To reduce the energy supply for pyrolysis, autothermal pyrolysis is one of the most promising approaches to upcycle plastic waste. In this work, both single-step and multi-step methods were applied ...to perform kinetic studies of low-density polyethylene (LDPE) pyrolysis under oxidative atmospheres (0, 5, and 10% O2 balanced by N2) by changing the heating rate from 5 to 20 K min−1. Miura integral method was then used to estimate the apparent activation energy. The major findings showed that the multi-step method using asymmetric double sigmoidal (Asym2Sig) deconvolution procedure was more appropriate to study kinetic behaviors of LDPE autothermal pyrolysis. The activation energy needed for LDPE pyrolysis under N2 was 271 kJ·mol−1, while the activation energies of the three pseudo-reactions under 5% O2 were 71, 153 and 189 kJ·mol−1, and under 10% O2 were 74, 224 and 169 kJ·mol−1, indicating that LDPE autothermal pyrolysis was more energy-saving than conventional LDPE pyrolysis. Additionally, the reaction mechanism was proposed to provide an accurate and critical guideline for commercializing this novel technical route, which is beneficial to achieving sustainable plastic waste management and mitigating plastic pollution, simultaneously.
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•Kinetics of LDPE autothermal pyrolysis was investigated using Miura method.•Asym2Sig deconvolution function is used to divide stages of pyrolysis reaction.•E0 (kJ·mol−1) for autothermal pyrolysis (<225) is lower than that under N2 (271).
Interconnect scaling has become a major design challenge for traditional planar (2D) integrated circuits (ICs). Three-dimensional (3D) IC that stacks multiple device layers through 3D stacking ...technology is regarded as an effective solution to this dilemma. A promising 3D IC design direction is to construct 3D processors. However, 3D processors are likely to suffer from more serious thermal issues as compared to conventional 2D processors, which may hinder the employment or even offset the benefits of 3D stacking. Therefore, thermal-aware design techniques should be adopted to alleviate the thermal problems with 3D processors. In this survey, we review works on system level optimization techniques for thermal-aware 3D processor design from hierarchical perspectives of architecture, floorplanning, memory management, and task scheduling. We first survey 3D processor architectures to demonstrate how a 3D processor can be constructed by using 3D stacking technology, and present an overview of thermal characteristics of the constructed 3D processors. We then review thermal-aware floorplanning, memory management and task scheduling techniques to show how the thermal impact on 3D processor performance can be reduced. A systematic classification method is utilized throughout the survey to emphasize similarities and differences of various thermal-aware 3D processor optimization techniques. This paper shows that the thermal impact on 3D processors is manageable by adopting thermal-aware techniques, thus making 3D processors into the mainstream in the near future.
•Extraction pH (9–11) and pH treatment favorably affected different characteristics of amaranth protein isolates (APIs).•APIs obtained at pH 9 showed highest purity, solubility and lowest ...yield.•Particle size was reduced when the treatment pH was increased.•Storage modulus (G') and loss modulus (G“) were found higher in APIs obtained at pH 9.•Functional properties showed significant improvement when the extraction and treatment pH of APIs was maintained at 9.
Results for the effect of extraction pH and pH treatment on the functional, physicochemical, rheological and thermal characteristics of amaranth protein isolates (APIs) are reported in this study. Four amaranth protein isolates (P1, P2, P3 and P4) were prepared by varying the extraction pH (9–11). These four protein isolate samples were further treated at pH values from 3 to 9. The total protein content and purity of protein isolates were found to be higher for P1 than P2, P3 and P4 samples. The particle size of P1 was significantly (p ≤ 0.05) higher (299.68 µm) than other samples. Solubility, emulsifying capacity and stability, foaming properties, water and oil binding capacities were higher for the P1 sample treated at pH 9. Gelation characteristics like storage modulus (G') and loss modulus (G“) were higher for P1 samples. APIs obtained at extraction pH 9 (P1) also exhibited better thermal properties in comparison with other three samples.
In the present study, thermal performance of greenhouse solar dryer (GHSD) was analyzed at full load of peppermint leaves for dehydration. The experiments were conducted in both GHSD and sun drying ...processes to compare drying characteristics, thermal properties, and quality assessment of peppermint leaves. The maximum drying cabin temperature attained during the experimentation was 58.3 °C at solar radiation 864W/m2. Initial moisture content of peppermint leaves 81.25% reduced to 11.22% and 22% within 10 h in GHSD and sun drying, respectively. Drying rate was obtained as 0.65 kg water/kg solid.hr and 0.61 kg water/kg solid.hr for GHSD and sun drying process at the end of the experiment. Verma et al. model accurately defined the drying characteristics of peppermint leaves in GHSD and sun drying. Average effective moisture diffusivity (Deff), mass transfer coefficient (hm) and heat transfer coefficient (h) of peppermint leaves were increased by 12.76%, 17.71%, and 64.23%, correspondingly in GHSD compared to sun drying. Activation energy (Ea) of peppermint leaves was computed as 32.25 kJ/mol in GHSD, while in sun drying method, it was 59.68 kJ/mol. Water activity (Aw) peppermint leaves were 0.850, 0.705, 0.385 and 0.850, 0.765, 0.520 at 8, 14, 19 h in GHSD and sun drying.
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•Greenhouse solar dryer (GHSD) was designed and fabricated for peppermint leaves.•Thermal characteristics, drying kinetics, and quality assessment of peppermint leaves were evaluated in GHSD and sun drying.•Verma et al. model was best fit drying model to explain drying behaviour of peppermint leaves in GHSD and sun drying.•Activation energy (Ea) of peppermint leaves was computed as 32.25 kJ/mol and59.68kJ/mol in GHSD and sun drying respectively.
Flow control using surface Dielectric Barrier Discharge (DBD) plasma actuators driven by a sinusoidal alternating-current power supply has gained significant attention from the aeronautic industry. ...The induced flow field of the plasma actuator, with the starting vortex in the wall jet, plays an important role in flow control. However, the energy consumed for producing the induced flow field is only a small fraction of the total energy utilized by the plasma actuator, and most of the total energy is used in gas heating and dielectric heating. Therefore, an in-depth analysis of the thermal characteristics of the plasma actuator is the key to develop its potential capability further. In addition, compared with the investigation on the aerodynamic characteristics of the plasma actuator, there is a relative lack of detail in the study of its thermal characteristics. Understanding the thermal characteristics of the plasma actuator is of great interest for providing a deeper insight into the underlying working principles, advancing its numerical simulation model, prolonging its life, and achieving several potential engineering applications, such as anti-icing and deicing. The present paper reviews the thermal characteristics of the plasma actuator, summarizes the influence of the dielectric film and actuation parameters on heating, and discusses the formation and transfer mechanism of the induced heating based on the discharge regimes of the plasma actuator in one cycle.
•Develop a second-order thermal network model and a hybrid parameter identification scheme for residential buildings.•Characterize dynamics of space air and interior wall surface temperatures ...separately.•Enable automatic, sequential, and optimal estimation of the model parameters.•Yield reliable parameter estimates and accurate prediction using only a modest amount of training data.•Provide a tool to facilitate grid-interactive Heating, Ventilation, and Air Conditioning (HVAC) operation.
Heating, Ventilation, and Air Conditioning (HVAC) systems can maintain the space air temperature of residential buildings, either directly by heating/cooling the air, or indirectly via heat transfer to and from the building structure that acts as a thermal mass. Hence, HVAC systems can help achieve load shifting, peak load reduction, and/or energy cost saving, thus enabling grid-interactive HVAC operation. A home thermal model that can accurately reflect the dynamics of the space air and interior wall surface temperatures, is therefore valuable. This paper develops such a model using the standard RC (resistance-capacitance) approach. The model contains a virtual envelope node and an internal space node and is thus second-order. A hybrid parameter identification scheme, made up of the least-squares and optimal search methods, is also developed. The proposed model and scheme were validated using data collected from a test home. It was found that a modest amount of training data was sufficient to yield reliable parameter estimates and accurate prediction. It was also found that when making 24-hour-ahead prediction of the space air temperature, both methods had comparable performances when the training data began in a transition season. However, when they began in an HVAC season, the optimal search method performed better. Therefore, the least-squares method is recommended during a transition season due to its lower computational burden, while the optimal search method is recommended during an HVAC season due to its better estimation performance.
•A calorimetry method for heat generation measurement of batteries is presented.•Method is based on lumped capacitance model and forced convection environment.•Effects of current and temperature on ...heat generation characteristics are measured.•The effect of cycle aging on heat generation characteristics is measured.•The effect of cycle charge current on battery cycle life is significant.
This paper presents a forced convection calorimetry method, based on the lumped capacitance model, to measure the continuous noise-free heat generation rate of batteries. The method was verified via reference sample calibration. Battery test results indicated that the discharge current, ambient temperature, and cycle aging significantly affect the heat generation characteristics of batteries. A larger discharge current and lower ambient temperature of 20–45 °C caused a greater heat generation rate and faster temperature increase. The average heat generation rate over the discharge period exhibited a quadratic polynomial correlation with the discharge current and a negative quadratic polynomial correlation with the ambient temperature. The cycling process increased the heat generation rate, reflecting battery aging. The cycle charge rate had a significant impact on the battery life. Moreover, the two cells started to display different heat generation characteristics after being cycled by different currents even at a similar state of health, revealing that the cycling process and different cycle rates may aggravate the battery inconsistency.
A three-dimensional electrochemical-thermal coupled model is developed to investigate the interactive electrochemical and thermal characteristics of pouch-type lithium-ion batteries under natural ...convection conditions. The heat generation rate calculated by the electrochemical model is applied to the thermal model as the heat source, while the temperature derived from the thermal model is regarded as the initial condition for the electrochemical model. The simulations are verified by the experimental data under different discharge rates (1, 3, and 5 C). Numerical results reveal that the average particle size of electrodes directly affects the heat generation rate of the battery during the discharge process. More importantly, it is found that in the in-plane direction, the maximum local current density appears near the tabs initially and moves to the bottom side with the progress of the discharge as the regions away from tabs becomes more favorable for electrochemical reactions. The uneven distribution of local current density results in a non-uniform distribution of the heat generation rate and thus the uneven temperature distribution. In addition, the temperature gradient in the through-plane direction is relatively small under natural convection conditions. This work offers more insights into heat generation mechanisms in lithium-ion batteries, which will assist the design of efficient battery thermal management systems.
We investigate the electronic, the thermal, and the optical properties of BN-codoped MgO monolayers taking into account the interaction effects between the B and the N dopant atoms. The relatively ...wide indirect band gap of a pure MgO nanosheet can be changed to a narrow direct band gap by tuning the B-N attractive interaction. The band gap reduction does not only enhance the optical properties, including the absorption spectra and the optical conductivity, but also the most intense peak is shifted from the Deep-UV to the visible light region. The red shifting of the absorption spectra and the optical conductivity are caused by the attractive interaction. In addition, both isotropic and anisotropic characteristics are seen in the optical properties depending on the strength of the B-N attractive interaction. The heat capacity is reduced for the BN-doped MgO monolayer, which can be referred to changes in the bond dissociation energy. The bond dissociation energy decreases as the difference in the electronegativities of the bonded atoms decreases. The lower difference in the electronegativities leads to a weaker endothermic process resulting in reduction of the heat capacity. An ab initio molecular dynamics, AIMD, calculation is utilized to check the thermodynamic stability of the pure and the BN-codoped MgO monolayers. We thus confirm that the BN-codopant atoms can be used to gain control of the properties of MgO monolayers for thermo- and opto-electronic devices.
•Attractive interaction between dopant atoms improves optical properties.•Anisotropic optical behavior is found due to attractive interaction.•BN-codopant converts a wide band gap behavior of MgO monolayer to a narrow semiconductor.•Thermal reducation is seen for BN-codoped MgO monolayer.
The electronic, thermal, magnetic and optical properties of BN-codoped strontium oxide (SrO) monolayers are studied taking into account the interaction effects between the B and the N dopant atoms. ...The indirect band gap of a pure two dimensional SrO is modified to a narrow direct band gap by tuning the B-N attractive interaction. The B or N separately doped SrO leads to a metallic behavior, while a BN-codoped SrO has a semiconductor character. The pure SrO monolayer has a band gap of 1.6eV, which is reduced to 0.15 and 1.04eV in the presence of a BN-codopant depending on the interatomic interaction strength of the dopant atoms. The strong B-N attractive interaction changes a non-magnetic SrO to a magnetic system and reduces its heat capacity. An ab initio molecular dynamics, AIMD, calculations are also utilized to check the thermodynamic stability of the pure and BN-codoped SrO monolayers. The band gap reduction of SrO increases the optical conductivity shifting the most intense peak from the Deep-UV to the visible light region. The red shifted optical conductivity emerges due to the B-N attractive interaction. In addition, both iso- and anisotropic characters are seen in the optical properties depending on the strength of the B-N attractive interaction. It can thus be confirmed that the interaction effects of the BN-codopants can be used to control the properties of SrO monolayers for thermo- and opto-electronic devices.
•Attractive interaction between dopant atoms improves optical properties.•Anisotropic optical behavior is found due to attractive interaction.•Attractive interaction between dopant atoms generates magnetic behavior of the SrO monolayer.•Thermal reduction is seen for BN-codoped SrO monolayer due to attractive interaction.
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