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Prenatal exposure to anesthetics has raised increasing attention about the neuronal development in offspring. Animal models are usually used for investigation. As a new drug, esketamine is the s-isoform of ketamine and is twice as potent as the racemic ketamine with less reported adverse effects. Esketamine is currently being used and become more favorable in clinical anesthesia work, including surgeries during pregnancy, yet the effect on the offspring is unknown. The present study aimed to elucidate the effects of gestational administration of esketamine on neuronal development in offspring, using a rat model. Gestational day 14.5 pregnant rats received intravenous injections of esketamine. The postnatal day 0 (P0) hippocampus was digested and cultured in vitro to display the neuronal growth morphology. On Day 4 the in vitro experiments revealed a shorter axon length and fewer dendrite branches in the esketamine group. The results from the EdU- imaging kit showed decreased proliferative capacity in the subventricular zone (SVZ) and dentate gyrus (DG) in both P0 and P30 offspring brains in the esketamine group. Moreover, neurogenesis, neuron maturity and spine density were impaired, resulting in attenuated long-term potentiation (LTP). Compromised hippocampal function accounted for the deficits in neuronal cognition, memory and emotion. The evidence obtained suggests that the neurobehavioral deficit due to prenatal exposure to esketamine may be related to the decrease phosphorylation of CREB and abnormalities in N-methyl-d-aspartic acid receptor subunits. Taken together, these results demonstrate the negative effect of prenatal esketamine exposure on neuronal development in offspring rats. Graphical Abstract G14.5 esketamine administration influenced the neurobehavior of the offspring in adolescence. Poorer neuronal growth and reduced brain proliferative capacity in late gestation and juvenile pups resulted in impaired P30 neuronal plasticity and synaptic spines as well as abnormalities in NMDAR subunits. Attenuated LTP reflected compromised hippocampal function, as confirmed by behavioral tests of cognition, memory and emotions. This figure was completed on the website of Figdraw.

The conductive foamed silicone rubber was prepared by Polymethylvinylsiloxane (PMVS) mixed with acetylene black, fumed silica, and AC foaming agent (azodicarbonamide). Influences of fillers on the microstructure, electrical conductivity and mechanical property were discussed. The results showed that the pore structure was affected by acetylene black. Acetylene black delayed the vulcanization speed of silicone rubbers, leading to bigger pores. Higher content of acetylene black decreased the mechanical properties and the electrical resistivity of rubbers. Fumed silica increased the mechanical properties and limited the aggregation of gas. Higher content of fumed silica led to small and obturator pores generated. Higher content of fumed silica increase the mechanical properties and the electrical resistivity of rubbers. AC foaming agents generated more gas, leading to bigger and irregular pores which affected the mechanical properties negatively, meanwhile AC foaming agents increased the conductivity of rubbers.

Investigating the genesis of geothermal resources requires a thorough understanding of the heat source mechanism, which is also a vital basis for the efficient exploration and utilization of geothermal resources. Situated in the eastern Himalayan syntax, western Sichuan is considered to be one of the main concentration regions of high-temperature geothermal resources in China. To date, various studies have been carried out to reveal the heat source and genesis of the abundant high-temperature resources in this area; however, studies on the contribution of the radioactive heat generated by the widely distributed granitoids to the high-temperature geothermal resources remain scarce. In order to resolve this knowledge gap, we attempted to obtain evidence from the geochemical data published in the literature in the past few decades. A total of 548 radiogenic heat production rate data were determined. The statistical data indicate that the average concentrations of the heat-producing elements U, Th, and K are 6.09±5.22 ppm, 26.74±16.78 ppm, and 3.51±0.82%, respectively. The calculated heat production values of the granitoids vary from 0.52 to 10.86 μW/m3, yielding an arithmetic average value of 3.74±2.15 μW/m3, which is higher than that of global Mesozoic–Cenozoic granites (3.09±1.62 μW/m3). Based on the heat production values, the capacity of the granitic batholiths to store heat was assessed, and the Dongcuo pluton was found to be the largest heat reservoir (382.88×1013 J/a). The distribution of the crustal heat flow was examined using the calculated heat production data and the stratigraphic structure obtained via deep seismic sounding in the study area. The results indicate that the crustal heat flow is 48.3–56.2 mW/m2, which is mainly contributed by the radioactive decay in the granitoids in the upper crust. The fact that it accounts for nearly half of the regional background heat flow indicates that the radiogenic heat from the granitoids is an important heat source for the formation of the thermal anomaly and the high-temperature geothermal resources in the study area. Thus, the results obtained in this study highlight the importance of the widely distributed granitoids to high-temperature geothermal resources in western Sichuan.

Silicon-containing polyester from tetramethoxysilane, ethylene glycol, and o-Phthalic anhydride were used as encapsulating materials for silicon nano powders (SiNP) via electrospinning, with Polyacrylonitrile (PAN) as spinning additives. In the correct quantities, SiNP could be well encapsulated in nano fibers (200–400 nm) using scanning electron microscopy (SEM). The encapsulating materials were then carbonized to a Si-O-C material at 755 °C (Si@C-SiNF-5 and Si@C-SiNF-10, with different SiNP content). Fiber structure and SiNP crystalline structure were reserved even after high-temperature treatment, as SEM and X-ray diffraction (XRD) verified. When used as lithium ion battery (LIB) anode materials, the cycling stability of SiNPs increased after encapsulation. The capacity of SiNPs decreased to ~10 mAh/g within 30 cycles, while those from Si@C-SiNF-5 and Si@C-SiNF-10 remained over 500 mAh/g at the 30th cycle. We also found that adequate SiNP content is necessary for good encapsulation and better cycling stability. In the anode from Si@C-SiNF-10 in which SiNPs were not well encapsulated, fibers were broken and pulverized as SEM confirmed; thus, its cycling stability is poorer than that from Si@C-SiNF-5.

An investigation is done upon the lean H2-air flame under turbulent conditions to clarify the role of inherent instabilities and turbulence in self-acceleration of expanding flames. The result shows that, in weak turbulent flow fields, the two-stage self-acceleration feature still exists. As the turbulent intensity increases, the originally evident two-stage “transition-saturation” feature is weakened. When the Karlovitz number becomes greater than 1, the self-acceleration process no longer experiences the transition stage and performs a single-stage feature. These observations are correlated with the distribution and evolution of length scales in the cellular structure of the flamefront. A theoretical analysis is conducted to compare growth rates of disturbances induced by instability and turbulence, with consideration of their wavelength dependence. On this basis, interpretations are proposed on afore-mentioned phenomenal observations and response of quantitative parameters such as fractal excess and average cell wavelength.

Silicon polyester (Si-PET) was synthesized with ethylene glycol and phthalic anhydride, and then it was carbonized and hydrothermally coated with glucose. The forming SiOx with layered graphene as the 3D network had amorphous carbon layer.

Experiments and quantitative evaluation are conducted upon the cellular morphology and self-acceleration in lean H2-air expanding flames, trying to interpret the inherent relationship between them. Results confirm the existence of two distinct self-acceleration stages (transition and saturation). The transition between them happens when the averaged cell radius decreases to a minimum stable value. Self-similar laws exist both in the transition stage and the saturation stage, with the fractal excess of transition stage much greater than saturation stage. In the saturation stage, fractal excess slowly increases with pressure but is always smaller than 0.33. Basing on evolution profiles of cell radius, the physical interpretation of greater self-acceleration exponent in the transition stage is quantitatively confirmed by correlating the decreasing rate of cell wavelength with flame radius. Finally, the inconsistency of fractal excess in the saturation stage is interpreted from the perspective of the discrete wavelength spectrum in cellular flames.

To decrease the modulus and increase the mechanical properties of recycled PET by introducing the flexible segments, the recycled polyethylene-terephthalate (PET) was modified by the chain extender produced with 2, 4, 6, 8-tetramethyl-2, 4, 6, 8-tetra (2, 3-epoxypropoxy) propylcyclotetrasiloxane by the hydrosilylation reaction. Different percentages of chain extender were used in order to investigate the effect of chain extender content on the modulus of PET. The dynamic mechanical analysis was performed on PET samples, which showed that Tg of PET was firstly raised by the addition of chain extender and then decreased. Small amplitude shearing test performed on PET samples confirmed that the addition of the flexible segments could remarkably decrease the modulus of PET, which would be helpful for the extrusion process. The entanglements from branches were also influenced by the addition of extender.

In this study, a simple and novel hydrothermal approach was developed for the controllable synthesis of monoclinic scheelite BiVO4 using V2O5, Bi(NO3)3 and H2O2 as the starting materials. Diverse morphologies of BiVO4 including rods and branches were obtained by adjusting the H2O2 addition. We characterized these samples using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, in situ UV–vis diffuse reflectance spectroscopy and Fourier transform infrared spectroscopy to investigate the effects of crystal structure deformation on their thermochromic behaviors. The results showed that the greater was the degree of structural distortion, the better was the thermochromic performance. As compared to rod-like morphology, the branch-like BiVO4 material exhibited better thermochromic properties owing to the greater distortion of crystal structure.

Due to absence of quantitative and evolutionary view on flame-front's wrinkling morphonology, descriptions upon instability onset of premixed expanding spherical flames in previous literatures are implicit and inconsistent. This paper utilized shadowgraphy and high-magnification lens in the optical configuration, which clearly manifested cracks in wrinkled flame images and facilitated precise segmentation of them. A simple algorithm was developed to reconstruct real lengths of cracks from these planar projected images. Furthermore, a meaningful parameter, the averaged cell radius, was deducted from the total crack length. Application of this novel methodology on the near-equidiffusive C 2 H 2 -air flame reveals similar growth speeds of flame cracks under different pressures before the flame front transits into cellular appearance. Before this transition, the averaged cell radius kept fluctuating around a roughly stable level which was intimately dependent on initial disturbances. Once the transition started, the effect of inherent instability dominates over initial disturbances and averaged cell radii of repeated tests gradually converged to a similar value. The above methodology builds up an automatic way to quantitatively characterizing cracks and cells' developing history, which extracts more useful and precise information from image series than merely manual estimation of cell sizes at individual shoots in previous studies.

Spray mixing and combustion processes are regarded as the major factors that determine the energy conversion efficiency and emission level of internal combustion engines. However, the related researches mainly rely on 3D flow simulation or optical engine experiments, which are highly expensive and time-consuming. In order to provide a more convenient solution, this paper developed a one-dimensional semi-phenomenological model to achieve accurate and efficient predictions on spray combustion characteristics. The model was constructed by a dimensionless spray theoretical model and limited experimental data of macroscopic spray characteristics. Inside the proposed model, a physical module was used to physical module spray air-fuel mixing conditions like fuel distribution and evaporation. Besides, an improved Arrhenius-typed correlation concerning injection parameters and environment variables was introduced to describe the chemical ignition characteristic of spray combustion. The optical experiment results showed that this method is simple and effective, and the forecasting is satisfactory. Based on the new model, the influences of blending n-pentanol on the spray combustion characteristics of diesel and biodiesel were investigated. On the physical aspect, the critical fuel concentration at liquid length position decreases with n-pentanol is blended into both fuels in the most cases, but witnessed a significant leap in 1200 K condition, especially for diesel blends; the physical ignition delay times of both diesel and biodiesel blends decreases first and go up later. On the chemical aspect, the join of n-pentanol caused the gap between the physical delay time and the chemical delay time much narrower, but the ignition patterns were different in diesel blends and biodiesel blends. Moreover, this paper proposed a series of correlations focused on the liquid length and ignition delay of n-pentanol blends sprays. These correlations covered wide conditions and showed better prediction accuracy than traditional ones.

Auto-ignition characteristics of a butanol-hexadecane droplet were researched under ambient gauge pressures of 5 and 10 bar and ambient temperatures of 553, 633 and 713 K. Butanol-hexadecane blends of 0%, 25% and 50% n-butanol by mass (hereafter denoted by BUT’XX′) were tested in a bilayer-structure chamber (BSC). Five sub-stages were observed, namely stable evaporation, faint partially premixed combustion, bright partially premixed combustion, diffusion combustion and droplet falling. Faint partially premixed combustion and droplet falling were observed under elevated pressures but not under atmospheric pressure. The temperature growth rate was generally different in these sub-stages. Four different temperature growth rates were found under 633 K and 5 bar, while only three different temperature growth rates were found under 713 K and 5 bar. The auto-ignition delay was negatively correlated with ambient pressure and temperature. The auto-ignition delay of BUT25 was shorter than that of BUT00 and BUT50 under 633 K and 5 bar, while the increase of n-butanol led to the increase of auto-ignition delay under 633 K and 10 bar. The auto-ignition distance reflected the transportation of fuel vapor in the auto-ignition delay. The auto-ignition distance changed in a similar manner with the auto-ignition delay.

This paper explored the spray and combustion characteristics of ethanol-diesel (E10), water-emulsified diesel (W10) and neat diesel (D100), especially micro-explosion of E10 and W10. The experiments were conducted in a constant volume combustion chamber under cold (383 K, 0% O2), evaporating (900 K, 0% O2) and combustion (900 K, 21% O2) conditions. Results showed that the spray expansion capacities of E10 and W10 under cold condition were much weaker than that of D100 due to the larger viscosity of emulsified diesels. Under evaporating condition, the spray volume of E10, W10 and D100 increased by 59%, 34% and 21% respectively comparing with cold spray volume. The higher increasing rates of E10 and W10 were mainly due to the micro-explosion effects of ethanol and water contents. Under combustion condition, the integrated natural flame luminosity (INFL) demonstrated that the ethanol content could accelerate the oxidation of soot, while the water content could prohibit soot generation. Therefore, both ethanol- and water-emulsified diesels could inhibit the soot emission, causing lower final residual soot emission of E10 and W10 than that of D100 by 21% and 39% respectively. Moreover, the flame lift-off length (LOL) and flame spread velocity showed that the effects of micro-explosion in E10 and W10 are different. The micro-explosion in ethanol occurred earlier, which enhanced the reaction rate in upstream flame and reduced the LOL. However, the micro-explosion in W10 occurred later, which enhanced the combustion rate in downstream flame.

Recently, diesel/biodiesel/alcohol blend fuels have attracted tremendous attention as a potential alternative fuel in internal combustion engines, because of their beneficial effects on pollution emission and engine performance. However, there are few chemical mechanisms to forecast combustion characteristics of the ternary blends, especially for those blending with long-chain alcohols, such as butanol and pentanol. The objective of this paper is to develop a combined reduced combustion mechanism for the combustion simulation of diesel/biodiesel/alcohol (up to n-pentanol). This new combined mechanism, consisting of 229 species and 902 elementary reactions, was constructed by integrating two separated reduced mechanisms; one is the PRF-alcohols’ mechanism (Liu et al., 2016), and another is the biodiesel mechanism (Luo et al., 2012). The new combined mechanism reproduced well predictions of fuel ignition and flame speed compared with those obtained using the original ones. Extensive validations were performed against various experimental data for 0-D homogenous systems, 1-D freely propagating premixed flames and 3-D spray combustion flames. The proposed combined mechanism was shown to be versatile and robust, successfully integrating the biodiesel reaction mechanism and the long-chain alcohol reaction mechanisms into a single reaction scheme. Coupling with advanced simulation technology, it could be a powerful numerical tool in the design and optimization of new generation engines which are fueled with clean alternative fuels, especially when concerning long-chain alcohols. In addition, the effects of adding biodiesel and different kinds of alcohols on fundamental combustion characteristics of diesel/biodiesel/alcohol blend fuels were investigated using the proposed combined mechanism.

Due to its potential of reducing NOx and soot emissions simultaneously while improving thermal efficiency, water emulsified diesel is considered as one of the most promising fuels for compression ignition engines. In this study, spray and combustion characteristics of neat diesel and water emulsified diesel with various water contents (10%, 20% and 30% by mass) were investigated. The influence of micro-explosion on high pressure spray characteristics of water emulsified diesel was optically observed and discussed. Experiments were conducted in a constant volume combustion chamber with a high-speed schlieren system to capture the spray and combustion processes. The results show that water content plays a significant role in affecting spray and combustion characteristics of water emulsified diesel. Under non-evaporating condition, the spray tip penetration increases with the water content but the corresponding spray angle decreases with the water content. Such an effect was found diminishing under evaporating condition. The spray volume of test fuels increases from non-evaporating to evaporating condition, and the relative volume increase of water emulsified diesel is at least 5 times higher than that of neat diesel. Both the ignition delay and flame lift-off length increase with water content. Consequently, the integrated natural flame luminosity decreases with the increase of water content. In addition, indirect evidences have proven that the occurrence of micro-explosion can enhance the breakup and evaporation processes of water emulsified diesel spray, and the use of water emulsified diesel can effectively reduce soot emission.

A novel potentiometric sensor based on a molecular imprinted polymer was developed for the determination of shikimic acid in herbal medicine. The imprinted polymer was synthesized via bulk polymerization of the functional monomer in the presence of trimethylolpropane triacrylate as the cross-linker with 2,2′-azo-bisisobutyronitrile as the initiator and shikimic acid as the template. The sensing membrane was constructed by the inclusion of imprinted polymer in the polyvinyl chloride matrix. The effect of the identity of the imprinted polymer on the potentiometric response was observed. The optimal imprinted polyacrylamide was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The performance of the imprinted membrane based sensor, including the effects of pH, response time and selectivity coefficient, was investigated. The imprinted sensor exhibited a fast near-Nernstian response in the concentration range of 1 × 10−5 to 1 × 10−1 mol/L with a detection limit ...

Subcooled boiling flow is the optimal choice for engine cooling system design, as no essential changes in its architecture are required while it is still possible to take advantage of the highest rates of heat transfer associated with nucleate boiling. The Chen's model is widely used for heat transfer coefficient (HTC) prediction in practical application conditions. However, direct validation based on experimental data upon the phenomenon interpreted by ‘suppression factor’ in the boiling component of Chen’s model is rarely shown in previous literatures. The present work conducted an experimental study on heat transfer from the bottom side of a rectangular heated block heated by the heating device to the upper side cooled by an internally flowing fluid in a rectangular channel. Tests were operated under representative pressure and temperature conditions with heat transfer coefficient (HTC) obtained in almost all the practical application velocity of flow. Results show that in the fully developed boiling region (FDB) the subcooled boiling heat transfer coefficient decreases as the flow velocity speeds up, which provides direct evidence for the validity of Chen's model. However, the wall heat transfer coefficient predicted by Chen's model doesn’t fit well with the present experimental data. Regarding this, a modified heat transfer model based on Chen style model for subcooled boiling flow is proposed. The HTC predicted by the modified model coincides well with the experimental data for all considered flow conditions in this paper.

As medical materials, silicone polymers are poor in mechanical properties and in resistance to fouling for its non-specific adsorption of proteins, cells, etc. This paper introduces a new type of silicone–silicone interpenetrating polymer network (IPN) composing of two curing reactions: One was radical coupled reaction, and the other was ring opening of epoxy by amino groups. The IPN were characterized by Fourier transform IR spectroscopy (FT-IR), dynamic mechanical analysis, cross section scanning electron microscope, and mechanical property. IPN structure could be formed in a co-continuous phase, while the sea–island phase could be also found up to amino content, and then tear strength and elongation at break were obviously increased. ATR FT-IR, X-ray photoelectron spectroscopy, and static water contact angles confirmed that IPN surfaces showed the hydrophilicity dependent on surface amino-epoxy component. The static water contact angles were greatly decreased to the lowest 69.3°. Both qualitative and quantitative bovine serum albumin (BSA) adsorption assay confirmed that, compared with pure polydimethylsiloxane, BSA adsorption on IPN substrates were greatly decreased, with the most 85%.

© 2018 Elsevier Ltd Puffing characteristics of BUT50 (50% n-butanol and 50% n-hexadecane by mass) were investigated using the droplet suspension technology under 638, 688 and 738 K. Experimental results showed that BUT50 underwent transient heating, fluctuation evaporation and equilibrium evaporation phases under all ambient temperatures. In the fluctuation evaporation phase, the fluctuation frequency of 738 K was higher than that of 638 K. (Dmax/D0)2 of 738 K was lower than that of 638 K. Easy bubble rupture led to high fluctuation frequency and low (Dmax/D0)2 at 738 K. Three turning points were found in transient temperature growth rate at 638 and 738 K. Four characteristic droplet temperatures were analyzed, including droplet temperatures at the start (T1) and end (T2) of transient heating phase, at (Dmax/D0)2 (T3) and at the end of total lifetime (T4). T2 was slightly lower and T3 was slightly higher than the boiling point of n-butanol. T4 was lower than the boiling point of n-hexadecane. Furthermore, the transient heating duration (tTH), fluctuation evaporation duration (tFE) and total lifetime (tTL) decreased with increasing ambient temperature. The reduction of tFE played an important role in the decrease of tTL. The percentages of tTH/tTL and tFE/tTL were stable with increasing ambient temperature.

The new discoveries of the high-temperature geothermal resources in the Gonghe-Guide area mark the significant breakthrough in the exploration of geothermal resources in the northeastern Tibetan Plateau. In this paper, we systematically reviewed all the available data presented in the geological, geophysical, geochemical and fundamental geothermal works that have been undertaken, in order to fully understand the characteristics of the geothermal resources in this area. The main features of the geothermal resources in this area can be summarized as follows: two distinct types of high-temperature geothermal resources have been identified, i.e., the hot dry rock (HDR) and hydrothermal geothermal resources in the Qiabuqia and Zhacang geothermal areas, respectively. The HDR reservoir in the Qiabuqia geothermal area is mainly composed of the Indosinian granitic rocks with the temperature gradient of 39 to 45.2 °C/km, thermal conductivity of 2.07 to 3.10 W/(m•K), and radiogenic heat production rate (RHPR) of 1.17 to 5.81 μW/m3. The geothermal water in the Zhacang geothermal area is meteoric origin with the relative enrichment of δ18O caused by the fluid-rock interaction under the high temperature condition. The chemical type of the geothermal water is SO4•Cl-Na. The local crustal partial melting or magma chamber at the 15 ∼ 35 km beneath the Gonghe basin, which is characterized with a relatively high geothermal background induced by the continental collision between the Indian and Eurasian plates, is the main cause of the HDR resources, whereas the hydrothermal resources in the Zhacang geothermal area are related to the deep circulation of the meteoric water in the damage zone of the west-east trending conductive Zhacang fault and upward transporting at the intersection of the Zhacang and the NNW-trending impermeable Reguang faults. Such a detailed review of the both geothermal resources can provide a glimpse of the geothermal resources of the northeastern Tibetan plateau as well as provide the direction for the subsequent searches for high-temperature resources elsewhere in China.

To investigate soot formation, concentration and morphology differences affected by adding butanol to diesel, an experimental study was performed to compare in-flame soot morphology of diesel and butanol–diesel blends in a constant volume combustion chamber. Direct thermophoretic soot sampling was conducted in single-shot spray flame of pure diesel and 30% butanol-70% diesel blends. Soot samples were observed with a Transmission Electron Microscope, and soot morphology was analyzed and compared by subsequent image processing. Spray flame combustion process was recorded by a high-speed digital schlieren optical diagnostic system. Flame status variance of adding butanol was discussed and connected with soot formation and morphology differences. The result indicates that blending butanol could promote fuel atomization, optimize fuel-air mixing, delay ignition, accelerate combustion, and restrain soot formation. In butanol diesel blending spray flame, soot number and mass concentration are significantly smaller, and average size is smaller than that of pure diesel fuel, soot geometry and morphology are also changed.

Geothermal extraction assessment is of considerable importance for the reservoir operation management. Based on the data of the high-temperature reservoir of the Zhacang geothermal field in the Guide basin, northeastern Tibetan plateau, this study explores the effects of the heterogeneity in the reservoir parameters on the assessment of the reservoir extraction ability via a 3D thermo-hydro-mechanical (THM) fully coupled model and compares the prediction discrepancies between the heterogeneous reservoir models with the constant and stress-dependent permeability. Modeling results show that the variance of the specific heat capacity has a negligible impact on the reservoir performance, whereas the changes in the correlation length can result to relatively apparent difference in both the outlet temperature and effective electric power rate. Compared with the specific heat capacity, the spatial heterogeneity in permeability has greater significant effect on the reservoir performance, which may be related to the occurrence of the preferential flow with the increasing variance and correlation length of the permeability. The prediction difference of the reservoir performance emphasizes the great importance of the stress-dependent reservoir permeability in a THM coupled reservoir numerical model to accurately assess the extraction ability of a geothermal reservoir concerned.

This paper aimed to develop a mechanistic model for wall heat flux partitioning based on bubble dynamics in horizontal subcooled flow boiling. The model was established from two dimensions of space and time. In the space dimension, the heating surface was divided into three regions based on the motion characteristics of bubbles, including bubble nucleation region, bubble sliding region, and non-boiling region. In the time dimension, the heat transfer mechanism on the heating surface of the bubble nucleation region and bubble sliding region could be divided into evaporation, condensation, and transient heat transfer. An evaporation model for subcooled boiling was developed based on condensation at the top of the bubble. A transient quench heat transfer model for subcooled flow boiling was modified. The heat flux of each region was obtained by the sum of the time-averaged heat fluxes of these heat transfer mechanisms during a bubble periodic time. The total wall heat flux was obtained by the sum of the area weights of the heat fluxes in these three regions. The new wall heat flux partitioning model and the RPI model were used to predict the experimental values at a variety of flow conditions. The results showed that the new model could well predict the experimental values and the deviation between the predicted heat flux and the experimental results was within 25%. The study also found that it was necessary to consider the condensation at the top of the bubble and the heat transfer mechanism caused by bubble sliding.

The simulation is used to research the effect of experimental parameters on evaporation characteristics of n-butanol-dodecane blends. These experimental parameters include droplet diameter, wire diameter, junction diameter, ambient temperature and n-butanol concentration. The equilibrium temperature (Tequ) slowly increases with time for the case with a thermocouple and it is nearly unchanged without a thermocouple. The change of droplet diameter at location 1# (D1#, location 1# is the beginning of droplet motion) has little impact on Tequ for the case without a thermocouple. With increasing D1#, the average evaporation rate (Kave) increases with a thermocouple and it is nearly constant without a thermocouple. Both Kave and Tequ firstly increase and then decrease with increasing wire diameter (Dwir) or junction diameter (Djun). From 600 to 800 K, Kave is the maximum when Dwir is 0.10 mm. The maximum is at Djun of 0.3 mm for 800 K and it is at 0.4 mm for 600 and 700 K. The change of Dwir or Djun has little effects on T2#, which is the droplet temperature at the location of 2# (location 2# is the end of droplet motion). Both T2# and Kave decrease with increasing n-butanol concentration. An obvious transition can be found for Kave when the mass fraction of n-butanol ranges from 12.5% to 25%. The normalized evaporation rate is reasonably predicted using a polynomial model.

s Puffing, auto-ignition and combustion characteristics of an n-pentanol-diesel droplet are investigated using the droplet suspension technology under ambient temperatures of 830–930 K and n-pentanol concentrations of 0%–75%. The evolution profile of OH∗ chemiluminiscence is detected by a monochromator. A spike is observed shortly after the auto-ignition time for all these profiles. After the spike, different n-pentanol concentrations lead to different evolution profiles of OH∗ intensity. The profile of D75P25 (75% diesel and 25% n-pentanol by mass) witnesses a slight increase and enters a plateau stage. For D25P75, the combustion and extinguishment of n-pentanol vapor lead to the increase and decrease of OH∗ intensity in a long period, respectively. Furthermore, two auto-ignition delays are obtained by a high-speed camera and a monochromator. The difference between the two auto-ignition delays is nearly irrelevant to n-pentanol concentration at 880 K, while a positive dependence on n-pentanol concentration is shown at 930 K. On the other hand, the higher n-pentanol concentration leads to a longer auto-ignition delay at 880 K but a shorter auto-ignition delay at 930 K. Surface and inner puffing modes are observed at 930 K for D25P75 and D75P25, respectively. Many factors lead to different turning phenomena in droplet temperature curves.

Due to their excellent physicochemical properties, biodiesel and n-pentanol are regarded as two promising alternative biofuels for automobile. However, the fundamental data of spray and combustion characteristics of n-pentanol/biodiesel blends are still scarce. The objective of this work is to investigate the effects of n-pentanol addition to waste cooking oil (WCO) biodiesel in different ratios (0%, 20%, and 40% in volume) on spray, ignition and combustion characteristics in a constant volume combustion bomb (CVCB). Ignition and combustion tests were performed at five ambient temperatures (800, 900, 1000, 1100 and 1200 K) with three oxygen concentration (10%, 15% and 21%), and spray tests were conducted at the same temperature ranges but with no oxygen involved to prevent combustion happening. The result shows liquid length decreases with increase of ambient temperature, and the falling slope increases significantly with the blended n-pentanol concentration. The liquid length of B60P40 is about 6% longer than that of B100 at 800 K condition, while it becomes about 10% shorter than B100 when ambient temperature rises to 1200 K. Although the cetane number of n-pentanol is much less than biodiesel, an increase of n-pentanol ratio has a promoting effect on the ignition event under most conditions. Under these conditions, addition of 40% n-pentanol has cut the ignition delay of biodiesel, on average, by 30.2%. The natural flame luminosity is found to be reduced significantly with an increasing n-pentanol ratio, meaning that addition of n-pentanol could reduce the soot level under all conditions. For example, the time integrated natural luminosity (TINL) of B60P40 is only 41.2% of that of B100 under 1000 K temperature conditions. The result also suggests that, for multi-component fuels, flame lift-off length (FL) is the most reliable factor that influence the soot concentration level under spray combustion processes, rather than ignition delay or soot formation time. Overall, blending n-pentanol into biodiesel has a great soot oxidation potential and could maintain suitable ignition phase at the same time.

A reactive flame retardant cross-linker (SPTES) was successfully synthesized with dichloropentate and 3-triethoxysilyl-propylamine (APTES) in this research. Then it was further applied into the room temperature vulcanized (RTV) silicone rubber to prepare novel flame retarded RTV silicone rubbers containing phosphorus. The structure, thermal degradation stability, mechanical properties and flammability properties of the novel RTV silicone rubbers were tested and characterized. The results showed that the mechanical and flammability properties of the RTV silicone rubber simultaneously got better with the SPTES content increased. Compared with the sample prepared by APTES, the tensile strength of novel RTV silicone rubbers increased from 0.12 MPa to 0.38 MPa and the limit oxygen index increased from 19.8 to 23.5.

In order to research puffing characteristics of biodiesel-butanol blends, single droplet experiments of BUT25 and BUT75 were conducted under the condition of atmospheric pressure and 800 °C. Experimental results showed that BUT25 only demonstrated core mode, while BUT75 demonstrated both surface and core mode simultaneously. The core mode was a periodic process including bubble nucleation, bubble expansion and bubble rupture inside the droplet. The surface mode was featured by the appearance of many micron sized child droplets. Two new parameters were proposed to analysis puffing characteristics, namely the similarity degree and the deformation degree. The puffing process usually contained the transient heating phase, fluctuation evaporation phase and equilibrium evaporation phase. Both the transient heating phase and equilibrium evaporation phase were stable evaporation processes. Analysis indicates that the three phases of the puffing process are more appropriately distinguished through the profile of similarity degree than that of the normalized squared diameter. Furthermore, the similarity degree of BUT25 displayed a wavy structure and BUT75 displayed a trapezoid structure in the fluctuation evaporation phase. On the other hand, the deformation degree remained unchanged in stable evaporation processes but exhibited a sharp rise at the instant of bubble expansion or rupture.

In this paper, a systematic experimental study was conducted to clarify characteristics of turbulence field generated by two opposite fans in a cubic constant volume combustion bomb (CVCB). The effect of the fan speed (1000–2900 rpm) and ambient pressure (0.1–3.0 MPa) on root-mean-square fluctuations, probability density functions, integral length scales and energy spectra was investigated. To overcome the limitation of the 2D-PIV, three sheet velocity fields were measured to reconstruct the three-dimensional boundary of the homogeneous region. Experimental results showed that a nearly homogeneous turbulence field in a flat region around the center of the CVCB was generated while a slight departure from isotropy was unavoidable in the current configuration. The turbulence intensity was independent of the ambient pressure, but positively proportional to the fan speed. Absence of both fan speed and ambient pressure’s effect was observed for the integral length scales. Analysis of the turbulent energy spectra implied that the increase of fan speed and ambient pressure resulted in a smaller critical eddy scale where the viscosity dissipation effect started emerging.

Regarding the high thermal load of piston in engines, a novel apparatus, memory test system (MTS), was designed for steady-state temperature measurement of piston. By heating MTS up to 100 °C and 120 °C respectively, a test was carried out to verify the system and measure its error. Considering poor working conditions in engine, the readings of MTS and thermal plugs were compared with each other through an engine test to confirm the reliability of MTS. Moreover, MTS was used to measure piston temperature under multiple working conditions. The results show that MTS has very high precision and reliability and is competent in multi-condition test. MTS is an effective tool to measure piston temperature.

Pentanol is considered as one of the most promising alternative biofuels due to its excellent physicochemical properties. The objective of this work was to compare the ignition and combustion characteristics of different n-pentanol/diesel blends in an optical constant volume combustion chamber. The tested fuels included 20% (D80P20) and 40% (D60P40) of n-pentanol blended with diesel in volume, and pure diesel (D100). Broadband chemiluminescence technique was used to measure the timing and location of spray ignition. A high-speed CCD camera with two ND8 dimmer lenses was used to capture the incandescence radiated from the soot particles during combustion. A wide range of experimental conditions was investigated. The ambient temperature ranged from 800 K to 1200 K and the oxygen concentration ranging from 10% to 21%, covering both the conventional and low temperature combustion regimes. The results show that pure diesel has shorter ignition delay and distance comparing to pentanol blends. A larger blending proportion of pentanol D60P40 advances the ignition phase more than the D80P20 in low oxygen concentration conditions. Due to the fuel-borne oxygen and the dilution effect, the natural flame luminosity is reduced significantly with the increase of pentanol ratio in most conditions except under the intermediate temperature region of 1000 K. In that condition, the shorter ignition delay and flame lift-off length of pentanol blends cause a slightly increase in the natural flame luminosity. The natural flame luminosity images showed that the oxygen-contained structure of pentanol could accelerate soot oxidation under all conditions. This indicates that pentanol blends could decrease final soot emissions in internal combustion engines.

Due to its excellent physicochemical property and renewable characters, pentanol is considered to be one of the most promising alternative biofuels applying to mobile vehicles. The objective of this study is to reveal the effects of pentanol addition to diesel in different ratios (0%, 20%, and 40% in volume) on the spray and evaporation characteristics under various injection and ambient conditions. The experiments were conducted in a premixed combustion heated constant volume combustion chamber with two different optical arrangements, high-speed schlieren technique and diffused back-illumination technique. The result shows pure diesel has a longer spray tip penetration and a smaller cone angle compared to pentanol blends under non-vaporizing conditions. With the increasing of ambient density, the difference of penetration characteristic between each blend becomes negligible but the gap of spray angle is still distinct. Compared to non-vaporizing condition, there is a downward trend for spray tip penetration of pure diesel under high temperature above 800 K while an increase trend for pentanol blends. The spray cone angles are unaffected by ambient temperature except increasing the blend ratio of pentanol to 40%. Air entrainment analysis such as spray volume and fuel equivalence ratio distribution were obtained by measured and model predicted respectively. The result shows pure diesel has a poor air-fuel mixing compared to pentanol blends. It also warned that the risk of liquid impingement on the wall becomes higher when the pentanol blend ratio reaches 40% at low temperature combustion conditions.

A silane containing isocynate groups (3-(trimethoxysilyl) propyl cyanic acid ester, NCO) associated with hexamethyldisilazane (HDMS) is used to modify the surface of poly-(p-phenylene terephthalamide) (PPTA) pulps. As concerns surface chemistry, Attenuated Total Reflection Flourier Transformed Infrared Spectroscopy (ATR FT-IR) and X-ray photoelectron spectroscopy (XPS) confirm that NCO associated with HDMS silylated PPTA pulp surface successfully. While the modified PPTA pulps are used as reinforcing fillers for silicone composites, the dispersibility and storage stability of the composites are improved as Mooney testing indicated. The silicone composites filled with modified PPTA pulps present a higher tensile strength and much higher broken elongation (3.30 MPa and 166.54%) than that with unmodified pulps (3.08 MPa and 68.47%), respectively.

In the engine crankcase, the splash of oil droplets colliding with the wall has a significant impact on the formation of oil mist. In order to clarify the influencing factors of droplet impact splash, this paper establishes a calculation model of droplet impact wetting wall surface by using local mesh instantaneous refinement technology combined with volume of fluid (VOF) and wall wetting model, and verifies the reliability of the model through experiments. The results show that the thickness of oil film on the wall, the viscosity and surface tension of the oil all affect the splash behavior of oil colliding with wall. The larger the oil viscosity, the less secondary droplets produced by splashing, but the viscosity has no significant effect on the Sauter mean diameter (SMD) of secondary droplets. The bigger the surface tension of the oil, the less secondary droplets are produced, and the SMD of the secondary droplets will obviously increase. The thicker the oil film on the wall, the more secondary droplets with the larger average size produced by the splash.

Urchinlike W-V-O microspheres have been successfully synthesized for the first time by a one-pot hydrothermal approach. The as-synthesized W-V-O material was characterized by several techniques such as XRD, SEM, TEM, FTIR, EDS, BET, and Raman spectroscopy. The characterization results have revealed that the W-V-O microspheres consist of numerous one-dimensional nanobelts radially grown from the center. The typical nanobelts display rectangular cross sections with lengths of several micrometers, widths of about 50 nm, and thicknesses of approximately 10-20 nm. Vanadium oxides are dispersed highly either on the external surface or inside the channel surface of the hexagonal WO

Ethanol direct injection plus gasoline port injection (EDI+GPI) is a new technology to utilise ethanol fuel more effectively and efficiently in spark-ignition engines by taking the advantages of ethanol fuel and direct injection, such as the cooling effect and anti-knock ability. A full cycle numerical modelling including both port and direct injection sprays was performed to understand the mechanisms behind the experimental results of the EDI+GPI engine. The turbulence-chemistry interaction of the two-fraction-mixture partially premixed combustion was solved by a five-dimensional presumed Probability Density Function table. Effects of direct injection timing on fuel evaporation, mixing, wall-wetting, combustion and emission processes were investigated. The results showed that when the direct injection timing was retarded, the mixture around the spark plug became leaner and the distribution of equivalence ratio became more uneven. Moreover, late direct injection resulted in severe fuel impingement and caused local over-cooling effect and over-rich mixture. Consequently, the combustion speed and temperature were decreased by retarded direct injection timing, leading to reduced NO emission and increased HC and CO emissions. Finally, numerical modelling was performed to investigate the strategy of injecting small amount of ethanol fuel on reducing the fuel impingement and incomplete combustion caused by late direct injection.

Although exhaust gas recirculation (EGR) is widely implemented to suppress the NOx, it can increase soot emissions and decrease the thermal efficiency in internal combustion engines. Water-emulsified diesel is a promising alternative approach, as it decreases soot emissions, suppresses NOx formation, and promotes thermal efficiency through improved mixing between the fuel and air. Based on the inhibiting functions of oxygen dilution and emulsified diesel on engine emissions, a visualization study on the spray combustion of water-emulsified diesel was experimentally explored in a constant volume combustion chamber at various ambient oxygen concentrations. This study firstly examined the different combustion characteristics of water-emulsified diesel and pure diesel. Secondly, the effects of ambient oxygen concentration on combustion characteristics of water-emulsified diesel and pure diesel were investigated. Furthermore, the characteristics of soot formation and oxidation during the combustion process were revealed by flame features observed using optical techniques. Experimental results showed that a micro-explosion arose in the emulsified diesel spray which promoted mixing between the fuel and air. Local temperatures were reduced due to water’s high specific heat and latent heat of vaporization, which also played important roles in ignition. The high specific heat and latent heat of vaporization had stronger effects than micro-explosions in the combustion process. The combined functions of the micro-explosion event, specific heat and latent heat of vaporization significantly decreased the soot emissions in water-emulsified diesel. Additionally, the ambient oxygen concentration affected the integrated flame luminosity and soot formation of the water-emulsified diesel. However, there were no obvious effects of the explored ambient oxygen concentrations on the ignition limit, flame boundary and flame area. The results showed that when the requirement of NOx emissions was held constant, the use of water-emulsified diesel could decrease the need for oxygen dilution by 10%.

The surface of carbonyl iron powder (CIP) was modified in supercritical fluid with silicone polymers containing reactive Si-OCH3 groups. Fourier-transformed infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and thermo gravimetric analysis were adopted to characterize CIP. The dispersibility of CIP in epoxy resin matrix was evaluated by castor oil absorption factor, dynamic viscosity, Mooney viscosity, and scanning electric micrograph. The electromagnetic reflectivity of the CIP-filled epoxy resin coatings was also checked. It was confirmed that comparing with those treated at atmosphere, the supercritical treated CIP presented higher surface carbon content, higher dispersibility, higher thermal stability, and its original crystalline structure did not change greatly. Even though it experienced a high temperature and a high pressure (250 °C, 7.8 Mpa) during supercritical treatment, it was not oxidized, and its electromagnetic reflectivity did not decrease. Copyright © 2016 John Wiley & Sons, Ltd.

Ethanol direct injection plus gasoline port injection (EDI + GPI) represents a more efficient and flexible way to utilize ethanol fuel in spark ignition engines. To exploit the potentials of EDI, the mixture formation characteristics need to be investigated. In this study, the spray and evaporation characteristics of ethanol and gasoline fuels injected from a multi-hole injector were investigated by high speed Shadowgraphy imaging technique in a constant volume chamber. The experiments covered a wide range of fuel temperature from 275 K (non-evaporating) to 400 K (flash-boiling) which corresponded to cold start and running conditions in an engine. The spray transition process from normal-evaporating to flash-boiling was investigated in greater details than the existed studies. Results showed that ethanol and gasoline sprays demonstrated the same patterns in non-evaporating conditions. The sprays could be considered as non-evaporating when vapour pressure was lower than 30 kPa. Ethanol evaporated more slowly than gasoline did in low temperature environment, but they reached the similar evaporation rates when temperature was higher than 375 K. This suggested that EDI should only be applied in high temperature engine environment. For both ethanol and gasoline sprays, when the excess temperature was smaller than 4 K, the sprays behaved the same as the subcooled sprays did. The sprays collapsed when the excess temperature was 9 K. Flash-boiling did not occur until the excess temperature reached 14 K. The fuel temperature changed not only the spray evaporation modes but also the breakup mechanisms.

Utilization of ethanol in diesel engines has been widely studied by means of engine experiments and emission detection. However, pertinent studies on the spray combustion process of ethanol–diesel blends are scarce. In order to verify the effect of ethanol in modern diesel engines, an experiment is conducted to visualize the spray combustion process of ethanol–diesel blend under LTC conditions. Stages including atomization, evaporation and combustion, are investigated individually to realize synergistic analysis. Meanwhile, considering the long time scale of combustion after fuel injection finishes, characteristics during and after injection period are both targeted in this paper. Moreover, measurement of macroscopic characteristics, such as spray tip penetration, spray spreading cone angle and flame lift off length, provides a quantitative profile of the spray structure. Results show that, evaporation, different from atomization, has little influence on spray penetration, but promotes the spray spreading angle and spray projected area. So does combustion, which enlarges the spray projected area further. Ignition takes place on the periphery behind the spray tip, then quickly extends to the whole head of the spray and forms a U-shape diffusion structure. After the injection period, the residual spray tail develops into wavelike structures due to absence of subsequent entrainment force. Also, the penetration speed falls greatly to an extent much slower than flame propagation, which frees the flame from the lift-off effect. Subsequently, the flame propagates upstream towards the nozzle orifice. After consumed all fuel in the spray tail, flame retreats downstream to the far end and combusts for a time much longer than the injection duration.

Ethanol direct injection has the potentials to increase the engine compression ratio and thermal efficiency by taking advantages of ethanol fuel such as the high octane number and latent heat. In this study, CFD modelling and experiments were carried out to investigate the charge cooling effect and combustion characteristics of ethanol direct injection in a gasoline port injection (EDI + GPI) engine. Experiments were conducted on a single-cylinder spark ignition engine equipped with EDI + GPI over a full range of ethanol ratio from 0% (GPI only) to 100% (EDI only). Multidimensional CFD simulations to the partially premixed dual-fuel spray combustion were performed to understand the experimental results. The simulations were verified by comparing with the experimental results. Simulation results showed that the overall cooling effect of EDI was enhanced with the increase of ethanol ratio from 0% to 58%, but was not enhanced with further increase of ethanol ratio. When the ethanol ratio was greater than 58%, a large number of liquid ethanol droplets were left in the combustion chamber during combustion and fuel impingement on the cylinder wall became significant, leading to local overcooling in the near-wall region and over-lean mixture at the spark plug gap. As a consequence, the CO and HC emissions increased due to incomplete combustion. Compared with GPI only, the faster flame speed of ethanol fuel contributed to the greater peak cylinder pressure of EDI + GPI condition, which resulted in higher power output and thermal efficiency. Meanwhile, the mixture became leaner with the increase of ethanol ratio. As a result, the IMEP was increased, combustion initiation duration and major combustion duration were decreased when ethanol ratio was in 0–58%. The combustion performance was deteriorated when ethanol ratio was greater than 58%. Experimental and numerical results showed that the IMEP, thermal efficiency and emissions of this EDI + GPI engine can be optimised in the range of ethanol ratio of 40–60%.

Modern engine cooling systems use subcooled boiling as an effective heat transfer form. The significantly higher heat transfer rate achievable with boiling can keep the temperature in key thermal areas within an acceptable level. In this study, a three-dimensional two-fluid model coupled with RPI wall boiling model was adopted to simulate the local two-phase characteristics of boiling at different passages under low-pressure condition. Moreover, a modified bubble departure diameter correlation was developed and implemented in computational fluid dynamics code with user-defined function, and the correlation was verified by two sets of experimental data under different flow conditions. Results showed an improved agreement with the measured local void fractions. Finally, the verified model was applied to a practical cooling passage for a water-cooled diesel engine. The simulation results showed that present two-fluid model could get an accurate temperature field for cylinder head. The distribution of vapor phase in cooling passage was obtained, and it could be used as a reference to evaluate the reliability of local boiling. Moreover, due to the function of interphase forces, the majority of bubbles were quickly removed from near wall and the void fraction was below 0.149.

Diesel engines working at high altitudes are prone to thermal failure. In this paper, a series of experiments and simulations were conducted to analyze the thermal balance, in-cylinder heat transfer, and performance of diesel engines at various altitudes. A six-cylinder four-stroke diesel engine was used to conduct the thermal balance tests at altitudes from 0 m to 4500 m. The experiment results show that the engine thermal efficiency declines from 37.8% to 33.9% at the rated speed as altitude rises. The heat loss through cooling water has no significant change in trend and remains about 22%-24% in most conditions. The heat loss through exhaust decreases as altitude rises and accounts for 26.7%-39.8% of total energy. The unaccounted losses increase greatly as altitude rises but it makes up no more than 12.1% of total energy at all altitudes. To acquire more detailed in-cylinder heat transfer parameters, a one-dimensional in-cylinder simulation was conducted. The simulation results show that the in-cylinder heat transfer coefficient and heat fluxes increase first and then decrease as altitude rises. In addition, with the increase of altitude, the in-cylinder average gas temperature substantially increases. This study has practical significance for reducing thermal load of the engines working at high altitudes.

Subcooled boiling heat transfer is widely used in modern high-power and high-load internal combustion engines (ICEs) because of its efficient heat transfer characteristics. In the present work, a numerical simulation of subcooled boiling under low-pressure conditions is performed on CFX with a user-defined program. Lee’s subcooled boiling experiment results are used for calculations. The bubble departure diameter is simulated by Du’s model. In order to apply the simulation method to engine cooling system with complex channel, the Favre Averaged Drag Model and Tomiyama Lift Force Model are used which makes up for shortcomings of the experience factor needed to be adjusted. The Multiple Size Group (MUSIG) model considering the effects of vapor bubbles coalescence and breakup is used to describe the different sizes of bubbles in the liquid phase. A qualitatively good agreement with the experimental data is achieved without changing model parameters, which lays a good foundation for the application of the simulation method in an engine cooling system.

An experiment is carried out using a high-speed camera to closely observe the bubble behaviors on a horizontal aluminum heating surface under high mass flux. Subcooled flow boiling experiments are conducted at Reynolds numbers of 61,850–124,041 for a range of density ratios (0.000647-0.001153), Jacob numbers corresponding to wall superheat (0.012201-0.025096) and for Jacob numbers corresponding to subcooling varying from 0.009549 to 0.02856. The experimental results indicate that both bubble departure diameter (BDD) and bubble contact diameter (BCD) reduce with increasing system pressure, increasing flow velocity, increasing subcooling, and decreasing wall superheat. The experiment confirms that the linear relationship between BCD and BDD is still valid under high mass flux. The BCD is 0.4027 times of the BDD. A force balance model based on the newly modified model of bubble growth rate is used to calculate BDD and its predicted values are in good agreement with the present measured values. The force balance model can be expressed by a series of dimensionless parameters: density ratio, Jacob number corresponding to wall superheat, Jacob number corresponding to subcooling, Prandtl number, Reynolds number, and contact angle. A new empirical formula of BDD in a horizontal channel is developed based on the dimensionless parameters using the Buckingham theorem. The empirical formula considers more comprehensive factors and predicts the BDD obtained in a horizontal channel with an average relative error of 12.08%.

© 2018 Elsevier Ltd A new model was developed to investigate the puffing process of a butanol-hexadecane droplet. The puffing model took into account all the key processes, including the surface evaporation, bubble formation, bubble growth and bubble breakup. The Rayleigh equation was modified to simulate the bubble growth inside a small droplet. The sub-models for surface evaporation and bubble growth were firstly verified against the previous experimental data. Then the droplet puffing experiments of butanol-hexadecane blends were conducted under 1 bar and 750 K condition using the droplet suspension technique to further verify the puffing model. Results showed that the puffing model well simulated three phases of BUT50 (50% butanol and 50% hexadecane by mass). The three phases were the transient heating, fluctuation evaporation and equilibrium evaporation phases. An extremely strong fluctuation and several weak fluctuations were observed during the fluctuation evaporation phase from the experimental normalized squared diameter. Due to the model hypotheses, these weak fluctuations were ignored and only the strong fluctuation was simulated in the present model. Furthermore, a significant turning point was observed in the experimental temperature curve when the droplet diameter had the strong fluctuation. The occurrence of the strong fluctuation was caused by the obvious bubble expansion inside the droplet. The numerical results showed that the significant heat absorption for the bubble expansion led to the turning point in the temperature curve.