Reduction Of CO2 Concentration Research Articles

A Numerical and Experimental Study to Compare Different IAQ-Based Smart Ventilation Techniques

Maintaining indoor environmental quality in residential buildings is essential for occupants’ comfort, productivity, and health, with effective mechanical ventilation playing a key role in removing or diluting indoor pollutants. A two-week experimental campaign was conducted in an apartment in Lyon, France, known for its poor urban air quality, assessing temperature, relative humidity, CO2, and PM2.5 concentrations. A model verification study was performed to compare experimental measurements against numerical modeling in the living room and bedroom, leading to errors in the accuracy of the sensors. In addition, this study also investigates the impact of different ventilation strategies on indoor air quality. This research evaluates a baseline mechanical exhaust-only ventilation approach with constant air volume against two innovative smart ventilation approaches: mechanical exhaust-only ventilation with humidity control and mechanical exhaust-only ventilation with room-level CO2 and humidity control. A key contribution of this research is the novel coupling of multizone simulation models (DOMUS and CONTAM) with a CFD tool to refine pressure coefficients on the building façade, which enhances the accuracy of indoor air quality predictions. The smart ventilation strategies showed improvements, including a 20% reduction in CO2 concentration and a 5% reduction in the third-quartile PM2.5 concentration, highlighting their effectiveness in enhancing ventilation and pollutant dilution. This research provides valuable insights into advanced ventilation strategies and modeling techniques in urban environments.

Consecutive annual mowing reduces soil respiration and increases the proportion of autotrophic component in a meadow steppe

BcakgroundSoil respiration (Rs), as the second largest CO2 emissions of terrestrial ecosystems, is sensitive to disturbance and consequent environmental changes. Mowing is strategically implemented as an management approach and has the potential to influence carbon cycling in meadow steppes. However, it remains unclear how and why Rs and its heterotrophic (Rh) and autotrophic (Ra) components respond to consecutive mowing and associated ecological consequences. Here, we conducted a field mowing experiment in a meadow steppe in 2018 and monitored Rs, Rh, and Ra from 2019 to 2022.ResultsWe observed a significant reduction in Rs by 4.8% across four years, primarily attributed to a decrease in Rh. This decline in Rs intensified over time, indicating an accumulative effect of mowing. In addition, mowing induced an generally increasing Ra/Rs ratio over the experimental years with a simultaneous increase in the ratio of belowground to aboveground biomass (BGB/AGB). Furthermore, structural equation modeling results revealed that the decline in Rs was largely ascribed to reduced microbial biomass carbon (MBC) under mowing, while the increased Ra/Rs was primarily explained by the enhanced BGB/AGB. Partial regression analysis suggested that the biotic factor of microbial biomass dominated changes in soil respiration induced by mowing rather than abiotic soil temperature.ConclusionsOur findings showed that consecutive mowing decreased Rs and raised Ra/Rs in meadow steppe by decreasing plant biomass and altering the proportion of biomass allocation. This observed decline in Rs would help to reduce CO2 concentration in atmosphere as well as alleviate global warming. However, considering the concurrent lower microbial biomass, the potential positive impacts of mowing on climate and ecosystem function should be reevaluated in future grassland management practices.

Hybrid solvent loop CO2 capture process for zero-emission hydrogen production

Natural gas reforming with CO2 capture is expected to play a crucial role in producing low-carbon hydrogen under the net-zero emission scenario. This work focuses on optimizing the CO2 capture processes for zero-emission hydrogen production, targeting an ultra-high CO2 capture ratio of 99.9 % from the shifted syngas. We present a novel hybrid solvent loop CO2 capture process that enhances capture efficiency by overcoming the inherent trade-off between CO2 absorption kinetics and capacity in conventional processes. This is achieved by utilizing two independent solvent loops, each operating within its optimal performance range. In the lower section of the absorber, a high-capacity solvent, aqueous potassium carbonate, is used to leverage the high CO2 partial pressure. In the upper section, a fast-kinetic solvent, aqueous monoethanolamine, is employed to reduce CO2 concentration to 100 ppm. The conventional process, split-flow process with a multi-pressure stripper, and the hybrid solvent loop process are modeled in Aspen Plus® and compared. Our results demonstrate that the proposed hybrid solvent loop configuration outperforms conventional methods, significantly reducing the CO2 regeneration duty by 25 % and total equivalent work by 16 %. This process enhances the feasibility of low-carbon hydrogen production and supports the goal of achieving net-zero emissions.

Effect of CO2 Concentration on the Performance of Polymer-Enhanced Foam at the Steam Front.

This study examines the impact of CO2 concentration on the stability and plugging performance of polymer-enhanced foam (PEF) under high-temperature and high-pressure conditions representative of the steam front in heavy oil reservoirs. Bulk foam experiments were conducted to analyze the foam performance, interfacial properties, and rheological behavior of CHSB surfactant and Z364 polymer in different CO2 and N2 gas environments. Additionally, core flooding experiments were performed to investigate the plugging performance of PEF in porous media and the factors influencing it. The results indicate that a reduction in CO2 concentration in the foam, due to the lower solubility of N2 in water and the reduced permeability of the liquid film, enhances foam stability and flow resistance in porous media. The addition of polymers was found to significantly improve the stability of the liquid film and the flow viscosity of the foam, particularly under high-temperature conditions, effectively mitigating the foam strength degradation caused by CO2 dissolution. However, at 200 °C, a notable decrease in foam stability and a sharp reduction in the resistance factor were observed. Overall, the study elucidates the effects of gas type, temperature, and polymer concentration on the flow and plugging performance of PEF in porous media, providing reference for fluid mobility control at the steam front in heavy oil recovery.

Experimental for depicting the influence upon gaseous emissions of an Otto engine by using hydrogen as fuel addition

Abstract Due to the higher pollution restrictions implemented globally upon the internal combustion engines, for new but also older vehicles, suitable solutions must be found, for solving major, attested incriminations concerning pollution. The present research focuses on the possibility of the reduction of the emission concentration values emitted by a classic Otto spark ignition engine (Otto ICE), by adding hydrogen to the normal used fuel (gasoline). The hydrogen is generated via a water electrolytic conversion technology, applied, in symbiosis with the internal combustion engine and it is known as hydrogen air (HHA). The hydrogen quantity, as resulted from the HHA generating process and fuelled into the engine, represents 10% (by volume) of the total volume of the intake capacity. Being directly correlated to the stoichiometric ratio used to create the fuel mixture, the intake of hydrogen is finally controlled; therefore, the total calorific power of the new fuel mixtures is increasing by approximate 30%. All the measurements have been achieved in a lab using certified and approved gas analyzers and measurement instruments. The novelty of the research consists of (i) presenting results of measurements with the gas analyzer, one at an engine speed of 800 RPM and the second at 2000 RPM using only gasoline as fuel (normal or standard fuel); (ii) concluding of comparative measurements at the same engine speeds, but with addition of hydrogen in the fuel mixture. Since carbon dioxide makes up the vast majority of greenhouse emissions, the results indicate also a more reduced CO2 concentration in the exhaust. One presents that the electrolytic convertor is capable of producing 1800 litters of HHO gas from 1 litre of water. By upgrading the oxyhydrogen system, one succeeded to produce more HHO gas and replacing the amount of conventional fuel. As conclusions one demonstrated that lower emission values can be obtained with the addition of hydrogen air (HHA).

Inlet injection as an alternative, simplified method of hydrogen application in a miniature gas turbine

Hydrogen-powered gas turbines have great potential, because, among other things, they allow the elimination of the use of fuels containing carbon in their composition, which involves the elimination of CO2 emissions, which are a product of the combustion of hydrocarbon fuels. The paper presents the results of experimental research conducted on a miniature gas turbine co-powered by hydrogen gas. The aim of the research was to demonstrate the impact of the addition of hydrogen on the operation of the unit and exhaust gas emissions during hydrogen application in a way that does not require engine modification. This was accomplished by applying hydrogen gas through the turbine inlet. Hydrogen gas accounted for up to 0.91% of the total volume of gas flowing through the compressor, which resulted in hydrogen contributing almost 10% of the energy supplied to the engine in the form of fuel. The research focused on measuring fuel consumption, thrust, and temperature, as well as the composition of exhaust gases. The emission of carbon monoxide, nitrogen oxides and the concentration of oxygen and carbon dioxide were measured. The addition of hydrogen resulted in a reduction of the total mass of fuel consumed by over 18%. It led to a significant decrease in the temperature behind the combustion chamber with an increase in the amount of hydrogen applied. The addition of hydrogen also resulted in a reduction in CO2 concentration in exhaust gases by more than 30%, but at the same time, an increase in NOx emissions was recorded. The obtained results were compared with the results of tests presented in the literature, in which hydrogen was supplied to units of analogous structure in a classical way, i.e. directly to the combustion chamber.

Human Circulatory/Respiratory-Inspired Comprehensive Air Purification System.

The circulatory and respiratory systems in humans are marvels of biological engineering that exhibit competence in maintaining homeostasis. These systems not only shield the organism from external contaminants but also orchestrate the vital gases via the bloodstream to sustain cellular respiration and metabolic processes across diverse tissues. It is noticed that spaces inhabited encounter challenges akin to those of the human body: protecting the indoor air from external pollutants while removing anthropogenic byproducts like carbon dioxide (CO2), particulate matters (PM), and volatile organic compounds (VOCs) tooutside. A biomimetic approach, composed of a microbubble-based gas exchanger and circulating liquid inspired by alveoli, capillary beds, and bloodstream of the human circulatory/respiratory system, offer an innovative solution for comprehensive air purification of hermetic spaces. Circulatory/respiratory-inspired air purification system (CAPS) ensure both continuous removal of PM and exchange of gas species between indoor and outdoor environments to maintain homeostasis. The effectiveness of this system is also supported by animal behavior experiments with and without CAPS, showing an effect of reducing CO2 concentration by 30% and increasing mice locomotor activity by 53%. CAPS is expected to evolve into robust and comprehensive air purification schemes through the networked integration of plural internal and external environments.

CARBON SEQUESTRATION FOR AGROSILVICULTURE AGROFORESTRY PRACTICES: PRELIMINARY RESULTS FROM THREE INVESTIGATED VILLAGES IN UTTARADIT PROVINCE, NORTHERN, THAILAND

ARTICLE HIGLIGHTS- Agroforestry boosts carbon storage, reducing greenhouse gas emissions significantly.- Diverse tree-based farming enhances biodiversity, soil health, and climate resilience.- Carbon sequestration in agroforestry supports sustainable agriculture and environmental balance.- Agroforestry practices mitigate climate change by storing carbon in trees and soil.- Combining trees with crops provides multiple ecological and economic benefits.ABSTRACTOne of the processes for compensating greenhouse gas emissions is atmospheric carbon removal and storage in the terrestrial biosphere. Agricultural systems to which trees are returned for careful management alongside crops and animals are thought to be substantial CO2 sinks. People are increasingly realizing the importance of agroforestry because it is good for the environment and farming. In this study, total carbon pools from the aboveground biomass carbon (ABGC), forest floor carbon (FFC), and soil organic carbon (SOC) were investigated and carbon storage data for some agroforestry practices native to Uttaradit in northern Thailand were analyzed. The role of these carbon pools in reducing CO2 concentrations in the atmosphere was also discussed. The results showed differences in the total carbon stock sourced from traditional agroforestry (TAF), applied agroforestry (AAF), and developed agroforestry (DAF). The total carbon store (ABGC + TFFC + SOC) of TAF, AAF, and DAF was 267.05 Mg C/ha, 226.48 Mg C/ha, and 324.70 Mg C/ha, respectively. SOC contributed 47.64%, 54.26%, and 44.81% and ABGC contributed 22.75%, 19.79%, and 23.90% to the total carbon stock in TAF, AAF, and DAF, respectively. The CO2 adsorption was 979.27 Mg CO2/ha, 830.50 Mg CO2/ha, and 1,190.6 Mg CO2/ha in TAF, AAF, and DAF, respectively. It is clear that agroforestry systems serve as carbon sinks in terrestrial ecosystems. Although the comparison of agroforestry practices and other land use types is important for carbon mitigation and the implementation of the “Land Use, Land Use Change, and Forestry” concept for CO2 sinks, it is also crucial to compare the potential of carbon sequestration in different CO2 pools.

Impact of windcatcher on the thermal comfort and indoor air quality in a modern house

ABSTRACT As the residential construction sector grows more quickly than other building sectors in Oman and other GCC nations, the proportion of total energy consumption in housing rises. The native inhabitants have implemented various strategies to enhance the thermal conditions in structures. The windcatcher was one of those methods used in hot climates when it was vital to achieve thermal comfort. Computational Fluid Dynamics (CFD) is used in this research to find the best orientation of a windcatcher attached to a modern house in Muscat. In addition, thermal comfort and indoor air quality based on CO2 concentration were also studied. This paper tries to fill the gap in research on using windcatchers with modern houses and find the best design for such windcatchers. Results indicate that placing a windcatcher with a rotation of 30° from the north towards the east will give better air velocity than a windcatcher with angles of 0°, 45°, and 60°. Furthermore, it was found that the windcatcher improved the Predicted Mean Vote (PMV) by 34% and the Predicted Percentage of Dissatisfaction (PPD) by 48%. In addition, a modern house with a windcatcher reduced CO2 concentration by more than 5% compared to a house without a windcatcher.

Small soil wetted proportion and emitter flow rate of drip irrigation enhance potato yield by improving soil water and aeration in the sandy loam in arid Northwest China

Creating an ideal soil microclimate through appropriate drip irrigation management practices is crucial for enhancing potato production. Field experiments were conducted during 2021 and 2022 in Wuwei, Gansu Province, Northwest China, with two soil wetted proportion levels (P1: 35 %, and P2: 55 %) and three emitter flow rates (F1: 1.3 L/h, F2: 2.0 L/h, and F3: 3.0 L/h). Results showed that for the same soil wetted proportion, soil water content was reduced in the 0–20 cm soil layer and increased in the 20–40 cm for F1 compared to F2 and F3, with no differences in the 40–60 cm depth. During the tuber initiation and bulking stages, the soil wetted proportion P1 increased soil oxygen saturation by 2.8 % and 0.7 % and reduced CO2 concentration by 26.7 % and 19.2 % in 2021 and 2022, respectively, compared to P2 in the 20–40 cm soil layer. The emitter flow rate F1 exhibited significantly greater soil oxygen (0.7–4.6 %) and lower CO2 concentration (16–46 %) than F2 and F3 in the 0–20 cm. Soil oxygen was significantly higher (0.5–2.1 %) and CO2 concentration was significantly lower (10–39 %) in the 20–40 cm in F1 than in F3. In the 0–40 cm soil layer, both the highest soil oxygen concentration and lowest CO2 concentration were observed for the P1F1 combination. The soil wetted proportion P1 increased average yield by 5.6 % in 2021 and 11.9 % in 2022 compared to P2, while F2 and F3 reduced yield by 2.4 % and 4.6 % in 2021, 4.1 % and 13.8 % in 2022 compared to F1. The soil wetted proportion P2 promoted source growth compared to P1 but limited sink expansion. Source capacity, sink growth, and average tuber growth rates decreased from F1 to F3. Overall, the 35 % soil wetted proportion and 1.3 L/h emitter flow rate are recommended for potato cultivation in sandy loam. This study clarified the importance of coordinating soil water and aeration by drip irrigation management to improve potato tuber production.

Impact of ventilation system retrofitting on indoor air quality in a single-family building

Due to prolonged human occupancy within indoor environments, the quality of indoor air holds significant importance. This study evaluates the impact of retrofitting a ventilation system from natural to mechanical on indoor air quality (IAQ) in a bedroom during heating seasons in 2017/18 and 2020/21. Measurements were conducted before and after modernization to assess CO2 concentrations, temperature, humidity, particulate matter (PM) and bacterial and fungal aerosols levels indoors and outdoors. Results show a significant decrease in CO2 concentration (from 1000 ± 240 ppm to 806 ± 165 ppm) and relative humidity (from 53.0 ± 3.6 % to 28.2 ± 4.1 %) post-modernization. Notable reduction in CO2 concentrations averaging 20 % was recorded, thereby elevating air quality category from IDAIII to IDAII. Additionally, the study determined the infiltration coefficient for PM2.5, which increased from 0.48 under natural ventilation to 0.63 after retrofitting. PM2.5 concentrations increased indoors (from 23.49 ± 11.21 μg/m3 to 56.68 ± 13.47 μg/m3) due to higher infiltration rates with mechanical ventilation. Bioaerosol measurements indicate fluctuating concentrations, with bacterial aerosols peaking in the evening. The use of mechanical ventilation led to increased transport and dispersion of bacterial bioaerosols indoors. In contrast, this was not observed for fungal aerosols. Additionally, the study highlights limitations in ventilation filtration efficiency and recommends the installation of PM2.5 sensors to regulate airflow during periods of high outdoor PM2.5 concentrations. Overall, while mechanical ventilation improved some IAQ parameters, it posed challenges in controlling particulate matter infiltration, emphasizing the need for comprehensive ventilation strategies to ensure indoor air quality and occupants' well-being.

Seamless reconstruction and spatiotemporal analysis of satellite-based XCO2 incorporating temporal characteristics: A case study in China during 2015–2020

Carbon dioxide (CO2) is a crucial greenhouse gas, and its concentration and spatiotemporal characteristics are among the principal sources of uncertainty in global warming assessments. Satellite remote sensing is a widely adopted, high-accuracy approach for monitoring atmospheric CO2. However, limited swath width and cloud cover significantly reduce satellite observation coverage. This study addresses the temporal changes in CO2 concentration and utilizes a machine learning-based fusion of multiple data sources to generate daily, full-coverage, 0.05° spatial resolution column-averaged CO2 concentration data for China from 2015 to 2020. Ten-fold cross-validation yielded a determination coefficient R2 of 0.97, root mean square error of 0.92 ppm, and mean absolute error of 0.59 ppm. Compared to other datasets, this study’s dataset exhibits superior accuracy and spatiotemporal detail. Using the produced CO2 concentration data in this study, we conducted a spatiotemporal analysis of CO2 concentrations in China. The results indicate that, in general, the Western region exhibits a higher growth rate in CO2 concentration than the Eastern and Central regions, with areas of lower CO2 concentration experiencing higher growth rates while regions with higher CO2 concentration have lower growth rates. Moreover, the highest increase in CO2 concentration occurred in 2016, with a substantial decrease in CO2 concentration growth observed in 2018. Notably, the reduction in CO2 concentration in the Qinghai-Tibet Plateau region during the summer is considerably smaller than in other regions, possibly due to atmospheric transport from the Indian Peninsula.

Computational design of isotropic and anisotropic ultralow thermal conductivity polymer foams

Current state-of-the-art commercial polymer thermal insulation foam exhibits a thermal conductivity of 24 mW⸳m−1⸳K−1 (equivalently thermal resistivity of R-6/in.), similar to that of static air. To further optimize building energy efficiency, achieving even lower thermal conductivity is needed, which is, however, highly challenging. This paper presents computational evidence that demonstrates the feasibility of achieving an ultra-low thermal conductivity of less than 14.4 mW⸳m−1⸳K−1 (equivalently R-10/in.) using isotropic and anisotropic foam cell designs. For the isotropic design, we have identified analytical effective medium approximation (EMA) models within the accuracy of ±5% as finite element analysis (FEA) in predicting the effective thermal conductivity of foams with various porosities and filler gases. For the anisotropic design, we have developed and validated new EMA models against FEA in predicting the effective thermal conductivity of general anisotropic cuboids and Voronoi foams. For both isotropic and anisotropic designs, the design spaces for 18, 16, and 14.4 mW⸳m−1⸳K−1 (equivalently R-8, R-9 and R-10/in.) using various filler gases are obtained. It is found that polymer foams can be improved to achieve ultralow thermal conductivity by reducing CO2 concentration, reducing radiation, increasing porosity, and using anisotropic pore geometry. These findings contribute to the development of highly efficient thermal insulation materials, enhancing building energy efficiency and promoting sustainable construction practices.

Investigation into the photothermal catalytic CO2 decomposition over CeO2 with different morphologies: Behaviors of oxygen vacancies

CO2 is a viable renewable energy source, as global CO2 emissions are perennially increasing. The decomposition of CO2 to CO and O2 through high-temperature cracking of metal oxides via a two-step thermochemical cycle has been an effective strategy to reduce CO2 concentrations in the atmosphere. However, this thermochemical cycle requires a high reaction temperature (1273 K). Hence, in this study, we investigated photothermal CO2 decomposition over three CeO2 catalysts with different morphologies: porous CeO2 nanosheets (2D-CeO2), cubic-shaped CeO2 (C-CeO2), and octahedral CeO2 (O-CeO2). The photothermal synergistic effect eliminated the necessity of high temperatures, where light illumination increased the generation of oxygen vacancies and electron transfer to promote CO2 decomposition. The maximum rate of CO production by 2D-CeO2 at 250 °C was 69 μmol g-1h−1, which is significantly higher than those of O-CeO2 (47 μmol g-1h−1) and C-CeO2 (19 μmol g-1h−1). However, no activity was observed in dark conditions, even at 250 °C. In-situ DRIFTS, quasi in-situ EPR, XPS, and Ar-TPD experiments revealed that light irradiation promotes the production of oxygen vacancies on the catalyst surface and generates the intermediate CO2•− species, which cleave the C=O bonds and CO2 conversion, while temperature promotes the adsorption of CO2 on the catalyst surface and facilitates electron transfer. DFT calculations revealed the differences in oxygen vacancy formation and CO2 adsorption among various exposed crystal facets of CeO2. These findings provide new avenues for CO2 decomposition based on the adsorption and activation of CO2 on metal oxide surfaces and the low-temperature synergistic photothermal effect.

An integrated experimental and CFD analysis of ceiling-fan-integrated air conditioning system: Indoor air quality and air velocity

The Ceiling-Fan-Integrated-Air Conditioning (CFIAC) represents an innovative HVAC design, which involves directing supply air towards the vicinity of ceiling fans, facilitating the mixture and distribution of air within a room. By eliminating the need for terminal ductwork and diffusers, CFIAC offers an efficient cooling solution for occupants. This study employs experimental and CFD methodologies to assess various parameters, including airflow, air pollution, and temperature related to this system. Experimental tests were conducted in a controlled chamber, with the lowest inlet air velocity and the temperature, where supply air was projected from a high-sidewall vent directly towards a ceiling fan's centerline. Different operational conditions of the ceiling fan were examined (off, Level 2 and Level 4 downwards, and Upwards). Carbon dioxide (CO2), employed as a tracer gas, was released near a thermal manikin at three distinct locations within the chamber: the middle, lower left, and upper right, and the corresponding CO2 concentration distributions were evaluated. Additionally, air velocity measurements were collected and analyzed. The effectiveness of ventilation and potential health exposure was quantified using the age of air and intake fraction (IF) metrics. The findings indicate that operating the fan at Level 4 with downward airflow enhances air velocities and heat loss while reducing CO2 concentrations and age of air by an average of 14 % and 4 min, respectively. Moreover, the IF values for Level 4 operations, both downward and upward, were marginally lower compared to those recorded for Level 2 downward and fan-off scenarios, suggesting a decreased risk of cross-infection.

Introducing sodium lignosulfonate as an effective promoter for CO2 sequestration as hydrates targeting gaseous and liquid CO2

Hydrate-based CO2 sequestration (HBCS) emerges as a promising solution to sequestrate CO2 as solid hydrates for the benefit of reducing CO2 concentration in the atmosphere. The natural conditions of high-pressure and low-temperature in marine seabed provide an ideal reservoir for CO2 hydrate, enabling long-term sequestration. A significant challenge in the application of HBCS is the identification of an environmental-friendly promoter to enhance or tune CO2 hydrate kinetics, which is intrinsically sluggish. In addition, the promoter identified should be effective in all CO2 sequestration conditions, covering CO2 injection as gas or liquid. In this study, we introduced sodium lignosulfonate (SL), a by-product from the papermaking industry, as an eco-friendly kinetic promoter for CO2 hydrate formation. The impact of SL (0–3.0 wt.%) on the kinetics of CO2 hydrate formation from gaseous and liquid CO2 was systematically investigated. CO2 hydrate morphology images were acquired for both gaseous and liquid CO2 in the presence of SL for the explanation of the observed promotion effect. The promotion effect of SL on CO2 hydrate formation is optimal at 1.0 wt.% with induction time reduced to 5.3 min and 21.1 min for gaseous and liquid CO2, respectively. Moreover, CO2 storage capacity increases by around two times at 1.0 wt.% SL, reaching 85.1 v/v and 57.1 v/v for gaseous and liquid CO2, respectively. The applicability of SL as an effective kinetic promoter for both gaseous and liquid CO2 was first demonstrated. A mechanism explaining how SL promotes CO2 hydrate formation was formulated with additional nucleation sites by SL micelles and the extended contact surface offered by generated gas bubbles or liquid droplets with SL. The study demonstrates that SL as an effective promoter for CO2 hydrate kinetics is possible for adoption in large-scale HBCS projects both nearshore and offshore.

Numerical Simulation of Hydrogen–Coal Blending Combustion in a 660 MW Tangential Boiler

With the adjustment of energy structure, the utilization of hydrogen energy has been widely attended. China’s carbon neutrality targets make it urgent to change traditional coal-fired power generation. The paper investigates the combustion of pulverized coal blended with hydrogen to reduce carbon emissions. In terms of calorific value, the pulverized coal combustion with hydrogen at 1%, 5%, and 10% blending ratios is investigated. The results show that there is a significant reduction in CO2 concentration after hydrogen blending. The CO2 concentration (mole fraction) decreased from 15.6% to 13.6% for the 10% hydrogen blending condition compared to the non-hydrogen blending condition. The rapid combustion of hydrogen produces large amounts of heat in a short period, which helps the ignition of pulverized coal. However, as the proportion of hydrogen blending increases, the production of large amounts of H2O gives an overall lower temperature. On the other hand, the temperature distribution is more uniform. The concentrations of O2 and CO in the upper part of the furnace increased. The current air distribution pattern cannot satisfy the adequate combustion of the fuel after hydrogen blending.

Light Spectral Regimes under a Closed and Dense Canopy: Evidence from Mesua ferrea Trees for Human Comfort in Urban Landscape Planning


 
 
 Trees play an important role in urban landscape planning due to their multi-faceted functions including the provision of human comfort through shade and cooling and air pollution abatement. Mesua ferrea is the national tree of Sri Lanka with multi-colored leaves and pyramidal dense canopy architecture, which can be promoted to grow in roadside gardens and parks to gain more attraction and attention. It is important to know how different trees provide human comfort under the canopy. In the present study, we measured the transmittance spectra in the 318-885 nm range using a high-resolution spectroradiometer under the canopy of selected Mesua ferrea trees on bright sunny days. The change in shade casting on the ground during the day was modeled. In addition, the temperature, CO2, and relative humidity were also measured. The light transmittance through the canopy is reduced when moving from the outer edge of the canopy (1,142 μW.cm-2.nm1) to the trunk-base (0.82 μW.cm-2.nm-1) on the horizontal plane. It was obvious that the irradiance received closer to the base of the tree is not sufficient to support the understory plant growth. The irradiance levels of blue (B: 400-500 nm), red (R: 650-680 nm), and far-red (FR: 700-885 nm) components of the transmittance spectra under the canopy were also found significantly low compared to sunlight, with significantly altered R:B, R:FR and B:FR ratios. Importantly, a 14 fold cut down in the UV radiation (318-400 nm) under the canopy beyond half of the canopy diameter towards the trunk was also observed. Under the canopy, there was a temperature reduction of about 1° C on bright sunny days perhaps due to the reduced irradiance and the altered spectrum, and the reduced CO2 concentration (by 5%). We identified that the Mesua trees are suitable for human comfort, and thus can be recommended for roadside planting and for public parks in urban landscape planning.
 Keywords: Shade caste, Radiation spectrum, Mesua ferrea, Landscape planning, Urban planning
 
 

INTERNET OF THINGS-BASED AIR QUALITY ANALYSIS FOR MONITORING CO2 CONCENTRATION IN ROOFTOP BUILDING AREAS

This research aims to comprehend the air quality in rooftop areas in the city of DKI Jakarta, renowned for its high population density and rapid infrastructure development. The main focus is on the concentration of carbon dioxide (CO2) in the roof area, serving as an indicator of air quality influenced by air pollution, industrial activity, and heavy transportation. The utilization of Internet of Things (IoT) technology and CO2 sensors proves to be an effective solution for real-time monitoring of CO2 concentrations. This research holds significance for air pollution control measures, providing insight into the impact of rooftop gardens in reducing CO2 emissions and inspiring future research in the realms of air quality and IoT technology. Through prior literature, three notable studies underscore the industrial and technological impact of CO2 monitoring. The research was conducted in two locations in DKI Jakarta, namely the Garden Roof and Ordinary Roof areas. Monitoring took place over four parts of the day with a four-hour interval to compare CO2 levels. The tools employed included the NodeMCU ESP8266, DHT-22 sensor, and MQ-135 sensor. Results revealed that roof areas with gardens exhibited lower average CO2 levels (295 PPM) compared to regular roofs (360 PPM), indicating the potential of garden roof designs to reduce CO2 concentrations. Research recommendations include increasing the frequency of data collection and considering additional factors for a more comprehensive understanding of urban air quality.

Optimizing Winter Air Quality in Pig-Fattening Houses: A Plasma Deodorization Approach.

This study aimed to evaluate the effect of two circulation modes of a plasma deodorization unit on the air environment of pig-fattening houses in winter. Two pig-fattening houses were selected, one of which was installed with a plasma deodorizing device with two modes of operation, alternating internal and external circulation on a day-by-day basis. The other house did not have any form of treatment and was used as the control house. Upon installing the system, this study revealed that in the internal circulation mode, indoor temperature and humidity were sustained at elevated levels, with the NH3 and H2S concentrations decreasing by 63.87% and 100%, respectively, in comparison to the control house. Conversely, in the external circulation mode, the indoor temperature and humidity remained subdued, accompanied by a 16.43% reduction in CO2 concentration. The adept interchange between these two operational modes facilitates the regulation of indoor air quality within a secure environment. This not only effectively diminishes deleterious gases in the pig-fattening house but also achieves the remote automation of environmental monitoring and hazardous gas management; thereby, it mitigates the likelihood of diseases and minimizes breeding risks.