Explore the vast range of titles available.

Desiccant cooling systems have been considered as an efficient method of controlling moisture content in supply air. They do not use any ozone-depleting coolants and consume less energy as compared with the vapour compression systems. This communication provides an extensive review of liquid desiccant systems (LDSs). All the components of an LDS such as dehumidifier, regenerator, packing material and liquid desiccant properties along with its energy storage capabilities have been discussed in detail. In addition, hybrid of LDSs with sensible cooling technologies has been studied. Various types of mathematical models to predict the outlet parameters of the desiccant system and current issues in liquid desiccants have been reviewed in detail. Moreover, solid and other advanced desiccants have also been discussed briefly. Finally, a summary of some successful case studies and economic evaluation of desiccant systems have been given.

As an alternative form of vapor compression air conditioning devices, solid desiccant cooling (SDC) techniques have increasingly been explored recently. The overall performances of SDC primarily rely on the capability of dehumidification and regeneration of desiccant. A desiccant with a great uptake capability and excellent regeneration potential is preferred in an SDC system. Although traditional desiccants like silica gels and zeolites are able to absorb moisture at moderate levels, hygroscopic polymers show a superior ability in moisture sorption and desorption. Significant research has been conducted to investigate the hygroscopic polymers in SDC for household and industrial applications. Here, first, an introduction to SDC systems is presented, and then hygroscopic polymers from natural and synthetic origins are discussed. Synthetic polymers discussed are metal–organic frameworks (MOFs), covalent organic frameworks (COFs), covalent triazine frameworks (CTFs), amorphous porous organic polymers (POPs), polyelectrolytes, and polymer‐based composites. Their dehumidification behaviors in SDC systems, primarily desiccant‐coated heat exchanger (DCHE) systems, are compared and summarized. Binders employed in SDC systems are also summarized, as a proper binder enhances the overall performance of the desiccant system. It can be anticipated that hygroscopic polymers and binder materials would witness extensive applications in the future. The summary of various hygroscopic polymers from natural and synthetic origins used in solid desiccant cooling (SDC) systems for household applications are presented. Synthetic polymers reviewed are metal–organic frameworks (MOFs), covalent organic frameworks (COFs), covalent triazine frameworks (CTFs), amorphous porous organic polymers (POPs), and so on. Their dehumidification behaviors and regeneration ability in desiccant‐coated heat exchanger are summarized.

The desiccant air conditioning system has multiple advantages (e.g., no use of ozone-depleting refrigerants, highly efficient moisture control, easy regenerative integration) over traditional vapor-compression refrigeration systems, thus increasingly attracting more research interest. Recently, several studies have been conducted that primarily aimed to enhance the overall performance of desiccant air conditioners by innovating new desiccant materials, innovating new system configurations and improving system designs and controls, and integrating different hybrid energy sub-systems technologies. Therefore, this paper provides a comprehensive review of the studies mentioned earlier. The present comprehensive review dealt with several axes: first, an overview of the importance of using desiccant air conditioners and their operations, and performance indicators. Second, a summary statement for desiccant materials that includes: the new innovative desiccant materials and the most important composite desiccant materials. Third, detailed information on the newest innovative designs and configurations of desiccant air conditioning systems and their control systems. Fourth, a detailed statement on the most important hybrid energy sub-systems technologies integrated with desiccant air conditioners. Based on the latest developments in desiccant air conditioning systems, this study presents discussions of urgent issues and recommendations for future work that can help focus necessary efforts to find solutions to critical and pending problems, which lead to further improvements in the overall performance of desiccant air conditioners.

The superfine dry powder fire extinguishing agent has the characteristics of high fire extinguishing efficiency and low cost and has been widely used in the field of fire extinguishing. This paper briefly describes the classification and current problems of dry powder and analyzes the current technology of micronization and surface modification. The superfine dry powder fire extinguishing agent is greatly improved in water resistance by surface grafting modification, the water repellency meets the standard requirements, and the D90 particle size of the dry powder extinguishing agent after modification is ≤15μm.

Desiccants play vital roles in dehumidification and atmospheric water harvesting; however, current desiccants have mediocre hygroscopicity, limited recyclability, and high energy consumption. Herein, we report a wood-inspired moisture pump based on electrospun nanofibrous membrane for solar-driven continuous indoor dehumidification. The developed moisture pump with multilayer wood-like cellular networks and interconnected open channels is composed of a desiccant layer and a photothermal layer. The desiccant layer exhibits an unprecedented moisture absorption capacity of 3.01 g g −1 at 90% relative humidity (RH), fast moisture absorption and transport rates, enabling atmospheric water harvesting. The photothermal layer shows a high solar absorption of 93%, efficient solar thermal conversion, and good moisture permeability, thus promoting water evaporation. The moisture pump efficiently reduces the indoor relative humidity to a comfort level (40‒60% RH) under one-sun illumination. This work opens the way to develop new-generation, high-performance nanofibrous membrane-based desiccants for energy-efficient humidity control and atmospheric water harvesting. Desiccants are important for dehumidification, but application is hindered by limited hygroscopicity, recyclability, and energy efficiency. Here, the authors report a moisture pump comprised of an electrospun nanofibrous memebrane for solar-driven continuous indoor dehumidification.

Natural gasmust be dehydrated before it can be transported and used, but conventional drying agents such as activated alumina or inorganic molecular sieves require an energy-intensive desiccant-regeneration step. We report a hydrolytically stable fluorinated metal-organic framework, AlFFIVE-1-Ni (KAUST-8), with a periodic array of open metal coordination sites and fluorine moieties within the contracted square-shaped one-dimensional channel. This material selectively removed water vapor from gas streams containing CO₂, N₂, CH₄, and higher hydrocarbons typical of natural gas, as well as selectively removed both H₂O and CO₂ in N₂-containing streams. The complete desorption of the adsorbed water molecules contained by the AlFFIVE-1-Ni sorbent requires relatively moderate temperature (∼105°C) and about half the energy input for commonly used desiccants.

Atmospheric water harvesting (AWH) is a promising alternative to address immediate water needs. Desiccant-based AWH could compete effectively with other commercially available AWH technologies. One of the primary challenges facing desiccant-based AWH is the energy required to desorb the captured water vapor from the desiccant. This work presents a multi-faceted approach targeted explicitly at low-humidity and arid regions, aiming to overcome the limitations of the refrigerant-based AWH system. It includes assessing common desiccants (zeolite, activated alumina, and silica gel) and their forms (beads, powdered, or coated on a substrate). A bench-scale test rig was designed to evaluate different types and forms of desiccants for adsorption and desorption cycles and overall adsorption capacity (g/g), kinetic profiles, and rates. Experimental results indicate that beaded desiccants possess the highest adsorption capacity compared to powdered or coated forms. Furthermore, coated desiccants double the water uptake (1.12 vs. 0.56 g water/g desiccant) and improve adsorption/desorption cycling by 52% compared to beaded forms under the same conditions. Additionally, Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and dynamic vapor sorption (DVS) analysis show the pore geometry, morphology, and sorption capacity. The goal is to integrate these performance improvements and propose a more effective, energy-efficient desiccant-based AWH system.

A solid desiccant-based novel dehumidification technique in indoor cooling is a viable substitute for a traditional dehumidification system in regions with high humidity levels. The ozone layer is being steadily destroyed by vapour compression-based conventional dehumidification systems, which also have a number of other disadvantages such as excessive power consumption and a rise in the amount of chlorofluorocarbons type refrigerant leakage in the atmosphere. As compared to traditionally used vapour compression type refrigeration air conditioners, solid desiccant-integrated novel cooling may be more advantageous as it provides more easily accessible, cost-effective, and ecologically sound cooling. It can be more competitive when it is reactivated by freely available renewable heat available from solar power and industrial waste heat. Not only marginally saving energy, but it can also help in drastically lower operational costs. Recently, many studies have been carried out with aim of ameliorating desiccant air conditioners' overall performance through the development of novel system configurations, enhanced system designs and better controls, and the integration of hybrid energy sources for desiccant reactivation as well as sub-systems technological advancements. By this means, the present study offers a thorough analysis of the previously described investigations. This offers detailed study on possible suggestions and recommendations for possible future work direction based on the most recent investigations in the field of the desiccant-powered novel cooling techniques. These recommendations can help to amplify the efforts to find better solutions to concurrent technological issues, which will definitely ameliorate the overall performance of desiccant-integrated dehumidification and hybrid cooling in the field of heating, ventilation and air conditioning.

The purpose of this study is to analyse the proposed liquid desiccant absorber with low solution flow rate compared with the conventional packbed-type absorber. The total exergy destruction and exergy efficiency were estimated to assess the system performance. To determine the total exergy destruction and exergy efficiency, it was predicted that the specific thermal and chemical exergy in the inlet and outlet both air and solution side of the absorber. The results indicated that the average total thermal and chemical exergy destruction is 0.054 kW and 0.080 kW in the proposed system while it is 0.292 kW and 0.093 kW in the conventional absorber. The exergy efficiency is 0.573 and 0.114 on average in the proposed and conventional absorber, respectively.