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This paper introduces a new optimization model for the single and multiple-effect evaporation (SEE/MEE) systems design, including vapor recompression cycle and thermal integration. The SEE/MEE model is specially developed for shale gas flowback water desalination. A superstructure is proposed to solve the problem, comprising several evaporation effects coupled with intermediate flashing tanks that are used to enhance thermal integration by recovering condensate vapor. Multistage equipment with intercooling is used to compress the vapor formed by flashing and evaporation. The compression cycle is driven by electricity to operate on the vapor originating from the SEE/MEE system, providing all the energy needed in the process. The mathematical model is formulated as a nonlinear programming (NLP) problem optimized under GAMS software by minimizing the total annualized cost. The SEE/MEE system application for zero liquid discharge (ZLD) is investigated by allowing brine salinity discharge near to salt saturation conditions. Additionally, sensitivity analysis is carried out to evaluate the optimal process configuration and performance under distinct feed water salinity conditions. The results highlight the potential of the proposed model to cost-effectively optimize SEE/MEE systems by producing fresh water and reducing brine discharges and associated environmental impacts. ; This project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under grant agreement No. 640979. The financial support provided by the National Council for Scientific and Technological Development of Brazil (CNPq), under process No. 233953/2014-0 is also gratefully acknowledged.

Shale gas has recently emerged as a promising energy source to face the increasing global demand. This paper introduces a new rigorous optimization model for the simultaneous synthesis of single and multiple-effect evaporation (SEE/MEE) systems, considering mechanical vapor recompression (MVR) and energy recovery. The proposed model has been especially developed for the desalination of high-salinity produced water from shale gas hydraulic fracturing ("fracking"). Its main objective is to enhance the system energy efficiency through the reduction of brine discharges. Therefore, the outflow brine salinity should be near to salt saturation conditions to achieve zero liquid discharge (ZLD). The multiple-effect superstructure is comprised by several effects of horizontal-tube falling film evaporation. Due to the inclusion of the electric-driven mechanical compressor, no other external energy source is needed in the SEE/MEE system. A more accurate process design is attained through the calculation of the overall heat transfer coefficients in function of the individual coefficients for the falling boiling film and vapor condensation. Additionally, the SEE/MEE-MVR model allows the estimation of the major geometrical characteristics of the evaporation system. The non-linear programming (NLP)-based model is optimized using the CONOPT solver under GAMS by the minimization of the process total annualized cost. Thermal analysis is carried out to evaluate the effects of the feed salinity and geometrical parameters on system heat transfer performance. The results highlight the ability of the developed model to rigorously design SEE/MEE-MVR systems by improving their cost-effectively and reaching ZLD conditions. ; This project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under grant agreement No. 640979. The authors also acknowledge financial support from the National Council for Scientific and Technological Development of Brazil (CNPq), under process No. 233953/2014-0.

This study is on the effect of salinity on evaporation from water bodies and probable influence on the water cycle. Five different salts were used in this study, different concentrations of Magnesium Sulphate, Sodium Hydroxide, Sodium Chloride, Ammonium Chloride and Potassium Nitrate solutions in the neighbourhood of 0.04, 0.08, 0.12, 0.16, 0.20 and 0.24 g/cm3 were prepared by dissolving 20, 40, 60, 80, 100 and 120 g weights of these salts in 500 cm3 of distilled water. The first evaporation can contained only 500 cm3 of distilled water and served as the control experiment. The solutions were introduced in evaporation cans each of capacity 700 cm3, stored under room temperature and evaporation allowed to take place. Evaporation from the cans were measured at 24 hours intervals for a period of 14 days. Results showed that in all salts, as salinity increases, evaporation is reduced. On the 10th day, evaporation retardation factors for Magnesium Sulphate, Sodium Hydroxide, Sodium Chloride, Ammonium Chloride and Potassium Nitrate were found to be 0.800, 0.490, 0.712, 0.820 and 0.822 respectively. Ratios of evaporation retardation factors were 1:1.6327 for Sodium hydroxide : Magnesium Sulphate; 1:1.4531 for Sodium Hydroxide : Sodium Chloride; 1:1.6735 for Sodium Hydroxide : Magnesium Sulphate; 1:1.4531 for Sodium Hydroxide: Sodium Chloride; 1:1.6327 for Sodium Hydroxide : Ammonium Chloride and 1:1.6776 for Sodium Hydroxide : Potassium Nitrate solutions. Highest evaporation took place in Potassium Nitrate solution at the ultimate concentration of 0.24 g/cm3, this was followed by Ammonium Chloride, Magnesium Sulphate, Sodium Chloride and Sodium Hydroxide. These salinity effects will impact on the outflow parameter in the water cycle with consequent reduction in evaporation which reduces precipitation, hence the formation of rain in the cloud would be inhibited and ultimately lead to climate change.

ABSTRACTFor many years, the standard method for estimating rates of evaporation from open water has been to apply empirical factors to potential evaporation data. However, significant errors can occur through the use of these factors, essentially due to the limitations of the measurements upon which they are based. New empirical factors are presented here for use with the Meteorological Office Rainfall and Evaporation Calculation System for grass potential evaporation and Penman potential evaporation. However, uncertainty in the estimated evaporation rates remains at least 5–12 mm per month.