High CO2 Concentration Research Articles

Various Cultivars of Citrus Fruits: Effects of Construction on Gas Diffusion Resistance and Internal Gas Concentration of Oxygen and Carbon Dioxide

Various cultivars of citrus fruits have unique constructions, such as thick outer skin. These constructions generate gas diffusion resistance between the atmosphere and the fruit, which can limit the gas exchange of O2 and CO2.This has not been sufficiently investigated. This study on seven cultivars of citrus fruit firstly aimed to investigate gas diffusion resistance utilizing the ethane efflux method; secondly, this study aimed to investigate the internal gas concentration of O2 and CO2. As a result, a cultivar of citrus fruit with slimmer outer skin thickness had lower resistance. For the internal gas, a high CO2 concentration in comparison with the atmosphere was observed even in the fruits with the minimum resistance, and no considerable difference was observed among all cultivars, regardless of the gas diffusion resistance value. However, when the fruits were stored at 25 °C for 2 weeks, CO2 gas concentration tended to increase and O2 gas concentration tended to decrease, with an increase in the resistance value. Therefore, when the respiration of citrus fruits is activated at ambient temperature, the self-control system of internal gas concentration can be driven to suppress the respiration which was induced by gas diffusion resistance generated from their construction.

Briquetting of black soldier fly frass as a post-harvest stabilization strategy

ABSTRACT The production–consumption cycle needs a transition towards a circular economy where waste valorization is included. This study investigated briquetting as a stabilization method for black soldier fly frass (BSFF) with faecal matter, pig manure, and poultry manure as the larvae feed. Herein, dried BSFF was pyrolyzed at 350 °C for 2 h to produce biochar then mixed with charcoal dust in equal ratio to produce biobriquettes through densification, with cassava gel (10 wt%) as binder. One-way ANOVA showed statistical significance in carbon, nitrogen, hydrogen, and oxygen. There were significant differences (p < 0.05) between the calorific value, moisture content, ash content, volatile matter, and fixed carbon of the briquettes. The fixed carbon, volatile matter, moisture, and ash content ranged from 29.66 ± 0.86 to 42.01 ± 0.92, 29.26 ± 0.52 to 32.59 ± 0.80, 2.95 ± 0.1 to 5.08 ± 0.04, and 21.48 ± 0.14 to 37.20 ± 0.29, respectively. The calorific value of the produced briquettes ranged from 16.25 ± 0.57 to 20.70 ± 0.53 MJ/kg, which exceeds the minimum requirement of 14.5 MJ/kg recommended for non-woody briquettes. During combustion, concentrations of NOx, N2O, CO, and CO2 varied significantly across the treatments with the acacia charcoal having the highest concentration of CO. Briquetting is a potential stabilization method for frass resulting in waste reduction, bioenergy production, reduced adverse effects of climate change, and enhanced sustainability.

An automated AI-powered IoT algorithm with data processing and noise elimination for plant monitoring and actuating

This article aims to develop a novel Artificial Intelligence-powered Internet of Things (AI-powered IoT) system that can automatically monitor the conditions of the plant (crop) and apply the necessary action without human interaction. The system can remotely send a report on the plant conditions to the farmers through IoT, enabling them for tracking the healthiness of plants. Chili plant has been selected to test the proposed AI-powered IoT monitoring and actuating system as it is so sensitive to the soil moisture, weather changes and can be attacked by several types of diseases. The structure of the proposed system is passed through five main stages, namely, AI-powered IoT system design, prototype fabrication, signal and image processing, noise elimination and proposed system testing. The prototype for monitoring is equipped with multiple sensors, namely, soil moisture, carbon dioxide (CO2) detector, temperature, and camera sensors, which are utilized to continuously monitor the conditions of the plant. Several signal and image processing operations have been applied on the acquired sensors data to prepare them for further post-processing stage. In the post processing step, a new AI based noise elimination algorithm has been introduced to eliminate the noise in the images and take the right actions which are performed using actuators such as pumps, fans to make the necessary actions. The experimental results show that the prototype is functioning well with the proposed AI-powered IoT algorithm, where the water pump, exhausted fan and pesticide pump are actuated when the sensors detect a low moisture level, high CO2 concentration level, and video processing-based pests’ detection, respectively. The results also show that the algorithm is capable to detect the pests on the leaves with 75% successful rate.

A highly-efficient peroxymonosulfate activator using a sewage sludge derived biochar supported cobalt oxide: Mechanism and characteristics

The application of biochar derived from sewage sludge (BS) in Fenton-like reactions for contaminant removal has attracted considerable attention. Herein, a BS-supported Co3O4 (BS-Co3O4) catalyst was synthesized using a simple two-step hydrothermal-calcination process to achieve highly efficient activation of peroxymonosulfate (PMS). The introduction of biochar effectively inhibited the aggregation of Co3O4 and reduced cobalt leaching. Compared to Co3O4, the mesoporous BS-Co3O4 exhibited an 8-fold increase in specific surface area (SSA) to 111.92 m2∙g−1, and a 46 %-66.4 % reduction in crystal plane size. The interaction between biochar and cobalt oxide resulted in several notable enhancements in the BS-Co3O4 composite. Specifically, there was an increase in sp2 carbon content, a 42.69 % rise in capacitance, and a 79.99 % reduction in charge transfer resistance. These improvements contributed to enhanced PMS activation performance. The BS-Co3O4 also contained a higher content of Co(II), sp2 carbon, and oxygen vacancies (OV). Co(II) played a crucial role in the redox reaction, accelerating the formation of SO4•− and 1O2 during the PMS activation process. Additionally, OV acted as electron capture centers, further promoting the generation of 1O2. Evidence from reactive species investigations and electron paramagnetic resonance (EPR) tests indicated that SO4•− and 1O2 were the main reactive radicals for eliminating tetracycline (TC). Based on the identification of TC intermediates, two potential degradation pathways were proposed, and a reduction in intermediate toxicity was observed. Experiments involving interference and repetition demonstrated that the BS-Co3O4 catalyst was stable and reusable. This work provides a solution with low metal leaching, high recycling performance, and safety for antibiotic wastewater treatment.

Effects of hydrogen blending ratios and CO2 on hydrogen embrittlement of X65 steel in high-pressure offshore hydrogen-blended natural gas pipelines

In this study, the effects of hydrogen blending ratios and high CO2 content on hydrogen embrittlement (HE) of offshore natural gas X65 pipeline steel were investigated. In high-pressure hydrogen gas, the impact of hydrogen content on yield strength and tensile strength was minimal. However, the effect on elongation was more significant, with the area decreasing and the HE index increasing until the hydrogen-blended ratio approached 30%, at which point the HE index reached 8.94%. Introducing CO2 into high-pressure hydrogen-rich gas further increased the HE index with high CO2 content. At 40% CO2, the HE index was 2.42 times higher than in high-pressure hydrogen-blended mixtures (30% H2). Additionally, the local fracture morphology transitions from ductile to quasi-cleavage fracture with the addition of CO2 and H2.

Chromium and cobalt in leather: A Danish market survey.

Leather has been a significant source of chromium (Cr) allergy in Denmark since the 1990s. More recently, cobalt (Co) allergy has been identified in leather as a source of allergic contact dermatitis. To measure Cr and Co levels in Danish leather goods. A total of 87 leather samples were collected, all tanned in Europe. Handheld X-ray fluorescence (XRF) device was used to screen for the presence of Cr and Co. The 20 leather samples with the highest concentrations of Co and Co were tested using International Organization for Standardization (ISO)-standards. XRF analysis showed Cr in 78/87 (83.9%) samples and Co in 52/87 (59.7%), with average concentrations of 41 mg/kg (range: 0.0-77 mg/kg) and 0.22 mg/kg (range: 0.0-2.9 mg/kg), respectively. ISO 10195 and 17 075-1 testing identified Cr (VI) in 7 out of 20 samples (1.4; 0.3-4.2 mg/kg), while ISO 17072-1 detected Co in 6 of 20 samples, averaging 3.95 mg/kg (range: 0.22-7.9 mg/kg). Most leather samples contained Cr, which was expected, while Cr (VI) was detectable in seven out of twenty tested samples but only detected in one product above the regulatory limit of 3 mg/kg. A potentially significant concentration was found for Co.

Enhancing CO tolerance in hydrogen oxidation reaction through synergy of surface-modified MoOx with PtRu alloy

Even trace amounts of CO impurities present in low-cost crude hydrogen can severely poison Pt-based catalysts. For proton exchange membrane fuel cells (PEMFCs), the development of hydrogen oxidation reaction (HOR) catalysts capable of enduring CO contamination is of significant economic importance. In this study, we propose a new strategy to synergistically enhance the CO tolerance of PtRu alloys by incorporating MoOx. The MoOx modified on PtRu/C catalysts can initiate the oxidation of CO adsorbed on its surface at potentials as low as 0.125 V. The synergy effect of MoOx and bifunctional PtRu ensures sufficient HOR stability even under hydrogen containing high CO concentrations. The resulting PtRu-MoOx/C catalyst exhibits a 4.6-fold increase in remained HOR current compared to commercial PtRu/C, after two hours in a hydrogen environment containing 10,000 ppm CO. Under typical testing condition of H2/1,000 ppm CO, PtRu-MoOx/C maintains over 80 % of the initial current density even after ten hours, significantly outperforming PtRu/C (30 %) and most previously reported catalysts.

Trace metal evolution of the Late Cretaceous Ocean

The Cenomanian-Turonian boundary (Late Cretaceous) witnessed the last spectacular manifestation of Mesozoic Anoxic Events (OAE 2, ~94 Ma), marked by a prominent carbon isotope excursion (CIE) and burial of organic-matter-rich sediments under high atmospheric CO2 concentrations. But the Late Cretaceous generally was a time of profound environmental change. OAE 2 was preceded by other CIEs, including the Mid-Cenomanian Event (MCE), and was punctuated by a short re‑oxygenation and cooling event (the Plenus Cold Event, PCE). Extensive previous studies, including many trace metal studies, have focused on OAE 2, but there is still debate concerning the degree of drawdown of oceanic trace metal reservoirs during OAE 2, whether this drawdown is global or local, its causes and consequences for ocean ecology. Here, we present records of eight trace metals, over about 5 Myr of the Late Cretaceous, from the Tarfaya Basin in the proto-North Atlantic. The long records from a core preserving a continuous sedimentary succession allow us to set changes occurring across OAE 2 in the broader context of Late Cretaceous, including the lead up to OAE 2. Moreover, the multiple trace metal dataset allows us to broadly investigate the oceanographic setting in the context of recent studies of multiple trace metals in modern organic-rich sediments aimed at refining the proxies.Trace metal enrichments in these organic-rich sediments are discussed on three different timescales. Firstly, comparison of these Late Cretaceous sediments with modern organic-rich sediments are consistent with deposition in an open ocean upwelling margin in the Late Cretaceous, very like the modern Peru or Namibian Margin, although the deep proto-North Atlantic was probably partially restricted. Secondly, in common with previous studies, metal/TOC ratios often show sharp drops in the early part of OAE 2. Thirdly, however, this sharp drop occurs within a framework of pseudo-cyclical variations in metal/TOC, with a period of about 143 ±19 kyr (1 SD), that is a feature of these long records well before OAE 2, including across the MCE. Different metals respond differently to the perturbation in the early part of OAE 2 itself. Simple mass balance considerations suggest that trace metal drawdown with organic carbon must be at least partially compensated by changes in the rate of chemical weathering on the continents, as previously inferred from Li and Ca isotopes. Moreover, changes in the patterns of variation between different metals, as well as covariation of metal/TOC ratios and Os isotopes, hint at changes in the pattern of chemical weathering, most prominently in the contribution of mafic rocks to the chemical weathering flux.

Diagnosis of GHG Emissions in an Offshore Oil and Gas Production Facility

This work presents a diagnosis of greenhouse gas (GHG) emissions for floating production storage and offloading (FPSO) platforms for oil and gas production offshore, using calculation methodologies from the American Petroleum Institute (API) and U.S. Environmental Protection Agency (EPA). To carry out this analysis, design data of an FPSO platform is used for the GHG emissions estimation, considering operations under steady conditions and oil and gas processing system simulations in the Aspen HYSYS® software. The main direct emission sources of GHG are identified, including the main combustion processes (gas turbines for electric generation and gas turbine-driven CO2 compressors), flaring and venting, as well as fugitive emissions. The study assesses a high CO2 content in molar composition of the associated gas, an important factor that is considered in estimating fugitive emissions during the processes of primary separation and main gas compression. The resulting information indicates that, on average, 95% of total emissions are produced by combustion sources. In the latest production stages of the oil and gas field, it consumes 2 times more energy and emits 2.3 times CO2 in terms of produced hydrocarbons. This diagnosis provides a baseline and starting point for the implementation of energy efficiency measures and/or carbon capture and storage (CCS) technologies on the FPSO in order to reduce CO2 and CH4 emissions, as well as identify the major sources of emissions in the production process.

Optimizing Syngas Production from Municipal Solid Waste Gasification: A Dual Reactor Fluidized Bed Study with Steam and CO2 as Gasification Agents

The escalating production of municipal solid waste (MSW) poses significant environmental and health hazards due to air, water, and soil pollution. Utilizing MSW as an energy source through gasification offers a promising solution to mitigate these impacts. This study investigates the gasification of MSW using a Dual Reactor Fluidized Bed, a thermal technology that converts solid substrates into usable gaseous fuels. The primary objective is to optimize the quality of the produced syngas by employing specific gasification agents, namely steam and CO2, and their mixtures. The research examines the effect of these agents on H2/CO ratios across a wide range of low operating temperatures, from 400°C to 700°C, using silica sand as a heat conduction medium between interconnected combustion and gasification reactors. The results demonstrate that the composition of syngas is strongly influenced by gasification temperature fluctuations. Increasing temperatures from 400°C to 700°C correlate with higher concentrations of CO and H2 in the syngas. The use of steam as a gasification agent yields H2 concentrations up to 25%, while transitioning from steam to CO2 leads to a substantial increase in CO composition, reaching 22.73%. Further analysis reveals that the H2/CO ratio decreases from 1,78 with steam and 0.64 with CO2, highlighting the crucial role of gasification agents in syngas quality. This study underscores the potential for optimizing syngas production from MSW by manipulating gasification temperatures and transitioning between different agents (steam, CO2, and their mixtures), resulting in an overall increase in the calorific value of the produced gas. These findings emphasize the opportunity to transform substantial environmental challenges associated with MSW into promising sustainable energy solutions through advanced gasification technologies.

Catalytic enhancement of water gas shift reaction with Cu/ZnO/ZSM-5: Overcoming challenges of CO2 and H2 rich feeds

Water gas shift (WGS) reaction commonly converts CO to CO2 using H2O and produces H2 and CO2 in a catalytic fixed bed reactor. This study aims to develop a Cu/ZnO/ZSM-5 catalyst loaded in water gas shift reactor for converting typical synthesis gas produced from dry reforming of methane (DRM) at medium temperature shift (MTS, 200–350 oC) conditions and for preventing reverse reaction due to high feed concentrations of CO2 and H2. The Cu/ZnO/ZSM-5 catalyst was prepared by impregnation method with lower Cu metal loading of 5, 10, and 15 wt%, respectively, compared to commercial catalysts. The synthesized catalyst was characterized using XRF, XRD, SEM, H2-TPR, NH3-TPD, and TGA. The catalyst activity and stability for the WGS reaction were tested in the fixed bed reactor at atmospheric pressure and temperature of 325 °C. The experimental results show that CO conversion increases with increasing Cu loading. The 15 wt% Cu/ZnO/ZSM-5 catalyst showed the best results with a CO conversion of 35% and a yield of H2 of 36% and showed good stability for 32 h. Based on the TGA, the 15 wt% Cu/ZnO/ZSM-5 catalyst forms a 0.04 g carbon/g catalyst, which is much lower when compared to commercial catalyst (0.105 g carbon/g catalyst). The relative activity of the synthesized catalyst indicates 2.4 times better when compared to commercial catalysts. High concentrations of H2 and CO2 in the feed may initiate side reactions, including reverse WGS, methanation, and carbon formation, which will decrease H2 yield.

MPS@BWO with High Adsorption Capacity for Efficient Photocatalytic Reduction of CO2

Photocatalysis can reduce CO2 to available energy by means of light energy, which is considered to be an effective solution to alleviate energy and environmental problems. In this paper, an MPS@Bi2WO6 composite photocatalyst was prepared by in situ hydrothermal method. BWO grew on the surface of MPS, which increased the CO2 absorption capacity of the photocatalyst and improved the microstructure. Under the synergistic effect of the two aspects, BWS achieves the enhancement of light energy absorption capacity and can effectively excite electron-hole pairs. The transition electrons with high reduction ability migrate to the surface and contact with high concentrations of CO2, achieving efficient CO2 reduction under visible light. Among the photocatalysts in this paper, BWS-1 (BWO: MPS = 1:1) has efficient CO2 gas phase reduction ability under visible light, and the CO yield reaches 29.51 μmol/g. The MPS@BWO photocatalyst is a low-cost and efficient CO2 photoreduction catalyst with broad application prospects.

Geochemical characterization of trace fossil assemblages in spotted marls and limestones of the Lower Jurassic of the Western Carpathians: environmental implications

AbstractThe trace fossils of the spotted limestones and marls from upper Pliensbachian of the Skladaná Skala section, Western Carpathians (Slovakia), are characteristic of Zoophycos ichnofacies preserved in outer shelf deposits. The ichnoassociation is dominated by Lamellaeichnus and Chondrites, while Palaeophycus, Planolites, Teichichnus, Thalassinoides, Trichichnus, and Zoophycos, are less abundant. The presence of relatively large sized traces (reaching a decimetre in horizontal dimension for Thalassinoides and Zoophycos) and continuously well bioturbated deposits point to well oxygenated shallow zone (mixed layer) and deeper part of stiffed substrate of the transitional layer of bottom substrate up to the first tens of centimetres to depth. A first tier (tier I) corresponds to the shallowest sediment occupied by Bathysiphon tests and other epifaunal body fossils. The tier II is characterized by shallow infaunal burrows of deposit feeders (Planolites) and permanent dwelling, open burrows (Palaeophycus, Thalassinoides) located in a Ca-rich sediment (corresponding to CaCO3). The tier III is dominated by deposit feeders (Lamellaeichnus, Teichichnus) that burrowed stiff Ca-rich sediment below the redox boundary. Trace fossils of tier III are rich in fine siliciclastics (high content in Si, Al, K mainly associated to clays) and pyrite framboids (enrichment in Fe, S and Co). The deposit-feeders of tier III maintain connection to the sediment-water interface. Tier IV (Zoophycos, Teichichnus and large Chondrites), and deepest infaunal forms of the tier V. (Trichichnus, Pilichnus and tiny forms of Chondrites) comprises trace fossils commonly rich in pyrite framboids with relatively high content of Fe, S, and Co, congruent with chemosymbiotic behaviour commonly inferred for Chondrites, Trichichnus, and the organic-matter storage of Zoophycos.

Quadratic-soliton-enhanced mid-IR molecular sensing

Optical solitons have long been of interest both from a fundamental perspective and because of their application potential. Both cubic (Kerr) and quadratic nonlinearities can lead to soliton formation, but quadratic solitons can practically benefit from stronger nonlinearity and achieve substantial wavelength conversion. However, despite their rich physics, quadratic cavity solitons have been used only for broadband frequency comb generation, especially in the mid-infrared. Here, we show that the formation dynamics of mid-infrared quadratic cavity solitons, specifically temporal simultons in optical parametric oscillators, can be effectively leveraged to enhance molecular sensing. We demonstrate significant sensitivity enhancement while circumventing constraints of traditional cavity enhancement mechanisms. We perform experiments sensing CO2 using cavity simultons around 4 μm and achieve an enhancement of 6000. Additionally, we demonstrate large sensitivity at high concentrations of CO2, beyond what can be achieved using an equivalent high-finesse linear cavity by orders of magnitude. Our results highlight a path for utilizing quadratic cavity nonlinear dynamics and solitons for molecular sensing beyond what can be achieved using linear methods.

Transport characteristics and dispersion evolution of CO-NOx mixture exhaust for shuttle movement emission in short-wall continuous mining face.

To investigate the evolution of CO and NOx pollution in the exhaust gas from diesel-powered shuttles under the double lane ventilation system of short-walled continuous mining face, this article uses a combination of numerical simulation and field tests to numerically simulate and analyze the pollution transport law of CO and NOx emitted from the shuttles at three locations: heading tunnel, contact alley and supporting tunnel. The results show that when the shuttle car in heading tunnel, the CO and NOx discharged from the shuttle discharge port move toward the exit of the tunnel at an average speed of 1.25m/s. The high CO and NOx concentration area appears at the discharge port, with the highest CO volume fraction of 82.5ppm and the highest NOx volume fraction of 28.25ppm. When the shuttle car at the contact alley, by the two walls of the alleyway on the gas diffusion space extrusion effect, CO and NOx in X = 37.5m ~ 42.5m range gathered, appear high CO and NOx concentration band. When the shuttle car in supporting tunnel, it is hindered by the belt conveyor within the range of X = 63m ~ 64.5m, so CO and NOx fail to spread to the outlet of the roadway in time and pile up at the bottom of the roadway. The highest CO volume fraction is 76.25ppm and the highest NOx volume fraction is 28.28ppm.According to the different positions of the car, the pollution areas of CO and NOx exceeding the specified threshold (24ppm, 2.5ppm) were divided, and the distribution characteristics of CO and NOx pollution were obtained by quantitative analysis through curve fitting, which provided a theoretical basis for the prevention and control of harmful substances emitted by fuel power equipment in underground environment.

Recent advances in adaptation genomics in fumarole fields, an overlooked extreme environment.

Extreme environments and plants thriving in them, known as extremophytes, offer promising platforms for studying the diverse adaptive mechanisms that have evolved in plants. However, research on adaptation to extreme environments is still limited to those environments where model species or their relative can survive. Fumarole fields, an extreme environment often overlooked, are characterized by multi-hazardous abiotic stressors, including atmospheric contamination (high concentration of H2S, SO2, and CO2), high soil temperature (~60℃), and strong soil acidification (pH=2-3). These conditions make fumarole fields a rich source for studying stress tolerance mechanisms in plants. In this review, we highlight the recent ecological, physiological, and genomic advances involved in fumarole field adaptation, and discuss the forward avenues. The studies outlined in this paper demonstrate that the extreme levels of abiotic stressors found in fumarole fields make them unparalleled field laboratories for studying the unknown stress tolerance mechanisms, warranting further genomic assessments. Some studies succeeded in identifying genes associated with fumarole field adaptation and shedding light on evolutionary implications; however, they have also encountered challenges such as limited genome resources and high genetic differentiation from related species and/or neighboring populations. To overcome such difficulties, we propose integrating ecophysiological and genomic approaches, drawing from the recent studies in other extreme environments. We expect that further studies in the fumarole fields will contribute to broadening our general knowledge of the limits of life.

Effects of different gas energy shares on combustion and emission characteristics of compression ignition engine fueled with dual-fossil fuel and dual-biofuel

This study systematically investigates the energetic and environmental performance of a four-cylinder compression ignition (CI) engine fueled by gaseous and liquid dual-fuel (D-F), utilising various combinations of fossil fuels and biofuels. Fossil diesel or pure hydrotreated vegetable oil (HVO) – new generation biodiesel was used as the pilot fuel to initiate ignition of the gaseous fuel. The gaseous fuels used were natural gas (NG) and simulated biogas (BG) composed of 60 % NG and 40 % CO2 by volume, injected into the intake manifold at varying gas energy shares (GES) of 40 %, 60 %, and 80 %. Reference values were provided from conventional combustion of diesel fuel and HVO. This study used numerical simulations to examine indicators of combustion, such as ignition delay, premixed combustion phase, diffusion combustion phase, and subsequent combustion phases, across diverse fuel combinations. Within lean dual-fuel mixtures, when the gaseous fuel remained below the flammability threshold, the peak pressure was diminished, the rate of pressure rise was lowered, and the combustion process decelerated, facilitating a faster transition to the diffusion phase. As the engine load and GES increased, the excess air ratio decreased, bringing the air-fuel mixture closer to the flammability limit, which in turn altered the combustion characteristics and engine performance trends. Combustion with increasing BG content showed partial similarities to that of NG, though the high CO2 content in biogas was found to suppress combustion, functioning similarly to an exhaust gas recirculation. The study also compared brake thermal efficiency (BTE), as well as specific emissions of CO, HC, NOX, CO2, and smoke for the D-F engine operation against pure diesel and HVO at different loads and GES levels. Additionally, an overlimit function was used to assess the emission levels of D-F engines with reference to emission limits.

Analysis of the Interplay between Indoor Air Quality and Thermal Comfort in University Classrooms for Enhanced HVAC Control

While aspects of indoor environmental quality, such as thermal comfort, indoor air quality (IAQ), acoustic, and visual comfort, are usually studied separately, their interactions are crucial yet often overlooked. Understanding how these factors influence each other is essential for a comprehensive perception of the indoor environment. This paper investigates the relationship between indoor air quality (IAQ) and thermal comfort using an extensive field investigation conducted in university classrooms during the heating season, collecting 712 samples of subjective responses correlated with environmental measurements. Key findings reveal significant correlations between subjective responses related to the thermal environment and those related to air quality. Perceived control over the thermal environment shows stronger correlations with IAQ responses than with thermal responses, particularly with perceived ventilation (r = 0.41), COVID-19 risk (r = 0.28), and air quality (r = 0.28). Additionally, environmental parameters demonstrate stronger correlations with thermal responses than with IAQ responses. Higher CO2 concentration is associated with increased thermal sensation and decreased thermal preference and perceived control. Conversely, IAQ responses remain relatively stable with changes in indoor operative temperature. The difference between the operative temperature to which the occupants are exposed and their expressed neutral temperature widens as CO2 concentration rises, indicating a reduced adaptive capacity of occupants which is associated with increasing CO2 levels. These insights are crucial for providing HVAC system management strategies that consider the interaction between different aspects of IEQ, aiming to improve occupants’ well-being and reduce energy consumption.

Research on the effect of CO2 and H2O on NO reduction of biomass char by the equivalent characteristic spectrum method via an on-line mass spectrometer

Despite extensive experimental studies on NO reduction by biomass char, the impact of high concentrations of CO2 and H2O on the NO-char reaction remains insufficiently understood. This study investigates the effects of CO2, H2O, and CO2+H2O atmospheres on NO reduction by biomass char in a micro-fluidized bed (MFB). Experiments were conducted at 900 °C, with CO2 concentrations ranging from 20 % to 80 % and H2O concentrations from 10 % to 40 %. The results show that increasing concentrations of CO2 and H2O accelerate the NO reduction rate. However, under high CO2 and H2O concentrations, both the maximum NO reduction efficiency and the mass consumption of nitrogen decrease. In a CO2 atmosphere, nearly all nitrogen from NO converts to N2, but this conversion efficiency declines in the presence of H2O. When both CO2 and H2O are present, H2O predominantly governs the NO consumption rate. Additionally, the apparent activation energy for NO reduction is higher in an H2O atmosphere compared to a CO2 atmosphere at similar concentrations.

The combustion mechanism of aluminium in the steam/carbon dioxide mixed atmosphere

AbstractThe ignition and combustion characteristics of aluminium (Al) in the steam/carbon dioxide (H2O/CO2) mixed atmosphere were calculated by using a close homogeneous catch reactor and premixed laminar flame‐speed of CHEMKIN‐PRO. The effects of initial reaction temperature and H2O/CO2 ratios on the system temperature, products, and ignition delay time were explored. The main reaction paths were analyzed by the temperature sensitivity. Al (l) entered the system with a pronounced phase transition and only one heating stage, but there are two heating stages in the Al (g) system. The reaction of Al in the H2O/CO2 mixed atmosphere has a positive effect on the ignition delay time of the system. The high contents of CO2 in the H2O/CO2 mixed atmosphere can increase the maximum temperature of system and decrease the ignition delay time. Temperature sensitivity analysis shows that AlO, Al2O, and AlOH are important intermediate products, and Al2O2 is the main substance that produces Al2O3. The dominant reaction path is Al → AlOH→AlO → Al2O → Al2O2 → Al2O3. In addition, when the initial temperature was 2300 K, the laminar flame velocity was calculated to reach 35.6 m/s.