Increase In Liquid Temperature Research Articles

Quantifying the effects of external factors on the behavior of vertical wicking in a warp stretch woven fabric

Wicking ability of textiles is a key indicator in determining the physiological comfort provided by a fabric. The property is shaped by various factors internal and external to the fabric. Herein, the effects of some external factors such as the degree of (fabric) extension, the wetting liquid’s temperature and relative humidity on the vertical wicking behavior of a previously prepared warp stretch woven fabric were investigated. The fabric, which could be reversibly extended up to 60%, was prepared using a nylon/spandex air-covered yarn in the warp and cotton yarn in the weft. The results indicated that these external factors had a great influence on the vertical wicking equilibrium height with the degree of fabric extension having a more pronounced effect compared with the other two factors. Furthermore, extension and relative humidity were negatively related to the height of the vertical wicking, whilst an increase in liquid temperature resulted in an increase in vertical wicking height. The underlying mechanisms associated with these effects were examined using a specially constructed test chamber and tensioning device. The experimental data were also verified using the classical Laughlin-Davies model, and the results demonstrated the proposed wicking model could be used to predict the changes in fabric wicking height. These findings provide a more in-depth understanding of the wicking behavior of stretchable textiles in a comprehensive and objective manner.

A Study on the Flow Resistance of Fluids Flowing in the Engine Oil-Cooler Chosen

Oil-coolers are necessary components in high performance diesel engines. The heat removed by the cooler is a component in the total heat rejection via the engine coolant. Oil-cooler absorbs the heat rejected during the piston cooling and engine rubbing friction power loss. During flows of both coolant and engine oil via the oil-cooler, some flow resistances occur. The aim of the study is to determine values of the flow resistance coefficient for oil going through the cooler at various temperatures. The test stand was developed to determine time needed to empty tanks from liquids flowing through oil-cooler. The flow model was elaborated to study the mentioned flow resistance coefficient with respect to changing liquid temperature. The 20 °C increase in liquid temperature resulted in a flow resistance coefficient decrease of 30% for coolant and of the much more for engine oil. It was found that better results would be achieved with flows forced by means of pumps instead of using gravitational forces on the test stand.

Horn ultrasonic‐assisted pregelatinized starch with various streamline patterns as a green process: Computational fluid dynamics and microbubble formation of process

AbstractThe ultrasound‐assisted pregelatinization starch (UAPS) is considered as a physical method for starch modification. In this study, the effect of ultrasonic control parameters, including power, probe size, temperature, and time was investigated in order to predict microbubble formation and cavitation process as a two dimensional axisymmetric computational fluid dynamics (CFD) model to optimize the UAPS process. The cavitation phenomenon and the bubble dynamics were further investigated with regards to the mentioned parameters. Results showed that with the increase in probe diameter from 20 mm to 100 mm, a new pattern of streamlines were generated at the bottom of the container, increasing the turbulence among bubbles. This is mainly due to collapsing bubbles, resulting in a huge amount of energy released which accelerates heat and mass transfer to the fluid. According to the results obtained from the dynamics of bubbles, the maximum radius of the bubbles had a rising pattern with the increase in the probe size (from 20 to 100 mm), amplitude (from 25 to 45%) and temperature (from 35 to 65°C); moreover, the energy of the bubble slightly increased with the increase in liquid temperature and probe size.Practical applicationsThe physical modifications of starch structure are more widely employed since it is safer and without impurities, which have strong effects on different component functionalities. Pregelatinization is one of the most popular industrial methods of physically modifying starch. Pregelatinized. The ultrasound‐assisted pregelatinized starch as physical modification offers many advantages, mainly the declined utilize of chemicals and processing time, serving as an environment‐friendly processing technology, high selectivity method. Use of computational fluid dynamics is a suitable approach to assessing the data pertaining to the physical features of the ultrasonication process. We underscored the importance of filling the gaps of knowledge concerning modeling sonication process to produce the efficient ultrasound‐assisted pregelatinized starch under various ultrasound power, probe size and fluid temperature to predict microbubble formation, heat and energy transfer.

Influences of thermal effects on cavitation dynamics in liquid nitrogen through venturi tube

Investigation on cavitation features in cryogenic liquids is of great importance to rocket engine design due to their complicated physics. This paper experimentally investigates the characteristics of unsteady liquid nitrogen (LN2) cavitating flow through a transparent venturi tube with image processing techniques. The numerical simulations based on the computational fluid dynamic approach are also performed to help explain the mechanisms. A pressure ratio (Pr) associated with the inlet and the outlet subcooling is found to have a linear relationship with the cavitation number. The nondimensional thermal effect parameter derived from the single bubble dynamics is used to quantify thermal effect intensity. The cavity length derived from standard derivation results has an inversely linear relation with Pr, and there exists an inflection point of the pressure ratio (Prc) below which the cavity length growth rate is relatively larger. The effects of the bulk temperature on the magnitude of Prc are numerically investigated, which reveals that Prc increases as the liquid temperature increases. The oscillating frequencies of the sheet and cloud cavitating flow are also analyzed according to two Strouhal numbers based on cavity length (Stc) and venturi throat diameter (Std), respectively. For cloud cavitation, Stc lies in between 0.30 and 0.40 for all Pr values, while for sheet cavitation, it decreases to 0.04–0.08. Besides, in the cloud cavitation region, Std increases linearly with Pr but has a weak relation with ∑⋅C/uth3. It is also found that with increased values of ∑⋅C/uth3, the transition point of Pr from sheet cavitation to cloud cavitation is delayed.

Thermodynamic Performance and Wave Propagation Sensor System of Fiber Bragg Grating in Liquid Media

Although the measurement of liquids temperature is commonly used by Fiber Bragg Grating (FBG) sensor but its thermodynamic performance has interesting phenomena. This paper proposes the measurement and simulation of liquids temperature using FBG. Laser diode was launched into human blood, water, and vegetable oil, then transmitted power is measured by optical powermeter to determine its corresponding temperature. The results showed that the increasing temperature changes led to the widening of the wave shift. The largest change of wavelength is water temperature and the smallest One is vegetable oil temperature. Increase in liquid temperature causes the output power is greater. FBG simulation of sine and square function are also designed for temperature range of 30°C to 41°C with matrix transfer method based on coupled mode theory. Peak value of transmission spectrum of each function is shown by the change of temperature which indicates the sensor is sensitive to sine and square function variations. The peak at temperature of 30°C for each sine and square are -78.32 dB and -102.66 dB and increased to 41°C at 46.72 dB and -79.89 dB, respectively.

Effects of ambient pressure and fluid temperature in ultrasonic cavitation machining

One of the prevalent material removal mechanisms in vibratory ultrasonic machining (USM) is cavitation erosion. The slurry-used USM process contains a mixture of water and abrasive particles—hence, strictly not pure cavitation. Cavitation erosion is the process of surface modification by generation and collapse of vapor bubbles on the workpiece surface inside a liquid medium. Although considerable research has been devoted in finding the material removal mechanism, rather less attention has been paid on the effect of pressure and temperature in cavitation erosion. Hence, efforts have been taken in this investigation to identify the mechanism of cavitation collapse at various ambient pressures and fluid temperatures and to investigate their effects in machining using AISI 304 stainless steel and aluminum 6061-T4 with wire EDM surface. Ambient pressure and temperature were varied from 100 to 400 kPa and 10 to 90 °C respectively. The outcomes showed that mass loss increased until 400 kPa and 50 °C and then declined with increase in liquid temperature. Scanning electron microscope (SEM) images showed that most of the test surface deformed plastically with surface undulations and material removal was by micro-pitting. Further, suggestions are provided to control the machining conditions from the identified cavitation collapse mechanism. Optimal conditions to accelerate the machining process were found to be 50 °C and 400 kPa.

Study of mixed mode fracture toughness and fracture characteristic in gypsum rock under brine saturation

In the deep geological situation, the gypsum is almost always associated with high temperature and the other mineral substances such as sodium chloride. And, hot saline brine will greatly affect the strength and deformability of gypsum by influencing the petrographic characteristics such as microstructure, granular minerals, composition content and morphology. To quantify the effect of brine temperature and concentration on fracture toughness and fracture characteristics of gypsum, a serious of tests, including cracked straight through Brazilian disc (CSTBD) tests and scanning electron microscopy (SEM), were carried out. The results demonstrated that, when at a given crack inclination angle, the fracture peak of gypsum decreases with the increase of liquid temperature. When at a given liquid temperature, due to common-ion effect, the fracture peak first decrease then increase with the increase of brine concentration. In all these cases, due to the effect of friction coefficient, the fracture peak first decreases then increases with the increase of prefabricated crack angle. From SEM morphology results, the microcrack density increases with liquid temperature increasing, whereas first increase then decrease with brine concentration increasing. Subsequently, by adopting the approach of back-propagation neural network, the effective FPZ at different conditions were obtained. It was found that the size of effective FPZ is closely dependent on brine temperature and concentration.

Vibratory cavitation erosion behavior of AISI 304 stainless steel in water at elevated temperatures

The cavitation erosion behavior of AISI 304 stainless steel was investigated using an ultrasonic vibratory apparatus at elevated temperatures and the morphologies of the eroded surface and the cross section were observed by scanning electron microscopy (SEM) and optical microscopy. The results show that the cumulative mass loss increases, shows a peak and then decreases with increase in liquid temperature. The cavitation damage of the eroded surface was relatively uniform at 20–60°C and at 80°C it was localized; the depth of local deeper pit at 80°C was about 1.7 times deeper than at 50°C. The initial results based on the cumulative mass loss could not predict the degree of cavitation damage, and the depth of local erosion pit may be an effective method for judging erosion damage.

Spray of gelled propellants from an impinging-jet injector under different temperatures

This paper presents the results of an experimental study on the spray characteristics of gelled propellant from an impinging jet injector under different liquid temperatures. A high-speed camera was used to record detailed information about the liquid sheet breakup process and spray development. The rheological characteristics of the gel simulant under different temperatures were tested. It was found that the consistency coefficient decreases and the flow index increases as the liquid temperature increases. The flow characteristics and spray patterns for injectors with tapered orifices and straight orifices were tested, respectively. Because the injection of fluid through tapered orifices can decrease the viscosity of the fluid, the mass flow rate is increased and the liquid sheet behaves more unstably for injector with tapered orifices. The influence of liquid temperature on the mass flow rate for both injectors is minor. The spray photos showed that the liquid sheet is more unstable and easier to break up at higher temperature for both injectors. Generally, the liquid sheet breakup length decreases and the disturbance wavelength increases as the liquid temperature increases.

Study of the influence of interfacial waves on heat transfer in turbulent falling films

This study explores the influence of interfacial waves on mass, momentum and heat transfer in turbulent, free-falling water films that are subjected to sensible heating. Measured temporal records of film thickness and temperature profile across the film are used to examine the film’s thermal response to the passage of large waves. The temporal variations of liquid temperature and heat transfer coefficient are generally opposite to that of film thickness; the heat transfer coefficient is highest in the substrate regions upstream and downstream of large waves and lowest in the waves themselves. Increasing the film’s Reynolds number increases the mean thickness and wave amplitude, and decreases the wave period, but results in appreciable attenuation in the measured liquid temperature response to the large waves. Using FLUENT, a computational model of the falling film is constructed and its predictions compared to the data. The computed results show good agreement with the measured mean film thickness, wave form and period, and both wall and mean film temperatures. The model captures the measured increase in liquid temperature in the film substrate and decrease corresponding to the large waves, but the predicted temperature response is less attenuated for higher Reynolds numbers than the measured. Velocity predictions point to acceleration of high temperature liquid from the upstream substrate toward the cold region within the large wave before losing the excess heat due to mixing downstream from the wave crest. Overall, the present study demonstrates the effectiveness of computational tools at predicting the hydrodynamic and thermal characteristics of separated flows involving a wavy liquid-vapor interface.

Energy analysis during acoustic bubble oscillations: Relationship between bubble energy and sonochemical parameters

In this work, energy analysis of an oscillating isolated spherical bubble in water irradiated by an ultrasonic wave has been theoretically studied for various conditions of acoustic amplitude, ultrasound frequency, static pressure and liquid temperature in order to explain the effects of these key parameters on both sonochemistry and sonoluminescence. The Keller–Miksis equation for the temporal variation of the bubble radius in compressible and viscous medium has been employed as a dynamics model. The numerical calculations showed that the rate of energy accumulation, dE/dt, increased linearly with increasing acoustic amplitude in the range of 1.5–3.0atm and decreased sharply with increasing frequency in the range 200–1000kHz. There exists an optimal static pressure at which the power w is highest. This optimum shifts toward a higher value as the acoustic amplitude increases. The energy of the bubble slightly increases with the increase in liquid temperature from 10 to 60°C. The results of this study should be a helpful means to explain a variety of experimental observations conducted in the field of sonochemistry and sonoluminescence concerning the effects of operational parameters.

폴리우레탄 바인더를 활용한 친환경 도로포장용 혼합물 개발

PURPOSES : The objectives of this study are to develop the eco-friendly pavement material using polyurethane binder and evaluate mechanical properties of the developed binder and concrete. METHODS : The bending beam test was conducted to select the sample candidates of polyurethane binder based on the bending strength. The characteristics of viscosity, curing time, and temperature change of sample binder was examined on different temperature conditions. The mechanical properties of polyurethane binder was estimated using the dynamic modulus testing. The indirect tensile strength test was conducted on polyurethane binder concrete with different gradation and binder content for evaluating the mechanical properties of concretes. RESULTS : Based on the beading beam test, four different binder samples were prepared for estimate the mechanical properties. The viscosity of polyurethane binder tends to increase with increase of liquid temperature and the hardening phenomenon begins 10 to 15 minutes at room temperature after mixing the resin and hardener. It is observed that the dynamic modulus of binder increases as loading frequency increases and change of modulus is found to be the highest in the PU-2I binder type. The PU-2I binder concretes shows the largest value of indirect tensile strength and indirect tensile energy. CONCLUSIONS : The use of polyurethane binder as pavement materials is capable of increasing the pavement performance and reducing the detrimental environmental effect during the highway construction.

J026024 液体の温度上昇に及ぼすマイクロバブルの非線形振動の影響

J026024 液体の温度上昇に及ぼすマイクロバブルの非線形振動の影響

Removal of benzene from nitrogen by using polypropylene hollow fiber gas–liquid membrane contactor

In this paper, an experimental and theoretical study was carried out to evaluate the performance of gas–liquid membrane contactor in benzene/nitrogen separation process by using an aqueous N-Formylmorpholine (NFM) solution as absorbent. The effects of operating parameters such as the gas and liquid flow rates, the feed gas and the initial liquid concentrations, the liquid temperature, the absorbent concentration and the long term operation on the benzene flux and removal efficiency were investigated. A mathematical model was developed to simulate the absorption process in order to gain an insight into the experimental observation. Both simulative and experimental results show that benzene mass transfer flux increases with the gas flow rate and the feed gas concentration, while the liquid flow rate has no significant effect on it. The increase in liquid temperature and initial liquid benzene concentration results in a decrease in benzene flux. Long term performance test shows that the aqueous NFM solution is a suitable absorbent to be applied to the polypropylene (PP) hollow fiber gas–liquid membrane contactor.

Regeneration of CO 2 from CO 2-rich alkanolamines solution by using reduced thickness and vacuum technology: Regeneration feasibility and characteristic of thin-layer solvent

The novel regeneration concept by using reduced thickness and vacuum technology was put forward in this paper to solve the higher regeneration energy consumption in the chemical absorption process for CO 2 separation from flue gas. A 120-mm I.D. vessel was precisely designed to regenerate the CO 2-rich solution, and the change of the thickness of thin-layer solutions was simulated by controlling the volume of rich solution added into the vessel. The experimental results show that vacuum regeneration may be viable if the CO 2-rich solution can be easily partitioned into the continuous single thin-layer solutions with an appropriate thickness. The great decrease of thin-layer solution thickness and regeneration pressure, and the increase of liquid temperature can improve the regeneration performance considerably. In addition, it is worthy to determine the optimum initial CO 2 loading of rich solution, regeneration time and absorbent concentration due to the contradiction between the CO 2 loading of lean solution and regeneration energy consumption per kg of CO 2. Finally, the simple comparison between vacuum and heating regeneration methods shows that the novel regeneration method may have the potential to reduce the regeneration energy requirement.

Pulsed laser ablation in a cooled liquid environment

Pulsed laser ablation of a Si substrate in cooled KOH solution and a water-confined region is investigated. The liquid temperature is varied from room temperature down to 4°C. For laser ablation in water, the material removal rate reduces slightly as liquid temperature increases. However, the material removal rate for laser ablation in KOH solution is twice as high as that in the water at a cooled liquid environment (temperature ∼10°C). This enhancement results from a strong chemical interaction between the KOH solution and Si materials around the ablated crater during fast cooling of the substrate surface from the vaporization temperature after the laser ablation. It is also found that the material removal rate is reduced greatly in the KOH solution as the liquid temperature increases. It is because at a liquid temperature above 20°C, the KOH solution starts to interact strongly with Si when the two materials are in contact. The formation of Si(OH)x chemical debris blocks the incident laser beam to reach the Si surface and reduces the laser ablation effect. This result of the investigation is applied to set up a cooled KOH flow system for wafer thinning to thin substrate thickness down to 50 μm.

Removal of Zn +2 and Ni +2 by adsorption in a fixed bed of wheat straw

Zn +2 and Ni +2 in a solution were removed by biosorption in a fixed bed of wheat straw Triticum aestivum. The removal rate and the mass transfer coefficient for Zn +2 and Ni +2 were found to be proportional to the liquid superficial velocity to the power of 0.31 for the range of the particle Reynolds number from 18 to 445 (equivalent liquid rates of 0.00070–0.0175 m 3 m −2 s −1). This agrees well with reported literature for mass transfer in a packed bed of solid particles under a laminar flow regime. Effect of the solution pH, temperature and the particle size (0.5, 1.0, 1.5 and 2.0 in.) on biosorption of Zn +2 and Ni +2 was also investigated. Biosorption of both Zn +2 and Ni +2 increased significantly with the solution pH from 4.0 to 7.0. On the other hand, Zn +2 and Ni +2 removal appeared to be insensitive to liquid temperature from 25 to 30 °C. Nevertheless, a 25% increase in the percentage removal of metal ions was observed with further increase of liquid temperature from 30 to 35 °C. However, the biosorbent particle size did not seem to have a systematic effect on the biosorption of Zn +2 and Ni +2. In addition, biosorption of Zn +2 was not affected considerably by co-adsorption of the bimetal solution while biosorption of Ni +2 decreased about 14%.

Study of Surface Acoustic Wave Streaming Phenomenon Based on Temperature Measurement and Observation of Streaming in Liquids

A longitudinal wave is radiated into a liquid when the liquid is placed on a surface acoustic wave (SAW) propagating surface. The radiated longitudinal wave induces liquid dynamics, such as vibrating and streaming. This phenomenon is called SAW streaming. The liquid's temperature increases, as the radiated longitudinal wave becomes attenuated inside the liquid. In this paper, the measurement and observation results of temperature and streaming in liquids are described. First, the sol–gel formation of agar–agar is observed. Second, a highly viscous liquid droplet is placed on the SAW propagation surface. However, the stable measurements are difficult. Therefore, a U-type cell is developed and the pattern of the streaming in this cell is observed. The results show that there is an association between the attenuation of a longitudinal wave and the temperature distribution.

An investigation on pulsed electric fields technology using new treatment chamber design

A pulsed electric field (PEF) system was designed and constructed using modern IGBT technology. The main focus of this work was to design a new PEF treatment chamber that operate at high electric field intensities with limited increase in liquid temperature and limited fouling of electrodes. Four multi-pass treatment chambers were designed consisting of two stainless steel mesh electrodes in each chamber, with the treated fluid flowing through the openings of the mesh electrodes. The two electrodes are electrically isolated from each other by an insulator element designed to form a small orifice where most of the electric field is concentrated. Dielectric breakdown inside the chambers was prevented by removing the electrodes far from the narrow gap. The effect of PEF treatment on the inactivation of gram-negative Escherichia coli ATCC 25922 suspended in simulated milk ultra-filtrate (SMUF) of 100%, 66.67% and 50% w/w was investigated. Treatments with the same electrical input power but with higher electric field strengths provided larger degree of killing. The effect of PEF treatment using suspensions at different flow rates and different pulse frequencies was also investigated. In general, the inactivation rate of E. coli increased with increasing electric field strength, treatment time and processing temperature. More than 6 log reductions in E. coli suspended in SMUF was achieved using electric field intensity in the range of (37.2–49.6 kV/cm) with a treatment temperature not exceeding 38 °C.

Experimental studies on perturbed acoustic resonant spectroscopy by a small rock sample in a cylindrical cavity

A measurement system for acoustic resonant spectroscopy (ARS) is established, and the effects of resonant cavity geometry, inner perturbation samples and environmental temperature on the ARS are investigated. The ARSs of the small samples with various sizes and acoustic properties are measured. The results show that at the normal pressure, the resonant frequency decreases gradually with the increase of liquid temperature in the cylindrical cavity, while the resonant amplitude increases. At certain pressure and temperature, both the resonant frequency and the amplitude decrease greatly when there exist air bubbles inside the cavity fluid. The ARS is apparently affected by the sample porosity and the sample location in the resonant cavity. At the middle of the cavity, the resonant frequencies reach their maximum values for all of the measurement samples. The resonant frequencies of the porous rock samples are smaller than those of the compacted samples if other acoustic parameters are the same. As the sample is moved from the top to the middle of the cavity along its axis, the resonant amplitude increases gradually for the compacted rocks while decreases for the unconsolidated rocks. Furthermore, the resonant amplitude increases firstly and then decreases if the porosity of the rock sample is relatively small. In addition, through the comparisons between the experimental and theoretical results, it is found that the effects of the acoustic parameters and sizes of the samples and the size of the cylindrical cavity on the laboratory results agree well with the theoretical ones qualitatively. These results may provide basic reference for the experiment study of rock acoustic properties in a low frequency using ARS.