Humidity Regulation Research Articles

Lightweight waste-based gypsum composites for building temperature and moisture control using coal fly ash and plant fibers

Due to raw material shortages and waste management concerns, composite building materials made from industrial by-products have become a key component of tomorrow's construction sector. Herein, the synergetic effects of coal fly ash (CFA) and shot plant fibers (Alfa fibers – AF) on the thermophysical, mechanical and moisture-related properties of gypsum plaster were investigated. CFA was used as a partial gypsum substitute at a range of 0–80 wt%, while short AF were used as bio-aggregates ranging from 0 to 6 wt%. The developed composites presented bulk density, compressive strength, thermal conductivity and moisture buffering values between 934–1340 kg/m3, 1.38–6.98 MPa, 0.26–0.57 W/mK and 0.41–1.71 g/m2%RH, respectively. Experimental results proved the efficacy of CFA as hygrothermal optimizer, while AF served as hygroscopic agent and reinforcement to offset the compressive strength loss caused by generated porosity. Combining 50 wt% CFA with 6 wt% short AF resulted in a lightweight gypsum composite with enhanced hygrothermal capabilities that met compressive strength requirements (>2MPa). The proposed gypsum composite showed a good application prospect in passive thermal and humidity regulation in buildings.

Implementasi Telegram untuk Budidaya Lumbricus Rubellus Berbasis IoT

Lumbricus Rubellus (earthworm) has various benefits: serving as livestock feed, medicine, cosmetics ingredients, and organic fertilizer from vermicompost. Earthworm cultivation is not difficult, but requires extra monitoring due to various challenges that affect their growth and development. One key factor to consider is the weather, as prolonged hot temperatures during droughts can disrupt the growth of earthworms. To address this challenge, a monitoring and control device was designed to regulate the temperature and humidity of the cultivation area automatically. Additionally, the device provides information about the age of the cultivated earthworms for predicting the harvesting period. These functions were realized by utilizing various sensors, such as the DHT11 sensor for room temperature measurement with 95.05% accuracy and the Soil Moisture sensor for soil humidity measurement with 96.3% accuracy. Furthermore, a fan and water pump were employed to automate temperature and humidity regulation. The main control unit for this system is the NodeMCU ESP8266. Telegram application was used as a platform to monitor and control this IoT-based device remotely. With this device, the process of earthworm cultivation is expected to be more accessible.

Novel Graphene-Based Materials as a Tool for Improving Long-Term Storage of Cultural Heritage.

The very serious problem of temperature and humidity regulation, especially for small and medium-sized museums, galleries, and private collections, can be mitigated by the introduction of novel materials that are easily applicable and of low cost. Within this study, archive boxes with innovative technology are proposed as "smart" boxes that can be used for storage and transportation, in combination with a nanocomposite material consisting of polyvinyl alcohol (PVA) and graphene oxide (GO). The synthesis and characterization of the PVA/GO structure with SEM, Raman, AFM, XRD, Optical Microscopy, and profilometry are fully discussed. It is shown that the composite material can be integrated into the archive box either as a stand-alone film or attached onto fitting carriers, for example, those made of corrugated board. By applying the PVA/GO membrane this way, even with strong daily temperature fluctuations of ΔT = ±24.1 °C, strong external humidity fluctuations can be reduced by -87% inside the box. Furthermore, these humidity regulators were examined as Volatile Organic Compounds (VOCs) adsorbers since gas pollutants like formic acid, formaldehyde, acetic acid, and acetaldehyde are known to exist in museums and induce damages in the displayed or stored items. High rates of VOC adsorption have been measured, with the highest ones corresponding to formic acid (521% weight increase) and formaldehyde (223% weight increase).

Constrained temperature and relative humidity predictive control: Agricultural greenhouse case of study

The importance of Model Predictive Control (MPC) has significant applications in the agricultural industry, more specifically for greenhouse’s control tasks. However, the complexity of the greenhouse and its limited prior knowledge prevent an exact mathematical description of the system. Subspace methods provide a promising solution to this issue through their capacity to identify the system’s comportment using the fit between model output and observed data. In this paper, we introduce an application of Constrained Model Predictive Control (CMPC) for a greenhouse temperature and relative humidity. For this purpose, two Multi Input Single Output (MISO) systems, using Numerical Subspace State Space System Identification (N4SID) algorithm, are firstly suggested to identify the temperature and the relative humidity comportment to heating and ventilation actions. In this sense, linear state space models were adopted in order to evaluate the robustness of the control strategy. Once the system is identified, the MPC technique is applied for the temperature and the humidity regulation. Simulation results show that the regulation of the temperature and the relative humidity under constraints was guaranteed, both parameters respect the ranges 15 °C ≤ Tint ≤ 30 °C and 50 % ≤ Hint ≤ 70 % respectively. On the other hand, the control signals uf and uh applied to the fan and the heater, respect the hard constraints notion, the control signals for the fan and the heater did not exceed 0 ≤ uf ≤ 4.3 Volts and 0 ≤ uh ≤ 5 Volts, respectively, which proves the effectiveness of the MPC and the tracking tasks. Moreover, we show that with the proposed technique, using a new optimization toolbox, the computational complexity has been significantly reduced. The greenhouse in question is devoted to Schefflera Arboricola cultivation.

Unusual Temperature Dependence of Water Sorption in Semicrystalline Hydrogels.

Water vapor sorption is a ubiquitous phenomenon in nature and plays an important role in various applications, including humidity regulation, energy storage, thermal management, and water harvesting. In particular, capturing moisture at elevated temperatures is highly desirable to prevent dehydration and to enlarge the tunability of water uptake. However, owing to the thermodynamic limit of conventional materials, sorbents inevitably tend to capture less water vapor at higher temperatures, impeding their broad applications. Here, an inverse temperature dependence of water sorption in poly(ethylene glycol) (PEG) hydrogels, where their water uptake can be doubled with increasing temperature from 25 to 50°C, is reported. With mechanistic modeling of water-polymer interactions, this unusual water sorption is attributed to the first-order phase transformation of PEG structures, and the key parameters for a more generalized strategy in materials development are identified. This work elucidates a new regime of water sorption with an unusual temperature dependence, enabling a promising engineering space for harnessing moisture and heat.

Self‐Powered and Humidity‐Modulable Optoelectronic Synapse

AbstractWith the advantage of high bandwidth, low power consumption, and low crosstalk from optical signal stimulation, optoelectronic synapses are attracting more and more attention. Herein, a self‐powered two‐terminal optoelectronic synapse based on a lead‐free Cs2AgBiBr6 perovskite/P(VDF‐TrFE)/pentacene heterostructure is designed, which shows bidirectional responses to optical stimuli with different wavelengths (λ = 445 nm/660 nm). This feature enables the device to emulate both excitatory and inhibitory synaptic behaviors in a fully optical pathway. Besides optical stimulus, humidity is used as an additional stimulus to modulate the synaptic performance of the device under 445 nm illumination. The device is successfully applied to stimulate the behavior of the weather tree forecast and visual learning and forgetting processes under different mood states via humidity regulation.

Revealing the Potential of Waste Fibers from Timber Production and Clearings for the Development of Local Bio-based Insulation Fiberboards in French Guiana

In French Guiana, the development of bio-circular value chains to convert residual biomass into insulation fiberboard represents a promising opportunity for energy-efficient construction. The objectives of this work are to identify and characterize resources of interest and discuss the relationships between fiber properties, manufacturing parameters, and fiberboard performance. Five wood and bark fibers were fractionated from residual biomass of 4 local species, and their fractions analyzed by: laser granulometry, thermal gravimetric analysis (TGA), and pyrolysis combustion flow calorimetry (PCFC). Fiberboards were produced using a thermomechanical process and their microstructure, thermal, and sorption properties were characterized by X-ray tomography, hot plate technique, and dynamic vapor sorption (DVS). Morphological analysis showed that large and elongated wood fractions form thick and cohesive fibrous networks, while small-sized bark fractions are more difficult to process, requiring more compaction and synthetic fiber additives due to lower natural self-adhesion. Despite processing difficulties, bark fiberboards showed the best insulation performance, comparable to commercial reference products. TGA and PCFC tests revealed that bark fibers have better thermal stability and fire behavior compared to wood, and a stronger water affinity compared to wood fractions, highlighting the need for further investigations of durability performance in tropical conditions in the long term, but also a potential interest for humidity regulation.

Mesoporous Silica‐Guided Synthesis of Metal–Organic Framework with Enhanced Water Adsorption Capacity for Smart Indoor Humidity Regulation

Metal–organic frameworks (MOFs) are promising for indoor humidity regulation due to steep stepwise water uptake and moderate regeneration temperature. Current approaches for performance improvement of MOFs such as impregnating hygroscopic salts and grafting functional groups face the challenge of corrosion and instability. Herein, a template‐guided tuning strategy is proposed to synthesize binary nanocomposite. Highly ordered mesoporous channels of MCM‐41 provide uniform nucleation sites for MOF growth, enabling a 21.5% promotion of specific surface area (3188.14 m2 g−1) and 23.4% improvement of water uptake (1.53 g g−1 at 20°C/90% relative humidity) for the nanocomposite compared with parent MIL‐101(Cr). The fast kinetics and superior stability together guarantee its practical application. Further, a paradigm of continuous indoor humidity regulation driven by sunlight is demonstrated, which realizes smart regulation of the indoor humidity to the human comfort zone (40–60%) with near‐zero energy input.

A review of regulating ecosystem services in the context of urban planning

There is a high growing demand for regulating ecosystem services such as air quality regulation, regulation of air temperature and humidity, and flood regulation, in urban ecosystems which is important for urban planning. A comprehensive review of the current studies of the urban ecosystem, regulating ecosystem services, and their connection with urban planning actions is needed. The current paper presents such a review conducted in six stages to evaluate the state-of-the-art of regulating ecosystem services and their relationship with urban planning. It includes 58 papers selected after a precise keywords search and developed by publication screening, defining indicators, developing an assessment template, and meta-analysis of the results. The analyses are focused on spatial data used in the studies, the methods applied for ecosystem services assessment, and the relationships between regulating ecosystem services, urban planning, and green infrastructure. The most studied regulating ecosystem services within reviewed publications are regulation of chemical composition of atmosphere and oceans, regulation of temperature and humidity, including ventilation and transpiration, and hydrological cycle and water flow regulation (including flood control, and coastal protection). Although urban planning-related papers are only 1/3 of the pool of papers, appropriate results have been obtained for assessing the urban planning-regulating ecosystem services relation. The review also identified some significant knowledge gaps that can be used as a starting point for future studies.

Penerapan Sistem Proposional-Integral-Derivatif Pada Hatchery untuk Meningkatkan Produktivitas Day Old Chick (DOC)

The Livestock Product Processing Technology Laboratory is one of the centers of practicum, research or community service activities at the Banyuwangi State Polytechnic where it has a hatchery machine with a capacity of 500 grains, the hatchery machine has been modified so that the temperature and humidity can be controlled properly, but the machine still has some disadvantages. In addition to frequent errors in the heater, The system used still uses an on/off control system as a temperature and humidity regulator, so it can cause over shoot or under shoot which can cause fluctuations in temperature and humidity, so it is necessary to apply Proposional-Integral-Derifativ (PID) control which is able to accelerate the response of a system, eliminate offsets and produce large initial changes The purpose of this study was to determine the performance of the tool by applying PID control to hatchery machines that were tested to hatchability and Knowing the temperature and humidity settings to get the best results from the application of PID control on the hatchery machine. This research began with the preparation of the PID control series, namely making hardware and software designs using Arduino, sterilizing hatchery machines and setting temperatures of 37ºC and temperatures of 38ºC and humidity of 65 and 67%, entering eggs for 21 days and collecting data, hatchability and hatching. The results showed that PID control provided constant temperature and humidity stability at 37ºC and 38ºC temperatures, the best temperature and humidity use treatment at 38ºC was able to hatchability of 78.26%.

Electrospinning and multilayer modification to construct NH2/EPSP-modified polyacrylonitrile nanofiber films for humidity regulation

Photoresponsive materials may be used to improve the humidity of a microenvironment, thus improving the comfort of people occupying that space. In this work, by constructing a synergistic layer (amino groups) and a regulating layer (spiropyran compounds) on the surface of polyacrylonitrile (PAN) electrospun membranes, we successfully developed fiber materials with excellent mechanical stability that can reversibly regulate the humidity of the microenvironment. Spiropyran molecules can undergo photoisomerization (reversible polar-nonpolar structure interconversion) by conversion of ultraviolet/visible light. The wettability and microenvironment humidity can be controlled bidirectionally under different light sources. More importantly, the amino groups on the fiber surface can assist the ring-opened merocyanine in absorbing water molecule, thus playing a synergistic role. Moreover, changing the electrospinning voltages can help regulate the porosity of the fiber materials, which can change wettability and the humidity range regulation. The energy change of spiropyran before and after water absorption was obtained by density functional theory calculations, and it is further proven that the synergistic layer can promote the ability of humidity regulation.

A review of aircraft environmental control system simulation and diagnostics

The aircraft Environmental Control System (ECS) enables the aircraft to maintain a comfortable and safe environment for its passengers throughout its operating envelope. The Pressurised Air Conditioner (PACK) is the heart of the ECS, and is composed of multiple sub-systems: heat exchangers, valves, compressor, turbine, and a water separator. The PACK’s principle function is to enable conditioning of the hot, high pressure bleed air from the engine or APU, for temperature, pressure and humidity against the cabin requirements. The operation of the PACK is governed by a control system which has the ability to mask degradation in its component during operation until severe degradation or failure results. The required maintenance is then both costly and disruptive. The PACK has been reported as major driver of unscheduled maintenance by the operators. The aviation industry is currently proactively exploring innovative health management solutions that aid the maintenance of aircraft key systems based on predictive based maintenance approaches using online condition monitoring techniques. This paper presents a comprehensive review of the simulation and diagnostic methodologies applicable to fault diagnostics of the ECS PACK. The existing literature suggests that model-based and data-driven methods are effective for conducting fault detection and isolation of the PACK system. The conceived findings indicate that the model-based diagnostic approach have been extensively employed to conduct PACK diagnostics at component level only. Their successful implementation requires robust experimental verification and validation against the actual data under healthy and faulty conditions. Although a substantial amount of work has been reported on developing first principles based simulation models and diagnostic strategies for the ECS, the acquired findings suggest that there is a compelling need for a verified and validated ECS simulation model to enable accurate PACK system-level diagnostics based on single and multiple component level degradation scenarios. It has also been identified that the existing literature lacks the evaluation of humidity regulation and the effect of the control system on the PACK performance characteristics. Finally, a taxonomy of diagnostic techniques and simulation models is compiled based on the available literature.

Pet Temperature, Humidity, and Light Control System Design Based on Single Chip Microcomputer

It is a domestic demand nowadays that people have a pet, plants, and kids or elders at home that must look after on. Sometimes, it is hard to tell if they are living in an appropriate environment where they feel comfortable. That would be troublesome when people go to work or have a vacation, leaving them at home alone. Also, some of the aspects are subjective and difficult to quantify, especially humidity and temperature. In order to reflect the surrounding environment accurately and intuitively, a pet-sitter system is implemented. In this design, the use of high reliability of the Microprogrammed Control Unit (MCU) as the processing core, to improve the pet environment of temperature and humidity, and light to achieve the function of the sub-function design. The main functions of the design include the collection, display, automatic control, and adjustment of temperature and humidity illumination. For the selection of equipment, with the goal of running stability and cost performance, the corresponding equipment is selected, and the final realization of temperature, humidity, and light regulation.

Engineering and scaling-up ceramic tiles with humidity self-regulation functionality

The humidity regulation in the interior spaces of buildings by means of passive solutions that do not require energy consumption is a topic of great interest due to the current needs for comfort and energy efficiency. This paper addresses the engineering of humidity regulating ceramic tiles that incorporate a functional coating formulated from gibbsite together with other common raw materials whose moisture regulating capacity has been demonstrated previously. A multi-layer coating tile system has been proposed, consisting of the following elements: an engobe layer, the functional coating with the regulating capacity, a decoration by inkjet technology and a protective topcoat glaze.This system has been analysed with moisture adsorption–desorption tests. The moisture regulation capacity and the effect of the coating thickness on this property have been determined, allowing to optimise the functionality.Finally, an analysis of the humidity regulation has been performed on the basis of demonstrators or small-sized cubicles that simulate the conditions of final use in rooms of buildings. The results show the different behaviour of the demonstrator with functional tiles in relation to conventional tiles, with an indoor ambient humidity that remains in the comfort zone for longer periods of time.

Construction of an active humidity regulation setup for NMR/MRI-Observation and simulation of the controlled evaporation of sessile water droplets

Controlling and improving processes like for example the production of organic semiconductors via printing depends on understanding the interplay of wetting and evaporation of complex fluids. Therefore, examination of the time dependent composition of complex fluid droplets during wetting or evaporation is of interest. The evaporation rate of sessile droplets containing largely water depends on the vapor pressures of the individual components and on the humidity (or partial pressure) of the surrounding gas phase. Hence, for a complete picture of an evaporation process and the comparability of the results of different measurements, it is essential to measure and control the humidity and temperature in the measurement compartment. Accordingly, climate chambers are available in different scales to fit a variety of techniques like contact angle goniometry to obtain results in a controlled atmosphere. We recently reported the application of MRI (Magnetic Resonance Imaging) and spatially resolved NMR (Nuclear Magnetic Resonance) spectroscopy for the examination of the evaporation of sessile droplets on surfaces in 10 mm NMR tubes. These are considered to be closed compartments. Here, we present an apparatus to a) measure and b) control the relative humidity within the sample compartment of the NMR setup by introducing preconditioned gas into the NMR tube. We monitored the evaporation of water droplets using RARE images and compared the volume decay with a) a simple diffusive evaporation model and b) with detailed FEM (finite element numerical model) simulations using COMSOL for validation. We find three evaporation regimes depending on the flow rate as well as on the distance of the gas outlet and the evaporating droplet. In one of the sample configurations tested the evaporation takes place in such a way that it can be described with the help of the simple diffusive model without convection. Thus, the presented approach opens comparative measurements with other methods as well as the observation of droplet evaporation in very dry or very humid environments with and without the influence of convection. Finally, using PRESS spectra, it is shown that the evaporation rate of water from a water/DMSO droplet can be controlled. This shows how the setup presented here can be used to study the evaporation of droplets of more complex mixtures.

Porous Electrospun Films with Reversible Photoresponsive Microenvironmental Humidity Regulation: A Controllable Hydrogen-Bonding Synergistic Effect Exhibited by Acrylic Acid Segments

Suitable relative humidity is essential for the preservation of cultural relics, food storage, and so on. A special material that can regulate the relative humidity in the microenvironment is particularly important. In this work, several innovative electrospun films with reversible photoresponsive wettability and the ability to regulate microenvironmental relative humidity were prepared. The spiropyran unit of the synthesized copolymer played the most important role in humidity regulation due to its reversible transition between a nonpolar ring-closed state and a polar ring-opened state induced by alternating ultraviolet/visible illumination. More interestingly, the introduction of acrylic acid segments exhibited a controllable hydrogen bond synergistic effect for increasing the range of humidity regulation. The color change and the reversible change ranges of wettability and microenvironmental relative humidity under ultraviolet/visible irradiation are all closely related to the number of acrylic acid segments. Cassie theory, density functional theory (DFT), and interaction region indicator (IRI) analysis were used to characterize this phenomenon. Electrospinning is a promising method to achieve large-scale production that can put such material into practical applications.

Fresh food shelf-life improvement by humidity regulation in domestic refrigeration

Air humidity plays a vital role in domestic refrigerators, with direct impact in water loss. The water loss is an adverse result in postharvest condition once food can no longer replace water. However, food products are normally submitted to improper refrigeration conditions. For this reason, this study evaluates the fresh food quality (mushrooms and crispy lettuce) stored in the crisper compartment from a domestic refrigerator. Two tests were performed by oscillating the relative humidity (high and lower level). Mass loss, total color difference and sensorial analysis were conducted in order to determine the food quality during 14 days of storage. Results presented improved preservation from the mushrooms and crispy lettuce when relative humidity high was kept, inside the crisper compartment. Briefly, these results can support the development of new domestic refrigeration projected with improved preservation technologies.

Technological innovation in earth constructions: prefabrication and 3D printing

This article focuses on the use and application of innovative technologies and tools in earth construction processes. It reviews the rammed earth construction system and its evolution towards prefabrication, as well as the use of earth as a raw material in the production of housing prototypes through 3D printing technology.In order to validate earth construction as a modern and viable material, several recognized and award-winning works and prototypes at a global scale are collected and analyzed. These case studies utilize earth as the initial raw material for prefabrication and 3D printing, thus identifying the best technique that can be transferred to a developing country like Ecuador. The results of this research serve to highlight earth as a modern, alternative, and viable material that meets current demands for sustainability, energy efficiency, and housing deficit. Furthermore, its use in buildings can enhance thermal and acoustic performance due to its temperature and humidity regulation capabilities. Earth construction is also associated with promoting sustainable architecture and preserving cultural heritage. In conclusion, earth construction is a valuable option to address housing and sustainability challenges.

Natural materials in building construction - annual evaluation

The construction industry's focus on a low-carbon economy will result in the need for a deeper examination of natural-based building materials. From an environmental point of view, the benefits of these materials are undeniable. However, it is necessary to consider their shortcomings in other areas of design in terms of building thermal engineering. This article observes and evaluates a wall designed for a wooden building with almost zero energy demand in year-round operation and subsequent assessment in confrontation with a different composition, seemingly more advantageous in thermal resistance and humidity regime. These assemblies are under long-term examination within the pavilion research of the authors' workplace, in laboratory conditions from the interior side. At the same time, they are exposed to the realistic boundary conditions of the external environment. The paper includes an environmental assessment of two compositions, variating in the used material. The research shows that the wall composition of natural materials is more advantageous from an ecological perspective and can also show favourable effects in terms of temperature and relative humidity regulation.

Experimental and Theoretical Study of Adsorption/Desorption Isotherms of Straw Earth Material Used in the Construction of Shell Huts in the Far North of Cameroon

Earth-based materials (EBM) provides a valuable avenue for improving thermal comfort, energy consumption, indoor air quality and humidity regulation. However, in the literature, very few studies have addressed hygrometric characteristics of shell huts in EBM from the far north region of Cameroon. The use EBM is hampered by the non-availability of databases related to their intrinsic properties and through unfamiliarity of their behavior over time. In the meantime, these shell huts in EBM are known for their moisture which regulates properties and thus contributes to the comfort of their occupants. This study aims to determine experimentally the adsorption/desorption isotherms at 30, 40 and 50 °C of the straw earth material carried out by the static gravimetric method for eight saturated salt solutions (LiCl, MgCl2, Mg(NO3)2, NaBr, IK, NaCl, KCl and K2SO4). The experimental curves obtained for absorption / desorption show that for a given water activity, the equilibrium water content Weq increases inversely with temperature (i.e. decreases with increasing temperature, and vice versa). In addition, the absorption curve does not overlap with the desorption curve. As a result, these shell huts in EBM display interesting humidity regulation characteristics.