Peak Heating Rate Research Articles

Hydration, phase assemblage and microstructure of cementitious blends with low-grade limestone

Limestone of the purity mandated by the standards for use in cement manufacture (as raw material or as performance improver) is only a fraction of the mined material. Sometimes, limestone contains impurities like silica, clay, dolomite etc. beyond the levels specified for use as an additive or for cement production. This limestone, commonly known as low-grade limestone, also may have a potential to be used as a supplementary cementitious material. This paper reports a study conducted to understand the hydration behaviour of ordinary Portland cement in combination with low-grade limestone. Low-grade limestone samples with dolomite, silica and clay impurities were collected from various limestone mines in India and used in cementitious blends at various replacement levels after suitable processing. Reaction kinetics was studied using calorimetry and phase assemblage using techniques like X-ray diffraction and thermogravimetry. Mercury intrusion porosimetry was employed to study the microstructure of cementitious blends. Dilution effect of low-grade limestone was studied by measuring compressive strength of cement mortar cubes for various replacement levels. Shortening of induction period, increased peak heat rate and reduced time to peak were observed in the blends of ordinary Portland cement with low-grade limestone. Carboaluminate formation, ettringite stabilisation and higher bound water content were also seen. The studies showed that low-grade limestone also can be used as a partial replacement for ordinary Portland cement without compromising the strength up to 15% replacement. Higher replacement levels, although showing a reduction in strength due to dilution effect, could still be considered for non-structural applications.

Beta irradiation-induced thermoluminescence: Glow curve analysis and kinetic parameters in combustion-synthesized undoped Ca4YO(BO3)3

This study examines the thermoluminescent (TL) properties of undoped Ca4YO(BO3)3 phosphor, focusing on how it behaves under a variety of experimental conditions. The IRSL-TL 565 nm was chosen as the appropriate detection filter among various optical detection filter combinations. During the preheating trials conducted at a rate of 2 °C/s, the TL peak exhibited increased intensity, particularly around 200 °C. The experimental outcomes demonstrated a reliable linear relationship (R2 = 0.996 and b = 1.015) in the dose response of undoped preheated Ca4YO(BO3)3 within the range of 1–200 Gy. The investigation encompasses a range of techniques, including the TM-Tstop method, computerized glow curve deconvolution (CGCD) analysis, and theoretical modelling. The application of the TM-Tstop method to samples irradiated with a 5 Gy dose revealed distinct zones on the TM versus Tstop diagram, signifying the presence of at least two discernible components within the TL glow curve, specifically, a single general order kinetics peak and a continuous distribution. The analysis of activation energy versus preheated temperature exhibited a stepwise curve, indicating five trap levels with depths ranging between 1.13 eV and 1.40 eV. The CGCD method also revealed the superposition of at least five distinct TL glow peaks. It was observed that their activation energies were consistent with the Tm-Tstop experiment. Furthermore, the low Figure of Merit (FOM) value of 1.18% indicates high reliability in the goodness-of-fit measure. These findings affirm the reliability and effectiveness of the employed methods in characterizing the TL properties of the Ca4YO(BO3)3 phosphor under investigation. Theoretical models, including the semi-localized transition model, were introduced to explain anomalous observations in TL glow peak intensities and heating rate patterns. While providing a conceptual framework, these models may require adjustments to accurately capture the specific characteristics uncovered through CGCD analysis. As a potential application, the study suggests that the characterized TL properties of Ca4YO(BO3)3 phosphor could be utilized in dosimetric applications, such as radiation dose measurements, owing to its reliable linear response within a broad dose range.

Experimental and numerical study on the tensile ductility of an aluminium alloy with heat-affected zones

In the case of aluminium structures, welding may introduce weak zones, so-called heat-affected zones (HAZ), close to the weld. Such zones should be accounted for when predicting the overall behaviour of structures since the deformation tends to localise within such weak zones leading to the initiation of failure. Whereas the effect of welding on mechanical properties such as yield stress and work hardening is known, the ductility of a HAZ and how to model it in numerical simulations remain uncertain. To address this challenge, this article presents a combined experimental and numerical study on ductile fracture modelling of an aluminium alloy AA6063-T6 exposed to complex heat treatments. The first part includes preparation of specimens and uniaxial tension testing. A Gleeble machine is used to generate well-defined heat treatments involving high peak temperatures and heating rates. Subsequently, uniaxial tension tests at low and high strain rates are conducted. The results show the effect of the complex heat treatments on strength, strain-rate sensitivity, and fracture. The numerical part of this study concerns two widely used damage models, namely the Cockcroft–Latham fracture criterion and the Gurson–Tvergaard model. Calibration of material models and a parameter study are carried out based on analyses of the tension tests. To this end, a case study is conducted elaborating on the importance of the damage parameters within an idealised heat-affected zone and plane-strain tension. The main objective of this study is to obtain a more general understanding of ductile fracture modelling of aluminium alloys exposed to complex heat treatments representative of welding.

Comprehensive analysis method of acquiring wall heat fluxes in rotating detonation combustors

Accurate perception of the combustor thermal environment is crucial for thermal protection design of a rotating detonation combustor (RDC). In this study, a comprehensive analysis method is established to calculate the non-uniform heat flux distribution of the RDC by utilizing the measured temperature distribution of the combustor outer wall obtained by the high-speed infrared thermal imager. Firstly, a physical model based on the geometric characteristics of the RDC is constructed and its thermal conductive process is simulated, given by different heat flux boundary conditions. The analysis results indicate that the method used in current research for computing the heat flux of RDC leads to significant discrepancies, particularly in regions of obvious axial heat flux gradients near the top of the combustor. Then the Levenberg-Marquardt (L-M) method for inversely solving non-uniform heat flux is developed based on the two-dimensional heat conduction equation, and the wall heat fluxes are inversely calculated by the L-M method based on the above numerical data. Results show that the L-M method can obtain more accurate heat flux distribution even in the zones with large heat flux gradients, considering the axial heat conduction within the combustor outer wall caused by the non-uniform heat flux. Finally, the wall heat flux distribution is analyzed coupling the L-M method together with the experimental measurements in kerosene two-phase RDC. The analyses show that the wall heat flux exhibits non-uniform distributions both circumferentially and axially, with axial non-uniformity being particularly pronounced. The highest temperature of combustor outer surface and the highest wall heat flux occurs within the region of 20 mm from the combustor head, which corresponds to nearly 14 % of the combustor length. The heat flux peak and thermal heat rate are positively correlated with the combustor equivalence ratio in the range between 0.44 and 0.64. In this study, the distribution of wall temperature field in the two-phase RDC is obtained for the first time and the wall heat flux is calculated inversely by L-M method. This work provides a more accurate method for calculating heat flux in RDC and offers references for thermal protection designs in RDCs.

Experimental study on acoustic emission characteristics of high temperature thermal shock directional fracturing of granite with different heating conditions

High temperature thermal shock directional fracturing of hard rock has tremendous promise in the mining and tunneling industries, but the utilization mechanism is unclear and must be resolved before taking it to the field application stage. In this study, the granite specimens were subjected to bidirectional horizontal loads using the real triaxial pressure testing machine, and the thermal shock fracturing tests were conducted utilizing the homemade thermal shock system. The AE (acoustic emission) system tracked the whole granite fracture process throughout the test in real time. The results showed that the granite‘s fracture time under the high temperature thermal shock was negatively related to the peak heating temperature and heating rate. The spectral analysis of the AE was employed to consider a large number of 20–40 kHz AE signals as a sign of thermal shock damage. By spatial localization of AE events, it was determined that the thermal shock cracks sprouted at the borehole edge in the specimen’s center. In the horizontal direction, the cracks extended from the center to the specimen edge; in the vertical direction, the cracks extended from the specimen surface to the deeper portion of the specimen. The RA-AF value analysis indicated that the granite thermal shock damage mode was a mixed tensile-shear damage mode dominated by tensile damage. In addition, the higher the heating rate, the higher the percentage of tensile cracks. Increasing the heating temperature promoted the formation of shear damage inside the specimen when the heating rate was equal. Analyzing the b-value and βt-value indicated that at low heating rates (10 and 60 °C/min), many micro-cracks formed inside the granite before merging into macro-cracks. However, with the higher heating rate (110 °C/min), the formation of micro-cracks and the macro-cracks within the granite proceeded almost simultaneously. The research results provided some experimental foundation and theoretical guidance for high temperature thermal shock directional fracturing of hard rocks.

Thermomechanical Responses of Microcracks in a Honeycomb Particulate Filter

Manufacturing honeycomb‐structured catalysts require a careful understanding of the microstructure of the solid substrate and its dependence on thermal‐processing conditions. Herein, it is the thermal responses of microcracks in an uncoated microcracked aluminum titanate honeycomb catalyst is investigated by analyzing the material's resonance frequency using the high‐temperature impulse excitation technique. The resonance frequencies are presented as Young's modulus values to avoid sample size effects. Dynamic Young's modulus measurements show closed‐loop hysteresis due to microcracks healing and reopening, causing a reversible response. The hysteresis is further used to understand microcracks’ dependence on critical thermal‐processing conditions used in a catalyst manufacturing plant, including peak operating temperature (800–1000 °C), dwell period (1–3 h), and heating rates (1–5 °C min−1). Microcracks are observed to have two healing responses: instantaneous and delayed healing. Both responses significantly influence the design of catalyst manufacturing. Complete reopening of microcracks from their healing temperature (1150 °C) is a very time‐consuming process (50–60 h). However, it is shown in the analysis that microcrack relaxation is a critical phenomenon that must be considered in quality‐controlled environments.

Biomass combustion behaviors based on online monitoring system: Morphological, thermodynamic and kinetic analysis

Identifying the matching law between the morphology, thermodynamic and kinetic characteristics of single biomass can significantly achieve high-efficiency combustion. A visual combustion furnace with online monitoring system was designed and built to record in real-time the apparent volume shrinkage, particle heating process and gas releasing behaviors of single biomass briquette during the combustion process. Furthermore, this work aimed to present a new method to infer the effect of ambient temperature on the pore structure of volatile precipitation and char combustion, mainly through a comparative analysis of the changes in shrinkage ratio and activation energy with carbon conversion efficiency (CCE). The higher the ambient temperature, the faster the biomass heating rate, and the earlier it reached the peak heating rate and the ambient temperature, but the heating process of biomass in the water evaporation stage was almost the same at different ambient temperatures. Oxygen concentration had a significant effect on the volume shrinkage and gas product releasing characteristics, but less on the particle heat transfer. After deducting the experimental system errors, the biomass reaction mode, activation energy and pore structure changed significantly around 40–45% CCE. When the CCE was less than 40%, the biomass mainly underwent volatile precipitation and combustion, with smaller apparent volume shrinkage but larger pore volume at 700 °C compared to 900°C ambient temperature. With the CCE greater than 45% and less than 70%, the char combustion dominated the reaction process, the apparent volume shrinkage was smaller, but the pore structure was more developed at higher ambient temperatures compared to lower temperatures. When the CCE exceeded 70%, the apparent volume and carbon conversion remained almost constant at 700°C, but the volume shrinkage ratio continued to decrease at 900°C ambient temperature. This research and proposed method provide more accurate fundamental support for modeling particle combustion at the reactor scale and designing biomass combustion systems.

Advanced biorefinery feedstock from non-recyclable municipal solid waste by mechanical preprocessing

Because of accelerated urbanization and the development of a global economy, a large quantity of municipal solid waste (MSW) has been collected and disposed of by the municipalities. Due to this drastic increase in the disposal of MSW, the need for its management is a must to preserve the environment. Currently, approximately 50% of the total MSW generated in the United States has been utilized through various recycling, combustion, and composting technologies, which means the remaining 50% is sent to landfill; this is often known as non-recyclable MSW (nMSW). As this nMSW is physically and chemically heterogenous and contains very high amounts of inorganic material, processing is required prior to using it as a biorefinery feedstock. Thus, this study focused on how mechanical preprocessing advanced the physical and chemical properties of nMSW. The physical and chemical properties were investigated in terms of particle size distribution, bulk density, ultimate and proximate analysis, and the higher heating value (HHV). The combustion properties were examined in terms of ignition temperature, peak heat release rate, and combustion efficiency. Results showed that the variability of physical and chemical properties of nMSW can be reduced by mechanical preprocessing. For example, the variability of the bulk density of the as-received nMSW was approximately 17.3% while it reduced to 5.8% when the sample size was reduced to 2 mm. Similarly, the variability of ash and HHV reduced from 49.2% to 11.0% and 13.4%–4.2%, respectively. Combustion thermograms showed that the size reduction positively improved the combustion properties. For example, 2 mm of spec sample started to ignite approximately 4 times earlier and took 6.5 folds less time to reach the peak heating rate compared to as-received nMSW. Overall, the mechanical preprocessing reduced the variability of physical and chemical properties in addition to the improvement of combustion behavior of the nMSW which is one step forward toward the biorefinery feedstock.

Temperature Response of Metabolic Activity of an Antarctic Nematode.

Because of climate change, the McMurdo Dry Valleys of Antarctica (MCM) have experienced an increase in the frequency and magnitude of summer pulse warming and surface ice and snow melting events. In response to these environmental changes, some nematode species in the MCM have experienced steady population declines over the last three decades, but Plectus murrayi, a mesophilic nematode species, has responded with a steady increase in range and abundance. To determine how P. murrayi responds to increasing temperatures, we measured metabolic heat and CO2 production rates and calculated O2 consumption rates as a function of temperature at 5 °C intervals from 5 to 50 °C. Heat, CO2 production, and O2 consumption rates increase approximately exponentially up to 40 °C, a temperature never experienced in their polar habitat. Metabolic rates decline rapidly above 40 °C and are irreversibly lost at 50 °C due to thermal stress and mortality. Caenorhabditis elegans, a much more widespread nematode that is found in more temperate environments reaches peak metabolic heat rate at just 27 °C, above which it experiences high mortality due to thermal stress. At temperatures from 10 to 40 °C, P. murrayi produces about 6 times more CO2 than the O2 it consumes, a respiratory quotient indicative of either acetogenesis or de novo lipogenesis. No potential acetogenic microbes were identified in the P. murrayi microbiome, suggesting that P. murrayi is producing increased CO2 as a byproduct of de novo lipogenesis. This phenomenon, in conjunction with increased summer temperatures in their polar habitat, will likely lead to increased demand for carbon and subsequent increases in CO2 production, population abundance, and range expansion. If such changes are not concomitant with increased carbon inputs, we predict the MCM soil ecosystems will experience dramatic declines in functional and taxonomic diversity.

Energy-saving COVID–19 biomedical plastic waste treatment using the thermal - Catalytic pyrolysis

The rate of Biomedical waste generation increases exponentially during infectious diseases, such as the SARS-CoV-2 virus, which burst in December 2019 and spread worldwide in a very short time, causing over 6 M casualties worldwide till May 2022. As per the WHO guidelines, the facemask has been used by every person to prevent the infection of the SARS-CoV-2 virus and discarded as biomedical waste. In the present work, a 3-ply facemask was chosen to be treated using the solvent, which was extracted from the different types of waste plastics through the thermal–catalytic pyrolysis process using a novel catalyst. The facemask was dispersed in the solvent in a heating process, followed by dissolution and precipitation of the facemask in the solvent and by filtration of the solid facemask residue out of the solvent. The effect of peak temperature, heating rate, and type of solvent is observed experimentally, and it found that the facemask was dissolved completely with a clear supernate in the solvent extracted from the (polypropylene + poly-ethylene) plastic also saved energy, while the solvent from ABS plastic was not capable to dissolute the facemask. The potential of the presented approach on the global level is also examined.

Performance tests on embedded cooling tube type metal hydride reactor for heating and cooling applications

• Heating and cooling traits of two AB 5 -type metal hydride alloys were investigated. • Heating performances of the alloys were found to be superior compared to cooling. • Peak heating rate of 3.5 kW was accomplished, producing 514 kJ heat within 361 s. • A decentralized heating cum H 2 storage system was suggested based on test results. The present work reports the heating and cooling characteristics of two AB 5 type metal hydride (MH) alloys commercially labelled as A3® and LCC1®. A cylindrical MH reactor configuration comprising 48 Embedded Cooling Tubes (ECT) in a circular pattern and an outer jacket was considered to accomplish the set objectives. Two identical reactors were each filled with 3.4 kg of one of the alloys. The reactor configuration allows MH alloy to be filled in the shell space while the heat transfer fluid (HTF) could flow through the tubes and the outer jacket. A set of parametric investigations was conducted on the aforementioned alloys by varying the operational parameters. During the absorption set of the parametric study, hydrogen supply pressure was varied from 10 bar to 30 bar, and HTF temperature was varied from 15 °C to 35 °C, while during the desorption study, HTF temperature was varied from 5 °C to 25 °C. At the absorption condition of 30 bar and 25 °C, the alloys A3® and LCC1® attained absorption capacity of 1.24 wt.% and 1.38 wt.%, respectively. At this condition, LCC1® was able to generate 514.5 kJ cumulative heat output in 361 s, yielding a maximum heating rate of 3.57 kW. The parametric study revealed that the absorption behaviour of A3® was more sensitive towards changes in supply pressure as well as HTF temperature compared to LCC1®. Compared to heating performance, the cooling performance of both the alloys was lower. Based on the outcomes of the experimental study, it was suggested to utilize LCC1® for decentralized hydrogen storage cum heating applications in the temperature range of 15–35 °C.

Thermomechanical and Fire Properties of Polyethylene-Composite-Filled Ammonium Polyphosphate and Inorganic Fillers: An Evaluation of Their Modification Efficiency.

The development of new polymer compositions characterized by a reduced environmental impact while lowering the price for applications in large-scale production requires the search for solutions based on the reduction in the polymer content in composites’ structure, as well as the use of fillers from sustainable sources. The study aimed to comprehensively evaluate introducing low-cost inorganic fillers, such as copper slag (CS), basalt powder (BP), and expanded vermiculite (VM), into the flame-retarded ammonium polyphosphate polyethylene composition (PE/APP). The addition of fillers (5–20 wt%) increased the stiffness and hardness of PE/APP, both at room and at elevated temperatures, which may increase the applicability range of the flame retardant polyethylene. The deterioration of composites’ tensile strength and impact strength induced by the presence of inorganic fillers compared to the unmodified polymer is described in detail. The addition of BP, CS, and VM with the simultaneous participation of APP with a total share of 40 wt% caused only a 3.1, 4.6, and 3 MPa decrease in the tensile strength compared to the reference value of 23 MPa found for PE. In turn, the cone calorimeter measurements allowed for the observation of a synergistic effect between APP and VM, reducing the peak heat rate release (pHRR) by 60% compared to unmodified PE. Incorporating fillers with a similar thermal stability but differing particle size distribution and shape led to additional information on their effectiveness in changing the properties of polyethylene. Critical examinations of changes in the mechanical and thermomechanical properties related to the structure analysis enabled the definition of the potential application perspectives analyzed in terms of burning behavior in a cone calorimetry test. Adding inorganic fillers derived from waste significantly reduces the flammability of composites with a matrix of thermoplastic polymers while increasing their sustainability and lowering their price without considerably reducing their mechanical properties, which allows for assigning developed materials as a replacement for flame-retarded polyethylene in large-scale non-loaded parts.

A bio-based epoxy resin derived from p-hydroxycinnamic acid with high mechanical properties and flame retardancy

Recent advances in epoxy resins have been forward to achieving high mechanical performance, thermal stability, and flame retardancy. However, seeking sustainable bio-based epoxy precursors and avoiding introduction of additional flame-retardant agents are still of increasing demand. Here we report the synthesis of p-hydroxycinnamic acid-derived epoxy monomer (HCA-EP) via a simple one-step reaction, and the HCA-EP can be cured with 4,4′-diaminodiphenylmethane (DDM) to prepare epoxy resins. Compared with the typical petroleum-based epoxy resin, bisphenol A epoxy resin, the HCA-EP-DDM shows a relatively high glass transition temperature (192.9 °C) and impressive mechanical properties (tensile strength of 98.3 MPa and flexural strength of 158.9 MPa). Furthermore, the HCA-EP-DDM passes the V-1 flammability rating in UL-94 test and presents the limiting oxygen index of 32.6%. Notably, its char yield is as high as 31.6% under N2, and the peak heat rate release is 60% lower than that of bisphenol A epoxy resin. Such findings provide a simple way of using p-hydroxycinnamic acid instead of bisphenol A to construct high-performance bio-based thermosets.

Synthesis of non-phosphorylated epoxidised corn oil as a novel green flame retardant thermoset resin

This study aimed to produce a new potential flame retardant thermoset resin from epoxidised corn oil through a one-pot method using liquid inorganic catalysed with hydrogen peroxide. Using a gas chromatography–mass selective detector, attenuated total reflectance-fourier transform infrared spectroscopy, proton nuclear magnetic resonance imaging, optical microscopy, and scanning emission microscopy, we synthesised a bio-based resin based on newly designed parameters. The flame retardant capacity was fully established using thermogravimetric analysis and a micro calorimeter. The produced epoxidised corn oil had a relative percentage conversion of oxirane of approximately 91.70%, wherein the amount of double bonds converted into epoxides was calculated. A significant reduction from 17 to 40% in peak heat rate release (pHRR) and 26–30% in total heat release was observed, confirming its flame retardant property. Thus, the potential of epoxidised corn oil was demonstrated.

Investigating the Role of Energy Density in Thermal Runaway of Lithium-Ion Batteries with Accelerating Rate Calorimetry

This work uses accelerating rate calorimetry to evaluate the impact of cell chemistry, state of charge, cell capacity, and ultimately cell energy density on the total energy release and peak heating rates observed during thermal runaway of Li-ion batteries. While the traditional focus has been using calorimetry to compare different chemistries in cells of similar sizes, this work seeks to better understand how applicable small cell data is to understand the thermal runaway behavior of large cells as well as determine if thermal runaway behaviors can be more generally tied to aspects of lithium-ion cells such as total stored energy and specific energy. We have found a strong linear correlation between the total enthalpy of the thermal runaway process and the stored energy of the cell, apparently independent of cell size and state of charge. We have also shown that peak heating rates and peak temperatures reached during thermal runaway events are more closely tied to specific energy, increasing exponentially in the case of peak heating rates.

(Invited) Calorimetry of Cell Failure in Multiple Formats and Capacity

Accelerating Rate Calorimetry (ARC) has previously been used to evaluate differences observed in various active materials with a typical comparison shown in the figure below. This evaluation is usually performed on small cells of roughly the same capacity (~1 AH) to allow for an easy comparison of active materials as they are developed. However, this and similar calorimetry methods present a means to perform more quantitative measurements of the heat generated and kinetics of thermal runaway. Sandia National Laboratories has performed testing on cells in the 10s of amp hours and analyzed the thermal runaway behavior of these cells.This work uses accelerating rate calorimetry to evaluate the impact of cell chemistry, state of charge, cell capacity, and ultimately cell energy density on the total energy release and peak heating rates observed during thermal runaway of Li-ion batteries. This work seeks to better understand how applicable small cell data is to understand the thermal runaway behavior of large cells as well as determine if thermal runaway behaviors can be more generally tied to aspects of lithium-ion cells such as total stored energy and specific energy. We have found a strong linear correlation between the total enthalpy of the thermal runaway process and the stored energy of the cell, apparently independent of cell size and state of charge. We have also shown that peak heating rates and peak temperatures reached during thermal runaway events are more closely tied to specific energy, increasing exponentially in the case of peak heating rates.Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. Figure 1

Biochar from slow pyrolysis of biological sludge from wastewater treatment: characteristics and effect as soil amendment

AbstractBiological sludge from wastewater treatment is a by‐product from the pulp and paper industry, for which several management approaches are being researched to develop added‐value applications and to decrease the disposal costs. This work studied biological sludge pyrolysis to produce biochar for further use as soil amendment. The pyrolysis was conducted in a bench‐scale fixed‐bed reactor using distinct operating conditions, namely heating rate between 2 °C min−1 and 30 °C min−1 and peak temperature between 300 °C and 600 °C. The results demonstrated that biochar yield was between 0.40 and 0.73 kg kg–1 dry sludge. A trend for biochar yield to decrease with increasing peak temperature and heating rate was observed. The carbon content of biochar was between 42.8 and 47.0 wt%. The biochar pH was between 6.9 and 11.2. The effect of the biochar produced by pyrolysis as a soil corrective was evaluated in this work. Samples of biochar produced at 450 °C and 10 °C min−1 were incubated in a selected soil and its influence on soil properties and plant growth was evaluated. It was observed that the biochar portion 2.5%, 5%, and 10% promoted an increase in soil pH and an increase in water retention. The biochar portion 2.5% and 5% promoted a higher growth of Lepidium sativum plants. The results demonstrated the potential of the pyrolysis of biological sludge from the pulp and paper industry to produce biochar to be further used as a soil amendment. This strategy is of major importance in this industrial sector, thus contributing to the European Union goals on circular economy and industrial sustainability. © 2021 Society of Industrial Chemistry and John Wiley & Sons Ltd.

Aerocapture Assessment for NASA Ice Giants Pre-Decadal Survey Mission Study

A performance analysis for aerocapture at Uranus and Neptune is presented and considers entry corridor width, peak deceleration, peak heat rate, total heat load, and the effect of postcapture orbit on the design parameters. Aerocapture mass benefit vs chemical capture is also quantified. Design relationships are found that can be used in flight system sizing for future studies involving aerocapture. Results are obtained for interplanetary trajectories for launch years from 2025 to 2036, including both chemical capture and high arrival . The results show that based on the current assumption for errors and uncertainties aerocapture at Uranus and Neptune requires a mid-lift-to-drag ratio between 0.6 and 0.8. Technology recommendations are made for aerocapture missions to Uranus and Neptune.

Heat of hydration, bleeding, viscosity, setting of Ca(OH)2-GGBS and MgO-GGBS grouts

Hydrated lime (Ca(OH)2)- and reactive magnesia (MgO)-activated ground granulated blast-furnace slag (GGBS) have shown advantages in geotechnical applications compared with Portland cement (PC). To apply these two novel binders in slurry form to field applications, the properties of their grouts need to be investigated, which is the objective of this study. The heat of hydration, bleeding, viscosity, and setting behavior of Ca(OH)2-GGBS and MgO-GGBS grouts were investigated and compared with PC and pure GGBS grouts in this study. All grouts indicated a decrease in bleeding and setting time, but an increase in viscosity with decreasing the water/cementitious material (W/C) ratio. Compared with the PC grout, the pure GGBS grout with the same W/C ratio demonstrated higher bleeding and setting time, and lower heat rate and viscosity. Bleeding and setting time decreased and peak heat rate and viscosity increased with an increase in the activator (Ca(OH)2 or MgO)/GGBS ratio within GGBS-based grouts. The peak heat rate in Ca(OH)2-GGBS grouts was higher than that of pure GGBS or Ca(OH)2 grout, indicating that Ca(OH)2 was effective on activating hydration of GGBS. The peak heat rate in MgO-GGBS grouts was significantly lower than MgO grout and the heat rate was limited after 8 h. The bleeding and setting times of MgO-GGBS grouts were significantly lower than those of Ca(OH)2-GGBS grouts, which was primarily attributed to the hydration of MgO.

Effect of brazing parameters on fillet size and microstructure of cladded fin-microchannel tube joints

Abstract This work concerns the optimization of furnace brazing conditions for joining micro-multiport aluminum tubes and fins made with AA4343/AA3003/AA4343 brazing sheet in mini-assemblies mimicking the core of an automotive heat exchanger. Taguchi method was used for design of experiment, considering five process parameters with two levels of values. The aim was to maximize the fillet size of the brazed joints, which has an important influence on the thermal integrity and mechanical properties. Fillet length measurements of brazed joints were performed with a metallographic microscope. The statistical analysis allowed to obtain the optimum values of process parameters (peak temperature, residence time, heating rate, microchannel tube type and flux). At a 95% confidence level, the variability of fillet length is most significantly affected by the peak brazing temperature (77%), residence time (15%) and heating rate (7%). The predicted maximum fillet length was (152±11) µm, which was corroborated by confirmation trials. The microstructural analysis of tube−fin joints showed that variations in peak temperature and residence time affect only the size of the eutectic zone of fillet formed, but not the nature or composition of the constituent phases.