced an entransy theory to improve the VMD system performance. Mathematical models were built and verified via an experimental setup. System performance was investigated through the experiment and simulation from entransy dissipation standpoint. Experimental results indicated that an excellent separation performance with a membrane flux of 1.8 kg·m−2·h−1 and condensate conductivity within 20 μS·cm−1 were obtained at feed concentration of 10 %, feed temperature of 353.0 K, feed velocity of 1.0 m·s−1and vacuum side pressure of 24 kPa. Moreover, a thermal efficiency of 57.8 % was obtained with an entransy dissipation resistance of 0.00012 K·W−1. Simulation results showed that decreasing feed concentration and vacuum side pressure or increasing feed temperature and feed velocity decrease entransy dissipation resistance and improve heat transfer capability. More importantly, the prediction model of entransy dissipation resistance was established by a multiple linear regression method, and influence degrees of operation parameters on entransy dissipation resistance were obtained by a single factor analysis method. These findings are beneficial to optimize the VMD system in the future.