A multiprobe miniature thermistor system for the measurement of temperature profiles

Water is important for life and development. About 1.8 billion people will be living in absolute water scarcity by 2025.Non availability of safe drinkable water is the major source of diseases in the different regions of the world especially remote rural and coastal areas. About 97% of water on earth is comprised of seawater. Desalination of saline water is a prominent approach to handle the problem of water scarcity. Conventional desalination technologies cause economic and environmental problems due to their dependency upon fossil fuels. Solar flash desalination is one of the best desalination techniques in the developing stages. Solar energy, passive vacuum and recovery of latent heat of condensation make this system a sustainable option for desalination. In this paper, economic analysis of the solar thermal desalination system of saline water is presented. The unit cost of desalinated water is found to be US$ 0.0147 per litre. The energy and emission payback (EEP) period for vacuum chamber and solar collector has also been presented. The energy payback period of solar collector and vacuum chamber are found to be 1.3 years and 1.5 years respectively. The emission payback period of solar collector and vacuum chamber are found to be 1.8 years and 2.1 years respectively.

A problem on stability of the viscous heat-conducting liquid flow in the vertical channel at given heat flux on the permeable solid walls is studied. The two-dimensional flow is described by an exact invariant solution of the microconvection equations. The investigation of the exact solution allows one to find out the extent of influence of the thermal load, gravity and the system geometry on the flow structure. Stability of the solution is investigated in the framework of the linear theory. The spectrum of the spatial characteristic perturbations is analyzed in the space of problem parameters. Typical forms of the hydrodynamic and thermal disturbances are presented and dependence of characteristics of the arising structures on the thermal load and gravity is established. Convective cells, hydrothermal rolls and polygonal structures can appear in the channel. By weak gravity the hydrothermal rolls are not formed. Changing heat flux and disturbance wave length lead to deformation of the cells and complication of the spatial form of the structures.

Understanding spatiotemporal patterns of fish density and their environmental drivers is critical for managing river-lake ecosystems, yet dynamic interactions in heterogeneous habitats remain poorly quantified. This study combined hydroacoustic surveys, spatial autocorrelation analysis (Moran's I), and generalized additive models (GAMs) to investigate seasonal and spatial fish distribution, aggregation characteristics, and regulatory mechanisms in China's Zhelin Reservoir. The results reveal pronounced seasonal fluctuations, with summer fish density peaking at 13.70 ± 0.91 ind./1000 m3 and declining to 1.95 ± 0.13 ind./1000 m3 in winter. Spatial heterogeneity was evident, with the Xiuhe region sustaining the highest density (15.69 ± 1.09 ind./1000 m3) and persistent hotspots in upstream bays. Transient high-density clusters (90-99% confidence) near the Zhelin Dam during summer suggested thermal or hydrodynamic disturbances. GAM analysis (R2adj = 0.712, 78.5% deviance explained) identified seasonal transitions (12.26% variance), water depth (16.54%), conductivity (13.75%), and dissolved oxygen (13.29%) as dominant drivers, with nonlinear responses to depth and bimodal patterns for conductivity/oxygen. These findings demonstrate that hydrological seasonality and habitat heterogeneity jointly govern fish aggregation, underscoring the ecological priority of Xiuhe and upstream bays as core habitats. This study provides a mechanistic framework for guiding reservoir management, including targeted conservation, dam operation adjustments to mitigate hydrodynamic impacts, and integrated strategies for balancing hydrological and ecological needs in similar ecosystems.

Natural convection was considered over a circular heated plate in the framework of experimental studies. The main attention is paid to the initial stage of axisymmetric convective flow development. It was observed in a cavity with distilled water. The cavity edge exceeds the diameter of the heat source. Images of the fluid flow structure were obtained at the stage of thermal boundary layer deformation and evolution of starting plume by using a laser knife and light- scattering particles suspended in a fluid. Evolution of streamlines in an observation plane was also studied by injection of fluorophore based on the Rhodamine-B dyestuff into the fluid. Based on the results of observations we can indirectly regard the interaction of thermal and hydrodynamic disturbances during spreading a starting plume in the cavity. Nevertheless, used visualization methods can help to describe the flow development while forming a starting plume.

Analysis of the characteristic perturbations spectrum of the exact invariant solution of the microconvection equations

Porous functional materials with excellent solar-thermal and electro-thermal properties for desalination of saline water

Desalination of saline water by nanochannel arrays through manipulation of electrical double layer

Fouling, performance and cost analysis of membrane-based water desalination technologies: A critical review

Irradiation of insulation and sheath for large wire and cable

Direct aeroacoustic simulation, which simulates acoustic radiation associated with unsteady fluid flows, involves capturing waves in both aerodynamic and acoustic scales. The presence of a thermal field further complicates this simulation. There are few analytical thermal-acoustic problems that could serve as benchmark to validate computational aeroacoustics schemes. This paper attempts to seek a theoretical solution of a simple problem involving scattering of acoustic plane waves by a localized zero-heat-gain/loss thermal disturbance and use it as a benchmark to verify the validity and extent of a numerical gas-kinetic scheme based on the modeled Boltzmann equation for the study of aeroacoustics resulting from thermal-flow/acoustic interaction. Two limiting cases with different acoustic wavelengths are attempted. Theoretical solutions are established for both cases, with the center of an axisymmetric thermal disturbance located at the origin of the physical domain. The incident acoustic wave has a dimensionless amplitude given by 1 x 10 -4 and is propagated from left to right of the coordinate system. The simulation of the gas-kinetic scheme is carried out using the same computational setting as for the theoretical solutions. Riemann invariants are stipulated at the open boundaries. Numerical results are compared with the theoretical solutions and good agreement is obtained for the short-wavelength case only. The discrepancy for the long-wavelength case could be partially attributed to the inappropriateness of the Riemann invariants for oblique waves at the boundaries.

Forward osmosis is an emerging membrane technology in water desalination. In this study, desalination of saline water via forward osmosis was investigated using a new magnetic osmotic agent. For this purpose, Fe3O4 nanoparticles covalently functionalised with tri-sodium citrate was synthesised and characterised. The structural examinations revealed that the sodium citrate had been immobilised onto the magnetic nanoparticles. The highest water flux was obtained 17.1 L M−2 h (LMH) per 80 g L−1 osmotic agent solution against deionised water, while the ratio of salt flux to water flux was very low (0.088 g L−1). The osmotic solution was evaluated for saline water desalination using different concentrations of sodium chloride (NaCl) as feed solutions. The average water fluxes of 6.2, 4.5, and 2.7 LMH was obtained for 0.1, 0.2, and 0.5 M salt solutions, respectively. The magnetic osmotic agent was separated by a magnet and re-used for several times without considerable decrease in the water flux.

Climate change, population growth, and increased industrial activities are exacerbating freshwater scarcity and leading to increased interest in desalination of saline water. Brackish water is an attractive alternative to freshwater due to its low salinity and widespread availability in many water-scarce areas. However, partial or total desalination of brackish water is essential to reach the water quality requirements for a variety of applications. Selection of appropriate technology requires knowledge and understanding of the operational principles, capabilities, and limitations of the available desalination processes. Proper combination of feedwater technology improves the energy efficiency of desalination. In this article, we focus on pressure-driven and electro-driven membrane desalination processes. We review the principles, as well as challenges and recent improvements for reverse osmosis (RO), nanofiltration (NF), electrodialysis (ED), and membrane capacitive deionization (MCDI). RO is the dominant membrane process for large-scale desalination of brackish water with higher salinity, while ED and MCDI are energy-efficient for lower salinity ranges. Selective removal of multivalent components makes NF an excellent option for water softening. Brackish water desalination with membrane processes faces a series of challenges. Membrane fouling and scaling are the common issues associated with these processes, resulting in a reduction in their water recovery and energy efficiency. To overcome such adverse effects, many efforts have been dedicated toward development of pre-treatment steps, surface modification of membranes, use of anti-scalant, and modification of operational conditions. However, the effectiveness of these approaches depends on the fouling propensity of the feed water. In addition to the fouling and scaling, each process may face other challenges depending on their state of development and maturity. This review provides recent advances in the material, architecture, and operation of these processes that can assist in the selection and design of technologies for particular applications. The active research directions to improve the performance of these processes are also identified. The review shows that technologies that are tunable and particularly efficient for partial desalination such as ED and MCDI are increasingly competitive with traditional RO processes. Development of cost-effective ion exchange membranes with high chemical and mechanical stability can further improve the economy of desalination with electro-membrane processes and advance their future applications.

Synthesis and application of NiO-ZrO2@g-C3N4 nanocomposite for high-performance hybrid capacitive deionisation

Solar distillation systems have been found economically feasible in desalination of saline water. It is a simple and cost-effective low-carbon technology. Free of cost, non-polluting, non-exhaustible solar energy is used to produce distilled water inside a solar still. In this article, the usual economic analysis model has been modified by incorporating the factor of equivalent cost of environmental degradation and high-grade energy savings for solar stills. The unit cost of desalination of saline water is estimated to be US$ 0.034/L corresponding to 30.42% energy efficiency of a passive solar still. It decreases to US$ 0.024/L using the modified model. Double-slope passive solar stills desalinate at a lowest cost of US$ 0.007/L. Due to higher capital cost of active solar stills, the unit cost of desalination of saline water is higher even if productivity is more. Effects of variation of energy efficiency, useful life, capital cost, etc. are also studied. The payback periods of the passive solar still are found to be in the range of 1.1 to 7.6 years if the selling price of distilled water decreases from US$ 0.18 to 0.04/L.

Thermal energy optimization using salt-based phase change materials obtained from the desalination of saline water