Steam Explosion Research Articles

Steam explosion pretreatment: Dramatic reduction in energy consumption for wheat bran grinding

Wheat bran has attracted attention for its high dietary fiber content with unique nutritional value. Grinding wheat bran into flour to produce whole wheat products effectively meets the surging demand for functional foods. Nonetheless, the grinding of high-tenacity wheat bran requires a huge amount of energy, which raises the costs of wheat bran flour. To reduce the energy consumption in wheat bran flour, we proposed a steam explosion pretreatment assisted wheat bran grinding process in this study. Steam explosion (0.5 MPa, 2 min) allows effective destruction of the wheat bran dense structure, reduces the mechanical properties of the wheat bran, and increases the yield and cell wall breakage rate of the wheat bran flour. The steam explosion pretreatment can reduce energy consumption by 57.6% in the wheat bran grinding process, which offers tremendous opportunities for making industrial production a success story. Besides, reconstituted whole wheat flour with the addition of steam-exploded wheat bran exhibited excellent processing properties. Overall, this work demonstrates that steam explosion pretreatment has a significant effect on wheat bran and drastically reduces energy consumption during wheat bran grinding, and steam-exploded wheat bran flour can upgrade the processability of reconstituted whole wheat flour, which holds tremendous application potential.

Low-temperature and low-concentration sodium hydroxide pretreatment for enhanced enzyme hydrolysis rate from Quercus variabilis Blume

A surface response design was employed to develop a sodium hydroxide (NaOH) pretreatment method for Quercus variabilis Blume using low NaOH concentration at low temperature. Nevertheless, the persistent issues associated with alkaline pretreatment of lignocellulose, namely high-water consumption and wastewater generation, remain prevalent in this pretreatment process. To address these challenges, this study aimed to conduct enzymatic hydrolysis of NaOH-treated Q. variabilis Blume without the intermediary washing steps. The results revealed that, following pretreatment and solid-liquid separation, NaOH-treated Q. variabilis Blume could be directly subjected to cellulase-mediated hydrolysis with pH adjustment, eliminating the need for washing steps. The maximum enzymatic hydrolysis efficiency reached 95.9% under specific conditions (1.2% NaOH, 8.9 °C, 32.1 h). This approach offers a promising avenue to enhance the enzyme hydrolysis rate of NaOH-treated lignocellulose. Notably, the low-temperature and low-concentration NaOH treatment effectively removed a substantial portion of lignin and hemicelluloses, resulting in a higher crystallinity index of the cellulose-rich residue compared to substrates treated solely with steam explosion. The integration of direct pretreatment and alkaline treatment emerges as an environmentally friendly and economically viable method for producing glucose and high-purity lignin. The obtained lignin can be further transformed into high-value products within the biorefinery framework.

Leveraging machine learning for acid catalyzed steam explosion pretreatment: Towards supporting fermentation by the trade-off between glucose and inhibitors

Pretreatment is essential for enhancing the sugar release from lignocellulose. Acid-catalyzed steam explosion (ACSE), a widely-used pretreatment method, still faces challenges, including inhibitors accumulation, which can be overcome by modeling. Here, artificial neural network models were constructed for sulfuric acid-based ACSE to predict sugars and inhibitors, from 12 variables regarding lignocellulose, acid, and steam explosion. Two expanding applications were demonstrated. Firstly, a constraint-based optimization strategy can provide the optimal ACSE condition for fermentation by considering glucose and the synergistic effect of inhibitors on microbial growth simultaneously. Compared to published works, the strategy led to 94% glucose with 22% inhibitors for corn stover, and 100% glucose with 13% inhibitors for wheat straw. Secondly, transfer learning was employed to model phosphoric acid-based ACSE with high accuracy (MSE 0.004) and low data requirement (∼30% of sulfuric acid-based ACSE). The proposed models and applications offer an effective optimization strategy for ACSE and other pretreatment methods for the following fermentation.

Steam Explosion-Based Method for the Extraction of Cellulose and Lignin from Rice Straw Waste

This paper focuses on the optimisation of an efficient extraction process for cellulose and lignin from rice straw waste from the Albufera of Valencia using the steam explosion method. This method is particularly pertinent given the environmental and economic challenges posed by the current disposal practices of agricultural waste. The technique comprises a high-temperature cooking stage followed by instantaneous decompression, effectively altering the biomass’s physical and chemical properties to enhance its surface area and porosity. Our adaptation of the steam explosion technique specifically addresses the challenges of rice straw waste, marking a significant departure from previous applications. This innovation is crucial in addressing the urgent need for more sustainable waste management practices, as it effectively deconstructs the lignocellulosic matrix of rice straw. This facilitates the selective extraction of cellulose at a 70% efficiency, with a 20% yield and the subsequent recovery of lignin. The results of this study are significant for sustainable biomaterial production, offering novel insights into optimising these crucial biomass components. By refining the process and focusing on critical parameters, our work advances the application of steam explosion methods for agricultural waste, enhancing efficiency and sustainability. By utilising rice straw biowaste, this research not only proposes a solution to a pressing environmental issue but also demonstrates the potential to create new market opportunities, increase the economic value for rice producers, and significantly reduce the environmental footprint of existing waste disposal methods. The holistic and ecological approach of this study underscores the vital need for innovative strategies in agricultural waste management, positioning the valorisation of rice straw waste as a key component in the pursuit of environmental sustainability.

Study on the Pyrolysis Characteristics of Tobacco Stems Under Different Steam Explosion Pressures

Thermal weight loss behavior of tobacco stems is the key to studying the chemical properties of tobacco stalks. In this research, four steam explosion pressure gradients with three heating rates were investigated for the pyrolysis characteristics of tobacco stems. Three methods were employed to analyze pyrolysis reaction kinetics. The results showed that pyrolysis of tobacco stems consists of three phases: dehydration, degradation, and carbonization. The influence of steam explosion pressure on the thermal stability of tobacco stems was as follows: 0.5 MPa > 0.2 MPa > 0.8 MPa > block sample > 1.1 MPa. The pyrolysis of tobacco stems followed the first-order reaction kinetics equation, and the pyrolysis experiments fit the Kissinger equation, Tang equation, and Hu-Gao-Zhang equation well. The experimental results provide a reference for research on the subject of pyrolysis of tobacco stems.

Physicochemical and emulsification properties of okara-derived soluble dietary fiber modified by steam explosion

The effective utilization of by-products still poses a challenge in the food industry. In this work, soluble dietary fiber (SDF) extracted from okara was modified by steam explosion (SE) via adjusting steam pressure (1.0, 1.5, and 2.0 MPa) and SE duration (60 and 120 s). The structural and emulsification properties of modified SDF were studied. The untreated SDF exhibited a low yield (5.17%) and poor emulsification properties due to its large molecular weight (162.67 kDa), compact structure, and high interfacial tension (14.27 mN/m). SE increased SDF content by a maximum of 30.31%, 4.86 times higher than that of untreated SDF. Under mild SE conditions (1.0 MPa for 60 s), SDF displayed a loose structure with abundant side chains and a higher glyoxylate content (26.77%). Its near-neutral contact angle (82.0°) and lower interfacial tension (12.69 mN/m) endowed it with higher emulsification capacity, smaller emulsion droplet size, and enhanced emulsifying stability. The molecular weight of SDF decreased and the specific surface area enlarged with increasing SE intensity. Notably, SDF exhibited the best interfacial adsorption characteristics under SE of 2.0 MPa for 120 s, attributed to its low molecular weight (46.99 kDa) and higher protein content (7.58%). Overall, the improved emulsification properties of SDF were attributed to the synergistic effects of amphiphilic equilibrium, electrostatic repulsion, spatial resistance, and enhanced droplet-to-droplet interactions.

Effects of steam explosion on raspberry leaf structure and the release of water-soluble nutrients and phenolics

Raspberry leaves were subjected to steam explosion at 0.5 and 1.0 MPa for 60–120 s, aiming to disrupt their physical and chemical structure and, consequently, promote the release of phenolic compounds into the leaf aqueous infusion. Under optimal condition of 1.0 MPa for 60 s, steam explosion led to a notable 23 % increase in total phenolic content, a 29 % elevation in ABTS radical scavenging capacity, and a 13 % rise in DPPH radical scavenging capacity of the aqueous infusion. Utilizing UHPLC-Q-TOF-MS/MS and UHPLC-QE-MS/MS techniques, respectively, a total of 39 phenolic compounds were identified from raspberry leaves, and the changes in the contents of the most important 11 species were analyzed following steam explosion. Through correlation analysis and considering the content of each phenolic compound, it was inferred that the heightened antioxidant capacity of the aqueous infusion primarily stemmed from a substantial increase in the release of ellagic acid after steam explosion.

Alkaline pretreatment and steam explosion process on coffee silverskin and incorporation of cellulose fibers in poly(butylene adipate‐co‐terephthalate)

AbstractIn this work, coffee silverskin (CSS) fibers were subjected to alkali pretreatment (ALK‐CSS) and alkali pretreatment, followed by a 4‐bar steam explosion process (SEW4). Both treated fibers presented a higher degree of crystallinity, enhanced thermal resistance and also cleaner, rough, and defibrillated surface due to the removal of noncellulosic components, as was shown in scanning electron microscopy, thermogravimetric analysis, Fourier‐transform infrared spectra, and x‐ray diffraction (XRD) results. The SEW4 fibers were incorporated into the poly(butylene adipate‐co‐terephthalate) (PBAT) matrix in contents up to 5% wt. through melt processing. PBAT/SEW4 composites were evaluated by their microstructure, thermal properties, degree of crystallinity, and hydrophilic behavior. XRD results showed PBAT/SEW4 composites with higher degrees of crystallinity and contact angle tests revealed increased composite hydrophobicity with the increase of SEW4 content in the PBAT matrix. This work describes the importance of recovering coffee lignocellulosic waste and producing value‐added by‐products, especially in packaging manufacturing.

Mechanically robust, thermal insulating sustainable foams fully derived from bamboo fibers through high temperature drying

The development of lignocellulosic foams has been gaining momentum due to their sustainability and biodegradability. However, lignocellulosic foams often have low preparation efficiency and poor mechanical properties, especially compression performance. Here, we constructed mechanically robust and thermal insulating cellulosic foams through high-temperature drying, in which all bamboo-sourced lignin-containing pulp fibers (LPF) and steam explosion fibers (SEF) were chosen as a skeleton and high solid fibrillated cellulose (HSFC) as a binder. This study aimed to investigate the effects of the characteristics of bamboo fibers and the HSFC addition on the formation, and mechanical- and thermal insulation performances of the resulting foams. The HSFC incorporation endowed the foams with excellent mechanical performance, the stress at 10 % strain and compressive modulus were 0.29 MPa and 4.4 MPa, respectively, which were 10-fold and 44-fold compared to LPF foam without HSFC. The LPF/HSFC possessed excellent energy absorption capacity (170 kJ/m3 under 40 % strain) as well as good thermal insulating performance (0.054 W/(m·K)). The LPF/HSFC foam with a much more homogeneous cellular structure outperformed the SEF/HSFC foam. This work suggests that the developed bamboo fiber foams hold promise for use in protective packaging and thermal insulation applications.

Mold Fungal Resistance of Loose-Fill Thermal Insulation Materials Based on Processed Wheat Straw, Corn Stalk and Reed.

The present study evaluates the mold fungal resistance of newly developed loose-fill thermal insulation materials made of wheat straw, corn stalk and water reed. Three distinct techniques for the processing of raw materials were used: mechanical crushing (Raw, ≤20 mm), thermo-mechanical pulping (TMP) with 4% NaOH and steam explosion pulping (SEP). An admixture of boric acid (8%) and tetraborate (7%) was applied to all processed substrates due to their anti-fungal properties. The fourth sample group was prepared from SEP substrates without added fungicide (SEP*) as control. Samples from all treatments were separately inoculated by five different fungal species and incubated in darkness for 28 days at 28 °C and RH > 90%. The highest resistance to the colonization of mold fungi was achieved by TMP and SEP processing, coupled with the addition of boric acid and tetraborate, where molds infested only around 35% to 40% of the inoculated sample area. The lowest mold fungi resistance was detected for the Raw and SEP* samples, each ~75%; they were affected by rich amount of accessible nutrients, suggesting that boric acid and tetraborate additives alone did not prevent mold fungal growth as effectively as in combination with TMP and SEP treatments. Together, the achieved fungal colonization scores after combined fungicide and pulping treatments are very promising for the application of tested renewable materials in the future development of thermal insulation products.

Propionic acid production by Propionibacterium acidipropionici CDBB‐B‐1981 from enzymatic hydrolysates of Agave bagasse pretreated by steam explosion

AbstractThe biochemical pathway for propionic acid (PA) production is an interesting alternative that can include the utilization of biomass as feedstock. This study evaluated the utilization of Agave bagasse (AB), a lignocellulosic residue, to produce PA by Propionibacterium acidipropinici in batch systems (125 mL‐hermetic bottles and 1000 mL‐bioreactor). The process included a steam explosion pretreatment at 142°C for 15 min and enzymatic hydrolysis, where solid loading (2.75% and 5% in pretreatment and 2.5%, 3.75%, and 5% in enzymatic hydrolysis) was evaluated. Furthermore, the enzymatic concentrations of 18.3 filter paper unit (FPU)/gAB (1×) of Cellic® CTec2 and 1.5× and 3× were tested. The yields of total carbohydrates (TC) obtained at the two solid loadings tested in the pretreatment were statistically similar, but the 3x enzymatic concentration enhanced the yields of TC, glucose, and xylose (0.23 ± 0.01, 0.15 ± 0.01 and 0.03 ± 0.01 g/gAB, respectively). The hydrolysates obtained under these conditions were evaluated as carbon sources for PA production, obtaining a productivity of 0.069 ± 0.006 g/L h and a yield product/substrate of 0.44 gPA/gTC. The control of pH in the culture reduced the fermentation time in the bioreactor by 52% compared with the hermetic bottles without pH control. The potential of hydrolysates as carbon sources for PA production was evidenced, as approximately 50% of the initial carbon was converted to this product. The observed yield product/substrate was similar to those reported from hydrolysates of diverse biomass types, pretreatments, or enzymatic cocktails and the same or related microorganisms. However, the system studied has advantages, such as not requiring the addition of chemical or detoxification stage, and lower temperature and time compared to other pretreatments.

Effect of steam explosion pretreatment on chosen saccharides yield and cellulose structure from fast-growing poplar (Populus deltoides × maximowiczii) wood

The aim of this study was to determine the changes occurring in the wood cellulose of the fast-growing poplar (Populus deltoides × maximowiczii) under the influence of steam explosion (SE) pretreatment. Cellulose from native wood and after pretreatment at 160 and 205 °C was isolated. Cellulose polymerization degree by size exclusion chromatography (SEC) and cellulose crystallinity index by Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) were determined. The profiles of sugars in the native wood and in the solid fraction after pretreatment (using the acid hydrolysis method) were also determined. In addition, the profile of monosaccharides in the liquid fraction obtained after steam explosion and in the liquid fraction after acid hydrolysis of the oligosaccharides were investigated using high-performance liquid chromatography (HPLC). This allowed to determine the change in the yield of hexoses and pentoses in the studied material.The behavior of cellulose in wood subjected to steam explosion at 160 and 205 °C and isolated by the Kürschner–Hoffer method was studied by determining the absorption bands of FTIR-ATR spectra. The lateral order index (LOI) of cellulose was calculated from the ratio of the intensity of the corresponding absorption bands A1422/A896 cm−1. Total crystallinity index (TCI) of cellulose was calculated from the ratio of the intensity of absorption bands A1372/A2900 cm−1. TCI of Kürschner-Hoffer cellulose isolated from wood subjected to steam explosion at 160 and 205 °C decreased by 5.6 and 5.0%, respectively, with regard to the applied temperature. LOI increased in cellulose isolated from wood subjected to steam explosion at 160 °C (by 0.7%) and at 205 °C (by 19.2%) in relation to the index of cellulose isolated from native wood. Kürschner–Hoffer cellulose isolated from wood subjected to steam explosion at 160 and 205 °C exhibited, respectively, a reduced degree of polymerization of about 11% and about 8%. Polydispersity index in Kürschner–Hoffer cellulose was 1% lower after both pretreatments than native sample.

Chemical composition and structural features of cellolignin from steam explosion followed by enzymatic hydrolysis of Eucalyptus globulus bark

Bark is one of the main wastes of the chemical and mechanical processing of Eucalyptus globulus wood. The proposed biochemical processing of bark via saccharification pathway involves steam explosion (SE) pretreatment (severity factor log R0 of 4.22) followed by enzymatic hydrolysis using an enzymatic cocktail composed of cellulolytic and xylanolytic enzymes. Almost 70% cellulose saccharification was achieved. The remaining cellolignin residue (CLEZ) was analysed for its chemical composition and structural features by conventional wet chemistry methods and a series of spectroscopic tools (FTIR-ATR, solid-state CP/MAS 13C NMR spectroscopy and wide-angle X-ray scattering (WAXS)). The main CLEZ component (about 51%) is acid-insoluble lignin, the chemical composition of which in terms of the ratio of syringyl (S), guaiacyl (G) and p-hydroxyphenyl (H) units (70:28:2) is very close to that in the initial bark. This lignin is highly condensed and structurally associated with condensed tannins, which makes CLEZ recalcitrant to delignification by common methods. About one third of cellulose in eucalyptus bark after SE was inaccessible to enzymatic hydrolysis and remained in the CLEZ. This cellulose, structurally similar to microcrystalline cellulose, is imbedded into the lignin-tannins condensed matrix and extremely difficult to purify. In contrast to cellulose, bark hemicelluloses were effectively removed in enzymatic hydrolysis, with only small amounts (<2%) remaining in CLEZ. Among other CLEZ ingredients, proteins and inorganic/organic salts were the most abundant. The latter includes noticeable amounts of calcium oxalate phytoliths (up to 9%), Fe and Si salts. The eventual application areas of CLEZ are discussed.

Multifunctional bamboo-based composites in-situ coated with graphene via continuous steam explosion

Biomass materials like bamboo have received much attention in studies of triboelectric nanogenerators (TENGs) electrode materials because its sustainability, however, it is a major challenge to construct high-quality conductive networks, originating from the agglomeration of conductive fillers and inferior interfacial properties. In this work, the continuous steam explosion in-situ coating technique (CSEICT) was innovatively adopted to fabricate bamboo/graphene/PVA composites (BGP) with an advanced structure of graphene in-situ coated on the surface of bamboo fibers. The BGP-based triboelectric nanogenerator (BGP-TENG) possessed a high output charge density of 155.86 μC/m2, 1.57 times higher compared with that of natural wood. The BGP-TENG was proven to be used as smart floors to harvest human walking energy. Notably, the BGP had extremely high electromagnetic interference (EMI) shielding effectiveness of 51.51 dB, electrical conductivity of 101.86 S/m with ultra-low percolation threshold of 0.06 vol%, and outstanding and stable electro-thermal management capabilities. On this basis, this work can provide a novel strategy for preparing bio-based composites and further expand the multiple functions of bio-based TENGs.

Extraction of Cellulases Produced through Solid-State Fermentation by Trichoderma reesei CCT-2768 Using Green Coconut Fibers Pretreated by Steam Explosion Combined with Alkali

The industrial processing of coconut to produce valuable foods, such as water and milk, generates large volumes of waste, especially the fruit shell. Despite this, material can be used in bioprocess applications, e.g., the production of enzymes, its recalcitrance hinders the cultivation of microorganisms, and low productivity is usually achieved. In this study, the production of cellulolytic enzymes through solid-state fermentation (SSF) and their extraction was investigated using the green coconut fiber pretreated by steam explosion, followed by alkali. The fungus Trichoderma reesei CCT-2768 was cultivated, using an experimental design, to study the effect of the water activity and the amount of biomass in the reactor. The combination of the pretreatment strategies yielded more porous biomass, with less hemicellulose (5.38%, compared to 10.15% of the raw biomass) and more cellulose (47.77% and 33.96% in the pretreated and raw biomasses, respectively). The water activity significantly affected the production of cellulases, with maximum activity yielded at the highest investigated value (0.995). Lastly, the extraction of the enzymes from the cultivation medium was studied, and a 9 g/L NaCl solution recovered the highest CMCase and FPase activities (5.19 and 1.19 U/g, respectively). This study provides an important contribution to the valorization of the coconut residue through (i) the application of the steam explosion technology to optimize the production of cellulases using the SSF technology and (ii) their extraction using different solvents.

BIODELIGNIFICATION OF AGRO-INDUSTRIAL WASTE AS THE SUBSTRATE TO PRODUCE LACCASE ENZYME FROM TRAMETES VERSICOLOR

Agro-industrial waste in Indonesia is a significant problem for the environment. Optimization of agro-industrial waste utilization is an exciting thing to be researched further. This study aims to utilize agro-industrial waste to optimize laccase enzyme production. The agro-industrial waste used is in the form of bagasse, rice straw, and corn stalks. The waste is used as biomass and treated to extract cellulose through bio-delignification. Cellulose serves as a substrate substance in the production of laccase enzymes. Laccase enzymes can be applied as a biocatalyst in the environmental, pharmaceutical, and chemical industries. Cellulose from agroindustry waste was synthesized by heat treatment using steam explosion with the operation conditions 200°C and 10 bar for 10 minutes. The production of laccase enzymes was done using the green technology submerged fermentation method for 32 hours at 25°C. The optimal result in producing laccase enzyme is using substrate from corn stalks and adding nutrients with an activity value of 25.46 U/mL. The reaction kinetics of laccase enzyme and commercial enzyme against 0.1 M substrate were modelled using the Euler method, and the k value was 2x10-4 min-1 (crude laccase) and 1.9x10-2 min-1 (commercial laccase).

Production of mannooligosaccharides from orange peel waste with β-mannanase expressed in Trichosporonoides oedocephalis

A large quantity of orange peel waste (OPW) is generated per year, yet effective biorefinery methods are lacking. In this study, Trichosporonoides oedocephalis ATCC 16958 was employed for hydrolyzing OPW to produce soluble sugars. Glycosyl hydrolases from Paenibacillussp.LLZ1 which can hydrolyze cellulose and hemicellulose were mined and characterized, with the highest β-mannanase activity of 39.1 U/mg at pH 6.0 and 50 ℃. The enzyme was overexpressed in T. oedocephalis and the sugar production was enhanced by 16 %. The accumulated sugar contains 57 % value-added mannooligosaccharides by the hydrolysis of mannans. The process was intensified by a pretreatment combining H2O2 submergence and steam explosion to remove potential inhibitors. The mannooligosaccharides yield of 6.5 g/L was achieved in flask conversion and increased to 9.7 g/L in a 5-L fermenter. This study improved the effectiveness of orange peel waste processing, and provided a hydrolysis-based methodology for the utilization of fruit wastes.

Optimization of Process Parameters for Bamboo Fiber Extraction by Steam Explosion

ABSTRACT Bamboo fiber (BF) has emerged as a promising natural, environmentally friendly material for use in composite materials. The steam explosion process plays a crucial role in preparing BFs suitable for composites. In this study, the effects of solid–liquid ratio, explosion pressure, and explosion holding time on BF preparation were investigated by orthogonal experiments, and the structural and chemical changes occurring during the separation of BF were also investigated. The results showed that the combined method of alkali treatment and steam explosion successfully produced BFs with good morphology. The highest yield of fine fibers (39.07%) was obtained at a solid–liquid ratio of 2:1, explosion pressure of 2.2 MPa, and explosion holding time of 4 min. BFs obtained using the optimal values exhibited dispersed fiber bundles, partial removal of hemicellulose and lignin, and improved crystallinity. Furthermore, the hygroscopicity of BFs decreased, reaching a minimum of 15% under the optimal process conditions. The optimization of steam explosion parameters can help to improve the extraction efficiency of fine fibers for composites and promote the industrialization of BFs prepared by steam explosion.

Optimisation of recovery protein hydrolysate from chicken bone by steam explosion strategy and its calcium‐binding capacity and potential pro‐osteogenic activity

SummaryThis study aimed to recover protein hydrolysate from chicken bone by steam explosion and investigate its calcium‐binding capacity and potential pro‐osteogenic activity. The results showed that the recovery rate was significantly affected by pressure, time, and filling ratio. The molecular weight distribution and amino acid composition of the protein hydrolysate were also analysed. Furthermore, the protein hydrolysate extracted at 12 min, 1.8 MPa and 40% filling ratio showed well calcium‐binding capacity, and the peptides‐calcium chelate showed good stability at different temperatures. The cell experiment showed that the peptides‐calcium chelate can significantly improve the osteogenic activity of MC3T3‐E1 cells, including the proliferation, differentiation, and mineralisation. In conclusion, the steam explosion was an effective strategy to recover protein hydrolysate with well calcium‐binding capacity and potential pro‐osteogenic activity from chicken bone. This study provided new insights and theoretical bases for the application of steam explosion in extracting protein hydrolysate to improve bone health.

Sensitivity analysis of simulated premixed layer and vapour explosion in stratified configuration

Experiments of fuel–coolant interaction in stratified geometry at the PULiMS and SES (KTH, Sweden) test facilities resulted in spontaneous steam explosions. Prior to the explosion, a premixed layer of ejected melt drops in the water layer was observed in the experiments. Based on the experimental and analytical knowledge, we have recently developed a model for premixed layer formation in the Fuel-Coolant Interaction code MC3D and applied it to estimate steam explosion energetics.In the paper, a sensitivity study of this model is performed on the three main uncertain parameters of the premixed layer formation model, which define the melt fragmentation rate, the size of the ejected melt drops and the ejected melt drop velocity. The analysis is performed against the SES S1 and the PULiMS E6 experimental results. The chosen tests were selected as in both of them the same material was used, the geometry was similar, and both of them resulted in a spontaneous steam explosion. The effects can be observed in all the performed analyses and they are consistent in simulations of both experiments, affecting the premixed layer height as well as the explosion strength and duration. Some uncertainty of the experimental results is assessed, with the main limitation related to the visual observations. The combination of both analyses provides us with the assessment of future work necessity and prioritization.The presented sensitivity analysis of the premixed layer formation model enables a more reliable assessment of the stratified vapour explosion risk and its uncertainty in nuclear power plants and other industries.