A Review of Hybrid Humidification and Dehumidification Desalination Systems

The escalating threat of water scarcity, coupled with the inclusion of numerous countries in the list of water-scarce nations, has elevated the issue of water availability to a paramount concern in today\u27s global landscape. Freshwater sources are becoming increasingly scarce, with their proportional decline steadily progressing. Consequently, a growing number of nations have resorted to the desalination of seawater as a viable solution. In response to this critical need, a surge of studies and research endeavors has been dedicated to the development and refinement of desalination processes. One of the most promising innovations in this field is Humidification-Dehumidification (HDH) desalination technology. This paper aims to delve into the potential of HDH desalination technology and its integration with another advanced desalination method known as a hybrid system. By combining these two distinct approaches, it becomes possible to not only enhance productivity but also address certain limitations inherent in each technology. In this paper, we provide an overview of various desalination processes, shedding light on their classifications and characteristics. Our primary focus, however, lies in exploring how HDH desalination technology can be effectively harmonized within a hybrid system to maximize efficiency and mitigate shortcomings observed in individual technologies. The integration of HDH with existing desalination methods has demonstrated notable success, as evidenced by numerous research studies in the field. This research underscores the significance of hybridization in advancing HDH sustainability practices within the desalination sector, ultimately contributing to the global effort to combat water scarcity

A Review of Hybrid Humidification and Dehumidification Desalination Systems

The escalating threat of water scarcity, coupled with the inclusion of numerous countries in the list of water-scarce nations, has elevated the issue of water availability to a paramount concern in today\u27s global landscape. Freshwater sources are becoming increasingly scarce, with their proportional decline steadily progressing. Consequently, a growing number of nations have resorted to the desalination of seawater as a viable solution. In response to this critical need, a surge of studies and research endeavors has been dedicated to the development and refinement of desalination processes. One of the most promising innovations in this field is Humidification-Dehumidification (HDH) desalination technology. This paper aims to delve into the potential of HDH desalination technology and its integration with another advanced desalination method known as a hybrid system. By combining these two distinct approaches, it becomes possible to not only enhance productivity but also address certain limitations inherent in each technology. In this paper, we provide an overview of various desalination processes, shedding light on their classifications and characteristics. Our primary focus, however, lies in exploring how HDH desalination technology can be effectively harmonized within a hybrid system to maximize efficiency and mitigate shortcomings observed in individual technologies. The integration of HDH with existing desalination methods has demonstrated notable success, as evidenced by numerous research studies in the field. This research underscores the significance of hybridization in advancing HDH sustainability practices within the desalination sector, ultimately contributing to the global effort to combat water scarcity

Study on the effect of alumina nano-fluid on sharp-edge orifice flow characteristics in both cavitations and non-cavitations turbulent flow regimes

In the present study, the effects of alumina nano-fluid concentration on sharp-edge orifice flow characteristics in both cavitations and non-cavitations turbulent flow regimes are numerically investigated. At different concentration of AL2O3 nonmetallic particles (2%, 4%, 6%, 8%, and 10%) volume fractions in pure liquid water as a base fluid. A single-hole orifice pipe is with a small diameter ratio 0.297 and the orifice plate thickness 14 mm. The effects of alumina nano-fluid concentration on sharp-edge orifice flow characteristics have been investigated based on the turbulent kinetic energy, turbulent intensity, turbulent viscosity, and volume fraction of vapor. The results show that for increasing the nonmetallic particle volume fraction from 0.0 to 10%, the turbulent kinetic energy decreases by 20.87% in average downstream the orifice in the whole region, the turbulent intensity decreases by 11.11% in average downstream the orifice in the whole region, the turbulent intensity decreases by 11% in average in the whole region, and the volume fraction of vapor increases by 16.9%. Also, in the separation region downstream the orifice the turbulent kinetic energy increases by 160% in average and the turbulent intensity increases by 74% in average for increasing the nano-fluid concentration from 0.0% to 2%. These are mainly because for using the alumina nano-fluid the separation phenomena decrease due to the increase of the viscosity of the nano-fluid, the total losses in the sharp-edge orifice increase for the increase of the viscosity of the nano-fluid and this causes the increase of the rate of vaporization. In the orifice pipe the total-stress criterion predicts larger cavitating regions in the flow field. However using the nano-fluid with high concentration accelerates the cavitations at the orifice pipe

Water production for irrigation and drinking needs in remote arid communities using closed-system greenhouse: A review

Water needs for agriculture, food production and drinking are considered one of the most critical challenges facing the world in the present days. This is due mainly to the scarcity and lack of fresh water resources, and the increasing ground water salinity. Most of these countries have a high solar energy potential. This potential can be best developed by solar desalination concepts and methods specifically suited for rural water supply, irrigation. In this paper, a humidification–dehumidification (HD) water desalination system with several technologies for irrigation and drinking needs in remote arid areas is introduced from technical and economic point of views. This study has investigated (1) detailed discussion of technical developments, economical and sustainable aspects; (2) benefits of the new design over traditional applications, desalination and other irrigation methods; (3) specific requirements and implementation challenges in remote and cold regions; (4) performance and reliability improvement possible techniques. Recommended researches and projects leading to high efficiency, economical and sustainable applications of some desalination devices driven by solar energy are highlighted

Performance improvement of a hybrid air conditioning system using the indirect evaporative cooler with internal baffles as a pre-cooling unit

In the present paper, the effects of the indirect evaporative cooler with internal baffle on the performance of the hybrid air conditioning system are numerically investigated. The hybrid air conditioning system contains two indirect evaporative coolers with internal baffle, one is utilized to pre-cool the air inlet to the desiccant wheel and the other is utilized to pre-cool the supply air inlet to the room. The effects of the inlet conditions of the process and reactivation air and working air ratio on the thermal performance of the hybrid air conditioning system have been analyzed. The results of this study show that in the hybrid air conditioning system for using the indirect evaporative cooler with internal baffle as a pre-cooling unit, the supply air temperature reduced by 21% and the coefficient of performance improved by 71% as compared to previous designs of the hybrid air conditioning system at the same inlet conditions. For increasing process air inlet temperature from 25 °C to 45 °C, supply air temperature increases from 12.7 °C to 14.2 °C, thermal COP increases from 1.87 to 2.84, and supply air relative humidity increases from 76.7% to 77.4%. Also, for increasing the reactivation air inlet temperature from 70 °C to 110 °C, supply air temperature dropped from 15.9 °C to 10.9 °C, supply air relative humidity dropped from 82.7% to 71.8%, and thermal COP dropped from 4.5 to 1.7. The recommended optimal air working ratio in the indirect evaporative cooler with internal baffle should be 0.15. Keywords: Desiccant material, Solar air collector, Evaporative cooler, Internal baffles, Air conditionin

CFD analysis of flow fields for shrouded wind turbine’s diffuser model with different flange angles

The present study shows a development and analysis of 2-D axisymmetric CFD model of flanged diffuser that was used as a casing for developed small wind turbines to increase the generated power. The 2-D CFD diffuser model grids are developed by GAMBIT, while the flow field analysis has been carried out using commercial software FLUENT. This study focuses on the effect of flange’s angles as a varied parameter on velocity at diffuser entrance. All models have the same dimensions in diffuser length, entrance diameter, exit diameter and flange height but differ in flange angle. Flange angles of these tested models vary from −25° to +25°, where flange angles were measured to vertical axis. Present model verification indicates a good agreement between present numerical work and previous published experimental work. The numerical simulation shows the created vortices behind flange that cause pressure drop which increases mass flow rate through the diffuser. The results indicate also that the right flange angle at 15° is the optimum angle that accelerates flow at diffuser entrance. The increase of velocity at this optimum flange angles is higher than the case of normal angle, where the expected increase in the generated power by wind turbine can reach 5% more compared with normal flange

Premium jet cooling with two ribs over flat plate utilizing nanofluid mixed convection

In this study, a numerical simulation of the thermal performance of two ribs mounted over a horizontal flat plate and cooled by Cu-water nanofluid is performed. The plate is heated and maintained at a constant temperature and cooled by mixed convection of laminar flow at a relatively low temperature. The top wall is considered as an adiabatic condition. The effects of related parameters such as Richardson number (0.01 ≤ Ri ≤ 10), the solid volume fraction (0.01 ≤ ϕ ≤ 0.06), the distance ratio between the two ribs (d/W = 5, 10, and 15), and the rib height ratio (b/W = 1, 2, and 3) on the ribs thermal performance are studied. The numerical simulation results indicate that the heat transfer rate is significantly affected by the distance and the rib height. The heat transfer rate is improved by increasing the nanoparticles volume fraction. The influence of the solid volume fraction with the increase of heat transfer is more noticeable for lower values of the Richardson number. The numerical results are summarized in the effect of pertinent parameters on the average Nusselt number with the assistance of both streamlines and isothermal ones. Throughout the study, the Grashof and Prandtl numbers, for pure water are kept constant at 103 and 6.2, respectively. The numerical work was displayed out using, an in-house computational fluid dynamic code written in FORTRAN, which discretizes non-dimensional forms of the governing equations using the finite volume method and solves the resulting system of equations using Gauss-Seidal method utilizing a tri diagonal matrix algorithm