Methane Gas Concentration Research Articles

High-Q fano resonance metasurface sensor for refractive index and methane gas concentration measurement

High-quality-factor Fano resonances excited by metasurfaces have been playing an important role in the field of optical sensing. A high-performance sensor for refractive index and methane concentration measurement is designed and prepared in this paper. The symmetry of the structure is broken by altering the size of the rectangular holes in the tetramer, resulting fano resonance Q-factor of 34176 and modulation depth of 100%. The finite-difference time-domain (FDTD) method is used to simulate the structure. The results show that the refractive index and methane concentration sensitivity are 325 nm/RIU and −1.44 nm/%, respectively. The FOM can achieve 10156 RIU−1. Furthermore, experiments are carried out on the gas application of the structure and the sensitivity of methane concentration is −1.03 nm/%. Therefore, the proposed metasurface has more practical and feasible significance in background refractive index and gas environment monitoring.

A Low-power Environmental Supervision System Suitable for Livestock and Poultry Breeding

This paper is a kind of low power consumption environment suitable for livestock and poultry breeding regulation system, the system consists of livestock breeding related sensors, actuators, control equipment, LoRa gateway and control web parts, when the environment, carbon dioxide, carbon monoxide, methane, ammonia gas and hydrogen sulfide harmful gas concentration over the threshold will alarm and the system will take corresponding measures to ensure the production efficiency of animal husbandry and food safety, and reduce the incidence of livestock and poultry disease and environmental pollution.

Investigation into the variation characteristics and influencing factors of coalbed methane gas content in deep coal seams

Gas saturation is a critical parameter for the selection and development of coalbed methane, as well as a key indicator reflecting the challenges in coalbed methane development and productivity evaluation of coalbed methane wells. As one of the significant factors influencing gas saturation, gas content plays a vital role in comprehensively investigating coal pore properties to fully comprehend the process and conditions of methane adsorption and desorption. In this study, 3# and 15# coals from Qinshui Basin, China was selected as research subjects. The experimental evaluation encompassed an examination of composition, pore characteristics, permeability characteristics of coal, rock mechanical parameters while discussing the impact of temperature and pressure on coal's adsorption and desorption capacity. The mineral characteristics analysis revealed that vitrinite is the main component with varying percentages and reflectance values in both 3# and 15# coal seams. The gas content and methane concentration in the 15# coal seam are higher than those in the 3# coal seam. The relationship between gas content within a coal seam and burial depth depends on achieving a balance between positive pressure effects caused by overburden stress exertion on gases trapped within pores under high pressures during burial history versus negative temperature effects due to cooling during geological processes over time. Predictions were made regarding deep-coal gas content which holds significant implications for accurately understanding variations in desorption behavior along with optimizing fracturing engineering.

A Non-Source Optical Fiber Sensor for Multi-Point Methane Detection.

Fast, accurate, real-time measurement of gas concentration is an important task for preventing coal mining disasters. In order to develop an accurate monitoring method for methane gas concentration at different locations in a mine environment, a non-source optical fiber sensor for multi-point methane detection has been developed in this paper. A 16-channel fiber splitter and a multi-channel time-sharing acquisition module are employed within the sensor, enabling simultaneous detection of methane gas at 16 points by a host. Furthermore, the methane sensors are connected to the monitoring host via an all-optical method, achieving non-source and long-range detection of methane. To assess the performance of the methane gas sensor, experiments were conducted to evaluate its detection range, response time, and stability. The results indicated that the average detection error was approximately 1.84% across the full range, and the response time did not exceed 10 s. The minimum detection limit of the sensor, as determined by the 1σ criteria, was obtained as 58.42 ppm. Additionally, the concentrations of methane gas measured at varying distances (1 km, 2 km, 5 km) were found to be essentially consistent over an extended period. These results suggest that the development of this non-source optical fiber sensor holds significant potential for providing a method for mine environment, multi-point online methane gas detection.

Optimizing methane plasma pyrolysis for instant hydrogen and high-quality carbon production

The European Green Deal has set a target for Europe to achieve net-zero greenhouse gas emissions by 2050, necessitating a transition to more sustainable energy sources. Hydrogen gas (H2) has emerged as a promising solution, with methane pyrolysis presenting a viable method for its production. This study explores the optimization of methane plasma pyrolysis for hydrogen and high-quality carbon production. Employing a statistical approach by a design of experiment software, critical process parameters are systematically analyzed to predict their impact within a defined range. Additionally, the paper conducts comprehensive characterization of the solid carbon produced during pyrolysis using imaging, spectroscopic and elemental analysis, and gas sorption analysis methods. The experimental investigation was conducted using a thermal plasma reactor with several settings of influential parameters including methane gas (CH4) content in the plasma gas, electric current, and arc length. The DC-transferred plasma arc is formed using a variable gas mixture of argon gas (Ar) and CH4, with a constant flow rate of 5 Nl/min. Thirteen tests were designed, evaluating responses such as power input, process stability, and H2 yield. The H2 yield indicates the hydrogen produced from CH4, with 100% representing total conversion. While the process exhibited inconstancy, attributed to reactor design constraints, a high H2 yield of 67%–100% was achieved. The results indicate that a higher CH4 content in the plasma gas and extended arc lengths disturb the plasma arc, hence reducing the H2 yield. Increased power input, achieved through higher amperage levels, and a wider reaction zone eased by extending the arc length both led to an improved H2 yield. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) revealed microstructural differences, with carbon samples from the filter exhibiting finer textures and carbon samples from the reactor larger sizes and dendritic particles. Raman spectroscopy confirmed crystalline graphitic-like structures with low defect concentrations, a finding supported by X-ray diffraction (XRD) analysis. Inductively coupled plasma mass spectroscopy (ICP-MS) analysis confirmed high-purity carbon with slight impurities from initial filter contamination. Brunauer-Emmett-Teller (BET) specific surface area calculations based on gas sorption analysis showed significant variations, with filter-collected samples exhibiting 40–170 m2/g and reactor-collected ones showing 7–30 m2/g.

Gas Concentration Measuring-System (CH4, NH3, CO2) Upon Cow Feces in an Encased-Space Based on Arduino Uno

The goal of this exploration is to fabricate an estimating instrument for perceiving Methane, Smelling salts, and Carbon Dioxide gas concentrations in cow feces within a confined space. The feasibility of gas concentration detection devices using MQ-2 sensors, MQ-4 sensors, and Arduino Uno-based MQ-135 sensors will also be tested. This research relates to physics, particularly instrument physics. The research will employ hardware design, software design, and testing methodologies. The gas used for testing was produced from 500 grams of cow feces through three treatments: no treatment, addition of 50 grams of activated charcoal, and addition of 50 milliliters of EM4. The tool validation test was conducted by three experts, and the typical worth acquired was 95.8%, classified as entirely achievable. The experiment yielded the highest concentrations of CH4, NH3, and CO2 gases at 11:30 AM (plus EM4), 03:00 AM (plus EM4), and 24:00 AM (without treatment), respectively, with readings of 9.49 ppm, 26.89 ppm, and 4.57 ppm.

Methane (CH4) Detection System Using The TGS2611 Sensor and MQ-4 Sensor

Abstract This research focused on cow dung digesters as measurement samples, utilizing the TGS2611 and MQ-4 sensors, both known for their affordability. The objective was to develop a low-cost gas sensor system for monitoring methane gas concentrations through a straightforward web-based data acquisition platform. The DHT11 sensor was employed to measure air temperature and humidity. The electronic sensor circuit in this research utilized a voltage divider circuit. Testing the performance of the low-cost gas sensor involved integrating it with an anaerobic digestion system. For both the TGS2611 and MQ-4 sensors, the graph illustrating the relationship between sensor voltage (volts) and methane gas concentration (ppm) formed a logarithmic or non-linear pattern. The measurement range for the system was around 4700 ppm to 6300 ppm for TGS2611 and 4000 ppm to 5100 ppm for MQ-4. The sensor sensitivity was determined as 0.5433 Volts/ppm for TGS2611 and 0.5639 Volt/ppm for MQ-4. The TGS2611 sensor exhibited a higher response to changes in methane gas concentration, while the MQ-4 sensor successfully detected methane gas within its designated range. Interestingly, the TGS2611 sensor accurately detected methane gas concentrations above its specified range. The gas sampling procedure involved automatic gas sampling in a vacuum chamber for measurement, a strategy potentially enhancing sensor robustness. This research successfully amalgamated sensor advantages, circuit control, and data analysis to realize an economical yet reliable monitoring system.

Website-Based Monitoring System for Methane (CH4) Concentration, Humidity, and Temperature

Abstract The research developed a monitoring system that focuses on the development of a system and the acquisition of its readings into a simple website. This research was conducted in an effort to obtain data that can be used for managing methane gas pollution in the environment. Methane gas (CH 4) is a natural gas consisting of one carbon atom and four hydrogen atoms. Methane gas is one of the greenhouse gases that contribute to global warming, while humidity and temperature can increase or decrease methane gas productivity. Therefore, in this research, a monitoring system was created for methane gas concentration using TGS2611 sensor, humidity and temperature using DHT11 sensor through the creation of a chamber connected to test materials such as cow dung digesters and tofu wastewater as a source of methane gas production. The results obtained indicate that, in the development of the monitoring system as a measuring tool, it successfully detects the concentration of methane gas, humidity and temperature for each test material using calibration through characteristic equation V = 0,5591 ln(n) − 2,2657. For data acquisition in the form of methane gas concentration parameter readings by the TGS2611 sensor, humidity and temperature by the DHT11 sensor to the ESP8266 microcontroller to be displayed on the serial monitor, LCD, and the website that has been created in real-time. To display the data acquisition of the monitoring system, each component of the system is connected. Starting from software, hardware, and test materials. Data acquisition begins with sensor readings by ESP8266 through a program from Arduino IDE displayed on the serial monitor and LCD. Once connected to wifi or a hotspot and the data is successfully sent, the data will be checked by notepad++ and entered into the phpMyAdmin website database for storage. From this database. The data will then be displayed on the website that has been created in real-time. Additionally, humidity and temperature affect the increase and decrease in methane gas concentration productivity.

A sensitive methane gas sensor based on sagnac interferometer with a cryptophane-A film-coated birefringent photonic crystal fiber : design and FEM simulation

As being sensitive to methane gas, cryptophane-A is widely used in fiber optic methane gas sensors. In order to further improve the sensitivity, a Sagnac interference (SI) was constructed with a cryptophane-A film coated birefringent photonic crystal fiber (PCF) to realize the methane gas sensing. Cryptophane-A film absorbs the methane gas and as a result its refractive index decreases linearly with the increasing of methane gas concentration. Simulation results utilizing the finite element method demonstrate that sensitivity reaches 124.4 nm/% when the methane concentration ranges from 0% to 3.5%. The sensor is relatively simple to prepare and can achieve high sensitivity, which has potential application in the field of monitoring methane gas leakage.

Regularities of rocks zonal disintegration and methane emissions periodicity in mine roadways

The article presents the results of studies on the establishment of stable relationships between methane emissions into degassing wells and their spatial location, stress-strain state of rock massif and mining operations process. Vibroacoustic and electrometric of mine control methods have been used to establish zoning and alternation of fractured zones in the rock massif during mining operations. Using the finite element method, zones of different permeability in the roof above the longwall face were determined, and a qualitative transition from compressive deformations to tensile deformations was revealed. Based on data from mine experiments at 157 degassing wells, patterns of repeatability of rocks zonal disintegration and periodicity of gas emissions into mine roadways depending on the distance to the moving longwall face have been determined for the first time. It has been established that the concentration of methane gas in a wells with distance from the longwall face changes according to a damped quasi-periodic dependence with recombinant changes in stress-strain states. For wells aimed at the goafs, the period of the quasi-periodic function increases by 40%, the amplitude decreases to 30%. The obtained dependencies make it possible to increase the efficiency of degassing.

Density and volume of adsorbed methane in key applications for in-situ gas content: Insights from molecular simulation

The evaluation of the in-situ gas content in deep coal seams, potentially containing free gas in saturated-oversaturated reservoirs, holds practical significance for exploration and production compared with shallow undersaturated-saturated reservoirs dominated by adsorbed gas. However, owing to the inherent limitations of volumetric and gravimetric methods, the accurate assessment of adsorbed and free gases faces significant challenges. In this study, based on molecular simulations, we focused on slit-shaped pores to explore the microscopic interaction mechanisms between coal and methane molecules under different pore sizes, temperatures, and pressures. By combining isothermal adsorption and pore structure experiments, the distribution characteristics of the adsorbed phase density (APD) and adsorbed phase volume (APV) were determined. The results showed that, in pores smaller than 1.5 nm, methane exhibited an aggregated state distribution (containing only adsorbed methane) characterized by micropore filling adsorption. In pores larger than 1.5 nm, methane showed a dispersed state distribution (coexistence of adsorbed and free methane) characterized by monolayer adsorption. The APD increased with pressure and decreased with temperature and pore size, whereas the APV remained independent of the pressure and temperature. In the in-situ gas content evaluation, three adsorption models (SL, SDR, and SL + SDR models) considering APV and APD were utilized to describe the methane adsorption behavior. The SDR model considering the APV was consistent with the actual physical properties and molecular simulation results. Traditional correction methods often lead to an overestimation of the adsorbed methane content, and neglecting the APV can result in an overestimation of the free methane content. In summary, the SDR model considering the APV can provide more rigorous scientific support for the refined study of methane occurrence states and gas content distribution.

Combining TDLAS and multi-fusion algorithms for methane gas concentration detection

Combining TDLAS and multi-fusion algorithms for methane gas concentration detection

Deformation behavior of the hybrid S-phase layer formed on a stainless-steel substrate by thermochemical heat treatment under mechanical loading

The hybrid S-phase layer was formed on the surface of an austenitic stainless steel by the thermomechanical heat treatment, which was carried out at a low temperature (475 °C). The thickness of the layer depends on the methane (CH4) gas content in the heat treatment chamber. The microstructure of the layer contains plenty of microstructural defects, such as slip bands, twins, stacking faults, and entangle dislocations, as confirmed by detail electron microscopy investigations. The S-phase layers were subjected to nanoindentation and nanoscratching to investigate their micro-mechanical properties and deformation aspects; and compared against the substrate (bulk austenitic) material. This layer exhibit about 6 folds increase in hardness (11.65–14.65 GPa) to that of bulk austenitic (2.33 GPa), whereas the Young's modulus increased by 1.70 times (124.84–142.34 GPa for the S phase layers and 83.25 GPa for bulk material). This increase in hardness caused relatively less plastic deformation in the layer, compared to bulk austenitic under identical loading conditions. This induced different sub-surface deformation aspects, not only in terms of deformation depth, but also in microstructural aspects, as reviled through a transmission electron microscopy investigation on the residual nanoindentation imprint and scratch tracks.

Biogas Production in a Variety of Sawdust and Cow Dung Mixtures Using the Intermittent Mixing Method

Cow dung is livestock waste that is very useful for renewable energy sources. The acceleration of the gas rate in cow dung biogas fermentation can be accelerated by the addition of secondary material, sawdust is one of the organic materials that can accelerate the rate of gas production in the formation of cow dung biogas. This study used a mixture composition: (B1) 675 g cow dung and 0 g sawdust, (B2) 472.5 g cow dung and 202.5 sawdust, (B3) 450 g cow dung and 225 g sawdust, and (B4) 427.5 g cow dung and 247.5 g of sawdust by fermentation for 20 days. In the research process, measurements of pH at the beginning and at the end of the study, gas pressure, gas volume, biodigester temperature, production rate, methane gas content, and flame test were carried out. In this study, the pH values ranged from 7-7.5 and the biodigester temperature was 27.5-31°C. The results of this study indicate that an organic mixture with a mixture of sawdust can accelerate production faster than without organic sawdust. Optimal results are found in the variation of the organic mixture of sawdust with a mixture of 450 g cow dung and 250 g sawdust having the highest production rate of 281.72 ml/day.

Implementasi Algoritma Long Short-Term Memory dalam Prediksi Konsentrasi Gas Metana (CH4) di Kota Salatiga

Implementation of the Long Short Term Memory (LSTM) algorithm is done to build a prediction model that can handle complex time series data. Model development uses training and testing data and combines multiple time series to improve prediction accuracy. Model testing is done by measuring the root mean square error (RMSE) value as a performance indicator. The test results show that the application of the LSTM algorithm to the (CH4) sensor provides an optimal RMSE value, namely with a value for training data of 20% (0.09) and test data of 80% (0.14), indicating the prediction accuracy of methane gas (CH4) concentration is potentially unexploded, the results obtained have important implications for safety monitoring. This test contributes to the development of predictive methods to monitor and manage potential risks associated with (CH4) concentrations. The application of LSTM to (CH4) sensors not only improves prediction accuracy but also opens up opportunities for the development of safety systems that can more effectively predict and prevent potentially harmful phenomena due to methane gas.

ADVANCED EXPERIENCE IN GAS SITUATION MANAGEMENT AT THE COAL MINES OF THE KARAGANDA BASIN

This article presents the main methods of implementing degassing control systems, which allow for a radical reduction in the likelihood of accidents and achieving the most effective production results. The article discusses measures to prevent explosive gas concentrations during degassing operations, proposes optimal diameters and distances between degassing wells. Additionally, parameters influencing the volume of pumped methane are identified. A technology for sealing underground wells to maintain methane gas concentration is proposed. A modern mobile degassing unit is presented for methane extraction followed by utilization for electricity generation.

Mechanism of improving anaerobic fermentation performance of kitchen waste pretreated by ionizing irradiation-part 1: rice.

Ionizing irradiation, as a new pretreatment method for the anaerobic fermentation of organic pollutants, is featured with fast reaction speed, good treatment effect, no need to add any chemical reagents, and no secondary pollution. This study explores the mechanism of improving anaerobic fermentation performance of rice samples pretreated by cobalt-60 gamma irradiation through the influence on fermentation substrate, acidogenic phase and methanogenic phase. The results reveal that the soluble chemical oxygen demand of the irradiated rice sample at an absorbed dose of 9.6 kGy increases by 12.4 times due to the dissolution of small molecules of fat-soluble organic matter. The yield of biogas in the acidogenic phase increases by 22.2% with a slight increase in hydrogen gas content. The yield of biogas and methane gas content in the methanogenic phase increases by 27.3% and 15%, respectively. Microbial genome analysis, performed with MiSeq high-throughput sequencing and metagenomic methods, suggests the microbial abundance and metabolic functions in the anaerobic fermentation process change significantly as a result of the pretreatment by gamma irradiation.

Transformer Monitoring with Electromagnetic Energy Transmission and Wireless Sensing.

To ensure stable and normal transformer operation, light gas protection of the transformer Buchholz relay is essential. However, false alarms related to light gas protection are common, and troubleshooting them often requires on-site gas sampling by personnel. During this time, the transformer's operating state may rapidly deteriorate, posing a safety threat to field staff. To tackle these challenges, this work presents the near-field, thin-sliced transformer monitoring system that uses Electromagnetic Energy Transmission and Wireless Sensing Device (ETWSD). The system leverages external wireless energy input to power gas monitoring sensors. Simultaneously, it employs Near-Field Communication to obtain real-time concentrations of light gases, along with the electrified state and temperature. In field testing conducted on transformer relays' gas collection chambers, the ETWSD effortlessly monitors parameters within warning ranges, encompassing methane gas concentrations around 1000 ppm, leakage voltage ranging from 0-100 V, and relay working temperatures up to 90 °C. Additionally, to facilitate real-time diagnosis for electrical workers, we have developed an Android-based APP software that displays current light gas concentrations, leakage voltage collection values, and temperature, while also enabling threshold judgment, alarms, and data storage. The developed ETWSD is expected to aid on-site personnel in promptly and accurately evaluating transformer light gas protection error alarm faults. It provides a method for simultaneous, contactless, and rapid monitoring of multiple indicators.

Research on Multi-point Measurement System of Mine Gas Based on TDLA

Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology combines the advantages of wavelength modulation technology and direct absorption spectroscopy technology, and the system achieves highly sensitive and full-range detection of methane gas concentrations. In the system, only the pure optical methane probe is positioned under the mine, which establishes connectivity with the host computer on the surface through the optical fiber. This setup enables the simultaneous detection of 16 channels of methane gas through time-sharing multiplexing technology. Experimental results demonstrate a measurement error of less than ±6.0×10−4 at low concentrations (0∼1%) and within ±6% of the true value at high concentrations under normal temperature and pressure conditions. The full-range linear fit attains 0.9998. According to the one-fold standard deviation, the minimum detection lower limit of the system stands at 68.36 ppm and the measured gas concentrations across different channels of the methane probes remain consistent inhe same environment. This technology provides a new solution for continuous, accurate, and multi-point monitoring of mine gas.

Research on High Performance Methane Gas Concentration Sensor Based on Pyramid Beam Splitter Matrix.

Methane gas concentration detection faces the challenges of increasing accuracy and sensitivity, as well as high reliability in harsh environments. The special design of the optical path structure of the sensitive element provides an opportunity to improve methane gas concentration detection. In this study, the optical path structure of the sensitive element was newly designed based on the Pyramidal beam splitter matrix. The infrared light source was modulated by multi-frequency point-signal superimposed modulation technology. At the same time, concentration detection results and confidence levels were calculated using the four-channel methane gas concentration detection algorithm based on spectral refinement. Through the experiment, it was found that the sensor enables the full-range measurement of CH4; at the lower explosive limit (LEL, CH4 LEL of 5%), the reliability level is 0.01 parts-per-million (PPM), and the limit of detection is 0.5 ppm. The sensor is still capable of achieving PPM-level detections under extreme conditions in which the sensor's optical window is covered by two-thirds and humidity is 85% or dust concentration is 100 mg/m3. Those improve the sensitivity, robustness, reliability, and accuracy of the sensor.