Publisher：Thermal Science and Engineering Progress  

The porosity of activated carbon is significantly influenced by both the precursor biomass and the activation parameters. Waste sawmill wood (WSW) dust, an abundantly available precursor from the furniture manufacturing, construction, carpentry, and shipbuilding industries, was collected, dried, pulverized, carbonized, and activated using steam and a novel high-pressure CO2 activation approach. Activation was performed in a tubular furnace at 800 °C with a pure CO2 flow for 90 min at 1 MPa pressure (WSW-A800-CO2-90 min-1 MPa). Another activated carbon sample was synthesized from the same precursor at atmospheric pressure using steam flow at 700 °C for 20 min (WSW-A700-Steam-20 min). XRD and FTIR analyses were conducted to compare the structural information of both samples. Additionally, the thermal characteristics of the samples were determined by measuring their specific heat capacities. N2 and CO2 adsorption experiments were performed to investigate the porous properties and CO2 capture capacities of the synthesized samples. The activated carbon synthesized in a pressurized CO2 environment produced a BET surface area of 684 m2/g, while steam activation achieved a BET surface area of 947 m2/g. Interestingly, despite the lower surface area of the CO2-activated sample, it exhibited a higher CO2 adsorption capacity (106.29 mg/g at 5 °C and 110 kPa) compared to the steam-activated carbon due to its unique pore size distribution. The experimental CO2 adsorption data were also correlated with Langmuir, Freundlich, and modified Dubinin-Astakhov (D-A) models to elucidate the CO2 capture parameters, such as isosteric heat of adsorption, activation energy, and Gibbs free energy.

DOI： 10.1016/j.tsep.2024.103075

Scopus

Publisher：Journal of Environmental Chemical Engineering  

An adsorption cooling system (ACS) offers distinct advantages over conventional systems, including improved energy efficiency, waste heat power, low-emission refrigerant employment, and simplified mechanical design. The performance of ACS is greatly affected by the selection of the adsorbent/refrigerant pair. In this study, we experimentally investigate the adsorption capacity of difluoromethane (CH2F2) onto several highly porous waste palm-based activated carbons (PACs). Elemental analysis, SEM, XRD, and FT-IR spectroscopy are performed on raw, carbonized, and activated samples to gain deeper insights into their surface morphology and functional groups. Difluoromethane adsorption isotherms of the PACs are obtained using a high-precision thermogravimetric analyzer at typical operating adsorption and desorption temperatures of ACS. One of the studied PAC/difluoromethane pairs achieves a benchmark uptake of 2.741 kg difluoromethane per kg adsorbent at 30°C and 1893 kPa equilibrium pressure. The experimental data are correlated with substantial accuracy using the Dubinin-Astakhov (D–A) and Tóth isotherm models to predict adsorption performance under experimentally unexamined operating conditions. Furthermore, for this PAC/difluoromethane pair, key performance indicators such as specific cooling effect (SCE), coefficient of performance (COP), Clapeyron cycle (P-T-W) diagram, and heat of adsorption (Qst) are evaluated. The results demonstrate that the PAC/difluoromethane pairs have excellent potential for the development of high-performance, low-emission ACS.

DOI： 10.1016/j.jece.2024.114869

Web of Science

Scopus

Publisher：Colloids and Surfaces A: Physicochemical and Engineering Aspects  

Metal-organic frameworks (MOFs) are crystalline materials composed of metal ions and organic ligands, exhibiting distinctive physicochemical properties, including a large surface area, adjustable porosity, and malleability. These properties render MOFs superior to traditional porous matrices, particularly in adsorption and separation applications. In the present study, four metal ions (Mg²⁺, Co²⁺, Ni²⁺, and excess Ca²⁺) were directly integrated into the HKUST-1 structure to enhance its CO₂ adsorption capacity. Incorporating the four metals in excess resulted in a notable increase in the specific surface area and pore volume of N₂ adsorption compared to the pristine HKUST-1. Samples with larger specific surface area and pore volume exhibited enhanced CO₂ adsorption performance, indicating that doping excess metals introduces additional adsorption active sites. Notably, the combination of multiple analytical techniques, including powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR), demonstrates that the modified sample exhibits enhanced crystallinity compared to the parent sample. The grain morphology remains unaltered, and no new chemical structures have been generated. Gold is present in the structure, albeit in trace amounts. Thus, the increase in active sites is due to competition between copper in the structure, the introduced excess doped metal coordination, and the generation of defects. Among the samples tested, Ca-HKUST-1 has demonstrated the most notable advancement, exhibiting an unprecedented three-fold increase in CO₂ absorption capacity compared to the original MOF. The synthesis process of this material is straightforward and cost-effective, rendering it highly suitable for industrial applications.

DOI： 10.1016/j.colsurfa.2024.135179

Web of Science

Scopus

Publisher：International Communications in Heat and Mass Transfer  

Adsorption heat pumps (AHPs) have been envisioned to be the next generation of cooling systems owing to their low electricity consumption and negligible total equivalent warming impact (TEWI). This study investigated the adsorption characteristics, thermodynamic properties, and environmental impact of HFC32 onto six waste mangrove-derived activated carbons (MACs), which were synthesized at various operating conditions. Adsorption isotherms were acquired below and above critical temperatures (30, 50, 70, and 90 °C) by a high-precision thermogravimetric analyzer (TGA). Notably, the most promising sample exhibited a remarkable HFC32 adsorption capacity (2.628 kgref per kgads), which is a benchmark for any HFC/AC pair to date. Six sets of isotherm data were fitted with well-established Dubinin-Astakhov (D–A) and Tóth equations, resulting in a notably high goodness of fit. The isosteric heat of adsorptions was also assessed and elucidated using the ideal Clausius-Clapeyron model and modified non-ideal models proposed by Rahman et al. and Chakrabarty et al. Furthermore, a comprehensive thermodynamic and ecological footprint analysis, including the specific cooling effect (SCE), coefficient of performance (COP), Clapeyron analysis, and total equivalent warming impact (TEWI) assessment, were conducted. The implementation of the aforementioned MAC/HFC pair can potentially achieve an SCE of 457 kJ kgads–1 for space cooling and approximately 25% reduction in CO2 emissions. Adsorption uptake, SCE, COP, and TEWI analyses collectively emphasize the significant potential of pairing MACs with HFC32 in designing an environmentally sustainable AHP.

DOI： 10.1016/j.icheatmasstransfer.2024.107828

Web of Science

Scopus

Publisher：International Communications in Heat and Mass Transfer  

This study experimentally and numerically investigated CO2 adsorption characteristics onto a highly porous activated carbon. Adsorption kinetics and isotherms experiments were conducted using a high-precision thermogravimetric analyzer. The effects of key parameters, specifically adsorbent bed thickness, temperatures, and pressure, were considered. The two isotherm models were employed to correlate the measured data, and they showed a decent fit. Numerical simulations were carried out using COMSOL Multiphysics software under a coupled heat and mass transfer model. The simulated results showed a reasonable agreement with the experimental uptakes for all studied parameters. The results also showed that the diffusion time constant Ds0/Rp2 is pressure-dependent and varies with the adsorbent bed thickness. The Ds0/Rp2 at each adsorption temperature is calculated and fitted with the Arrhenius equation. Estimated averaged values of limiting Ds0/Rp2 for adsorbent bed thicknesses of 0.9, 5, and 25 mm, respectively, equal to 2.18 × 10−1, 8.64 × 10−2, and 2.05 × 10−2 1/s. Linearly increasing adsorbent bed thickness causes a rapid nonlinear drop in Ds0/Rp2. The findings from this research provide valuable information on the mass transfer characteristics of CO2 onto activated carbon. So, engineers can design optimized heating/cooling systems that operate more effectively, resulting in higher efficiency, reduced system costs, and lower carbon emissions.

DOI： 10.1016/j.icheatmasstransfer.2024.107779

Web of Science

Scopus

Responsible for pages：pp. 7–28, ISBN 9783030938444   Language：English  

Other Link： https://doi.org/10.1007/978-3-030-93845-1_2

Responsible for pages：pp. 87–111, ISBN 9783030938444   Language：English  

DOI： 10.1007/978-3-030-93845-1_4

Other Link： https://doi.org/10.1007/978-3-030-93845-1_4

A set of thermal compressors (often referred to as adsorption beds) is employed in an adsorption heat pump (AHP) system to achieve the desired cooling, whereas electricity-driven compressors are used in a conventional vapor compression refrigeration system (VCRS). Although an AHP is much more environmentally friendly than VCRS, its massive size is one of the major hindrances towards its commercial application. The primary reason for this bulkiness is the huge amount of adsorbents that are being used in the adsorption beds. A remedy to this major flaw can be the use of composite adsorbents instead of loosely packed powders. Another colossal issue is the poor efficiency of this system which can be partially resolved by (i) proper selection of adsorbent, adsorbate, binder, thermal conductivity enhancer and optimizing their composition; (ii) applying optimum pressure in the consolidation process; (iii) determining the thermophysical properties of adsorbents to select the most suitable one, and (iv) ensuring efficient operation of the system by optimizing the duration of different recovery schemes. In this chapter, the synthesis technique to prepare silica gel-based high-quality consolidated adsorbents is demonstrated, a comparison of several thermophysical properties of the parent and composite adsorbents is presented, and finally, the system operation is investigated and optimized through simulation studies.

DOI： 10.1007/978-3-030-93845-1_2

Scopus

Responsible for pages：pp. 147–177, ISBN 9789811506758   Language：English  

DOI： 10.1007/978-981-15-0675-8_9

Other Link： https://doi.org/10.1007/978-981-15-0675-8_9

Publisher：Advancements In Non-Conventional Cooling And Thermal Storage Strategies  

To contribute to the climate goals set by the Kigali amendment, the present study explores the potential of hydrofluoro refrigerants for adsorption cooling applications. A performance analysis is carried out in the present study using Maxsorb III activated carbon for the commercial hydrofluoro refrigerants of R134a, R32, R410A, and R1234ze(E) for an air-conditioning application. The distinct advantage of avoiding additional components and heat exchangers of such a commercial hydrofluoro refrigerant-based adsorption system when cascaded with a commercial vapor compression refrigeration (VCR) system is explored in the present study, through various cascaded configurations. The working pair of Maxsorb III–R1234ze(E) is seen to yield the best cooling performance among the considered pairs, in terms of both Coefficient of Performance (COP), specific cooling energy (SCE), and lower regeneration temperatures. Furthermore, a COP enhancement of over 60% is estimated for the VCR system with an appropriate cascaded configuration with the working pair of Maxsorb III–R1234ze(E). The present study identifies the potential of the upcoming low-GWP (global warming potential) hydrofluoroolefins (HFOs) for their deployment in the adsorption cooling systems for load reduction.

DOI： 10.1002/9781394189953.ch2

Scopus

Type：Competition, symposium, etc. 

バングラ留学生、起業最高賞 九大の支援プロジェクト

https://www.nishinippon.co.jp/item/n/509836/