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A methodology for selection of solid desiccants in energy recovery ventilators
(Elsevier, 2025-01-15) Krishnan, Easwaran N.; Ramin, Hadi; Gurubalan, A.; Muneeshwaran, M.; Li, Kai; Nawaz, Kashif; Simonson, Carey
Controlling indoor humidity levels is essential for maintaining acceptable indoor air quality in buildings. The use of energy recovery ventilators (ERVs) is an energy-efficient way to regulate indoor air humidity. Fixed-bed regenerators and rotary wheels are widely used ERVs because of their high sensible and latent effectiveness. These ERVs are made of desiccant-coated substrates, which enable them to transfer moisture between the supply and exhaust air streams. However, the moisture transfer ability of ERVs depends on the physiochemical and sorption properties of desiccants. Extensive, full-scale experiments are required to determine the best desiccant material for these systems. This paper presents a simplified method of selecting suitable desiccant materials for ERVs. The methodology involves important characterization methods, literature correlations for performance prediction, and cost-effective testing methods prior to full-scale testing, and full-scale test methods are discussed in detail. Furthermore, the performance of a few newly derived materials is evaluated and compared with that of conventional desiccants such as silica gel and molecular sieves. The highest latent effectiveness was obtained for composite of super absorbent polymer (SAP) with potassium formate (SAP-HCO2K-50 %), all-polymer porous solid desiccant (APPSD) and metal organic framework (MOF)–MIL–101 (Cr), followed by activated carbon fibre felt (ACFF) Silica sol-LiCl30, SAP, silica gel, MOF–303, and molecular sieve. Researchers and manufacturers would benefit from the proposed methodology and presented data in developing new desiccant materials for ERV applications.
A novel biochar adsorbent for treatment of perfluorooctanoic acid (PFOA) contaminated water: Exploring batch and dynamic adsorption behavior
(Journal of Water Process Engineering, 2024-11) Afrooz, Malihe; Zeynali, Rahman; Soltan, Jafar; McPhedran, Kerry
Perfluoroalkyl substances (PFAS), like perfluorooctanoic acid (PFOA), are of concern worldwide given they are ubiquitous in the environment. In this study, the treatment of PFOA-contaminated water was assessed using biochar adsorbents produced from raw canola straw (RCS) through chemical activation with H3PO4 and ZnCl2 and microwave-assisted pyrolysis (MWP). MWP conditions were evaluated to create optimal H3PO4-treated (PBC) and ZnCl2-treated (ZnBC) biochar adsorbents with treatments determined using a central composite design (CCD) based on the response surface methodology (RSM) considering activator concentration, and microwave heating time and power. The highest PFOA removal efficiency for PBC (3.0 mol/L) was achieved at 92 % (368 μg/g), while for ZnBC (0.55 mol/L) it was 84 % (336 μg/g). In contrast, untreated biochar and RCS had markedly lower PFOA removals of 5 % and 1 %, respectively. Activation of biochar under optimal pyrolysis conditions (6 min at 600 W) led to increased chemical functional groups, porosity, and surface area, as confirmed by FT-IR, XPS, and BET. The kinetic study indicated that chemisorption was the primary PFOA adsorption mechanism, while the Freundlich isotherm model suggested heterogeneous multilayer adsorption for PFOA removal. Further, background salts enhanced PFOA adsorption through divalent bridges and salting-out mechanisms. PBC and ZnBC adsorbents performed well over a broad pH range of 3 to 9. Lastly, Yan and Yoon-Nelson models were used to assess adsorption breakthrough for a model fixed-bed adsorption system. This study exhibits that PBC and ZnBC adsorbents, derived from accessible biomass, offer an environmentally friendly solution to remove PFOA from contaminated water.
A universal empirical equation to estimate the abundance of carbapenem-resistant genes during aerobic digestion of wastewater sludge
(Water Practice & Technology, 2024-11) Poorasgari, Eskandar; Örmeci, Banu
Carbapenem-resistant genes (CRGs) exist in wastewater and accumulate in wastewater sludge. Due to the potential threat posed by the CRGs, it is important to quantify CRGs and predict their removal and discharge concentrations during aerobic sludge digestion. Nonetheless, gene quantification is tedious, error-prone and expensive. This study aims to develop multiple regression models to estimate CRGs from sludge parameters that are routinely measured for the monitoring and design of aerobic sludge digesters. Batch reactors were operated at mesophilic and thermophilic temperatures for 20-35 days. Sludge samples were periodically taken during aerobic digestion. Three CRGs (blaGES, blaOXA-48 and blaIMP-27) together with 16S rRNA and integron class 1 genes were quantified. Aerobic digestion reduced the abundance of all target genes. Multiple regression modelling was conducted in linear (LM) and non-linear (NLM) modes. Sums of squared errors of the LM models were 0-0.048, whereas those of the NLM models were 0–0.003. Adjusted R2 ranges of the LM and NLM models were 0.774–0.931 and 0.986–1, respectively. Overall, the NLM models predicted the abundance of target genes more accurately than the LM models. NLM models may be used to modify the design and operational parameters of aerobic sludge digesters.
Antiviral Activities of Compounds Derived from Medicinal Plants against SARS-CoV-2 Based on Molecular Docking of Proteases
(Fez Multidisciplinary, 2024-07-30) CHEBAIBI, Mohamed; MSSILLOU, Ibrahim; Aimad, Allali; bourhia, mohammed; Bousta, Dalila; Gonçalves, Rene; Hoummani, Hasnae; Aboul-Soud, Mourad; Augustyniak, Maria; Giesy, John; Achour, Sanae
This work aimed to evaluate the inhibitory effect of the main polyphenols and flavonoids of Syzygium aromaticum and Citrus limon as well as the main organosulfur compounds of Allium sativum against SARS-CoV-2 6LU7 and 6Y2E proteases using in silico molecular docking analysis. Structures of 34 natural products found in three medicinal plants were docked to these two critical proteins. For 6LU7 protease, 24 compounds exhibited binding affinities greater than or equal to -6 Kcal/mol. While, for 6Y2E protease, 6 compounds exhibited binding affinities greater than or equal to -6 Kcal/mol. Molecules with a maximum binding affinity equal to -8.4 kcal/mol show good hydrogen bonds with the two proteases under investigation, 6LU7 and 6Y2E. Diosmin, ellagic acid, narirutin, neoeriocitrin, and neohesperidin were suggested as inhibitors of SARS-COV-2. These compounds might be used therapeutically as complementary medicines and/or to conceptualize new drugs against COVID-19.
Assessment of Rapid and Conventional RT-qPCR-Based Systems for Wastewater Surveillance
(ACS Publications, 2024-09-05) Asadi, Mohsen; Hamilton, Daniel; Shomachuk, Corwyn; Oloye, Femi F.; De Lange, Chantel; Liang, Jiaqi; Xia, Pu; Osunla, Charles A.; Cantin, Jenna; Mejia, Edgard M.; Gregorchuk, Branden S. J.; Becker, Michael G.; Mangat, Chand; Brinkmann, Markus; Jones, Paul D.; Giesy, John P.; McPhedran, Kerry M.
Conventional wastewater surveillance (WS) relies on highly trained personnel, advanced instrumentation, and significant resources, making the development and use of simple, rapid, and sensitive alternative technologies valuable for reducing costs, time, and labor intensity. For the first time, this study investigated the use of two well-developed rapid systems, including the GeneXpert and LuminUltra, in parallel with a conventional WS reference methodology for the assessment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in three cities: Saskatoon, Prince Albert, and North Battleford, Saskatchewan, Canada. RNA extractions from wastewater samples were carried out for the conventional reference and LuminUltra methods, while GeneXpert was used for both raw and concentrated wastewater samples. Bland–Altman plots showed a combination of systematic bias and random error between these real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR)-based systems. Additionally, results indicated the reasonable performance of GeneXpert in viral detection with a sensitivity rate of >98%, as compared to the conventional reference methodology of 100% and LuminUltra with >65%. A Spearman correlation test showed meaningful relationships between the GeneXpert and conventional reference methodology viral level results across all cities, indicating GeneXpert’s reliability for accurate viral detection and disease prevalence determination, specifically in limited-resource communities, with a shorter processing time and cost-effectiveness in analysis.
Characterization of the evolution of crystallization fouling in membranes
(ACS, 2018-12) Olufade, A.O.; Simonson, C.J.
Chiral nematic cellulose nanocrystal films: Sucrose modulation for structural color and dynamic behavior
(International Journal of Biological Macromolecules, 2025-01) Babaeighazvini, Amin; Vafakish, Bahareh; Acharya, Bishnu
This study explores the effect of sucrose addition on the properties of chiral nematic cellulose nanocrystal (CNC) films for potential food industry applications, including biodegradable packaging and food coloring. The addition of sucrose altered the films' structural color, shifting from blue in pure CNC films to aqua blue, green, yellow-green, and red with increasing sucrose concentrations (up to 21 %). Surface analysis revealed a reduction in contact angle from 96° to 48° due to sucrose's hydrophilic nature and smoother film surfaces. XRD results indicated a decrease in crystallinity from 84.5 % to 15.6 %, linked to the disruption of CNC alignment by sucrose. Mechanical testing showed reduced tensile strength (138 MPa to 35 MPa) and Young's modulus (1.634 GPa to 70 MPa) with higher sucrose content. Notably, over the storage time, films with 21 % sucrose exhibited dynamic structural coloration caused by localized sucrose recrystallization, leading to pitch shifts and color transitions. These findings demonstrate the tunable optical and mechanical properties of CNC-sucrose films, positioning them as promising materials for sustainable food packaging and responsive coatings.
Coarse for Fine: Bounding Box Supervised Thyroid Ultrasound Image Segmentation Using Spatial Arrangement and Hierarchical Prediction Consistency
(IEEE Journal of Biomedical and Health Informatics, 2025) Chi, Jianning; Lin, Geng; Li, Zelan; Zhang, Wenjun; Chen, Jia-hui; Huang, Ying
Weakly-supervised learning methods have become increasingly attractive for medical image segmentation, but suffered from a high dependence on quantifying the pixel-wise affinities of low-level features, which are easily corrupted in thyroid ultrasound images, resulting in segmentation over-fitting to weakly annotated regions without precise delineation of target boundaries. We propose a dual-branch weakly-supervised learning framework to optimize the backbone segmentation network by calibrating semantic features into rational spatial distribution under the indirect, coarse guidance of the bounding box mask. Specifically, in the spatial arrangement consistency branch, the maximum activations sampled from the preliminary segmentation prediction and the bounding box mask along the horizontal and vertical dimensions are compared to measure the rationality of the approximate target localization. In the hierarchical prediction consistency branch, the target and background prototypes are encapsulated from the semantic features under the combined guidance of the preliminary segmentation prediction and the bounding box mask. The secondary segmentation prediction induced from the prototypes is compared with the preliminary prediction to quantify the rationality of the elaborated target and background semantic feature perception. Experiments on three thyroid datasets illustrate that our model outperforms existing weakly-supervised methods for thyroid gland and nodule segmentation and is comparable to the performance of fully-supervised methods with reduced annotation time. The proposed method has provided a weakly-supervised segmentation strategy by simultaneously considering the target's location and the rationality of target and background semantic features distribution. It can improve the applicability of deep learning based segmentation in the clinical practice. The source code and relative datasets will be available at https://github.com/LanLanUp/SAHP-Net.
A Comprehensive Review of Dehumidifiers and Regenerators for Liquid Desiccant Air Conditioning System
(Elsevier, 2021-07) A, Gurubalan; Simonson, Carey J
Liquid desiccant air conditioning systems (LDAS) are an energy-efficient and eco-friendly alternative to conventional air conditioning systems. The performance of a LDAS significantly depends on its simultaneous heat and mass transfer components, namely dehumidifier and regenerator. These components are referred to as liquid desiccant energy exchangers (LDEEs) since the working fluids (air and desiccant) exchange both heat and moisture. There has been a lot of research on LDEEs over the last two decades to improve their performance, thereby enhancing the efficiency of the LDAS. The main objective of this comprehensive review paper is to summarize the developments of LDEEs. The desiccant material, and design, operating, and performance parameters of LDEEs are explained in detail. Even though a lot of research has been done on LDEEs, they are not much utilized in the practical heating, ventilation, and air conditioning (HVAC) systems. To address this issue, future research should prioritize its focus on (i) practical problems of LDEEs such as cross contamination, and leakage and blockage of the membrane, (ii) long term performance study in the practical systems, (iii) noncorrosive and inexpensive solution, (iv) compatible material for efficient heat and mass transfer, and (v) generalized design and performance control methodology. The discussions presented in this communication will be useful to ascertain the crucial research gaps that need to be addressed by future research studies.
Developing a universal equation to estimate the mass of dewatered wastewater sludge during biological digestion at mesophilic and thermophilic temperatures
(Water Science & Technology, 2024-11) Poorasgari, Eskandar; Örmeci, Banu
A series of dewaterability tests were conducted on various types of sludges to establish a wholistic relationship between sludge water fractions. Sludge samples were obtained from batch and continuous sludge digesters, which were operated anaerobically and aerobically under mesophilic and thermophilic conditions. Dewaterability of the sludge samples and the distribution of water fractions were studied using centrifugation and thermal drying. Thickened waste activated sludge (T-WAS) contained 10-11 g bound water (BW)/g of total solids (TS), and it was more hydrophilic than primary and digested sludges. During anaerobic digestion, BW content fluctuated between 3.2 and 4.2 g BW/g TS. However, aerobic digestion at 55°C reduced the BW content of the mixed T-WAS + primary sludges from 3.7 to 2.1 g BW/g TS. A linear function was developed to correlate supernatant and BW mass fractions (R2 = 0.995). An equation was derived from the linear function to estimate the mass of dewatered sludge based on the TS concentration of the initial wet sludge. The developed expression is applicable to different kinds of wastewater sludges. Such an expression would be helpful for the designers and operators of sludge thickening and dewatering systems that use centrifugal separation.
Development of a Small-Scale Test Facility for Effectiveness Evaluation of Fixed-Bed Regenerators
(Elsevier, 2020-06-25) Krishnan, Easwaran Nampoothiry; Ramin, Hadi; Shakouri, Mohsen; Wilson, Lee D; Simonson, Carey
Fixed-bed regenerators (FBR) transfer heat (and moisture) between supply and exhaust air streams in heating, ventilating and air conditioning (HVAC) systems to reduce building energy consumption. This paper presents a new small-scale testing facility to evaluate the performance (i.e. sensible effectiveness) of FBRs for HVAC applications. The major contributions of this paper are: development of a new small-scale experimental facility and methodology for testing FBRs, quantification of uncertainties, and verification of small-scale test data over a large range of FBR design conditions. A numerical model and two well-known design correlations are used to verify the results and testing methodology. The advantages of small-scale testing are that it requires low volume of conditioned airflow, has low uncertainty, requires less exchanger material and has a low cost per test. Moreover, the small-scale testing methodology of FBR would benefit heat exchanger manufacturers to perform detailed sensitivity studies and optimize the exchanger performance over a wide range of design and operating parameters prior to the fabrication of full-scale exchangers.
Effects of Variations in Incident Heat Flux When Using Cone Calorimeter Test Data for Prediction of Full-Scale Heat Release Rates of Polyurethane Foam
(Wiley, 2016) Robson, Luke; Torvi, David; Obach, Matthew; Weckman, Elizabeth
The development of methods to predict full-scale fire behaviour using small-scale test data is of great interest to the fire community. This study evaluated the ability of one model, originally developed during the European Combustion Behaviour of Upholstered Furniture (CBUF) project, to predict heat release rates. Polyurethane foam specimens were tested in the furniture calorimeter using both centre and edge ignition locations. Input data was obtained using cone calorimeter tests and infrared video-based flame area measurements. Two particular issues were investigated: how variations in incident heat flux in cone calorimeter tests impact heat release rate predictions, and the ability of the model to predict results for different foam thicknesses. Heat release rate predictions showed good agreement with experimental results, particularly during the growth phase of the fire. The model was more successful in predicting results for edge ignition tests than for centre ignition tests, and in predicting results for thinner foams. Results indicated that, due to sensitivity of the burning behaviour to foam specimen geometry and ignition location, a single incident heat flux could not be specified for generating input for the CBUF model. Potential methods to determine appropriate cone calorimeter input for various geometries and ignition locations are discussed.
Electrostatic Particle Ionization for Reduction in Livestock and Potash Dust
(MDPI, 2025-01-15) Martel, Myra; Taylor, Matthew; Kirychuk, Shelley; Choi, Kwangseok; Guo, Huiqing; Zhang, Lifeng
Airborne dust is an important contaminant affecting the health and the environment, and a crucial concern in many workplaces such as animal facilities and potash mines. One of the techniques used for dust control is electrostatic particle ionization (EPI). This technology has been proven effective in reducing airborne dust; however, it has downsides, such as the generation of ozone and corrosion of electrodes. Thus, this study tested a corrosion-resistant carbon-fiber discharge electrode and compared it with electrodes commonly used in EPI systems, that is, stainless-steel and tungsten electrodes, in terms of collection efficiency for potash dust and wheat flour (representative of livestock dust), ozone production, and power consumption. The carbon-fiber electrode performed comparably to stainless-steel electrodes, particularly for potash dust, and performed better than the tungsten electrode in terms of dust collection efficiency. Moreover, it had the lowest energy consumption and generated the least amount of ozone. However, because of the limitations of this study (e.g., fewer samples, low air velocity, controlled conditions, and the use of wheat flour instead of livestock dust), tests under real barn or mining conditions are necessary to confirm the results.
Energy recovery ventilators to combat indoor airborne disease transmission: A Sustainable approach
(Taylor & Francis, 2024-09-17) Annadurai, Gurubalan; Mathews, Ashwin Joseph; Krishnan, Easwaran Nampoothiry; Gollamudi, Siddhartha; Simonson, Carey
Ventilation plays a crucial role in preventing indoor airborne disease transmission. Nevertheless, ventilation increases the energy consumption of heating, ventilation, and air conditioning (HVAC) systems. Therefore, energy efficiency measures or alternative methods must be adopted to reduce the energy demand of HVAC systems which is necessary to achieve sustainability in the building sector. The present study proposes a method of utilizing an Energy Recovery Ventilator (ERV) to provide supplementary ventilation to reduce the airborne disease transmission. The proposed method is tested for an office building with one source room (with an infected occupant) and two connected rooms (no infection source). The contributions of the present study are (i) the development and verification of a new supplement ventilation method using ERV to reduce the probability of infection from airborne pathogens and (ii) providing the economic and environmental benefits of the proposed method to promote its adaption by the building managers/HVAC engineers. The results of the present study show that the proposed method can reduce the probability of infection by 10 to 40% and demonstrate that utilizing ERV is the sustainable and economical method to improve ventilation to reduce indoor airborne disease transmission.
Enhancing drying efficiency and terpene retention of cannabis using cold plasma pretreatment
(Elsevier, 2025-02-11) Das, Pabitra Chandra; Heydari, Mohamad Mehdi; Baik, Oon-Doo; Zhang, Lifeng; Tabil, Lope
Hang-drying of cannabis at room conditions is a slow process and leads to the risk of microbial growth. This method can sometimes prevent cannabis from reaching the equilibrium moisture content (EMC) below the safe storage threshold. On the other hand, high-temperature drying techniques are faster but negatively impact the secondary metabolites. Cold plasma (CP) is a novel technique explored in this study to treat cannabis at various operational conditions of plasma jet (power: 300, 350, and 400 W, time: 20, 30, and 40 s) prior to drying at environmental conditions of 25°C and 50 % RH. The findings revealed that untreated cannabis samples reached an equilibrium moisture content (EMC) of approximately 16 % in 1260 min. In contrast, CP-pretreated samples achieved lower EMCs of 10–14 % within 690–840 min. CP pretreatment also resulted in high moisture diffusivity, lower energy consumption, and higher energy efficiency. Increasing CP power and residence time accelerated the decarboxylation of cannabinoids, leading to the formation of more tetrahydrocannabinol (THC) and less tetrahydrocannabinolic acid (THCA), without significantly affecting the total THC (27.45 % untreated vs. 25.82 % - 28.36 % g/ g of dry matter in CP pretreated samples). Compared with untreated dried inflorescences, the 400 W and 30 s CP treated inflorescences resulted in the retention of 96 % of terpenes, whereas all 300 W CP treated samples retained > 90 % of terpenes. Overall, the study highlights that CP pretreatment is a promising technology for the cannabis industry in shortening the drying time and preserving the product quality, especially terpenes.
Enhancing drying efficiency and terpene retention of cannabis using cold plasma pretreatment
(ScienceDirect, 2025-11) Das, Pabitra Chandra; HEYDARI FOROUSHANI, MOHAMAD MEHDI; Baik, Oon-Doo; Zhang, Lifeng; Tabil, Lope
Hang-drying of cannabis at room conditions is a slow process and leads to the risk of microbial growth. This method can sometimes prevent cannabis from reaching the equilibrium moisture content (EMC) below the safe storage threshold. On the other hand, high-temperature drying techniques are faster but negatively impact the secondary metabolites. Cold plasma (CP) is a novel technique explored in this study to treat cannabis at various operational conditions of plasma jet (power: 300, 350, and 400 W, time: 20, 30, and 40 s) prior to drying at environmental conditions of 25°C and 50 % RH. The findings revealed that untreated cannabis samples reached an equilibrium moisture content (EMC) of approximately 16 % in 1260 min. In contrast, CP-pretreated samples achieved lower EMCs of 10–14 % within 690–840 min. CP pretreatment also resulted in high moisture diffusivity, lower energy consumption, and higher energy efficiency. Increasing CP power and residence time accelerated the decarboxylation of cannabinoids, leading to the formation of more tetrahydrocannabinol (THC) and less tetrahydrocannabinolic acid (THCA), without significantly affecting the total THC (27.45 % untreated vs. 25.82 % - 28.36 % g/ g of dry matter in CP pretreated samples). Compared with untreated dried inflorescences, the 400 W and 30 s CP treated inflorescences resulted in the retention of 96 % of terpenes, whereas all 300 W CP treated samples retained > 90 % of terpenes. Overall, the study highlights that CP pretreatment is a promising technology for the cannabis industry in shortening the drying time and preserving the product quality, especially terpenes.
Ethnobotanical survey of medicinal plants used in north-central Morocco as natural analgesic and anti-inflammatory agents
(Elsevier, 2024-06-05) LEFRIOUI, Youssra; CHEBAIBI, Mohamed; djiddi bichara, mehdi; MSSILLOU, Ibrahim; BEKKARI, hicham; Giesy, John; BOUSTA, dalila
For centuries, the Moroccan population has relied on herbs as medicine to treat a variety of diseases, especially inflammation and pain-related ones. To the best of our knowledge, no survey had ever been conducted to address this subject in the Fez-Meknes region of Morocco. Thus, a survey was conducted of 544 interviewees, using a semi-structured ethnopharmacological survey designed with “Why-How” questions about plants used, their vernacular names, parts used, mode of preparation, and mode of administration. Fidelity level (FL), relative frequency of citation (RFC), frequency of citation (FC), informant consensus factor (ICF), and family importance value (FIV) were calculated. A total of 104 plant species belonging to 49 families used for inflammatory and pain treatment were documented. Lamiaceae (16 species) was the most used family and Curcuma longa L. (RFC=0.069) was the most frequently prescribed by local traditional healers and herbalists. Leaves were the most used part for herbal remedies, appearing in 30.8 % of preparations. Decoctions and infusions were the most popular preparation methods with percentages of 38.3 % and 19.2 %, respectively. Inflammations and pain in the digestive system had the largest widespread affections (IFC= 0.729) in the Fez-Meknes region. The findings of this study uncovered a reliable and original source of ethnomedicinal data pertaining to plants used to treat inflammation and inflammatory pain in the Fez-Meknes region, which could serve as a credible source of knowledge to determine new-based phytomedicines.
Experimental and Modeling Studies of Torrefaction of Spent Coffee Grounds and Coffee Husk: Effects on Surface Chemistry and Carbon Dioxide Capture Performance
(ACS Publications, 2022) Mukherjee, Alivia; OKOLIE, JUDE; Niu, Catherine; Dalai, Ajay K.
Torrefaction of biomass is a promising thermochemical pretreatment technique used to upgrade the properties of biomass to produce solid fuel with improved fuel properties. A comparative study of the effects of torrefaction temperatures (200, 250, and 300 °C) and residence times (0.5 and 1 h) on the quality of torrefied biomass samples derived from spent coffee grounds (SCG) and coffee husk (CH) were conducted. An increase in torrefaction temperature (200–300 °C) and residence time (0.5–1 h) for CH led to an improvement in the fixed carbon content (17.9–31.8 wt %), calorific value (18.3–25 MJ/kg), and carbon content (48.5–61.2 wt %). Similarly, the fixed carbon content, calorific value, and carbon content of SCG rose by 14.6–29 wt %, 22.3–30.3 MJ/kg, and 50–69.5 wt %, respectively, with increasing temperature and residence time. Moreover, torrefaction led to an improvement in the hydrophobicity and specific surface area of CH and SCG. The H/C and O/C atomic ratios for both CH- and SCG-derived torrefied biomass samples were in the range of 0.93–1.0 and 0.19–0.20, respectively. Moreover, a significant increase in volatile compound yield was observed at temperatures between 250 and 300 °C. Maximum volatile compound yields of 11.9 and 6.2 wt % were obtained for CH and SCG, respectively. A comprehensive torrefaction model for CH and SCG developed in Aspen Plus provided information on the mass and energy flows and the overall process energy efficiency. Based on the modeling results, it was observed that with increasing torrefaction temperature to 300 °C, the mass and energy yield values of the torrefied biomass samples declined remarkably (97.3% at 250 °C to 67.5% at 300 °C for CH and 96.7% at 250 °C to 75.1% at 300 °C for SCG). The SCG-derived torrefied biomass tested for CO2 adsorption at 25 °C had a comparatively higher adsorption capacity of 0.38 mmol/g owing to its better textural characteristics. SCG would need further thermal treatment or functionalization to tailor the surface properties to attract more CO2 molecules under a typical post-combustion scenario.
Experimental Investigation on Thermo-Hydraulic Performance of Triangular Cross-Corrugated Flow Passages
(Elsevier, 2021-03) Krishnan, Easwaran N; Ramin, Hadi; Guruabalan, A; Simonson, Carey J
Heat exchangers made of corrugated flow passages generally have better thermo-hydraulic performance compared to parallel flow passages. The corrugation angle (), corrugation pattern, and the ratio of depth to pitch (hch/Pch) are critical geometrical parameters influencing the heat transfer and pressure drop in corrugated flow passages. This paper experimentally investigates heat transfer and pressure drop characteristics of triangular-shaped cross-corrugated flow passages for the range of 25°<<75° and 0.13
Extrusion bioprinting from a fluid mechanics perspective
(ACCSCIENCE, 2024-08-30) Gharraei, Reza; Bergstrom, Donald; Chen, Xiongbiao (Daniel)
Bioprinting is an emerging technology for fabricating intricate and diverse structures that closely mimic natural tissues and organs for such applications as tissue engineering, drug delivery, and cancer research as well. Among the various bioprinting techniques, extrusion-based bioprinting stands out due to its capability to apply a wide range of biomaterials and living cells and its controllability over printed structures. In bioprinting, the bioink stored in a syringe is forced to flow through the nozzle connected to the syringe, and then to exit and deposit onto the printing stage to form three-dimensional (3D) structures. The bioprinting process involves the flow of bioink in both syringe and nozzle and then its flow or spreading on a printing stage. As a result, fluid mechanics plays a crucial role in extrusion bioprinting. Notably, the biomaterials used in bioprinting are typically non-Newtonian fluids, which have complex viscoelastic and thixotropic behaviors; and the influence of these behaviors on the bioprinting process has been drawn considerable attention by employing various methods, including the numerical simulations via computational fluid dynamics (CFD). This paper reviews the latest development in the fluid mechanics aspects of extrusion-based bioprinting to shed light on the challenges and key considerations involved. It covers the topics of extrusion bioprinting (including driving mechanisms, printability, cell viability), biomaterial rheology and its effect on bioprinting, multi-material bioprinting and numerical simulation of bioprinting. Key issues and challenges are also discussed along with the recommendations for future research.

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