Molecular dynamics simulations of methane adsorption and displacement from graphenylene shale reservoir nanochannels

Abstract Methane is the main component of shale gas and is adsorbed in shale pores. Methane adsorption not only affects the estimation of shale gas reserves but also reduces extraction efficiency. Therefore, investigating the behavior of methane adsorption in shale reservoirs is important for evaluating shale gas resources, as well as understanding its desorption and displacement from the nanochannels of shale gas reservoirs. In this research, molecular dynamics simulations were used to investigate the adsorption behavior of methane gas in organic shale pores made of graphenylene, followed by its displacement by CO2 and N2 injection gases. The effects of pore size, pressure, and temperature on adsorption were examined. It was observed that increasing the pore size at a constant pressure led to a decrease in the density of adsorbed methane molecules near the pore surface, while a stable free phase with constant density formed in the central region of the nanopore. Moreover, adsorption increased with increasing pressure, and at pressures ranging from 0 to 3 MPa, 15 and 20 Å pores exhibited lower methane adsorption compared to other pores. The amount of adsorption decreased with increasing temperature, and the observed adsorption isotherm followed the Langmuir adsorption isotherm. The mechanism of methane displacement by the two injected gases differed. Carbon dioxide filled both vacant adsorption sites and directly replaced the adsorbed methane. On the other hand, nitrogen only adsorbed onto the vacant sites and, by reducing the partial pressure of methane, facilitated the displacement of methane

Aluminum nanocomposites reinforced with monolayer polyaniline (C3N): assessing the mechanical and ballistic properties

This study unveils C3N, a new material that serves as an excellent reinforcement to enhance the mechanical properties of aluminum using a molecular dynamics simulation method. Results show that the C3N nanosheets greatly improve the mechanical properties of aluminum-based nanocomposites. With only 1.3 wt% C3N, the Young's modulus, fracture strength, and fracture strain increased by 27, 70, and 51 percent, respectively. A comparison between the reinforcement of graphene and C3N in an aluminum (Al) matrix shows that in terms of the mechanical properties, the graphene-aluminum composite is weaker than the C3N-aluminum composite in the tensile tests, but slightly stronger in the energy adsorption tests. Our findings show that the mechanical properties are highly dependent on the strain rate and temperature. The effects of various imperfections, such as the vacancy, crack, and void defects, on the mechanical properties were also studied. Results show that in the presence of void defects, the structure exhibited higher mechanical properties than when there were other defects. This phenomenon was found to be related to the decrease in the effective load transfer from aluminum to C3N. Furthermore, by increasing the weight percent of the nanosheets up to 5%, the energy absorption rate increased by 25% compared to the pure aluminum. When C3N was placed on top of the aluminum surface, the silicon nanoparticles were associated with a 35% energy adsorption by the nanocomposite. The results of this paper could be used to help understand and overcome some limitations in the fabrication of metallic nanocomposites with 2D material reinforcement.Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Investigating the effects of adding hybrid nanoparticles, graphene and boron nitride nanosheets, to octadecane on its thermal properties

Octadecane is an alkane that is used to store thermal energy at ambient temperature as a phase change material. A molecular dynamics study was conducted to investigate the effects of adding graphene and a boron nitride nanosheet on the thermal and structural properties of octadecane paraffin. The PCFF force field for paraffin, AIREBO potential for graphene, Tersoff potential for the boron nitride nanosheet, and Lennard-Jones potential for the van der Waals interaction between the nanoparticles and n-alkanes were used. Equilibrium and nonequilibrium molecular dynamics simulations were used to study the nano-enhanced phase change material properties. Results showed that the nanocomposite had a lower density change, more heat capacity (except at 300 K), more thermal conductivity, and a lower diffusion coefficient in comparison with pure paraffin. Additionally, the nanocomposite had a higher melting point, higher phonon density of state and radial distribution function peaks.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Two‐region semi‐analytical solution for latent heat thermal energy storage systems

Problems with latent heat thermal storage (LHTS) often contain several boundary conditions that an exact solution cannot solve. Therefore, novel methods to tackle such issues could fundamentally change the design of innovative energy storage systems. This study concentrates on the reformulation of the generalized differential quadrature method (GDQM) for the two-region freezing/melting Stefan problem as an essential LHTS challenge. Comparison and convergence show that there is sufficient confidence in the proposed approach. By monitoring the precision of the suggested approach for the LHTS problem, it was indicated that this method's error depends on Stefan's number. The maximum error of all Stefan numbers up to 0.3 is less than 6%. For such applications in a standard array of LHTS (Stefan numbers between 0 and 0.2), the proposed method is appropriate as it predicts the answers with a maximum of 4.2% error. In comparison to the heat capacity method, GDQM delivers a more precise result at higher processing times. Additionally, this GDQM priority is accompanied by a low computational cost, which is unquestionably superior.12 month embargo; first published: 05 September 2021This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Analysis of Sustainability Assets of Paddy Systems in Rasht City

Access and use of sustainable asset can improve farmer economics status and farmers livelihood affected by capitals quantity and balance between these capitals. The main purpose of this descriptive-conductive research was to analysis sustainability asset in paddy systems of Rasht city. Statistical population of this research contained of all paddy farmers of Rasht township in 1392 (N= 84772), where sample size determines by Krejcie and Morgan sample size (n= 401). The questionnaire included 42 indicators and 13 components for five sustainable livelihoods capitals (physical, human, social, financial and natural). Content and face validity of research tool was obtained by a panel of experts. In order to obtain reliability of questionnaire, Coder- Richardson was used (0.96). The results show that human capital has highest level among five sustainable capitals. Physical capital, social capital, financial capital and natural capital ranked in order. Total component indicators for physical, human, financial, social and natural capitals calculated 1.03, 1.361, 0.866 and 0.8, respectively. This results show that improve in current capitals of rural areas would help to sustainability of paddy cultivation systems

Assessing mechanical properties of single-layer B-doped C3N and N-doped BC3 nanosheets and their hybrid

In this study, we analyzed the mechanical properties of single-layers C3N doped with boron (B) atoms and BC3 doped with nitrogen (N) atoms, as well as hybrid C3N-BC3 nanosheets intra-plate by forming covalent bonds using molecular dynamics simulation. The results show that the monolayer of C3N has higher mechanical properties than common materials, but adding B atoms and a single-layer of BC3 to it causes irreparable mechanical damage. However, the BC3 sheets did not react similarly and the mechanical properties were not significantly reduced by adding nitrogen atoms and the C3N to it; in some cases, the mechanical properties of the structure did not increase. Therefore, by adding 5% of boron atom to the C3N structure in the armchair direction, Young's modulus, failure stress, and strain were reduced by 6, 19, and 20 percent, respectively. When we added a nitrogen atom to the BC3 structure, failure stress and strain reduced by 1.5 and 2 percent, respectively, but Young's modulus increased by 1%. One of the reasons for such behaviors is stronger binding energy between N-C atoms compared to B-C. Consequently, these weak bonds cause BC3 failure in hybrid systems. The results provide a fundamental understanding of the design of hybrid structures used in the nanodevices based on advanced 2D materials. © 2021 Elsevier B.V.24 month embargo; first published online 20 February 2021This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Enhanced atmospheric water harvesting efficiency through green-synthesized MOF-801: a comparative study with solvothermal synthesis

Abstract Adsorption-based atmospheric water harvesting has emerged as a compelling solution in response to growing global water demand. In this context, Metal–organic frameworks (MOFs) have garnered considerable interest due to their unique structure and intrinsic porosity. Here, MOF 801 was synthesized using two different methods: solvothermal and green room temperature synthesis. Comprehensive characterization indicated the formation of MOF-801 with high phase purity, small crystallite size, and excellent thermal stability. Nitrogen adsorption–desorption analysis revealed that green-synthesized MOF-801 possessed an 89% higher specific surface area than its solvothermal-synthesized counterpart. Both adsorbents required activation at a minimum temperature of 90 °C for optimal adsorption performance. Additionally, green-synthesized MOF-801 demonstrated superior adsorption performance compared to solvothermal-synthesized MOF-801, attributed to its small crystal size (around 66 nm), more hydrophilic functional groups, greater specific surface area (691.05 m2/g), and the possibility of having a higher quantity of defects. The maximum water adsorption capacity in green-synthesized MOF-801 was observed at 25 °C and 80% relative humidity, with a value of 41.1 g/100 g, a 12% improvement over the solvothermal-synthesized MOF-801. Remarkably, even at a 30% humidity level, green-synthesized MOF-801 displayed a considerable adsorption capacity of 31.5 g/100 g. Importantly, MOF-801 exhibited long-term effectiveness in multiple adsorption cycles without substantial efficiency decline

Factors affecting adoption of pressurized irrigation technology among olive farmers in Northern Iran

Abstract The main aim of this paper was to investigate factors affecting the adoption of pressurized irrigation technology among Roudbar County olive farmers by path-structural modeling and Unified Theory of Acceptance and Use of Technology. Data were collected through an information technology questionnaire addressing a cross section of 210 managers of olive farms (4.18% of the statistical population) in the Roudbar County, Northern Iran. Validity of the questionnaire was proofed using several tests (content, face, convergent and discriminant). Likewise, reliability of the questionnaire was tested employing principal component analysis, Cronbach’s alpha, Dillon–Goldstein’s ʃ and reagent stability. Descriptive and inferential statistical analysis of the data was accomplished using SPSSV19 and SmartPLSV3 software. For testing hypotheses, structural equation model and partial least squares that focus on reagent variance were used. Results show a significant relationship between: (a) performance expectancy and behavioral intention, (b) social influence and behavioral intention, (c) facilitating conditions and use behavior. A significant relationship was also observed between intention to use and use behavior of pressurized irrigation technology. The employed model explains 72% of behavioral intention variance and 42% of use behavior of pressurized irrigation technology variance among olive farmers. To increase willingness to accept technology among Roudbar County olive farmers, it is suggested to hold extension and education courses by organizations for raising knowledge and awareness of pressurized irrigation technology. Also, olive farmers can be provided with financial resources and knowledge to enable them to adopt this new irrigation technology