Browsing by Author "Golmakani, Ayub"

Now showing 1 - 11 of 11
  • Thumbnail Image
    ItemOpen Access
    Advances, challenges, and perspectives of biogas cleaning, upgrading, and utilisation
    (Elsevier, 2022-02-05) Golmakani, Ayub; Nabavi, Seyed Ali; Wadi, Basil; Manovic, Vasilije
    Biogas as a renewable energy resource can be broadly recognised as a carbon–neutral fuel which reduces anthropogenic greenhouse gas emissions, mitigates global warming, and diversifies energy supply. However, the biogas share in the global renewable energy supply chain and technology deployment and maturity are not commensurate with the potential. The first half of this study critically reviews state of the art developments in biogas cleaning and upgrading technologies by considering their present status, current challenges, and barriers associated with their future development. The second part of this paper aims to address critical gaps in converting biogas to biomethane, proposing required pre-treatment steps for different technologies. The third part focuses on current policies concerning the strict regulations implemented for flaring consent applications. In this section, biogas upgrading technologies were compared by estimating the global warming potential (GWP) resulting from waste gases (WG). It was observed that due to high methane losses, WGs from membrane technologies have the highest GWP, but with flaring have the lowest GWP. In the last part of this review, the recent applications of biogas in cogeneration (CHP), tri-generation (CCHP), quad-generation systems, heat, and vehicles are discussed. The use of biogas by different technologies, and their resulting efficiencies were analysed in CHP applications, including microturbines, micro humid air turbine (mHAT), solid oxide fuel cells (SOFC) and hybrid systems of SOFC-microturbines.
  • No Thumbnail Available
    ItemOpen Access
    Amine functionalised SBA-15 for DAC - Data Set
    (Cranfield University, 2021-08-23 08:55) Wadi, Basil; Golmakani, Ayub; ali Nabavi, Seyed; Manovic, Vasilije
    Raw Data Set accompanying scientific article titled: Evaluation of Moderately Grafted Primary, Diamine, and Triamine Sorbents for CO2 Adsorption from Ambient Air: Balancing Kinetics and Capacity Under Humid Conditions
  • Thumbnail Image
    ItemOpen Access
    Comparative evaluation of PSA, PVSA, and twin PSA processes for biogas upgrading: the purity, recovery, and energy consumption dilemma
    (MDPI, 2023-09-27) Golmakani, Ayub; Wadi, Basil; Manovic, Vasilije; Nabavi, Seyed Ali
    The current challenges of commercial cyclic adsorption processes for biogas upgrading are associated with either high energy consumption or low recovery. To address these challenges, this work evaluates the performance of a range of configurations for biogas separations, including pressure swing adsorption (PSA), pressure vacuum swing adsorption (PVSA), and twin double-bed PSA, by dynamic modelling. Moreover, a sensitivity analysis was performed to explore the effect of various operating conditions, including adsorption time, purge-to-feed ratio, biogas feed temperature, and vacuum level, on recovery and energy consumption. It was found that the required energy for a twin double-bed PSA to produce biomethane with 87% purity is 903 kJ/kg CH4 with 90% recovery, compared to 961 kJ/kg CH4 and 76% recovery for a PVSA process. With respect to minimum purity requirements, increasing product purity from 95.35 to 99.96% resulted in a 32% increase in energy demand and a 23% drop in recovery, illustrating the degree of loss in process efficiency and the costly trade-off to produce ultra-high-purity biomethane. It was concluded that in processes with moderate vacuum requirements (>0.5 bar), a PVSA should be utilised when a high purity biomethane product is desirable. On the other hand, to minimise CH4 loss and enhance recovery, a twin double-bed PSA should be employed.
  • No Thumbnail Available
    ItemOpen Access
    Data for the paper "Production of negative-emission biomethane by twin double-bed pressure swing adsorption with tail gas sequestration"
    (Cranfield University, 2020-11-03 09:37) Golmakani, Ayub; ali Nabavi, Seyed; Manovic, Vasilije
    the experimental results for adsorption capacity of CO2 and CH4 on polymeric porous adsorbent (PPB) as well as dynamic breakthrough measurements have been provided.
  • No Thumbnail Available
    ItemOpen Access
    Data for the paper 'Effect of impurities on ultra-pure hydrogen production by pressure vacuum swing adsorption'
    (Cranfield University, 2019-11-05 11:31) Golmakani, Ayub; ali Nabavi, Seyed; Manovic, Vasilije
    Dataset for "Effect of impurities on ultra-pure hydrogen production by pressure vacuum swing adsorption" article
  • Thumbnail Image
    ItemOpen Access
    Effect of combined primary and secondary amine loadings on the adsorption mechanism of CO2 and CH4 in biogas
    (Elsevier, 2021-05-12) Wadi, Basil; Golmakani, Ayub; Manovic, Vasilije; Nabavi, Seyed Ali
    Biomethane, produced by biogas upgrading, is a promising energy source that can play a key role towards net-zero emissions targets. The incorporation of amine functionalities into adsorbents for biogas upgrading can facilitate the selective adsorption of CO2, but their effect has not been comprehensively studied within the context of CH4 mixtures. In this work, the effectiveness of amine functionalities in selectively separating CO2 from biogas, is investigated. Primary, diamine, and triamine organo-silanes grafted at various loadings on SBA-15 were used to study the adsorption mechanisms associated with amine functionalities for CO2:CH4 gas mixtures. The successful incorporation of amines was confirmed with thermogravimetric analysis (TGA), Fourier Transform Infrared (FTIR), and elemental analysis (EA). The different amine reagents and loadings resulted in an alteration of adsorption mechanism that provided key information on the developing relationship between adsorption capacity, selectivity, and energy efficiency. Diamine with an amine loading of 2.5 mmol/g and a moderate silane coverage of 1.54 molecules/nm2 was found to provide the best balance of an enhanced CO2 adsorption capacity (1.12 mmol/g), a superior selectivity to densely grafted primary amines, and the lowest isosteric heat of adsorption of ∼25 kJ/mol at 1.12 mmol/g compared to ∼41 kJ/mol for primary and triamine materials. Amongst all the samples, a lower amine loading on the bare adsorbent enhanced CO2 adsorption capacity and selectivity while minimising the heat duty associated with adsorbent regeneration. Moreover, under isothermal desorption conditions at 25 °C, some samples achieved working capacities comparable to higher amine loaded materials
  • Thumbnail Image
    ItemOpen Access
    Effect of impurities on ultra-pure hydrogen production by pressure vacuum swing adsorption
    (Elsevier, 2019-10-29) Golmakani, Ayub; Nabavi, Seyed Ali; Manovic, Vasilije
    The most viable technology for production of ultra-pure hydrogen (>99.99%), required for fuel cells, is steam methane reforming (SMR) coupled with pressure vacuum swing adsorption (PVSA). A PVSA process with a two-layer bed of activated carbon (AC)/zeolite 5A for ultra-pure hydrogen production from syngas was developed and simulated with the aim of exploring the effect of impurities on energy intensity of the process. The simulated concentration profiles showed that CH4 was removed by first half of the AC layer, CO2 and CO were mostly removed by the end of that layer, but zeolite 5A (the second layer) could not completely remove the remaining N2. Further, the effect of the N2 on performance of the PVSA process was demonstrated by simulating purification of two feeds with 3.1 and 1.1 vol% N2, respectively. The 2% drop in N2 concentration in the syngas feed resulted in decreased energy consumption of the PVSA process from 940 kJ/kg to 430 kJ/kg H2, while H2 recovery increased from 47% to 55%. Therefore, the presence of N2 has a very large impact on recovery and energy intensity of the ultra-pure hydrogen production process, and development of adsorbents with better N2 removal performances is required.
  • Thumbnail Image
    ItemOpen Access
    Evaluation of moderately grafted primary, diamine, and triamine sorbents for CO2 adsorption from ambient air: balancing kinetics and capacity under humid conditions
    (American Chemical Society, 2021-08-30) Wadi, Basil; Golmakani, Ayub; Manovic, Vasilije; Nabavi, Seyed Ali
    Successful deployment of direct air capture (DAC) to mitigate the consequences of climate change depends on many factors, one of which is the development of kinetically efficient CO2 sorbents with a high sorption capacity, at ultralow CO2 concentrations. This work evaluated CO2 adsorption performance of primary-, diamine-, and triamine-grafted SBA-15 at pressures below 5 kPa for DAC applications, measured through volumetric sorption, followed by humid air (23% RH) adsorption by gravimetric analysis. Under humid air flow, triamines at an amine loading of 4.6 mmol/g showed the highest enhancement in adsorption, with an uptake of 26 mg/g, but the slowest average adsorption rate of 216 μg/g/min. Diamine at an amine loading of 2.78 mmol/g had an adsorption rate of 295 μg/g/min but demonstrated the lowest uptake of 13 mg/g. In comparison, primary amines at a loading of 2.6 mmol/g reached an equilibrium uptake of 22 mg/g, with a higher adsorption rate of 354 μg/g/min. Triamine grafted at 3.5 mmol/g had the fastest kinetics of all samples, reaching 525 μg/g/min. Results indicated that primary amines and moderate-to-high density triamine reagents incorporated into mesoporous media can offer a superior adsorption rate that can make up for lower adsorption capacities, by optimizing cyclic performance, and should be considered when designing for continuous DAC processes.
  • Thumbnail Image
    ItemOpen Access
    Molecular simulation techniques as applied to silica and carbon-based adsorbents for carbon capture
    (MDPI, 2023-06-28) Wadi, Basil; Golmakani, Ayub; Borhani, Tohid N.; Manovic, Vasilije; Nabavi, Seyed Ali
    There has been ongoing interest in research to mitigate climate change through carbon capture (CC) by adsorption. This guideline is meant to introduce computational chemistry techniques in CC by applying them to mesoporous structures and disordered morphologies. The molecular simulation techniques presented here use examples of literature studies on silica and carbon-based adsorbents. An initial summary of molecular simulation techniques and concepts is first presented. This is followed by a section on molecular simulation applications in mesoporous amorphous silica, both functionalized and not. Novel strategies to validate and output useful results are discussed, specifically when modelling chemisorption. The use of computational chemistry to build upon experimental results is reviewed, and a similar summation is presented for carbon-based adsorbents. The final section provides a short review of computational chemistry methods in novel applications and highlights potential complications. Computational chemistry techniques provide a streamlined method of gathering data across a range of conditions. Alongside experimental studies, these techniques can provide valuable information on underlying molecular mechanisms. This paper aims to be a starting point for navigating these numerical methods by providing an initial understanding of how these techniques can be applied to carbon capture while clarifying the current and inherent limitations present.
  • Thumbnail Image
    ItemOpen Access
    Production of negative-emission biomethane by twin double-bed pressure swing adsorption with tail gas sequestration
    (Elsevier, 2020-10-13) Golmakani, Ayub; Nabavi, Seyed Ali; Manovic, Vasilije
    Selective removal of CO2 during biogas upgrading and subsequent sequestration can transform the produced biomethane from a carbon-neutral to carbon-negative energy source. Such technology can be considered as bioenergy with carbon capture and storage (BECCS), i.e., as a negative-emission technology (NET). In this research, porous polymeric beads (PPBs) with a practical working capacity above atmospheric pressure and cyclic performance were developed to be used for biogas upgrading by pressure swing adsorption (PSA) without the need for vacuum. The CO2 and CH4 equilibrium isotherms of PPBs were measured in the temperature range of 0–70 °C and in the pressure range of 0–10 bar. The dynamic breakthrough curves of 40:60 (vol%) CO2/CH4 gas mixture were measured at 2 bar and 10 bar. These isotherms and breakthrough curves were used as inputs in a dynamic PSA simulation model to predict the performance of a twin double-bed PSA biogas upgrading process. The model indicated that biomethane with 91% CH4 recovery can be produced and a stream of >90% CO2 purity from the tail gas, suitable for geological storage, can be separated. It should be highlighted that unlike current state-of-the-art PSA units, the proposed process using PPBs can upgrade biogas with minimal energy consumption for regeneration of adsorbents. The proposed selective tail gas separation scheme can be used to produce carbon-negative biomethane.
  • No Thumbnail Available
    ItemOpen Access
    'Wadi et al. adsorption data set - Effect of combined primary and secondary amine loadings on the adsorption mechanism of CO2 and CH4 in biogas'
    (Cranfield University, 2021-05-25 09:17) Wadi, Basil; ali Nabavi, Seyed; Golmakani, Ayub; Manovic, Vasilije
    Data set for amine functinalised SBA-15 with primary, diamine and triamine reagents. The attached data includes volumetric gas adsorption and TGA adsorption results for CO2 and CH4, and associated with the publication listed above.