Humidity Control Research Articles

Separation and recycling of hydrofluorocarbon refrigerant mixtures with fluoropolymer-coated hollow fiber membranes.

Many hydrofluorocarbon refrigerants used in air-conditioning and refrigeration equipment are being phased out based on international restrictions to reduce global warming. Over 1 billion kilograms of hydrofluorocarbons are in use, and recycling is imperative to preventing the release of these greenhouse gases into the atmosphere. We report on composite hollow fiber membranes that can efficiently separate a mixture of difluoromethane and pentafluoroethane that is used worldwide in air conditioners. Selective hollow fiber membranes have been fabricated with a single submicrometer coating of a copolymer of 70 mol % perfluoro(butenyl vinyl ether) and 30 mol % perfluoro(2,2-dimethyl-1,3-dioxole) that separates the azeotropic mixture into a permeate stream with a difluoromethane purity of >95 mol %. Rather than incinerating these valuable materials, this technology can be used to recycle nonregulated difluoromethane for future products and recover pentafluoroethane for use as a chemical feedstock, creating a circular economy.

A Review of Advanced Reactive Materials in Fiber Sensor Technology: Challenges and Requirements of Precise Humidity Control in Mechanochemical Treatment Process

A Review of Advanced Reactive Materials in Fiber Sensor Technology: Challenges and Requirements of Precise Humidity Control in Mechanochemical Treatment Process

Fault diagnosis in split-system air conditioner by analyzing the chaos in the electrical current signal

Fault diagnosis in split-system air conditioner by analyzing the chaos in the electrical current signal

Antibacterial cellulose-based membrane with heat dissipation and liquid transportation for food packaging applications

Food spoilage, caused by fungi and bacteria, has drawn increasing attention due to the lack of suitable temperature and humidity control, resulting in food waste and health risks. It is still a great challenge to develop green packaging materials with excellent antibacterial activities and effective temperature/humidity control for food preservation. Herein, a new strategy is proposed to obtain food packaging material with antibacterial ability, heat dissipation, and liquid transportation functions. In this strategy, Zn-Al layered double hydroxide (LDH)@cellulose was obtained by extracting cellulose from sugarcane husks, followed by in-situ growth of LDH nanosheets on the surface of cellulose. Then, asymmetric structured packaging material, namely cellulose acetate/LDH@cellulose (CALC) membrane, was prepared by the combination of electrospinning and hydrophobic modification. The characterization results confirmed that the CALC membrane exhibits asymmetric surface structure and wettability properties, endowing heat dissipation and liquid transportation for food packaging applications. Due to the asymmetric reflectivity and infrared emissivity, the CALC membrane exhibited excellent heat dissipation properties with a surface temperature of 10.3℃, which is lower than that of commercial food packaging material. Furthermore, the excellent liquid transport properties of the CALC membrane are demonstrated by the fact that water can penetrate from the hydrophobic side to the hydrophilic side within 32s, providing the appropriate storage temperature and dry environment for foods. In addition, compared with PE film, the CALC membrane also has antibacterial properties and UV resistance, which is beneficial to improving the storage conditions for foods. This study shows that the developed CALC membrane and corresponding design strategy can be extended for the preparation of other packaging materials for applications in research and food industrial fields.

Probing the water adsorption and stability under steam flow of Zr-based metal-organic frameworks using 91Zr solid-state NMR spectroscopy.

The stability of metal-organic frameworks (MOFs) in the presence of water is crucial for a wide range of applications, including the production of freshwater, desiccation, humidity control, heat pumps/chillers and capture and separation of gases. In particular, their stability under steam flow is essential since most industrial streams contain water vapor. Nevertheless, to the best of our knowledge, the stability under steam flow of Zr-based MOFs, which are among the most widely studied MOFs, has not been investigated so far. We explore it herein for three UiO-like Zr-based MOFs built from the same Zr cluster but distinct organic linkers at temperature ranging from 80 to 200 °C. We demonstrate the possibility of acquiring their 91Zr NMR spectra using high magnetic field (18.8 T) and low temperature (140 K) and of interpreting them by comparing experimental data with NMR parameters calculated by DFT. NMR observation of this challenging isotope combined with more conventional techniques, such as N2 adsorption, X-ray diffraction, IR, and 1H and 13C solid-state NMR spectroscopies, provides information not only on the possible collapse of the MOF framework but also on the adsorption of molecules into the pores. We notably show that UiO-66(Zr) and UiO-66-Fum(Zr) built from terephthalate and fumarate linkers, respectively, are stable over 24 h (and even over 7 days for UiO-66(Zr)) under steam flow at all investigated temperatures, whereas UiO-67-NH2 containing a 2-amino-[1,1'-biphenyl]-4,4'-dicarboxylate linker degrades under steam flow at temperatures ranging from 80 to 150 °C but is preserved at 200 °C. The lower stability of UiO-67-NH2 stems from its larger pores and its weaker Zr-O coordination bonds, whereas its preservation at 200 °C results from a more limited condensation of water in the pores.

Thermal and humidity control in high-geothermal tunnel by natural ventilation during operational transition period: A case study

Thermal and humidity control in high-geothermal tunnel by natural ventilation during operational transition period: A case study

Retraction notice to “Experimental and a dual-scale analysis of the influence of coating on humidity control ability of hygroscopic materials with different porosity” Constr. Build. Mater. 426 (2024) 136163

Retraction notice to “Experimental and a dual-scale analysis of the influence of coating on humidity control ability of hygroscopic materials with different porosity” Constr. Build. Mater. 426 (2024) 136163

Problems of the process of moistening raw cotton and cotton fiber. Cotton fiber wetting process problems

The moistening of raw cotton and cotton fiber is a critical stage in the textile production process, significantly influencing the quality of the final product. However, achieving optimal moisture content presents numerous challenges. One of the primary problems is the uneven distribution of moisture during processing, which can lead to variations in fiber strength and quality. The inappropriate application of water or humidification methods often causes fiber shrinkage, reduced durability, and increased contamination. Furthermore, the control of temperature and humidity plays a vital role in preventing over-drying or excessive moisture retention, both of which can negatively affect the spinning and handling properties of cotton fibers. Technological limitations, coupled with the complexity of monitoring moisture levels accurately, result in inefficiencies in the cotton processing industry. Research has also shown that improper moisture regulation can lead to decreased efficiency in machinery, increased energy consumption, and a higher likelihood of fiber damage during transportation and storage. Therefore, addressing these issues requires advancements in moisture control technologies and the development of standardized procedures to ensure consistent and high-quality cotton fiber production.

Mango solar dryer prototype design with temperature and humidity control system with bluetooth monitoring

Mango is a fruit that is produced in the southeast of Mexico. To preserve the product, it is necessary to keep it refrigerated and this increases the sales price due to the high electricity consumption. An alternative to taking advantage of this fruit is to dehydrate the pulp, taking advantage of This way the product is not wasted. There are solar dryers where the fruits do not require electrical energy and their conservation is at a very low cost. In this document, the implementation of a project to dry the mango fruit taking advantage of solar energy is presented with evidence so that its temperature and humidity can be monitored via Bluetooth. For this purpose, sensors were adapted with the support of hardware and software. used an Arduino uno board. In the end it is shown that the project has been functional, being an alternative in reducing costs, drying and efficiency.

Isopods in the Bioremediation of Invasive Seaweeds? First Experience with the Seaweed Rugulopteryx okamurae Mass Dumped on Beaches

Since 2015, the invasive seaweed Rugulopteryx okamurae has triggered the most serious marine macrophyte invasion in Europe. Its huge coastal biomass dumped on beaches generates health problems, strong odors, impacts on tourism, and high clean-up costs, but it also constitutes a new potential marine resource that offers significant prospects for exploitation. In this sense, as a circular economy strategy, seaweed bioremediation with isopods (Isopoda, Crustacea, Arthropoda) was experimented on for the first time. Specimens of Porcellio laevis (native terrestrial isopod) were obtained from urban parks and kept in terrariums with adequate humidity and temperature control. A sample of 150 adult specimens was divided into six batches of 25 animals. Three batches were fed with 100 g of mulch of Quercus pyrenaica leaves (control) and three with a diet composed of 100 g of mulch of algae (treatment). P. laevis consumed up to 1.5 times their weight per day on the algae diet, with little or no weight loss and adequate reproduction rates. The weight of the isopods averaged 1.6 g in the seaweed group and 2.5 g in the control group. However, high mortality was observed in both mancas and adults in the treatment group. In this sense, the average number of mancas per cm2 was 0 in the algae group and 325 in the control group. Despite this, the results are promising, and consequently, we propose to encourage research with isopods due to their high voracity, high prolificacy, and resistance to invasive algal recycling. Future work should explore what percentage of R. okamurae prevents diterpene mortality of isopods and other invertebrates. This is a preliminary step towards the massive bioremediation of spring and summer blooms of R. okamurae. This work contributes to highlighting this abundant marine resource.

Architecting Ultra-Robust Zr(IV) Metal-Organic Framework for Energy-Efficient Desiccant Air Conditioning.

Air-conditioning systems, composed mainly of humidity control and heat reallocation units, play a pivotal role in upholding superior air quality and human well-being across diverse environments ranging from international space stations and pharmacies to granaries and cultural relic preservation sites, and to commercial and residential buildings. The adoption of sorbent water as the working pair and low-grade renewable or waste heat in adsorption-driven air-conditioning presents a state-of-the-art solution, notably for its energy efficiency and eco-friendliness vis-à-vis conventional electricity-driven vapor compression cycles. Here, we introduce a rational π-extension strategy to engineer an ultrarobust and highly porous zirconium metal-organic framework (Zr-MOF). This MOF sorbent showcases hysteresis-free S-shaped water sorption isotherms, characterized by a rapid ascent within the 40-60% relative humidity range with a working capacity of 0.63 g g-1, thus facilitating intelligent indoor humidity regulation. Moreover, we demonstrate, for the first time, that this material with such distinctive isotherms can yield a 10 °C temperature lift between ambient and chiller output with a high cooling capacity of 336 kW h m-3 per cycle, even at exceptionally low driving temperatures (below 50 °C), while also delivering a substantial coefficient of performance of 0.96. This material is amenable to scale-up and is chemically ultrastable that can endure strong acids and be cycled for at least 200 runs without compromising any of its capacity. These exceptional attributes signify the viability of this material as a pragmatic alternative for deployment in energy-efficient desiccant air-conditioning systems, particularly in hot and humid climatic regions.

Didactic application of the FMEA methodology for the operational optimization of air conditioning equipment

The facilities of a service company such as an educational institution must have a repair schedule by the maintenance area so that its internal functions are fulfilled and support academic activities. This project addresses one of the maintenance problems faced by an academic facility of higher secondary education and is directed to the air conditioning equipment to provide a comfortable learning environment. However, this equipment has presented recurrent failures. To address this situation, a maintenance plan will be implemented based on the Failure Modes and Effects Analysis (FMEA) methodology, a tool that allows identifying, analyzing and prioritizing potential failure modes in a system, evaluating their effects and causes to develop effective corrective and preventive actions. This proactive approach is crucial to anticipate and mitigate risks associated with failures, optimizing operational efficiency and equipment durability.

Design and Development of Tempe Fermentation Tool Based on Fuzzy Method to Determine Tempe Maturity Level

Purpose of the study: This study aims to design an innovative tempeh fermentation tool based on the Mamdani fuzzy method that is able to accelerate fermentation and determine the level of tempeh maturity accurately using weight parameters and visual image analysis. This tool is designed to improve the efficiency, productivity, and competitiveness of the tempeh industry by maintaining the quality of tempeh according to standards. Methodology: The results showed that this tool was able to accelerate fermentation with an average time of 21.7 hours, producing quality tempeh with evenly growing fungi without rot. The load cell sensor successfully weighed two tempeh at once with an average weight loss of 10.5 grams, and the ESP32CAM successfully monitored the tempeh visually during fermentation. Main Findings: From the results testing that has been done for 4× shows that tool This succeed speed up fermentation with eat average time 21.7 hours with criteria mold grow even and not rotten and loadcell sensor successful Weigh 2 tempeh at a time fermented with decline average weight 10.5 grams and ESP32CAM successfully monitored tempeh visually at the time fermented . Novelty/Originality of this study: The novelty of this research lies in the integration of DHT11 sensor technology, load cells, and ESP32CAM which enables automatic control of temperature and humidity, real-time monitoring, and accurate determination of tempeh maturity levels. This innovation provides a practical solution to improve the efficiency of the fermentation process and the quality of tempeh production, making it suitable for application on an industrial scale.

Progress in the Experimental Design and Performance Characterization of Artificial Accelerated Photodegradation of Wood

Wood, a natural and renewable material, is extensively utilized in furniture, construction, and outdoor landscapes due to its sustainability and esthetic appeal. However, exposure to environmental elements, particularly sunlight, leads to photodegradation, affecting wood’s chemical and physical structure. This degradation results in color fading, increased surface roughness, and reduced mechanical properties, shortening the lifespan of wooden products. Artificial accelerated photodegradation tests have become a crucial method for studying wood’s aging process under controlled laboratory conditions, mimicking prolonged exposure to sunlight. This review explores the mechanisms behind wood photodegradation, focusing on the effects of UV radiation on wood’s major components—cellulose, hemicellulose, lignin, and extractives. Additionally, it summarizes the latest advancements in experimental design for artificial aging tests, including factors like radiation source selection, temperature, and humidity control. The paper also highlights performance characterization methods for evaluating the impact of photodegradation on wood’s physical, chemical, and mechanical properties. Understanding these processes is essential for enhancing the durability of wood products and developing effective treatments for wood preservation in outdoor environments.

Fungi influence in the chemical composition, textural quality, buoyancy, and floatation time of poorly stored fish feeds

This study assessed the effects of fungal contamination on the chemical composition, texture, buoyancy, and floating time of poorly stored fish feed. Among 21 commercial and six artisanal feed samples analyzed, 81% showed fungal growth. Nutritional losses were significant: commercial feeds lost 41.97–50.61% of minerals, 17.11–21.69% of crude protein, 38.28% of lipids, 35.16–50.66% of carbohydrates, and 37.77% of raw energy. Artisanal feeds experienced even greater losses, with reductions of 66.12–84.06% in minerals, 43.29–47% in crude protein, and 25.60–42.40% in raw energy. Contamination altered pellet texture, causing hardening, crumbling, and increased fracturability in water, reducing buoyancy (~50%) and causing nutrient leaching. This led to feed accumulation at pond bottoms, accelerating eutrophication. These findings emphasize the economic and environmental risks of fungal contamination in fish farming. Proper storage with humidity and temperature control is crucial to prevent fungal growth, nutrient loss, and mycotoxin contamination.

Enhancing Dimensional Stability and Environmental Durability in Delrin-Molded Parts Through Advanced Annealing Techniques

This paper presents the implementation and optimization of an advanced annealing process designed to enhance the dimensional stability, moisture resistance, and crystallinity of Delrin-molded parts for demanding outdoor applications. Delrin, a widely used acetal resin, poses unique challenges in plastic injection molding due to its natural tendency to shrink post-molding and absorb moisture, which can compromise part performance in variable environmental conditions. By introducing a high-capacity annealing oven with precise temperature and humidity control, we achieved substantial improvements in part stability and durability. This process was developed through close collaboration with customer engineering teams and our in-house experts, ensuring the final product meets strict tolerance and environmental durability requirements. Results indicate that the annealing process effectively reduces dimensional variation, decreases moisture content by 75%, and increases crystallinity by 20%, making the parts robust enough to withstand extremes of heat, cold, and humidity. This study underscores the value of high-tech annealing solutions in the plastic injection molding industry, offering a blueprint for similar applications in advanced manufacturing. Keywords: Delrin Annealing, Crystallinity Enhancement, Dimensional Stability, Moisture Resistance, Environmental Durability, Plastic Injection Molding, Advanced Manufacturing Techniques, High-Capacity Annealing Oven, Quality Engineering, Process Optimization

Multi-plateau water adsorption of pyrene-based covalent organic frameworks for potential humidity control

Indoor air humidity significantly influences air quality, human health, and work performance. Covalent organic frameworks (COFs) have been proven effective in humidity regulation; however, challenges remain in broadening their range of humidity control. This study designs and synthesizes a series of pyrene-based crystalline COFs as humidity control materials, investigating the moisture adsorption–desorption characteristics under structural modulation. Among these, PY-3,3′-BPY-COF exhibits unique multi-step adsorption isotherms, achieving the highest water uptake capacity (1 g/g) and efficient water uptake-release cycles. Theoretical and experimental analyses reveal a linear relationship between the maximum water uptake rate and the specific surface area, while the adsorption inflection points are influenced by the water binding energy and pore size distribution. Importantly, the introduction of strong binding sites promotes multi-step adsorption phenomena, significantly enhancing the humidity control capabilities of COFs across a wide range of humidity levels. This research introduces an innovative approach for broad-spectrum indoor humidity control and reveals the fundamental relationship between the structure characteristics of COFs and their capabilities in water adsorption and release.

Experimental Investigation of Chloride Ion Monitoring in Concrete Considering the Coupling Effect of Temperature and Humidity

Ag/AgCl electrodes have acquired significant research attention due to their crucial role in the electrochemical monitoring of chloride ion concentration. However, the electrode potential is susceptible to changes in temperature and humidity, and comprehensive investigations regarding the influence of moisture are lacking. Existing studies on Ag/AgCl electrodes have been qualitative, primarily focusing on analyzing the trend of electrode potential to detect variations in Cl- concentration. This study proposes an experimental method that enables precise control of temperature and humidity within concrete. The effects of temperature and humidity coupling on Ag/AgCl electrode potential in a concrete environment and a fundamental model were established correlating Ag/AgCl electrode potential with temperature, humidity, and chloride ion concentration, thereby enhancing the sensing accuracy. The developed model corrected errors from temperature and humidity coupling effects on the Ag/AgCl electrode potential. A quantitative investigation on using Ag/AgCl electrodes for monitoring Cl- concentration was conducted, facilitating their application in engineering and the development of non-destructive monitoring systems for chloride ions in concrete structures.

Development of a novel isothermal heat and mass exchanger for humidity control

Development of a novel isothermal heat and mass exchanger for humidity control

Ti3C2Tx Aerogel-Based Wearable Humidity Sensors with Low Hysteresis and High Linearity for Expiratory Comfort Management.

Wearable and flexible humidity sensors hold great promise for expiratory comfort management. However, the high hysteresis and poor detection linearity restrict the immediate and accurate detection of humidity. Herein, we have prepared Ti3C2Tx MXene/chitosan/polyvinylidene difluoride aerogels with a controllable hydrophobic/hydrophilic surface to regulate the catch/escape behavior of H2O molecules. The MXene aerogel-based humidity sensor demonstrates low hysteresis (3.2% relative humidity) and a high linear relationship (R2 = 0.99). Integrated with a control circuit, an expiratory humidity monitoring system is constructed for nasal comfort management as a humidity switch. The exhaled breath humidity can be automatically regulated during dry exhalation conditions. This wearable humidity sensor enables the real-time monitoring and intelligent control of nasal exhaled humidity. This work represents a new avenue for improving breathing comfort and preventing respiratory diseases.