Humidity Swing Research Articles

Technology Transfer of Humidity and Temperature Control System Using Ultrasonic Mist Maker in the Lamongan Hydroponic Farm Area, Sidoharjo Lamongan District

Lamongan Hydroponic Farm's vegetable farming has a lot of potential, however managing humidity and temperature is a problem. While farmers there have been successful in creating fruitful hydroponic gardens, they struggle to keep the ideal growing environment. Severe temperature and humidity swings have an impact on harvest quality and raise production costs. The community service team suggested using solar energy and ultrasonic mist maker technologies to solve this issue. It is anticipated that this technology will lower operating costs, produce the perfect atmosphere for plant growth, and automatically control the amount of water in the air. Lamongan hydroponic farming may therefore be more productive and long-lasting. Lamongan Hydroponic Farm's community service program is implemented through the following phases: socializing, training, technology application, mentorship, and program sustainability evaluation. Two key technologies were developed as a result of this process: smart agricultural knowledge and ultrasonic mist makers with IoT and solar panel systems attached. According to the evaluation results, the three pretest and posttest questionnaires received resulted in an average improvement in partner knowledge from 49% to 74%.

In-situ pressure differential-accelerated mechanical fatigue testing and modeling of a reinforced fuel cell membrane

In-situ pressure differential-accelerated mechanical fatigue testing and modeling of a reinforced fuel cell membrane

Innovative dual-function system for efficient CO2 absorption and utilization: Local humidity swing fabric and microalgae-embedded hydrogel

Innovative dual-function system for efficient CO2 absorption and utilization: Local humidity swing fabric and microalgae-embedded hydrogel

Characterization of Responsive Plasters for Passive Moisture and Temperature Control

Ambient comfort maintenance accompanied by excessive energy consumption is hugely criticized concerning the limited sustainability of the building sector in the long-term. In this sense, the energy reduction strategies based on the employment of passive air-control techniques are viewed as a prospective solution for improved energy performance. In order to contribute to this significant issue, this paper is aimed at the design and material characterization of novel plaster with an improved thermal and humidity control performance. For this purpose, a form-stable diatomite/dodecanol-based phase change material together with superabsorbent polymer are used as admixtures for the passive moderation of indoor air quality by newly designed modified plasters. The experimental assessment of the functional properties by means of mechanical strength, thermal conductivity, and hygric properties is performed. Considering the goal of the paper, particular attention is paid to the characterization of water vapor storage and moisture buffering according to the Nordtest method. Differential scanning calorimetry is employed for the description of phase change intervals as well as the specific enthalpy of phase change. The obtained results point to significant improvements in the hygroscopic performance and increased thermal energy storage that can be used for passive moderation of the indoor temperature and reduction of the relative humidity swings.

Moisture Swing Ion-Exchange Resin-PO4 Sorbent for Reversible CO2 Capture from Ambient Air

Reversible CO2 capture from ambient air by a humidity swing has shown great potential in mitigating the greenhouse effect. In this work, we developed a new humidity-swing absorbent based on PO43–/H...

Humidity swing adsorption of H2S by fibrous polymeric ionic liquids (PILs)

Abstract A novel H2S adsorbent, fibrous polymeric ionic liquids (PILs), was proposed in this study, for they combine the advantages of ionic liquids and characteristics of macromolecular architecture. After modified with basic anion, the sorbent showed excellent performance for low concentration of H2S adsorption under room temperature. The fixed bed breakthrough experiment showed that the adsorption capacity is up to 1.75 mmol/g and the adsorption kinetics is comparable to that of mental oxide at 300 °C. Despite the strong affinity for H2S, the saturated sorbent could be regenerated under wet conditions, which inspires an economical water-promoting regeneration method. Further investigations through density functional theory (DFT) calculations revealed that the interface water would alter the reaction pathways of H2S adsorption and lower the activation energy of desorption reaction, which makes H2S desorption faster. After eight adsorption-desorption cycles, the sorbent did not show any detectable loss of H2S adsorption capacity. Therefore, the results of this study indicate that the fibrous PILs are promising regenerable sorbent for low concentration H2S removal at room temperature.

Quaternized Chitosan/PVA Aerogels for Reversible CO2 Capture from Ambient Air

Developing inexpensive and highly efficient CO2 air capture technologies is an important solution for solving the greenhouse problem. In this work, we used the low-cost quaternized chitosan (QCS)/poly(vinyl alcohol) (PVA) hybrid aerogels with quaternary ammonium groups and hydroxide ions to reversibly capture CO2 from ambient air by humidity swing. The CO2 capture capacity and adsorption rate of the aerogels were investigated over the temperature range 10–30 °C. The CO2 capture capacity of the aerogels was measured to be about 0.18 mmol/g, which is 38% higher than the state-of-the-art commercial membrane. In addition, we proposed a modified pseudo-first-order kinetic model considering both the CO2 adsorption and the H2O desorption, which describes the experimental results very well. For the first time, the moisture-swing CO2 adsorbent is built by low-cost biomass material, which opens up a new approach for the design of the moisture-swing CO2 adsorbent.

Feasibility study of simultaneous heating and dehumidification using an adsorbent desiccant wheel with humidity swing

Abstract Adsorptive desiccant dehumidification generates heat from adsorption, which can be used for space heating. Theoretically, a difference in relative humidity between the process air and the regeneration air is sufficient to produce the adsorption and desorption of water vapor onto and from the desiccant wheel. Taking advantage of this phenomenon, we proposed a desiccant wheel that used humidity swing adsorption (HSA), offering simultaneous heating and dehumidification. We first experimentally investigated the differences in the temperature and humidity of the adsorption air at the inlet and outlet of the desiccant wheel. We confirmed that the dehumidification and a rise in temperature occurred with only a difference in absolute humidity between the dehumidification and regeneration air. The theoretical maximum temperature rise assuming adiabatic dehumidification was estimated to be 15 °C for adsorption and desorption inlet air of 25 °C and 15 g/kg-DA and 25 °C and 3.6 g/kg-DA. The experimentally measured temperature rise was decreased to 9.4 °C mainly due to the heat capacity of the wheel used in the experiments. It was found that a regeneration temperature greater than 13 °C was required to obtain a heating effect under our experimental conditions.

A Life Cycle Assessment Case Study of Coal-Fired Electricity Generation with Humidity Swing Direct Air Capture of CO2 versus MEA-Based Postcombustion Capture.

Most carbon capture and storage (CCS) envisions capturing CO2 from flue gas. Direct air capture (DAC) of CO2 has hitherto been deemed unviable because of the higher energy associated with capture at low atmospheric concentrations. We present a Life Cycle Assessment of coal-fired electricity generation that compares monoethanolamine (MEA)-based postcombustion capture (PCC) of CO2 with distributed, humidity-swing-based direct air capture (HS-DAC). Given suitable temperature, humidity, wind, and water availability, HS-DAC can be largely passive. Comparing energy requirements of HS-DAC and MEA-PCC, we find that the parasitic load of HS-DAC is less than twice that of MEA-PCC (60-72 kJ/mol versus 33-46 kJ/mol, respectively). We also compare other environmental impacts as a function of net greenhouse gas (GHG) mitigation: To achieve the same 73% mitigation as MEA-PCC, HS-DAC would increase nine other environmental impacts by on average 38%, whereas MEA-PCC would increase them by 31%. Powering distributed HS-DAC with photovoltaics (instead of coal) while including recapture of all background GHG, reduces this increase to 18%, hypothetically enabling coal-based electricity with net-zero life-cycle GHG. We conclude that, in suitable geographies, HS-DAC can complement MEA-PCC to enable CO2 capture independent of time and location of emissions and recapture background GHG from fossil-based electricity beyond flue stack emissions.

Study on removal effect of suspended particulate matter by humidity swing air cleaning method

A humidity swing air cleaning method has been studied experimentally for improving a SPM (suspended particulate matter) removal effect. This method uses humidity swing of the air with evaporation of water and condensation of moisture, and removes the SPM by making a nuclear condensation with the SPM as nuclei and gravitational settling of the grown droplet. According to our previous study, the SPM removal effect of 90 % level was obtained at humidity swing of 0.2 kg/kgDA at flow rate of 5 L/min. The purpose of this study is to improve the SPM removal performance, especially in a high flow rate conditions. We have tested two ways; one is a modification of the dehumidifier geometry for promoting the nuclear condensation effect and the gravitational sedimentation effect. The other is an introduction of an inertial impaction as the grown droplets removal method using a coarse mesh filter as an obstacle in the fast flow condition. The geometry changes of the dehumidifier made the improvement in removal ratio up to 99.9% level at the flow rate of 5 L/min. Moreover, the introduction of the mesh filter resulted in the same removal ratio of 99.9% level at a fast flow condition of 10 L/min.

Theoretical studies on CO2 capture behavior of quaternary ammonium-based polymeric ionic liquids.

Quaternary ammonium-based polymeric ionic liquids (PILs) are novel CO2 sorbents as they have high capacity, high stability and high binding energy. Moreover, the binding energy of ionic pairs to CO2 is tunable by changing the hydration state so that the sorbent can be regenerated through humidity adjustment. In this study, theoretical calculations were conducted to reveal the mechanism of the humidity swing CO2 adsorption, based on model compounds of quaternary ammonium cation and carbonate anions. The electrostatic potential map demonstrates the anion, rather than the cation, is chemically preferential for CO2 adsorption. Further, the proton transfer process from water to carbonate at the sorbent interface is successfully depicted with an intermediate which has a higher energy state. By determining the CO2 adsorption energy and activation energy at different hydration states, it is discovered that water could promote CO2 adsorption by reducing the energy barrier of proton transfer. The adsorption/desorption equilibrium would shift to desorption by adding water, which constitutes the theoretical basis for humidity swing. By analyzing the hydrogen bonding and structure of the water molecules, it is interesting to find that the CO2 adsorption weakens the hydrophilicity of the sorbent and results in release of water. The requirement of latent heat for the phase change of water could significantly reduce the heat of adsorption. The special "self-cooling" effect during gas adsorption can lower the temperature of the sorbent and benefit the adsorption isotherms.

Removal characteristics of Suspended Particulate Matter with Humidity Swing Air Cleaning Method

Removal characteristics of Suspended Particulate Matter with Humidity Swing Air Cleaning Method

Theoretical Study on Removal Effect of Suspended Particulate Matter in Humidity Swing Air Cleaning Method

Theoretical Study on Removal Effect of Suspended Particulate Matter in Humidity Swing Air Cleaning Method

Porous polymers prepared via high internal phase emulsion polymerization for reversible CO2 capture

A series of porous polymers with different pore volumes, pore sizes, and crosslinking densities were synthesized by high internal phase emulsion (HIPE) polymerization. The crosslinked polymerized HIPEs (polyHIPEs) were formed by the copolymerization of 4-vinylbenzyl chloride and divinylbenzene using water droplets in conventional or Pickering HIPEs as the templates. These porous materials were further modified by quaternization and ion exchange to introduce quaternary ammonium hydroxide groups. The resulting polyHIPEs were utilized as sorbents for reversible CO2 capture from air using the humidity swing. The effect of pore structure on the CO2 adsorption and desorption processes was studied. The polyHIPEs containing large pores and interconnected porous structures showed improved swing sizes and faster adsorption/desorption kinetics of CO2 compared to a commercial Excellion membrane with similar functional groups.

Co-Location of Air Capture, Subseafloor CO2 Sequestration, and Energy Production on the Kerguelen Plateau

Reducing atmospheric CO2 using a combination of air capture and offshore geological storage can address technical and policy concerns with climate mitigation. Because CO2 mixes rapidly in the atmosphere, air capture could operate anywhere and in principle reduce CO2 to preindustrial levels. We investigate the Kerguelen plateau in the Indian Ocean, which offers steady wind resources, vast subseafloor storage capacities, and minimal risk of economic damages or human inconvenience and harm. The efficiency of humidity swing driven air capture under humid and windy conditions is tested in the laboratory. Powered by wind, we estimate ∼75 Mt CO2/yr could be collected using air capture and sequestered below seafloor or partially used for synfuel. Our analysis suggests that Kerguelen offers a remote and environmentally secure location for CO2 sequestration using renewable energy. Regional reservoirs could hold over 1500 Gt CO2, sequestering a large fraction of 21st century emissions.

Three‐Dimensionally Ordered Macroporous Polymeric Materials by Colloidal Crystal Templating for Reversible CO2 Capture

AbstractThe design and preparation of porous materials with controlled structures and functionalities is crucial to a variety of absorption‐ or separation‐relevant applications, including CO2 capture. Here, novel functional polymeric materials with three‐dimensionally ordered macroporous (3DOM) structures are prepared by using colloidal crystals as templates using relatively simple, rapid, and inexpensive approaches. These ordered structures are used for the reversible CO2 capture from ambient air by humidity swing. Typically, the colloidal crystal template is synthesized from polymer latex particles of poly(methyl methacrylate) (PMMA) or polystyrene (PS). To maintain the functionality of the material, it is important to prevent the porous structure collapsing, which can occur by the hydrolysis of the ester bonds in conventional crosslinkers under basic conditions. This hydrolysis can be prevented by using a water‐soluble crosslinker containing two quaternary ammonium moieties, which can be used to prepare stable porous crosslinked polymers with the monomer (vinylbenzyl)trimethylammonium chloride (VBTMACl) and using a PMMA‐based colloidal crystal template. The hydroxide‐containing monomer and dicationic crosslinker are synthesized from their chloride precursors, avoiding the ion‐exchange step which causes shrinkage of the pores. An analysis of different methods for infiltrating the monomer solution into the colloidal crystal template shows that infiltration using capillary forces leads to fewer defects than infiltration under a partial vacuum. In addition, functional macroporous films with micrometer thickness are prepared from a template of PS‐based colloidal crystals in a thin film. In general, the colloidal crystal templated materials showed improved CO2 absorption/desorption rates and swing sizes compared to a commercially available material with similar functional groups. This work could easily be extended to create a new generation of ordered macroporous polymeric materials with tunable functionalities for other applications.

6PM3-PMN-054 湿度操作空気清浄法による粒子除去率の改善(マイクロセンサとナノ計測,ポスターセッション)

6PM3-PMN-054 湿度操作空気清浄法による粒子除去率の改善(マイクロセンサとナノ計測,ポスターセッション)

湿度操作による空気清浄の研究:第3報：ナノサイズ粒子状物質の低減効果

湿度操作による空気清浄の研究:第3報：ナノサイズ粒子状物質の低減効果

湿度操作による空気中の浮遊微粒子除去効果(<小特集>第1回マイクロ・ナノ工学シンポジウム)

The removal effect of a humidity swing operation on suspended particulate matters (SPM) was experimentally studied. The experimental results show that the humidity swing operation increases number of SPM less than 5μm size and decreases that of more than 5μm size. Also, a large number of liquid droplets were found in a deposited matter collected by inertial impact method after the humidity swing operation. We concluded that the nuclear condensation takes place on the SPM in the supersaturated moist air during the humidity swing process. It is expected that new whole SPM removal method can be proposed, where the SPM grows to several micrometer size by the nuclear condensation, and then the grown particles can be removed by gravitational or inertial effects.

Viscoelastic Stress Analysis of Constrained Proton Exchange Membranes Under Humidity Cycling

Many premature failures in proton exchange membrane (PEM) fuel cells are attributed to crossover of the reactant gas from microcracks in the membranes. The formation of these microcracks is believed to result from chemical and/or mechanical degradation of the constrained membrane during fuel cell operation. By characterizing the through-membrane leakage, we report failures resulting from crack formation in several PEMs mounted in 50cm2 fuel cell fixtures and mechanically stressed as the environment was cycled between wet and dry conditions in the absence of chemical potential. The humidity cycling tests also show that the failure from crossover leaks is delayed if membranes are subjected to smaller humidity swings. To understand the mechanical response of PEMs constrained by bipolar plates and subjected to changing humidity levels, we use Nafion® NR-111 as a model membrane and conduct numerical stress analyses to simulate the humidity cycling test. We also report the measurement of material properties required for the stress analysis—water content, coefficient of hygral expansion, and creep compliance. From the creep test results, we have found that the principle of time-temperature-humidity superposition can be applied to Nafion® NR-111 to construct a creep compliance master curve by shifting individual compliance curves with respect to temperature and water content. The stress prediction obtained using the commercial finite element program ABAQUS® agrees well with the stress measurement of Nafion® NR-111 from both tensile and relaxation tests for strains up to 8%. The stress analysis used to model the humidity cycling test shows that the membrane can develop significant residual tensile stress after humidity cycling. The result shows that the larger the humidity swing and/or the faster the hydration/dehydration rate, the higher the residual tensile stress. This result is confirmed experimentally as PEM failure is significantly delayed by decreasing the magnitude of the relative humidity cycle. Based on the current study, we also discuss potential improvements for material characterization, material state diagnostics, and a stress model for PEMs.