Directional amine-based solvent extraction for simultaneous enhanced water recovery,salt separation and effective descaling from hypersaline brines

The feasibility of simultaneous water recovery,salt separation and effective descaling of hypersaline brine was investigated by diisopropylamine(DIPA)-based directional solvent extraction(DSE),using diluted/concentrated seawater with initial saline concentration range of 12–237 g/L at extraction temperatures of 5 and 15℃,respectively.The water recovery shows an obvious boundary at saline concentration of 115 g/L under dual effect of specific water extraction efficiency and extraction cycles.High Cl^(–) ion concentration in product water is in sharp contrast to the nearly complete removal of SO_(4)^(2–)and hardness ions,indicating that DIPA-based DSE process indeed achieved efficient separation and purification of Cl^(–) ion from hypersaline brines.Especially,the radical precipitation of Mg^(2+)and Ca^(2+)ions in form of Mg(OH)_(2)and CaCO_(3)demonstrates effective descaling potential,although it leads to more DIPA residues in dewatered raffinate than product water.Moreover,an exponential correlation between the Cl^(–) removal efficiency and specific water extraction efficiency further reveals the intrinsic relationship of water extraction process and transfer of Cl^(–) ion to the product water.Overall,the study provides a novel approach for integrating the water recovery and separation of Cl^(–) ion from ultra-high-salinity brines with radical precipitation of Mg^(2+)and Ca^(2+) ions in one step.

Performance improvement of a pulse tube cryocooler with a single compressor through cascade utilization of cold energy

The high-frequency pulse tube cryocooler(HPTC)has been attracting increasing and widespread attention in the field of cryogenic technology because of its compact structure,low vibration,and reliable operation.The gas-coupled HPTC,driven by a single compressor,is currently the simplest and most compact structure.For HPTCs operating below 20 K,in order to obtain the mW cooling capacity,hundreds or even thousands of watts of electrical power are consumed,where radiation heat leakage accounts for a large proportion of their cooling capacity.In this paper,based on SAGE10,a HPTC heat radiation calculation model was first established to study the effects of radiation heat leakage on apparent performance parameters(such as temperature and cooling capacity),and internal parameters(such as enthalpy flow and gas distribution)of the gas-coupled HPTC.An active thermal insulation method of cascade utilization of the cold energy of the system was proposed for the gas-coupled HPTC.Numerical simulations indicate that the reduction of external radiation heat leakage cannot only directly increase the net cooling power,but also decrease the internal gross losses and increase the mass and acoustic power in the lower-temperature section,which further enhances the refrigeration performance.The numerical calculation results were verified by experiments,and the test results showed that the no-load temperature of the developed cryocooler prototype decreased from 15.1 K to 6.4 K,and the relative Carnot efficiency at 15.5 K increased from 0.029%to 0.996%when substituting the proposed active method for the traditional passive method with multi-layer thermal insulation materials.