Liquid Fraction Research Articles

Simulating the seeder–feeder impacts on cloud ice and precipitation over the Alps

Abstract. The ice phase impacts many cloud properties as well as cloud lifetime. Ice particles that sediment into a lower cloud from an upper cloud (external seeder–feeder process) or into the mixed-phase region of a deep cloud from cirrus levels (internal seeder–feeder process) can influence the ice phase of the lower cloud, amplify cloud glaciation and enhance surface precipitation. Recently, numerical weather prediction modeling studies have aimed at representing the ice crystal number concentration in mixed-phase clouds more accurately by including secondary ice formation processes. The increase in the ice crystal number concentration can impact the number of ice particles that sediment into the lower cloud and alter its composition and precipitation formation. In the Swiss Alps, the orography permits the formation of orographic clouds, making it ideal for studying the occurrence of multi-layered clouds and the seeder–feeder process. We present results from a case study on 18 May 2016, showing the occurrence frequency of multi-layered clouds and the seeder–feeder process. About half of all observed clouds were categorized as multi-layered, and the external seeder–feeder process occurred in 10 % of these clouds. Between cloud layers, ≈60 % of the ice particle mass was lost due to sublimation or melting. The external seeder–feeder process was found to be more important than the internal seeder–feeder process with regard to the impact on precipitation. In the case where the external seeder–feeder process was inhibited, the average surface precipitation and riming rate over the domain were both reduced by 8.5 % and 3.9 %, respectively. When ice–graupel collisions were allowed, further large reductions were seen in the liquid water fraction and riming rate. Inhibiting the internal seeder–feeder process enhanced the liquid water fraction by 6 % compared to a reduction of 5.8 % in the cloud condensate, therefore pointing towards the de-amplification in cloud glaciation and a reduction in surface precipitation. Adding to the observational evidence of frequent seeder–feeder situations, at least over Switzerland, our study highlights the extensive influence of sedimenting ice particles on the properties of feeder clouds as well as on precipitation formation.

A new model to predict the small-hole decompression process of long CO2 pipeline

CO2 pipeline transportation is considered as an economical and safe way of moving large quantities of CO2 in Carbon Capture Utilization and Storage (CCUS) projects. However, design and planning of CO2 pipelines passing through populated areas require careful risk assessment of accidental pipeline failure scenarios leading to CO2 pipeline decompression. In this study, a new zero-dimensional multi-stage outflow model describing transient decompression of CO2 is developed. The model accounts for the experimentally observed liquid level variation along the pipeline and uses the liquid volume fraction threshold parameter (αt) to mark the end of the saturated liquid flow decompression stage. Besides, the Lee model is applied to describe the mass transfer in gas-liquid phases. The model was validated against experimental data obtained large-scale pipeline decompression tests and can be recommended for simulation of outflow of supercritical and liquid CO2 from pipelines longer than 258 m and the orifice-to-pipeline diameter ratios smaller than 0.21. The advantage of this model lies in its use of the relatively simple Vessel Blowdown Model (VBM) to accurately model the depressurization process. It addresses the inconvenience posed by the heavy computational burden of high-dimensional models when predicting long-duration leakages in large-capacity pipelines.

Performance improvement of the phase change material-assisted earth-air heat exchanger in summer

Studies confirmed that phase change material (PCM) can improve the cooling potential of an earth-air heat exchanger (EAHE). However, the poor utilization of the PCM unit’s latent heat storage (LHS) capacity and insufficient understanding of energy efficiency hinder its applications in EAHE. To solve these problems, this study made a structural improvement to the PCM unit and proposed a centrally located hollow cylindrical PCM-assisted EAHE (CHCPCM-EAHE). Then, numerical simulations were conducted on this CHCPCM-EAHE through a 3-D model built on the ANSYS FLUENT, and its cooling performance in Chongqing (China) summer was comparatively studied. The results found that the LHS performance of the PCM unit in this CHCPCM-EAHE was improved despite the significant reduction in material volume. Compared to the PCM unit in the previous PCM-assisted EAHE, the maximum liquid fraction and average charged latent heat in all charge–discharge cycles of the PCM unit in this CHCPCM-EAHE were increased by 56.82 % and 10.46 %∼56.43 %, respectively. The results also found that the CHCPCM-EAHE performed better in cooling potential and coefficient of performance (COP). Compared to the conventional EAHE and previous PCM-assisted EAHE, its average cooling capacity increased by 60.12 %∼70.75 % and 4.05 %∼10.96 %, and average COP increased by 47.22 %∼49.02 % and 6.88 %∼8.18 %, respectively.

Exergy performance analysis of hydrogen recirculation ejectors exhibiting phase change behaviour in PEMFC applications

A comprehensive analysis of flow behavior and exergy performance was conducted in hydrogen recirculation ejector, taking into account the phase change of humid hydrogen for proton exchange membrane fuel cell (PEMFC) systems. A two-phase nonequilibrium condensation CFD model integrating the entropy transport equations was established. The effect of phase change on ejectors’ performance under various primary pressure, secondary pressure and temperature, and back pressure were analyzed. When primary pressure was adjusted into 3.0 bar, a liquid fraction of 4.56% was observed at the outlet, while the liquid fraction will increase to 15.35% when the inlet pressure got to 5.0 bar. Then, the values of mass flow rate and liquid mass fraction on different sections under variable secondary temperature and back pressure were calculated. Finally, it is found that a larger primary pressure brought an increase in exergy destruction. So was exergy destruction ratio. However, increasing secondary pressure leads to the opposite result. With the increase of secondary temperature from 60 to 80 degrees Celsius, exergy destruction increases from 330.28 to 390.23 kJ/kg but the destruction ratio decreases from 29.85% to 26.19%.

Synergistic microwave and acidic deep eutectic solvent-based pretreatment of Theobroma cacao pod husk biomass for xylooligosaccharides production

The bioconversion of lignocellulosic biomass into novel bioproducts is crucial for sustainable biorefineries, providing an integrated solution for circular economy objectives. The current study investigated a novel microwave-assisted acidic deep eutectic solvent (DES) pretreatment of waste cocoa pod husk (CPH) biomass to extract xylooligosaccharides (XOS). The sequential DES (choline chloride/citric acid, molar ratio 1:1) and microwave (450W) pretreatment of CPH biomass was effective in 67.3% xylan removal with a 52% XOS yield from total xylan. Among different XOS of varying degrees of polymerization, a higher xylobiose content corresponding to 69.3% of the total XOS (68.22 mg/g CPH) from liquid fraction was observed. Enzymatic hydrolysis of residual xylan from pretreated CPH biomass with low commercial xylanase (10 IU/g) concentration yielded 24.2% XOS. The MW-ChCl/citric acid synergistic pretreatment approach holds great promise for developing a cost-effective and environmentally friendly method contributing to the sustainable production of XOS from agricultural waste streams.

In-situ observations of cloud microphysics over Arabian Sea during dust transport events

The unique in situ measurements of clouds and precipitation within the shallow and deep cumulus over the north-eastern Arabian Sea region during the Indian monsoon are illustrated in this study with a focus on droplet spectral parameters. The observational period showed a significant incursion of Arabian dust and the presence of giant cloud condensation nuclei (GCCN), modifying the cloud and precipitation spectral properties. Warm rain microphysics supported the mixed-phase development in these clouds and exhibited hydrometeors of snow, graupel and large aggregates as part of ice processes. Cloud base droplet number concentration is about 142 ± 79 cm−3 which is one third of the cloud condensation nuclei (CCN) number concentration at 0.2% supersaturation. A rapid broadening of droplet size distribution (DSD) near to the cloud base was noted in contrast to polluted continental clouds. Relationship between the relative dispersion ( ε; the ratio of DSD spectral width ( σ ) to mean radius ( rm )) and liquid water adiabatic fraction (AF) indicates that the entrainment effect has increased relative dispersion significantly (2–3 times larger) in these clouds. Effective radius ( reff ) is found to be proportional to mean volume radius ( rv ) with a proportionality constant ( β ) that varies between 1.0–1.6, depending on the spectral dispersion parameter. Drop size distributions for the small cloud droplets with size range 2–50 μ m and the large drizzle drops (or ice hydrometeors) with size range 100–6400 μ m are parameterized using the gamma function distributions useful for large-scale cloud models.

Selection of second step micro-morphology for anti-icing surfaces based on icing time

Superhydrophobicity are associated with surface two-step micro/nanostructure together morphology. However, it is uncertain for Superhydrophobic surface (SHS) whether having anti-icing ability if without detailed knowledge of the surface morphology. For this reason, we proposed a three-dimensional (3-D) icing model to analyze anti-icing properties and determine the second step morphology suitable for the anti-icing. Followed by it, representative samples (hydrophobic or hydrophilic, metal or nonmetal, organic or inorganic) were selected for freezing measurement to confirm theoretical results. Ranked order is a sine wave/cone frustum/prism/cylinder/cuboid/paraboloid, and a semi-sine-wave model by the anti-icing time from high to low. The anti-icing property still depends on the surface micro-scale and micro-morphology to a great extent as hydrophobicity does. Effect of morphology on anti–icing will be significantly reduced even neglected, if the solid–liquid contact fraction being small enough. Meanwhile we also found that both the time for drop in temperature and the icing time are directly related to the solid fraction, whether the freezing singularity appears depends on freezing velocity or hydrophilicity. The predictions of the model largely agree with the experimental observations, also opening up possibilities for rational design of anti-icing SHS by selecting suitable morphology in micro scales.

Numerical study of thermal performance of a PCM in a modifying tube-bundle latent heat thermal storage

The main aim of this study is to numerically investigate the thermal performance of a newly designed modifying tube-bundle Latent Heat Thermal Storage (LHTS). The new LHTS design proposed a half-cylindrical tube attached to the Heat Transfer Fluid tube, which implies making the PCM indirect contact with the HTF tube. This reduces the heat transfer resistance by eliminating the metal construction of the tubes. For this purpose, a 3D numerical model was developed based on mass, momentum and energy conservations using ANSYS Fluent software. After validating the model developed by comparing numerical results with those obtained experimentally by a published study, the PCM liquid fraction and amount of power stored during the melting and solidification were studied. Water and lauric acid as a working fluid and PCM were implemented in the model. In addition, three different Heat Transfer Fluid (HTF) inlet temperatures 15°C,20°Cand25°C, and HTF’s flow rates in terms of Reynolds number 1000,1500and2000 were tested. The thermal behaviour of the present LHSU design was compared with that of the same volume double pipe LHTS unit. Results showed that the melting and solidification processes of the proposed storage were very uniform, with convection and conduction heat dominating PCM melting and solidification, respectively. The increase in the heat transfer contact area between the HTF and the tube bundle contributed significantly to the PCM melting and solidification acceleration, making each tube bundle behave as a single storage unit. Therefore, the time required for complete melting and solidifying of the PCM was half (50%) of the time needed for the same amount in the double pipe LHTS. Similarly, the melting and solidification time in the preset storage was shortened by about 22% and 41.6%, respectively, compared with the regular tube LHTS unit.

Prediction of clog time of amorphous silica in the pipes of the wells from Los Humeros geothermal field – A new geochemical model along with a computational algorithm

The primary objective of this article is to introduce a physicochemical model along with a computational algorithm that is valuable for quantifying the occurrence of silica scaling and fouling within geothermal production wells. This model utilizes two-phase flow parameters, temperature and pressure profiles, as well as brine composition to forecast the timing of production pipe constriction caused by amorphous silica deposition over time. The model is applicable to systems with temperatures ranging from 270°C to 305°C, vapor pressures ranging from 55 to 93 bars, and enthalpies ranging from 1189 kJ/kg to 1400 kJ/kg. The predictive model was calibrated using data gathered from six distinct wells within the Los Humeros geothermal field in Mexico, and subsequently, it was applied to forecast outcomes in two additional wells. When the conditions of temperature, pressure, and enthalpy remain relatively constant throughout the production process, the model developed in this study accurately predicts the times at which a certain percentage of pipe sealing occurs in wells with high volumetric fractions of liquid (εl>0.5) and temperatures between 270°C and 305°C. The prediction error is less than 3%.

Natural convection and field synergy principle analysis of the influence of fins redistribution on the performance of a latent heat storage unit in a successive charge and discharge

The present study focuses on analyzing the impact of enhancing the heat exchanges on the shell side by surface extension on the kinetics of melting/solidification in a latent heat thermal energy storage (LHTES) unit. Particular attention is paid to the influence of fins redistribution on the performance of the LHTES unit, natural convection, and Phase Change Material (PCM) melting/solidification kinetics. The particularity of this study lies in the improvement of the LHTES unit performances in a successive charging-discharging operation by only redistributing the fins while keeping the same total heat transfer surface, PCM volume, and compactness. The first part of the study consists of evaluating the impact of fin redistribution for the same total heat transfer surface on the LHTES unit performance. Attention was paid to the fully charging and discharging times and the heat duty absorbed or released during the melting or solidification process. For this purpose, 4 configurations of LHTES units having 4 and 8 radial fins with the same total transfer surface were analyzed, with the aim of ensuring a maximum performance on charging process. In a second part, an improved configuration was proposed in order to minimize the successive charging and discharging time for a cyclic operation of the LHTES unit. The coordination factor derived from the field synergy principle, PCM liquid fraction, the heat duty exchanged, phase change kinetics, and liquid PCM velocity were used as performance key factors. They were used to analyze and compare the different configurations in order to find the best configuration for a successive charging-discharging operation. The selected improved configuration has been found to enhance both the charging and discharging processes. It leads to the reduction of the successive charging-discharging overall duration by 10 % to 47 % compared to the other configurations investigated with the same heat transfer surface. The enhanced LHTES unit developed in the present study is intended to improve the thermal comfort of buildings by valorizing and storing renewable and waste energies.

Assessment and validation of a numerical model for phase change materials heatsink on thermoelectric devices

The use of phase change materials (PCM) in heatsink designs are gaining attention due to its many favorable properties. Some PCM heatsinks designs have been suggested for use with thermoelectric cooling devices (TECs), however, the heatsink designs are often arbitrary where PCM is just added to voids within the heatsink to improve the thermal properties. There is a need to systematically understand the effects of PCM on TEC performance. While a numerical model is key to such systematic study and optimization, the application involves multiple physical phenomena and the resulting model can be prohibitively expensive to run. In this contribution, a numercical model using computational fluid dynamics (CFD) is built to predict the performance of PCM heatsink for use with TECs as cooling wearable. Experiments are calibrated and carried out to prescribe the boundary conditions and ensure that the multiphysics phenomena are accurately captured. The numerical methodology described here can be used for design optimizations of PCM heatsinks to be used in conjunction with TECs. Our numerical model shows that for maximum TEC efficiency, the PCM should be kept at a liquid fraction of less than 40%.

Simulation on paraffin melting enhancement in shell-tube phase change thermal storage equipment induced by natural convection

To enhance the thermal performance of the shell-tube phase change thermal storage equipment, the transient two-dimensional mathematical models of the RT35 melting were established. The transient evolution of temperature and velocity distribution and the effect of the positions of the inner tube on the intensity of natural convection for the RT35 and the melting times were analyzed. The results showed that the evolution process of the liquid fraction of RT35 could be divided into two stages: the natural convection stage and the conduction stage. In the natural convection stage, due to the buoyancy effect, the RT35 with high-temperature flowed upward and convectively heat transferred with the solid RT35 on the upper side of the inner tube, resulting in the promotion of the melting of RT35 on the upper side of the inner tube. With the increase in the eccentricity ratio (ε), the gradual increase in the mass of RT35 on the upper side of the inner tube enhanced the effect of natural convection on the melting of RT35, leading to a significant reduction in melting time. When the heat exchange temperature differences (ΔT) ranged between 9 °C and 21 °C, increasing ε from 0 to 0.8 could shorten the melting time by 87.3 %–89.73 %.

Numerical simulation of a thermal energy storage system using sunrise and sunset transient temperature models

The temperature of the sun was modeled in this study using two transient solar temperature equations for sunrise and sunset that were developed for designing a latent heat thermal energy storage (LHTES) system for a concentrated solar power (CSP) plant. The derivation of the equations was based on the existing solar hour angle and the fundamental periodic function equations. Ansys' computational fluid dynamics code was used to investigate numerically the transient response of the conjugate melting and solidification of a phase change material (PCM) in a cylindrical shell and helical heat pipe (HHP) thermal system. The models for both equations were applied as user-defined functions (UDFs). The heat transfer medium was air. The predicted liquid and solid fractions provide quantitative data on the temperature and the stored solar energy. The effectiveness of both models in enhancing heat transfer and their suitability as real-time transient solar temperature models in heat transfer engineering is demonstrated by comparisons between their outputs. With high agreement, experimental data from the open literature was used to validate the numerical model's predictions. The solar temperature models aim to contribute to heat transfer enhancement for a reduced PCM energy storage time in designing a high-temperature solar thermal storage that is adequate to maintain a steady supply of electricity and energy for domestic and commercial applications and to accelerate the global transition to low-carbon energy.

Characterization of Bioactive Metabolites and Antioxidant Activities in Solid and Liquid Fractions of Fresh Duckweed (Wolffia globosa) Subjected to Different Cell Wall Rupture Methods.

Fresh Wolffia globosa, the smallest flowering plant well-known for its favorable nutrient composition and rich content of bioactive compounds, was subjected to boiling, freeze-thawing, and mechanical crushing to reduce its excessive (95-96%) moisture level and consequent drying time. The resultant three wolffia matrixes were filtered through a plankton net to fractionate into the residue and the filtrate. The proximate composition, bioactive metabolites, antioxidant activity, and characterization of bioactive metabolites by LC-ESI-QTOF-MS/MS and Fourier transform infrared spectroscopy were made from oven-dried residues and filtrates. Among residues, crude protein (29.84%), crude lipid (5.77%), total carotenoids (TCC; 722.8 μg/g), and vitamin C (70.02 mg/100 g) were the highest (p < 0.05) for freeze-thawing against higher ash (7.99%), total phenolic content (TPC; 191.47 mg GAE g-1 dry weight), total flavonoid content (TFC; 91.54 mg QE g-1 dry weight), DPPH activity (47.46%), and ferric reducing antioxidant power (FRAP) activity (570.19 μmol FeSO4 equiv/mg) for the crushed counterpart and Chl-b in residues from boiling. No significant variation was evident in the total tannin content (TTC). Among filtrates, higher total phenolic content (773.29 mg GAE g-1 dry weight), TFC (392.77 mg QE g-1 dry weight), TTC (22.51 mg TAE g-1), and antioxidant activity as DPPH activity (66.46%) and FRAP (891.62 μmol FeSO4 equiv/mg) were evident for boiling, while that from crushing exhibited the highest TCC (1997.38 μg/g DM). LC-ESI-QTOF-MS/MS analysis identified 72 phenolic compounds with the maximum in residue (33) and filtrate (33) from freeze-thawing, followed by crushing (18 and 19) and boiling (14 and 13) in order, respectively. The results indicated that the predrying cell rupturing method significantly impacted quantitative, as well as qualitative compositions of residues and filtrates from fresh wolffia.

Comprehensive examination of topologically optimized thermo-fluid heat sinks

This study investigates the thermal performance of topologically optimized heat sinks. The primary aims are to conduct a comprehensive parametric study, compare thermal outputs with the benchmark model, and validate numerical simulations through experimental testing. Multi-objective topology optimization is formulated based on thermal compliance and power dissipation. Selected optimized models were built and tested. The parametric study revealed promising design variables, leading to numerical convergence with interconnected flow paths. The promising variables were found under weighted thermal compliances (wh) between 0.3 and 0.9 and targeted liquid fractions (θFV) between 0.5 and 0.8. Additionally, at low operating pressures, for example, at 0.01 kPa, the temperature difference between optimized and benchmark models could be as much as 30 °C. Nonetheless, the temperature difference between both models became smaller at higher operating pressures. Furthermore, the comparison of temperature measurements, pressure drops, and thermal imaging showed reasonable agreement between experimental and numerical results. Additionally, the effect of design variables on thermal performance was confirmed through experiments. The heat sink with higher wh exhibited a lower temperature than that of the model with lower wh. In summary, this research highlights the crucial role of design variables in achieving a balance between temperature and pressure drop.

Experimental and numerical investigation of a real-scale air to multiple PCM heat exchanger

Energy consumption by residential sectors has proliferated due to urbanization and lifestyle changes. Passive cooling and heating systems can reduce energy consumption and CO2 emissions in residential and commercial sectors. Phase change materials provide an efficient solution for passive energy storage, addressing a building's needs for free cooling and heating. These materials absorb and release heat energy, enhancing the overall efficiency of the energy management system. By employing energy storage devices, it becomes feasible to reduce and shift peak loads to off-peak hours. This study optimized the size and configuration of air-to-multiple PCM heat exchanger through the utilization of a 2D ANSYS (Fluent 19.2) model. This study employs multiple phase change materials (PCMs) with varying melting temperatures as a heat transfer technique to reduce the melting and solidifying times of the PCMs. Furthermore, it was observed that the arrangement of PCMs in series affected melting and solidification times, so two scenarios have been examined. The air-to-multiple PCM system has been investigated through numerical simulations and experimental analyses, focusing on the liquid fractions within the PCM and the outlet air temperatures across the air channels. The total time for entirely melting PCMs RT25HC and RT21HC is less than 4 h, but the solidification time for PCM-RT21HC needs more than 12 h. In both scenarios, PCM-RT21HC melted first, while PCM-RT25HC solidified first.

An Integrated Technique for Natural Gas Numerical PVT Modelling: Case Study of Retrograde Condensate Gas with Python Programming

After the discovery of a gas field, PVT analyses are performed in laboratory to understand the behavior of the reservoir f luid when pressure, temperature, or volume changes. Thereafter, physical or numerical representations of the fluid, called PVT fluid models, are designed to simulate the real fluid behavior when pressure, volume or temperature conditions change. This study aims to propose an integrated technique for natural gas numerical PVT modelling that will help petroleum engineers in determining the mol fractions and compositions of the vapor and liquid phases of hydrocarbon systems as function of pressure and temperature, as well as their trends in some pressure and temperature conditions. A case study has been performed on a historical retrograde condensate gas. The results show that over the production, when the reservoir pressure declines, the gas becomes much dryer and will therefore free less condensate into the reservoir. During its motion from the reservoir to the well head, the liquid phase mol fraction becomes lower so that the condensate-to-gas ratio (CGR) will be low. At pressures under 1000 psia, the decline rate of liquid phase mol fraction becomes higher. At the standard temperature, the more is pressure applied to the gas, the more the liquid phase proportion is. As a result, in the gas storage tanks, the more the gas is compressed, the more the condensate (liquid phase) deposit will be noticed. While transporting the gas through pipeline, the higher the pressure undergone by the gas, the more is the amount of condensate to be counted in pipelines. Moreover, at the standard temperature, the condensate proportion unit variation as function of pressure unit variation is higher when the pressure is under 20 bar.

Comparison of Struvite as a P Source with Chemical Fertilizers and Evaluation of Additional Contribution to Growth and Mineral Nutrition of Lettuce Grown on Acidic and Calcareous Soils

AbstractThis study investigated the effects of two different struvites (Struvite1 (STR1) and Struvite2 (STR2)) with different P amounts on the P nutrition of lettuce grown in acid and calcareous soils and fertilizer efficiency against di-ammonium phosphate (DAP), monoammonium phosphate (MAP), triple superphosphate (TSP), and 20–20-20 (NPK fertilizer). Two distinct forms of STR1 and STR2 obtained from the biogas liquid digestate (LD, liquid fraction of a centrifuge decanter) at different molar ratios (NH4+/Mg2+/PO43−), STR1 (1.0/1.3/1.0), and STR2 (1.0/1.3/1.3) were used. The results showed that struvites were the most effective treatments for plant growth. STR1 and STR2 treatments increased the plant fresh weights by 2.7-fold in acidic soil and 2.1-fold in alkaline soil. As for the plant dry weights, STR1 and STR2 treatments increased the plant dry weights by 2.4–2.2-fold and 2.3–2.2-fold in acid and alkaline soils, respectively. Struvites were more effective on the total plant weights than other fertilizers. Struvite-applied plants yielded higher P concentrations, uptakes, and recovery than MAP, DAP, TSP, and 20–20-20 fertilizers for both soils. Due to its constituent Mg, STR1 and STR2 were found to be the most effective materials for the Mg nutrition of the plants. It was also determined that they contributed to the N and K nutrition of the plants more than most other fertilizers. In conclusion, it was seen that struvites are not only a good source of P but also a fertilizer material with a high agronomic value. Therefore, they can be evaluated as an alternative fertilizer source.

Pyrolysis of Specific Non-Recyclable Waste Materials: Energy Recovery and Detailed Product Characteristics.

This study explores the pyrolysis process applied to various non-utilized waste materials, specifically focusing on separated plastics from municipal waste, wood waste (including pallets and window frames), paper rejects, and automotive carpets. Different combinations of these waste materials were subjected to pyrolysis, a process involving high-temperature treatment (600 °C) in a nitrogen atmosphere. The resulting products, including biochar, gas, and liquid fractions, as well as the residual waste materials, underwent comprehensive analysis. The evaluation of pyrolysis products emphasizes their quality, energy content, and potential applications. Notably, the pyrolysis gas derived from the combination of separated municipal plastics and waste wood exhibited the highest calorific value at 49.45 MJ/m3. Additionally, Mixture 2, consisting of plastic and wood waste, demonstrated the highest calorific value for the pyrolysis condensate, reaching 30.62 MJ/kg. Moreover, Mixture 3, benefiting from biochar utilization as a sorbent, displayed the highest iodine value at 90.01 mg/g.

Spray formation and spray-wall-flow interaction in a gasoline direct-injection (GDI) engine under early-injection conditions: A flow bench study

The work presented in this study aims to understand the spray-wall-flow interaction within a gasoline direct-injection (GDI) engine flow bench under simulated early-injection conditions. The Engine Combustion Network (ECN) Spray G injector is installed in the Darmstadt optically accessible engine flow bench. Under simulated early-injection conditions, the formation of a multi-hole spray and the interaction with characteristic intake flows, such as the intake jet and central tumble flow, are extensively discussed. By reducing the complexity in the number of variables inherent in engine flow and whole-engine simulation, an engine flow bench operating under various mass flow rates is applied in this study. The numerical simulation is carried out using Large Eddy Simulation (LES) under the Eulerian-Lagrangian framework for spray simulation. Experimental data, acquired through particle image velocimetry (PIV) measurements, provides 2-D flow fields on both the central tumble and valve planes, facilitating the validation of in-cylinder flow fields. Furthermore, experimental data obtained through Mie scattering is utilized to investigate spray formation and evolution within the GDI engine, providing the liquid penetration length and liquid spray angle. Comparison between the numerical and experimental data demonstrates several agreements. Moreover, the variation of different spray plumes under different mass flow rates is observed in the case of both experimental and numerical data. Increasing the mass flow rate distorts the overall plume shape and shifts it away from the intake port. This phenomenon is examined by extracting the liquid volume fraction and vapor fields of each plume. Spray plumes encounter different convective disturbances and evaporation due to their local characteristic in-cylinder flow. Furthermore, spray-wall-flow interaction and wall film deposits are observed during the injection. Lastly, the influence of the spray-induced turbulence is analyzed under different mass flow rates.