Solid desiccant dehumidification is a promising alternative to vapor compression-based air-dehumidification to reduce energy consumption and improve air quality. Desiccant coated heat exchanger ...(DCHE), as one type of solid desiccant dehumidification system, can improve system performance and efficiency. The thermal performance and moisture removal capability of the DCHE greatly influence its dehumidification performance.
The present work aims to critically analyze the designs, materials, and manufacturing methods of heat exchangers used for solid desiccant coating and look into recent developments in regular heat exchangers, potentially deployed as a substrate for DCHE applications. A comprehensive literature review of publications regarding solid desiccant materials, heat exchangers, manufacturing and coating methods, binder materials, and the performance of heat exchangers has been developed. Alternative heat exchangers are described as better options than fin and tube heat exchangers that have been considered thus far for DCHE applications. Additionally, the heat exchanger's manufacturing process and materials over their thermal and mass exchange performance have been analyzed. Despite the widespread use of fin and tube heat exchangers for solid desiccant coating, recent developments in heat exchanger design, and related fields such as manufacturing methods and materials, open the possibilities for their application in solid desiccant dehumidification systems.
Finally, the authors provide their outlook on possible developments of DCHE technology, aiming to increase systems' energy and dehumidification performance.
•Alternative designs of desiccant coated heat exchanger might improve performance.•Novel designs of heat exchangers use materials like metal foam and wire structure.•Additive manufacturing allows to generate high surface area heat exchangers.•Heat transfer coefficient and surface area can improve dehumidification performance.
Because of the rise in global temperature, heat stress has become a major concern for crop production. Heat stress deteriorates plant productivity and alters phenological and physiological responses ...that aid in precise monitoring and sensing of mild-to-severe transient heat stress. Plants have evolved several sophisticated mechanisms including hormone-signaling pathways to sense heat stimuli and acquire heat stress tolerance. In response to heat stress, ethylene, a gaseous hormone, is produced which is indispensable for plant growth and development and tolerance to various abiotic stresses including heat stress. The manipulation of ethylene in developing heat stress tolerance targeting ethylene biosynthesis and signaling pathways has brought promising out comes. Conversely increased ethylene biosynthesis and signaling seem to exhibit inhibitory effects in plant growth responses from primitive to maturity stages. This review mainly focuses on the recent studies of ethylene involvement in plant responses to heat stress and its functional regulation, and molecular mechanism underlying the plant responses in the mitigation of heat-induced damages. Furthermore, this review also describes the crosstalk between ethylene and other signaling molecules under heat stress and approaches to improve heat stress tolerance in plants.
Understanding the fundamental mechanisms governing vapor condensation on nonwetting surfaces is crucial to a wide range of energy and water applications. In this paper, we reconcile classical droplet ...growth modeling barriers by utilizing two-dimensional axisymmetric numerical simulations to study individual droplet heat transfer on nonwetting surfaces (90° < θa < 170°). Incorporation of an appropriate convective boundary condition at the liquid–vapor interface reveals that the majority of heat transfer occurs at the three phase contact line, where the local heat flux can be up to 4 orders of magnitude higher than at the droplet top. Droplet distribution theory is incorporated to show that previous modeling approaches underpredict the overall heat transfer by as much as 300% for dropwise and jumping-droplet condensation. To verify our simulation results, we study condensed water droplet growth using optical and environmental scanning electron microscopy on biphilic samples consisting of hydrophobic and nanostructured superhydrophobic regions, showing excellent agreement with the simulations for both constant base area and constant contact angle growth regimes. Our results demonstrate the importance of resolving local heat transfer effects for the fundamental understanding and high fidelity modeling of phase change heat transfer on nonwetting surfaces.
A metal–organic framework UiO‐66 was prepared and used as a sorbent for dispersive solid‐phase extraction combined with high‐performance liquid chromatography (DSPE‐HPLC) for extracting and ...determining four pyrethroids in water samples for the first time. The as‐synthesized material was confirmed by Fourier transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and N2 adsorption–desorption analysis. In addition, several important parameters affecting DSPE efficiency, including sorbent dosage, extraction time, salt concentration, pH, elution solvent, elution volume, and elution time, were optimized. Under the optimum conditions, the UiO‐66 based on the DSPE‐HPLC method displayed a wide linear range (10–1000 ng/ml), low limits of detection (2.8–3.5 ng/ml), and good precision (relative standard deviations RSDs < 3%) for the four pyrethroids. The recoveries at different spiked levels ranged from 89.3% to 107.7%. In addition, UiO‐66 featured good reusability and reproducibility. The results demonstrated that π–π stacking interactions, hydrophobic interactions, and van der Waals forces between UiO‐66 and the four pyrethroids played a crucial role in the adsorption process. Meanwhile, the maximum extraction capability could be obtained within 5 min. Thus, the DSPE coupled with the UiO‐66 sorbent can be successfully used in the analysis of four pyrethroids in environmental water samples.
Practitioner Points
Simultaneous determination of four pyrethroids using the developed UiO‐66‐based DSPE‐HPLC method in water samples.
The developed method had a short enrichment time, broad linear ranges, a low detection limit, and high enrichment factor.
It is showed that π–π stacking interaction, hydrophobic interaction, and van der Waals forces were the main mechanism.
A method for simultaneous determination of four pyrethroid pesticide residues in water samples was developed by dispersive solid‐phase extraction with UiO‐66 sorbent coupled with high‐performance liquid chromatography.
This study investigated the role of genetic variant rs8177374 in MAL/TIRAP gene in mediating the cytokine levels of IFN-γ, TNF-α, IL-10, and TGF-β in malaria patients due to Plasmodium falciparum or ...P. vivax infection. The study included human blood samples collected from patients with malaria (n = 228) and healthy controls (n = 226). P. falciparum and P. vivax groups were established based on the causative species of Plasmodium. Malaria samples were divided into mild and severe malaria groups based on the symptoms that appeared in the patients, according to the WHO criteria. In a previous study, we genotyped rs8177374 via allele specific PCR strategy. In this study, cytokine levels were estimated in the blood plasma of rs8177374 genotype samples via Sandwich Enzyme Linked Immunosorbent Assay kits. Increased IFN-γ and TNF-α levels in presence of CC genotype indicates the role of CC genotype in both severe and mild malaria groups. Enhanced IL-10 levels in the CT genotype and mild malaria groups suggest a role of CT genotype and IL-10 in the mild clinical outcomes of malaria. The rs8177374 polymorphism in MAL/TIRAP plays an important role in malaria pathogenesis.
Trans-critical CO2 vapor compression (VC) refrigeration cycles require a high compression ratio, which is associated with high expansion losses. To recover these expansion losses, a pressure exchange ...process between the low- and high-pressure sides of the VC cycle is proposed and examined in this study. The proposed pressure exchange system is an open type constant volume process where the high- and low-pressure flows mix inside the system. This prototype is inspired by the pressure exchangers used in reverse-osmosis (RO) desalination systems. In this system, a 2D model was generated and modeled using the computational fluid dynamics (CFD) technique. The numerical model ignored any losses due to leakage or hydraulic friction and the process is considered adiabatic. For the modeling, it was assumed that the inlet conditions for the two pressure exchanger flows are similar to the flow conditions at the evaporator and gas cooler outlets in a VC cycle. Two parameters are examined to test the validity of the system and understand their effect on the performance, including the inlet flow rate represented by the inlet velocity and the process time represented by the speed of rotation. A total of nine cases were simulated and analyzed in this study.
Aqueous-phase surface modification of nanocellulose is desirable because nanocellulose is generally produced via water-based fibrillation. In this study, a hydrogen bond–induced surface modification ...of cellulose nanofibrils (CNFs) in water was developed. Tannic acid and polyvinylpyrrolidone were chosen to modify the CNFs because of their strong capacity for hydrogen bond formation. By tuning the hydrogen bond formation between CNFs, tannic acid, and polyvinylpyrrolidone, CNFs with different surface hydrophilicity were achieved. The modified CNFs can assemble into strong and tough composites owing to the hydrogen bond network in the system. Modified CNFs demonstrated 76% higher tensile strength and 100% higher toughness than those of unmodified CNFs, reaching 162 MPa and 12.7 MJ/m
3
, respectively. This study provides a new water-based modification strategy for the nanocellulose, leading the way toward producing strong nanocellulose composites via noncovalent interaction.
Residential homes and light commercial buildings usually require substantial heat and electricity simultaneously. A combined heat and power system enables more efficient and environmentally friendly ...energy usage than that achieved when heat and electricity are produced in separate processes. However, due to financial and space constraints, residential and light commercial buildings often limit the use of traditional large-scale industrial equipment. Here we develop a micro-combined heat and power system powered by an opposed-piston engine to simultaneously generate electricity and provide heat to residential homes or light commercial buildings. The developed prototype attains the maximum AC electrical efficiency of 35.2%. The electrical efficiency breaks the typical upper boundary of 30% for micro-combined heat and power systems using small internal combustion engines (i.e., <10 kW). Moreover, the developed prototype enables maximum combined electrical and thermal efficiencies greater than 93%. The prototype is optimally designed for natural gas but can also run renewable biogas and hydrogen, supporting the transition from current conventional fossil fuels to zero carbon emissions in the future. The analysis of the unit's decarbonization and cost-saving potential indicate that, except for specific locations, the developed prototype might excel in achieving decarbonization and cost savings primarily in US northern and middle climate zones.
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