Higher Initial Temperature Research Articles

Quartz-Hosted Fluid Inclusions in Commercial Ores of Various Type at the Verninskoe Gold Deposit, Bodaibo District, Russia

The paper presents data on quartz-hosted fluid inclusions in commercial ores of various type (veinlet−disseminated and vein) of the Verninskoe gold deposit. The ores of various types were found out to significantly vary in the values of some of their physicochemical parameters of the fluids and in the composition of these fluids. The fluids that formed the gold veins have a somewhat higher initial temperature (356–246°C), a higher density of carbon dioxide in gas inclusions (1.00–0.84 g/cm3), and a higher fluid pressure (3170–1390 bar) than those of the fluids that formed the veinlet–disseminated ores (330–252°C, 0.87–0.54 g/cm3, and 1960–570 bar, respectively). The fluids that formed the gold veins were enriched in CО2, Sr, Ag, Ga, Ge, Mn, Fe, Ni, Sn, Ba, and REE, whereas the fluids that formed veinlet–disseminated mineralization were richer in HCO−3, Br, Sb, V, and Au. This situations may be explained by the interaction of the deep fluid with the terrigenous host rocks in the course of ore deposition. When vein quartz crystallized in relatively wide fractures, the fluid interacted with host rocks and changed not as much as when the veinlet−disseminated ores were formed in narrow fractures. The initial parameters of the fluid that formed the vein quartz were thus the closest to the characteristics of the fluid that transported the ore components, and the comparison of these data with the parameters of the fluids that formed the veinlet–disseminated mineralization demonstrates that they changed in the course of ore deposition. The mineral-forming fluids likely came from a deep-sitting source, and the mineral-forming processes may have involve granitoid-derived fluids.

Effect of pressure on regenerative cooling process of endothermic hydrocarbon fuel at severe pyrolysis conditions

Regenerative cooling technology with supercritical aviation kerosene as coolant is the optimal thermal management method for advanced aero engines. In order to fill the gap in existing research on the pressure effects at severe pyrolysis, the influence of pressure on the flow field, pyrolysis behaviours, heat transfer, and surface coking are numerically investigated in this study. The results indicate that the velocity-temperature curves at different pressures have two intersections due to the difference in initial pyrolysis temperature, reaction rate, and product distribution. Fuel pyrolysis more easily occurs at high pressure, and elevating pressure improves the fuel heat sink. Besides, a special deterioration of heat transfer is found at high conversion rates because of the combined contribution of weakened primary endothermic reaction and enhanced secondary exothermic reaction. Heat transfer deterioration is delayed at 3.5 MPa due to the high initial pyrolysis temperature and significant flow acceleration. The primary pyrolysis reaction provides more than 80% chemical heat sink and 60% flow acceleration at fully cracked conditions at 5.0 MPa. In addition, inhibiting catalytic coking is the principal method to reduce carbon deposition, and more attention should be paid to carbon deposition under high pressure. The results obtained in this study are expected to provide insights into the selection of operating pressures for advanced aero engines.

Plant Leaf-Inspired Separators with Hierarchical Structure and Exquisite Fluidic Channels for Dendrite-Free Lithium Metal Batteries.

Lithium (Li) metal batteries are among the most promising devices for high energy storage applications but suffer from severe and irregular Li dendrite growth. Here, it is demonstrated that the issue can be well tackled by precisely designing the leaf-like membrane with hierarchical structure and exquisite fluidic channels. As a proof of concept, plant leaf-inspired membrane (PLIM) separators are prepared using natural attapulgite nanorods. The PLIM separators feature super-electrolyte-philicity, high thermal stability and high ion-selectivity. Thus, the separators can guide uniform and directed Li growth on the Li anode. The Li//PLIM//Li cell with limited Li anode shows high Coulombic efficiency and cycling stability over 1500h with small overpotential and interface impedance. The Li//PLIM//S battery exhibits high initial capacity (1352 mAh g-1 ), cycling stability (0.019% capacity decay per cycle at 1 C over 500 cycles), rate performance (673 mAh g-1 at 4 C), and high operating temperature (65°C). The separators can also effectively improve reversibility and cycling stability of the Li/Li cell and Li//LFP battery with carbonate-based electrolyte. As such, this work provides fresh insights into the design of bioinspired separators for dendrite-free metal batteries.

Analysis and Modeling of No-Vent Filling Process for Liquid-Hydrogen Tank in Orbital Conditions

A four-node model is proposed to investigate the no-vent filling performance of liquid hydrogen (LH2) at microgravity. The no-vent filling method can directly prevent the influence of random gas–liquid distributions at microgravity, making it a good choice for cryogenic propellants to achieve orbital refueling. The typical phase distribution of the centrally located ullage was assumed and, in particular, the correlations for the boiling heat transfer of LH2 at microgravity were corrected in this model. After the accuracy of this model was effectively verified, the effects of different filling conditions, including the initial tank pressure, the initial temperature, and the temperature of the inlet liquid, were studied. The results showed that the initial pressure had a major influence on the initial pressure rise but only a slight influence on the final pressure development. A higher initial temperature would have led to an obvious increase in the tank pressure and an obvious decrease in the final filling level when reaching the upper pressure limit. Reducing the temperature of the inlet liquid has certain effects on the pressure control and the improvement of the final filling level. In conclusion, to achieve a higher filling level under a lower pressure level during the no-vent filling of LH2 at microgravity, sufficient pre-cooling of the filling system is required. Furthermore, appropriate evacuation of the receiver tank before filling and subcooling of the inlet liquid within an acceptable range of costs are both suggested. While the proposed model is less accurate than full-resolution CFD for the detailed evolution of physical fields, it offers much greater computational speed for quick parametric studies of key input conditions.

Reaction mechanisms of the wet torrefaction of oil palm trunks under the effect of initial pressurisation

Wet torrefaction of oil palm trunk with initial pressurisation of 1 and 6 MPa at 180 and 260 °C and residence times of 30, 60, and 180 min was carried out. The hydrochar’s solid yield treated at 180 and 260 °C ranged from 45.97% to 49.94% and 13.84–20.16%, respectively. The higher heating values of the hydrochar treated at 180 and 260 °C were 17.76–18.60 MJ kg−1 and 24.72–27.62 MJ kg−1, respectively. Increasing the initial pressure at 260 °C resulted in decreased solid yield and higher heating values. The reduced solid yield and higher heating values was postulated to come from the suppression of dehydration and decarboxylation reactions along with partial lignin decomposition. Repolymerisation of lignin likely occurred; however, the contributions to solid yield and higher heating values from repolymerised lignin were insignificant compared to its depolymerisation that came from increased temperature. Glucose formation was promoted at high initial pressure (6 MPa) and low temperature (180 °C) and vice versa (i.e. 1 MPa and 260 °C gave higher glucose yield). Furthermore, the rehydration of 5-hydroxymethylfurfural to levulinic acid was enhanced with the increase in initial pressure due to the increased water density. Increasing the initial pressure inhibited lactic acid formation from glucose 1,2-enediol.

Synthesis of new biobased benzoxazine through green strategy and its polybenzoxazine resin with high thermal resistance and mechanical strength

AbstractBenzoxazine resins from benzoxazine monomers synthesized with green strategies often do not have high thermal resistance and mechanical strength. Herein, starting from renewable resources citraconic anhydride, furfurylamine and tyramine, a new benzoxazine monomer (CT‐fa) was synthesized and purified in green solvents (ethanol and ethyl acetate), which has excellent molding processability reflected by low melting point (84.9 °C) and low curing temperature (207–245 °C). More attractively, the curedCT‐faresin (poly(CT‐fa)) has both high glass transition temperature (281 °C) and high initial thermal decomposition temperature (407 °C), the former is higher than those of all monofunctional benzoxazine resins synthesized though green strategies in literature, and the latter is even higher than those of all benzoxazine resins synthesized by green strategies (SCI database). In addition,poly(CT‐fa)also has high storage modulus (3955 MPa) and good tensile strength (51.60 MPa). These attractive properties demonstrate thatpoly(CT‐fa)is a promising green high performance resins.

Effect of water-cooling shock on fracture initiation and morphology of high-temperature granite: Application of hydraulic fracturing to enhanced geothermal systems

Deep geothermal energy exploitation is primarily accomplished using an enhanced geothermal system (EGS) to extract heat from hot dry rock (HDR). The use of hydraulic fracturing technology to build large-scale fracture networks is essential for improving the EGS heat extraction efficiency. Water-cooling shock on high-temperature rock degrades the mechanical properties of the rock while increasing the fracturing effect of HDR. A thermal–hydraulic–mechanical coupling model is proposed herein to investigate the effect of water-cooling shock on fracture initiation and morphology in HDR hydraulic fracturing. The validity of the coupling model is confirmed using theoretical analytical solutions and physical experimental results, such as hydraulic fracturing experiments on high-temperature granite, as well as analytical solutions for the stress shadow effect and fracture initiation pressure. The numerical simulation is performed using a coupling model to investigate the characteristics of fracture propagation and damage evolution during the HDR hydraulic fracturing process as well as to investigate the fracturing effect of water-cooling shock on high-temperature rock. Finally, the effects of initial rock temperature, in-situ stress, and heat transfer coefficient on fracture morphology are investigated. The results show that the combined effects of tensile strength deterioration water-cooling shock, thermal stress caused by cold shrinkage, and pore water pressure are primarily responsible for the initiation and propagation of hydraulic fractures. The water-cooling shock can considerably reduce the fracture initiation pressure, induce more secondary fractures, and form more complex fracture networks. The initial temperature and heat transfer coefficient of the rock affect the thermal stress and tensile strength deterioration. The formation of an intricate fracture network can be aided by a high initial rock temperature, a large surface heat transfer coefficient, and small in-situ stress differences.

Establishment of correlation between reaction kinetics and carbon structures in the char gasification process

For a gasification process, the char-CO2 gasification is the controlling step worthwhile to be deeply investigated. The article chosen corn stalk (CS), poplar sawdust (PS) and bagasse residue (BR) as the typical waste species derived from agricultural, forestal and industrial sources. The char-CO2 gasification behavior, reaction kinetics and carbon structure were studied to reveal the intrinsic factors determining the reaction kinetics. Generally, the carbon conversion and maximum conversion rate were influenced by the feedstocks species and char preparation temperatures, as influenced by ash proportion, potassium content in ash and carbon structure of char. The char-CO2 reaction for CS was subject more to the catalytic effect of alkali compositions, while pore structure affected more the gasification reaction for PS char. The isoconversional kinetic analysis indicated that the gasification reaction became stable at carbon conversion of 0.5. Subsequently, sectionalized kinetic parameters were calculated for the initial gasification temperature to the temperature reaching 50% conversion. The result showed that high initial gasification temperature increased the char-CO2 gasification barrier to hardly start the reaction but accelerate the reaction rate. The carbon structure analyses further clarified that the reaction activation energy was highly related to the microcrystalline structure of carbon, while the reaction rate was more determined by carbon pore structure.

Employing typicality in optimal control theory: Addressing large Hilbert spaces

Controlling the dynamics of quantum systems is a crucial task in quantum science and technology. Obtaining the driving field that transforms the quantum systems into its objective is a typical control task. This task is hard, scaling unfavorably with the size of the quantum map. To tackle this issue we employ typicality to assist in finding the control field for such transformation. To demonstrate the method we choose the control task of cooling the fine-structure states of the aluminum monofluoride molecule, at relatively high temperature. As a result high-rotational states are occupied, meaning a high effective Hilbert space. Using quantum typicality, we demonstrate that we can simulate an ensemble of states, enabling a control task addressing simultaneously many states. We employ this method to find a control field for cooling molecules with a large number of internal sates, corresponding to high initial temperatures.

A numerical simulation investigation on low permeability reservoirs air flooding: Oxidation reaction models and factors

A precise oxidation reaction model determines the reliability of numerical simulation results and the prediction of field performance of air injection-based enhanced oil recovery (EOR). By reviewing the classical oxidation reaction model and combining with geological characteristics of a low permeability reservoir, this work creatively divides pseudo-components and temperature regions and further proposes the improved low temperature oxidation (LTO), middle temperature oxidation (MTO), and high temperature oxidation (HTO) numerical models with chemical reaction coefficients. The EOR effects of reservoir temperature, permeability, air flow rate and bottom hole pressure during LTO and full temperature regions are determined on the basis of a 3D reservoir simulation model via CMG STARS. The results show that peak oil production rates of N2 flooding and LTO are 17.70 and 29.97 m3/d, respectively. The cumulative oil production in LTO stage is about 35%, which is higher than that in N2 flooding. The oxygen addition reaction in LTO stage can release much heat and increase sweep efficiency from thermal expansion and viscosity reduction. The peak oil production rates of LTO and full temperature oxidation (FTO) reactions are 42.16 and 44.34 m3/d, respectively, and the cumulative oil production of the FTO model was about 17% higher than that of LTO. The FTO model could more truly reflect the production performance during air flooding of low permeability oil reservoir. Strong oxygen consumption capacity and significant heat release effects can be observed under higher initial temperature, permeability, air flow rate, and lower bottom hole pressure. Thermal flooding and flue gas flooding are the main EOR mechanisms in FTO process. Considering the inescapable field problem of gas channeling, thorough contact between oil and air can be promoted by artificially preheating oil reservoir and adjusting air injection rate and pressure. Thus, oil recovery can be further improved under the premise of ensuring the safety of field application of air flooding technique.

Analysis of methyl pentanoate/air mixtures spherically expanding flame intrinsic instabilities

Recently, methyl pentanoate (MPe) has been considered an alternative fuel or additive in gasoline and diesel. Therefore, before its adoption in combustion devices, its combustion characteristics have to be thoroughly understood. Intrinsic flame instability and cellularity are combustion characteristics that influence the performance of combustion devices. In this light, the intrinsic instability and cellularity of MPe/air flames were investigated at the initial pressures of 1, 2, and 4 bar, temperatures of 453 K and 483 K, and equivalence ratios of 0.7–1.4 in a constant volume combustion chamber to understand the various combustion dynamics of MPe. The instability and cellularity were examined using physicochemical characteristics such as the stretch rate, Markstein length, Lewis number, thermal expansion ratio, and flame thickness. There were slight differences in the Markstein length at the various pressures, but generally, according to the Markstein length, MPe flames were unstable at higher pressures. The Lewis number revealed that MPe flames were thermal-diffusively stable, whereas the flame thickness showed MPe flames were more unstable at 483 K and 4 bar. Also, the MPe premixed flame growth rate and stability curves were obtained using theoretical analysis. The stability curves showed that at high initial pressures and temperatures, MPe flame instability occurs early at a smaller flame radius. Moreover, the experimental and theoretical critical radii agreed well. The research results provide a concrete foundation for advancing the knowledge of methyl pentanoate combustion.

Thermoelectric Cycle and the Second Law of Thermodynamics.

In 2019, Schilling et al. claimed that they achieved the supercooling of a body without external intervention in their thermoelectric experiments, thus arguing that the second law of thermodynamics was bent. Kostic suggested that their claim lacked full comprehension of the second law of thermodynamics. A review of history shows that what Clausius referred to as the second law of thermodynamics is the theorem of the equivalence of transformations (unfairly ignored historically) in a reversible heat-work cycle, rather than "heat can never pass from a cold to a hot body without some other change" that was only viewed by Clausius as a natural phenomenon. Here, we propose the theorem of the equivalence of transformations for reversible thermoelectric cycles. The analysis shows that the supercooling phenomenon Schilling et al. observed is achieved by a reversible combined power-refrigeration cycle. According to the theorem of equivalence of transformations in reversible thermoelectric cycles, the reduction in body temperature to below the ambient temperature requires the body itself to have a higher initial temperature than ambient as compensation. Not only does the supercooling phenomenon not bend the second law, but it provides strong evidence of the second law.

Experimental and numerical investigation of a hybrid battery thermal management system based on copper foam-paraffin composite phase change material and liquid cooling

• A liquid cooling-based BTMS using CPCM was investigated under different Re , current rates and ambient temperatures. • Elevated Re of liquid cooling will increase temperature non-uniformity within the battery pack, while the temperature differences will decrease once Re further improves. • For each battery pack, parametric study needs to be carried out to reach the equilibrium between the T max , Δ T max and pump power. • Liquid cooling controls the maximum battery temperature under high ambient temperature and warms up the battery under low ambient temperature. The battery thermal management system is essential to the electric vehicle. In this paper, a battery pack consisting of 20 cylindrical lithium-ion batteries, along with the copper foam/ paraffin composite phase change material, and liquid cooling channels were set up. A numerical model was built based on the physical model, which was validated by the experimental results. The experimental and numerical test revealed elevated Reynold numbers ( Re ) will increase temperature non-uniformity within the battery pack, while the temperature differences will decrease once Re further improves. Under 0.5C discharge, the maximum temperature difference ( Δ T max ) within difference cells increased from 0.2 to 1.2 K as Re increased from 0 to 28, then it decreased to 0.4 K with Re increased to 112. The study on the current rate effect revealed that a higher current rate could lead to both higher maximum battery temperature and higher Δ T max . Under different ambient temperatures, liquid cooling is necessary as it can help with warming up the battery in a cold environment or reducing the maximum temperature in a hot environment. Compared with pure phase change material (PCM) cooling, at the end of discharge, the hybrid PCM/liquid cooling formed an 8 K temperature increase and a 13K temperature decrease under a low initial temperature of 288 K and a high initial temperature of 318 K, respectively.

Investigation on high-energy Si anode mechanical-electrochemical-thermal characteristic under wide temperature range

Studying the cyclic evolution of high-energy Si anode, including the mechanical deformation, voltage hysteresis, heat generation and temperature response, is of great significance for its performance and safety. In this paper, a novel coupled semi-analytical model is developed to investigate the mechanical-electrochemical-thermal characteristic of Si particle anode. This model is adopted a series of temperature and concentration dependent parameters related to electrochemical reaction and Li+ diffusion. The results show that Li+ diffusion process will be limited at a lower initial temperature, which may increase the elastic–plastic stress. Thus, the stress-induced voltage hysteresis is more evident, resulting in the capacity loss and polarization heat increase. In the aspect of thermal behavior, the heat generation during lithiation is more than that during delithiation at each initial temperature, and the total heat accumulation after one cycle is greater at a higher initial temperature. Besides, the asymmetrical elastic–plastic deformation and heat accumulation during cyclic lithiation/delithiation may lead to ratcheting deformation of the Si particle electrode. The ratcheting deformation will be aggravated at a lower temperature. Additionally, the effects of charging rates (0.2C, 0.5C and 1C) are also discussed. The increased charging rate leads to a steeper concentration gradient, the more obvious asymmetrical elastic–plastic deformation, and earlier reaching the cut-off voltage. The electrode will produce more heat in a short time in the case of fast charging, and the resulting self-heating accumulation will affect its thermal stability. Based on this, ratcheting deformation at a fast charging rate is more severe, which will further decrease the mechanical stability of the Si electrode. The theoretical results are verified by the experiments. This study provides a theoretical and experimental basis for understanding the comprehensive performance of high-energy lithium-ion batteries, as well as design and management guidance.

Experimental study on energy transformation of static liquid pool during flash evaporation

Energy transformation during static liquid pool flash evaporation of pure water is examined on the basis of flashing experiments with superheats between 2 and 38 °C, initial water height ranging from 50 to 170 mm, and an initial liquid pool temperature from 50 to 85 °C. Energy balance link the flashed mass with the liquid pool temperature and then measure the variable parameters influence on several quantities: cooling rate, flashing time, and liquid mass evaporated. The non-dimensional numbers, Jakob number (Ja) and Non-Equilibrium Fraction (NEF) are applied to evaluate the heat transfer process. In addition, parametric study is performed to address the effect of superheat, initial temperature, and depressurization on the flashing phenomenon. Finally, a comparison of energy transformation during normal cooling and flash cooling is proposed. Results suggested that at higher initial temperature and lower initial pressure, a lower value of the equilibrium temperature obtained, and a more rapid temperature drop occurs. The maximum deviation obtained between the experimental and calculated ones is 11 % for larger vacuum tank pressure. The cooling rate and the flashing time also affected by these flashing parameters. With the increase of initial temperature by 15 °C, the cooling rate is enhanced by 41 %, and by dropping the vacuum tank initial pressure by 34.4 kPa, the cooling rate is improved by 56 %. A combined effect of different initial conditions on the flashing process has been shown to better understand their impact on evaporated mass. The present procedure is useful in designing the flashing system for a variety of thermal applications.

Coupled Analysis of Thermofluid-Structure Field for Thermal Properties of Early-Age Concrete Influenced by Electric Heating System

When heat energy is transferred to concrete through energy conversion by an electric heating system, the overall thermal performance of the early-age concrete is affected by the local high temperature of the concrete. This, in turn, affects the accuracy of the prediction and calculation of concrete deformation. Concrete thermal physical parameter models considering the mutual influence of heat and humidity were established to clarify the influence of an electric heat tracing system on the heat transfer performance of concrete at an early age, based on the concepts of equivalent age and hydration degree. Additionally, the COMSOL numerical simulation software was used for realizing the numerical solution of concrete heat transfer. The research indicates that the degree of hydration is affected by the heating provided by the electric heat tracing system. When curing for 40 h, the degree of hydration approaches 0.82 and remains unchanged, which indicates that the hydration of cement was almost complete in less than 2 days. The specific heat value of concrete in the early stage was significantly affected by electric heat tracing. This value of concrete at a high initial temperature was larger than that at a low temperature, while the specific heat of each point in the later stage tended to be the same. The thermal conductivity was significantly affected by the local electrical heating. The higher the temperature was, the lower the thermal conductivity was, which remained stable for two days under the influence of temperature. The key contribution of this research is to provide a coupling model for concrete curing. The findings from the study also provide industry practitioners with a comprehensive guide regarding the specific applications of the electric heating system in early-age concrete curing.

Dynamic Dissociation Behaviors of sII Hydrates in Liquid Water by Heating: A Molecular Dynamics Simulation Approach.

An understanding of the dynamic behavior of subtle hydrate dissociation in the liquid water phase is fundamental for gas production from marine hydrate reservoirs. Molecular dynamics simulations are performed in this study to investigate the dissociation kinetics of pure propane and binary propane + methane sII hydrates in a liquid water environment. The results show that faster hydrate dissociation rates are observed at higher initial temperatures. The hydrate phase dissociates from the cluster surface to the inside in a layer-by-layer manner under the simulation temperature conditions, which is similar to the behavior of sI hydrates and is independent of the hydrate crystal type. Compared to the binary sII hydrate, the pure sII hydrate dissociates more easily under the same initial temperature conditions, which can be attributed to the stabilizing effect of guest molecules in the hydrate cages. The empty cages collapse in one step, in contrast to the two-step pathway induced by the guest-host interaction. In addition, a hydrocarbon phase forms in the binary hydrate dissociation system instead of nanobubbles. These results can provide molecular-level insights into the dynamic mechanism of hydrate dissociation and theoretical guidance for gas recovery by thermal injection from marine hydrate reservoirs.

Design of a graphene oxide@melamine foam/polyaniline@erythritol composite phase change material for thermal energy storage

At present, only a single modification method is adopted to improve the shortcomings of erythritol (ET) as a phase change material (PCM). Compared with a single modification method, the synergistic effect of multiple modification methods can endow ET with comprehensive performance to meet the purpose of package, supercooling reduction, and enhancement of thermal conductivity. In this work, we innovatively combine graphene oxide (GO) nanosheet modified melamine foam (MF) and polyaniline (PANI) to construct a novel ET-based PCM by blending and porous material adsorption modification. PANI as the nucleation center can enhance the crystallization rate, thereby reducing the supercooling of ET. Meanwhile, GO@MF foam can not only be used as a porous support material to encapsulate ET but also as a heat conduction reinforcement to improve heat storage and release rate. As a result, the supercooling of GO@MF/PANI@ET (GMPET) composite PCM decreases from 91.2 °C of pure ET to 57.9 °C and its thermal conductivity (1.58 W⋅m−1⋅K−1) is about three times higher than that of pure ET (0.57 W⋅m−1⋅K−1). Moreover, after being placed at 140 °C for 2 h, there is almost no ET leakage in the GMPET composite PCM, and the mass loss ratio is less than 0.75%. In addition, the GMPET composite PCM displays a high melting enthalpy of about 259 J⋅g−1 and a high initial mass loss temperature of about 198 °C. Even after the 200th cycling test, the phase transition temperature and the latent heat storage capacity of the GMPET PCM all remain stable. This work offers an effective and promising strategy to design ET-based composite PCM for the field of energy storage.

Investigation of thermo-physical and chemical effects of in-cylinder steam injection on gasoline engine performance

In this study, for a gasoline engine, the effects of thermo-physical properties and chemistry of in-cylinder steam injection were discussed. The properties of steam directly influence the combustion and emissions characteristics of engines. A computational fluid dynamic model was established to investigate the combustion characteristics of engines with steam injection. A premixed laminar flame model was developed to examine the influence of steam injection on laminar flame speed. The findings of this study show that with increase in steam quantity, flow velocity and turbulent kinetic energy increased and tended to the core of combustor, and laminar flame speed decreased. When the steam dilution ratio changed from 0 to 0.5, the maximum laminar flame speed decreased from 37.3 cm/s to 26.9 cm/s. The effect of thermo-physical properties of steam injection was 80 % more potent than its chemical effect on the laminar flame speed. The chemical effect was gradually strengthened in high initial temperature and poor oxygen. The maximum consumption rate of the reaction, C8H18+H⇌C8H17+H2, decreased by 27.7 % and 3.2 % due to the thermal-physical and chemical effects of steam, respectively. The mole fractions of O, H and OH decreased with increase in steam quantity. The findings of this study demonstrate that by manipulating the thermo-physical properties of steam injection, engine performance can be improved.

Experimental investigation of producing ice slurry with water using opposed-nozzle impinging jet method

In order to improve the efficiency of producing ice slurry, an experimental device of opposed-nozzle impinging jet was established. Deionized water of 2.5–10.5 °C was jet impinged with chilled air in an ice-making tank. The spray and performance of impinging and non-impinging jet was evaluated. The results show the temperature around the water nozzle is higher, which is benefit for preventing ice blockage. The impinging jet makes the water droplets smaller, more evenly distributed and longer residence time, which strengthens the turbulence flow and heat transfer, as well as reduces supercooling degree of water, while increasing the production of ice particles. The ice packing factor (IPF) decreases with the rise of the water initial temperature, but the corresponding reduction rate is smaller at the higher initial temperature. Meanwhile, the maximum IPF and the utilization rate of cooling capacity of impinging jet are about 4 times than that of the traditional non-impinging jet as the initial water temperature is in the range of 2.5–10.5 °C. The refrigeration coefficient of the ice-making system increases with the initial water temperature. The impinging flow can greatly improve the refrigeration coefficient of the ice-making system. The average refrigeration coefficient of impinging flow system is about 1.6 times that of non-impinging flow system in the range of 2.5–10.5 °C of the initial water temperature. Moreover, the impinging flow improves the refrigeration coefficient of the system more significantly under the condition of lower initial water temperatures.