Статті в журналах з теми "Various pressure and temperature conditions"
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1
Phan, Thanh-Hoang, Ebrahim Kadivar, Van-Tu Nguyen, Ould el Moctar, and Warn-Gyu Park. "Thermodynamic effects on single cavitation bubble dynamics under various ambient temperature conditions." Physics of Fluids 34, no. 2 (February 2022): 023318. http://dx.doi.org/10.1063/5.0076913.
Анотація:
Thermodynamic characteristics and their effects on single cavitation bubble dynamics are important to elucidate the physical behaviors of cavitation phenomena. In this study, experimental and numerical methods were utilized to explore the thermodynamic effects on single cavitation bubble dynamics under various ambient temperature conditions. A series of experiments was performed to generate a single cavitation bubble at ambient temperatures between 20 and 80 °C using a laser-induced method and a high-speed camera to observe the dynamic behaviors of bubbles. By increasing the ambient temperature, a nonspherical bubble shape with a jet flow at the bubble rebound stage was observed. Next, the numerical simulation results in terms of the bubble radius and bubble shape were validated with the corresponding experimental data. Generally, the results exhibited reasonable agreement, particularly at the later collapse and rebound stages. Critical hydrodynamic and thermodynamic mechanisms over multiple oscillation stages at different ambient temperatures were analyzed. The bubble behaviors and their intensities were numerically quantified with respect to the bubble radius, collapsing time, internal pressure, internal temperature, and phase transition rate parameters. The results showed that the maximum bubble radius, first minimum bubble radius, and collapsing time increased with an increase in the ambient temperature. Nevertheless, the peak values of the internal pressure and internal temperature decreased with an increase in the ambient temperature. Generally, the bubble collapsed less violently at high temperatures than at low temperatures.
2
Walter, M. J., Y. Thibault, K. Wei, and R. W. Luth. "Characterizing experimental pressure and temperature conditions in multi-anvil apparatus." Canadian Journal of Physics 73, no. 5-6 (May 1, 1995): 273–86. http://dx.doi.org/10.1139/p95-039.
Анотація:
Octahedral media made of MgO–5%Cr2O3, with edge lengths of 18, 14, and 10 mm are used as pressure cells in experiments in a multi-anvil solid media apparatus at pressures of 4 to 27 GPa and temperatures to > 2700 °C. Calibrations of press-load versus sample pressure are based on room-temperature and high-temperature phase transitions, and are accurate to within ± 0.5 GPa. Calibrations of the temperature distribution were made in the central portion of the furnaces (graphite or LaCrO3) in the various sample assemblies used routinely in this laboratory. The following gradients away from the furnace midlines were observed: 18 mm: high-T straight graphite (−100 °C mm−1), high-T stepped graphite (+ 25 °C mm−1), low-T stepped graphite (−20 °C mm−1), high-T stepped LaCrO3 (−50 °C mm−1); 14 mm: high-T stepped LaCrO3 (−70 °C mm−1); 10 mm: straight LaCrO3 (−200 °C mm−1). The effect of increasing the wall thickness of the central segment of the furnace ("stepping") is to reduce the temperature gradient relative to a straight design. The relative effect of pressure on W3Re–W25Re and Pt–Pt13Rh thermocouples was measured by comparison of apparent temperatures recorded by each type in a given experiment. Corrections for the effect of pressure on thermocouple emf depend on the temperature distribution in the gasket regions surrounding the pressure cell, where pressure is reduced to ambient conditions. The temperature of this pressure seal controls the magnitude of the effect of pressure on thermocouple emf. Because this temperature will vary depending on the assembly, no universal pressure correction can be derived.
3
Lei, Fan, Yan Xue, and Donglin Liu. "Simulation of millimeter-sized microwave plasma discharge generator under various conditions." AIP Advances 12, no. 8 (August 1, 2022): 085015. http://dx.doi.org/10.1063/5.0105035.
Анотація:
A microwave plasma generator (MPG) of a sub-millimeter scale might be suitable for biomedical applications. However, there are still many unknowns regarding the MPG discharge behavior at this scale and specific conditions. A two-dimensional MPG model at the millimeter scale and its simulation and relative calculation in the COMSOL Multiphysics software are presented. A MPG filled with argon and helium is simulated, respectively. The frequency of a microwave source of about 5 GHz is considered. The number density and temperature of electrons as well as chemical composition are obtained at different power and pressure conditions. The electron density peaks slightly downstream of the crossing point, and the electron density is slightly asymmetrically in the y-plane due to the fact that the electromagnetic waves are absorbed asymmetrically. The electron temperature is relatively low everywhere, in part, due to the high operating pressure. The electron temperature peaks directly underneath the wave guide where the wave is absorbed. The electron density increases with the increase in the internal pressure and the input power of the MPG, the electron temperature decreases with the increase in the internal pressure of the MPG, but the electron temperature cannot be affected by the input power change of MPG. The amount of excited Ar+ and Ars (metastable atom) increases with the increase in the input power and pressure of MPG, but the amount of excited Ar almost remained unchanged. In addition, the amount of excited He almost remained unchanged, while the amount of excited He+, Hes (metastable atom), and He2+ increased with the increase in the input power and pressure of MPG. The simulation results of this model are thus informative for understanding the physical characteristics of millimeter-sized MPG, and it will provide a solid basis for the future development of such hardware in small plasma capsules for cancer therapy.
4
Mohammed, Suad Abdulmuttaleb, Areej Dalaf Abbas, and Laith Salem Sabry. "Effect of Operating Conditions on Reverse Osmosis (RO) Membrane Performance." Journal of Engineering 20, no. 12 (July 9, 2023): 61–70. http://dx.doi.org/10.31026/j.eng.2014.12.04.
Анотація:
The aim of this research is to study the effect of high concentrations of salts, pressure and temperature on the performance of the RO membrane with time. Four different (Na2CO3) concentrations (5000, 15000, 25000 and 35000) ppm and various pressures such as (1, 3 and 5) bars at different temperatures of the feed solution (i.e., 25, 35 and 45) ◦C were used in this work. It was found that, as the concentration of salt and feed temperatures increase, the rejection of the salt decrease. While the salt rejection of the membranes increases with increase of transmembrane pressure.
5
Zhao, Yanlin, Qiang Liu, Liming Tang, Jian Liao, Le Chang, Xiaguang Wang, Yang Li, and Sheng Ren. "Test Study of Seepage Characteristics of Coal Rock under Various Thermal, Hydraulic, and Mechanical Conditions." Machines 10, no. 11 (November 2, 2022): 1012. http://dx.doi.org/10.3390/machines10111012.
Анотація:
The seepage characteristics of rocks under conditions of multi-field activity have always been important in the field of rock mechanics. This study used the MTS815 multi-functional electro-hydraulic servo rock testing machine to conduct seepage tests on long-flame coal specimens under different confining pressures, water pressures, and temperatures. This paper presents and discusses the seepage characteristics of coal specimens under the action of thermal hydraulic mechanical multi-field combinations. Considering parameters such as volumetric strain, temperature, thermal expansion coefficient, and initial porosity, the relationships of each parameter with porosity were obtained. The test results revealed that the volumetric strain of coal specimens increased gradually with the increase of temperature. The dynamic viscosity of water decreased with the increase of temperature, which accelerated the movement and circulation of water molecules. The increase in temperature caused the volume of the coal specimen to expand, the pores in the coal specimen squeezed against each other, the pore volume decreased, and the size of the seepage channel slowly decreased, which inhibited the seepage process. Furthermore, permeability gradually decreased with the increase of temperature. This inhibited the occurrence of seepage, and the higher the confining pressure, the lower was the permeability. The porosity of coal specimens decreased with the increase in temperature, which had an inhibitory effect on the seepage behavior. The results of this study provide experimental and theoretical support for the safe mining of coal and rock in underground mines.
6
Rashid, Waleed Turki, Israa Aziz Alkadira, and Moayyed Gased Jalhoom. "Effect of Operating Conditions on Removal Heavy and Radioactive Elements by Reverse Osmosis Membrane." Al-Qadisiyah Journal for Engineering Sciences 13, no. 3 (September 30, 2020): 240–45. http://dx.doi.org/10.30772/qjes.v13i3.665.
Анотація:
The major goal of the presented study has been studying the reverse osmosis (RO) characteristics for (Ni, Fe, Pb, Ca, Cu, K, U, and Th) removal from aqueous solution. This was done by examining the impact related to temperature and pressure on the performance regarding the RO membrane in the removal of elements with time. Three temperatures (25,35 and 45 oC) and various pressures such as (2,4 and 6) bars were used in this work. It was found that, as the pressure increase, the flux permitted and rejection of elements are increased. The temperature increases the flux permitted while the rejection of elements was steady-state almost with the increase in temperature for all heavy and radioactive elements. It also shows that these a steady-state has stopped after 35 ºC and rejection start to decrease.
7
Wang, Jie, Jie Wang, and Christine Ehlig-Economides. "Effect of Predisolved Natural Gas on CO2 Solubility in Water With Various Salinities at Reservoir Conditions." Petrophysics – The SPWLA Journal of Formation Evaluation and Reservoir Description 64, no. 6 (December 1, 2023): 970–77. http://dx.doi.org/10.30632/pjv64n6-2023a11.
Анотація:
Dissolution of CO2 in saline waters is considered one of three main CO2 trapping mechanisms, along with structural/stratigraphic trapping and mineralization. CO2 can dissolve in fresh/saline water under typical reservoir pressure and temperatures. Its solubility is dependent on pressure, temperature, and salinity. CO2 solubility studies typically consider saline water or fresh water as a liquid without any predissolved gases. The reality is formation water may contain appreciable dissolved gases for all pressure and temperature conditions. An example of gas-water ratio (GWR) can be ~1 scf/stb for formation water in an oil reservoir and ~5 to 6 scf/stb for a deep saline aquifer. Therefore, it is essential to quantify the effect of brine salinity on CO2 solubility in “live” saline waters. Just as “live” oil denotes reservoir oil that contains solution gas, we define “live” brine as saline water that includes dissolved gases. Conversely, “dead” brine refers to saline water devoid of any dissolved gas content. Two sets of experiments were conducted under typical reservoir conditions. The first set of experiments evaluated the CO2 solubility in live formation water. The second set of experiments evaluated how variation in the live brine salinity affected CO2 solubility. These experiments involved 1) synthesis of the brine, 2) synthesis of natural gas mixture, 3) recombination of live formation water with a natural gas mixture and transfer into a high-pressure and high-temperature pressure-volume-temperature (PVT) visual cell, 4) CO2 addition to the PVT cell, and 5) bubblepoint pressure determination within the PVT cell. The results showed that CO2 solubility in live formation water is significantly less than that in “dead” water under reservoir conditions. In addition, the brine salinity affects CO2 solubility in live formation water by further reducing CO2 solubility with increasing live brine salinity. As the brine salinity increases, very little CO2 can be dissolved in the live brine once it reaches a certain solubility. An understanding of CO2 dissolution in live saline water is essential for future CCUS evaluation and execution.
8
Wang, Jianqiang, Yu Song, Shuaishuai Dong, Song Ding, Yukun Geng, and Xiaotong Gao. "Triaxial Experimental Study of Zinc Contaminated Red Clay under Different Temperature Conditions." Applied Sciences 12, no. 21 (October 23, 2022): 10742. http://dx.doi.org/10.3390/app122110742.
Анотація:
Temperature is one of the important factors affecting the mechanical properties of geotechnical soils, and its role in engineering construction in China cannot be underestimated. In order to study the effects of temperature and zinc contamination concentration on the mechanical properties of Guilin local red clay, a temperature-controlled triaxial shear test was conducted on Guilin red clay under three variables of temperature, zinc contamination concentration and surrounding pressure. The test findings revealed that there are significant differences in the effects of temperature, zinc contamination concentration and surrounding pressure on the mechanical properties of Guilin red clay. The stress–strain curves of the red clay at various temperatures, contamination concentrations and envelope pressures are of the strain-hardening type, and the deformation modulus showed a tendency to increase rapidly with increasing strain, then decrease rapidly, and finally, decrease slowly. With the increase of temperature, the cohesion of Zn-contaminated red clay increases, while the angle of internal friction increases and then decreases, both of which increase the shear strength of red clay. As the concentration of Zn contamination grows, the shear strength of the red clay increases, while the internal friction angle increases and then decreases, and the shear strength of the soil increases and then decreases. The shear strength of the Zn-contaminated red clay improved as the surrounding pressure increased.
9
Harfoush, M., S. A. Mirbagheri, M. Ehteshami, and S. Nejati. "Arsenic removal from drinking water using low-pressure nanofiltration under various operating conditions." Water Practice and Technology 13, no. 2 (June 1, 2018): 295–302. http://dx.doi.org/10.2166/wpt.2018.042.
Анотація:
Abstract Currently, one of the main environmental concerns is the toxicity caused by arsenic. Arsenic-polluted water can cause many human health problems including various cancerous diseases. In natural water, inorganic arsenic can be found in the forms of arsenite and arsenate, which have been found in several Iranian provinces – e.g., East Azerbaijan, Kurdistan, and the city of Bijar – in high concentrations. Modern nanofiltration (NF) technology enables a wide range of water resource pollutants to be controlled efficiently. In this study, in an attempt to enhance arsenic removal (both arsenite and arsenate) from drinking water using low pressure NF, operating conditions like arsenic concentration, the trans-membrane pressure applied, and a range of different temperatures have all been considered. The highest arsenate removal achieved was 94% with an initial concentration of 500 μg/L, at 7 bar pressure, and 28 °C. The highest arsenite removal was 90%, with an initial concentration of 100 μg/L, at 5 bar pressure, and also at 28 °C. Increasing the pressure had a positive effect on the removal of both species, however, increasing the temperature had negative impacts. It was always found that arsenate removal was better than arsenite removal.
10
Allen, Eric E., Daniel Facciotti, and Douglas H. Bartlett. "Monounsaturated but Not Polyunsaturated Fatty Acids Are Required for Growth of the Deep-Sea BacteriumPhotobacterium profundum SS9 at High Pressure and Low Temperature." Applied and Environmental Microbiology 65, no. 4 (April 1, 1999): 1710–20. http://dx.doi.org/10.1128/aem.65.4.1710-1720.1999.
Анотація:
ABSTRACT There is considerable evidence correlating the production of increased proportions of membrane unsaturated fatty acids (UFAs) with bacterial growth at low temperatures or high pressures. In order to assess the importance of UFAs to microbial growth under these conditions, the effects of conditions altering UFA levels in the psychrotolerant piezophilic deep-sea bacterium Photobacterium profundum SS9 were investigated. The fatty acids produced byP. profundum SS9 grown at various temperatures and pressures were characterized, and differences in fatty acid composition as a function of phase growth, and between inner and outer membranes, were noted. P. profundum SS9 was found to exhibit enhanced proportions of both monounsaturated (MUFAs) and polyunsaturated (PUFAs) fatty acids when grown at a decreased temperature or elevated pressure. Treatment of cells with cerulenin inhibited MUFA but not PUFA synthesis and led to a decreased growth rate and yield at low temperature and high pressure. In addition, oleic acid-auxotrophic mutants were isolated. One of these mutants, strain EA3, was deficient in the production of MUFAs and was both low-temperature sensitive and high-pressure sensitive in the absence of exogenous 18:1 fatty acid. Another mutant, strain EA2, produced little MUFA but elevated levels of the PUFA species eicosapentaenoic acid (EPA; 20:5n-3). This mutant grew slowly but was not low-temperature sensitive or high-pressure sensitive. Finally, reverse genetics was employed to construct a mutant unable to produce EPA. This mutant, strain EA10, was also not low-temperature sensitive or high-pressure sensitive. The significance of these results to the understanding of the role of UFAs in growth under low-temperature or high-pressure conditions is discussed.
11
Harharah, Ramzi H., Ghassan M. T. Abdalla, Abubakr Elkhaleefa, Ihab Shigidi, and Hamed N. Harharah. "A Study of Copper (II) Ions Removal by Reverse Osmosis under Various Operating Conditions." Separations 9, no. 6 (June 20, 2022): 155. http://dx.doi.org/10.3390/separations9060155.
Анотація:
The study aims to treat artificial wastewater contaminated with copper (II) ions by reverse osmosis using (SEPA CF042 Membrane Test Skid-TFC BW30XFR). Several concentrations of feedstock were prepared. Different operating pressure, temperature, and flow rate were applied. The effect of these operating conditions on both the amount of Cu (II) removal and the permeate flux was monitored. The results of the study revealed that both the permeate flux and Cu (II) removal amount were directly proportional to the operating pressure and feed temperature but inversely proportional to the feed concentration. In contrast, the feed flow rate showed a negligible effect on the permeate flux and Cu (II) removal amount. The temperature correction factor (TCF) of the membrane was calculated and was found to be directly proportional to the feed temperature but inversely proportional to the applied pressure. It was seen that the concentration and flow rate of that feed did not affect the temperature correction factor. Mathematical models have been developed based on these experimental data for both permeate flux and the Cu (II) removal. It was noted that the permeate flux model matched the experimental data, while the Cu (II) removal model did not show a perfect match. In addition to the above, the research highlights for subsequent studies the possibility of a deep link between experimental work and mathematical models.
12
Okojie, Robert S., Roger D. Meredith, Clarence T. Chang, and Ender Savrun. "High Temperature Dynamic Pressure Measurements Using Silicon Carbide Pressure Sensors." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2014, HITEC (January 1, 2014): 000047–52. http://dx.doi.org/10.4071/hitec-ta25.
Анотація:
Un-cooled, MEMS-based silicon carbide (SiC) static pressure sensors were used for the first time to measure pressure perturbations at temperatures as high as 600 °C during laboratory characterization, and subsequently evaluated in a combustor rig operated under various engine conditions to extract the frequencies that are associated with thermoacoustic instabilities. One SiC sensor was placed directly in the flow stream of the combustor rig while a benchmark commercial water-cooled piezoceramic dynamic pressure transducer was co-located axially but kept some distance away from the hot flow stream. In the combustor rig test, the SiC sensor detected thermoacoustic instabilities across a range of engine operating conditions, amplitude magnitude as low as 0.5 psi at 585 °C, in good agreement with the benchmark piezoceramic sensor. The SiC sensor experienced low signal to noise ratio at higher temperature, primarily due to the fact that it was a static sensor with low sensitivity.
13
Gong, Myungkeun, Changhyun Jin, and Youngseung Na. "Minimizing Area-Specific Resistance of Electrochemical Hydrogen Compressor under Various Operating Conditions Using Unsteady 3D Single-Channel Model." Membranes 13, no. 6 (May 26, 2023): 555. http://dx.doi.org/10.3390/membranes13060555.
Анотація:
Extensive research has been conducted over the past few decades on carbon-free hydrogen energy. Hydrogen, being an abundant energy source, requires high-pressure compression for storage and transportation due to its low volumetric density. Mechanical and electrochemical compression are two common methods used to compress hydrogen under high pressure. Mechanical compressors can potentially cause contamination due to the lubricating oil when compressing hydrogen, whereas electrochemical hydrogen compressors (EHCs) can produce high-purity, high-pressure hydrogen without any moving parts. A study was conducted using a 3D single-channel EHC model focusing on the water content and area-specific resistance of the membrane under various temperature, relative humidity, and gas diffusion layer (GDL) porosity conditions. Numerical analysis demonstrated that the higher the operating temperature, the higher the water content in the membrane. This is because the saturation vapor pressure increases with higher temperatures. When dry hydrogen is supplied to a sufficiently humidified membrane, the actual water vapor pressure decreases, leading to an increase in the membrane’s area-specific resistance. Furthermore, with a low GDL porosity, the viscous resistance increases, hindering the smooth supply of humidified hydrogen to the membrane. Through a transient analysis of an EHC, favorable operating conditions for rapidly hydrating membranes were identified.
14
Szilágyi, R., Ph Molinié, M. J. Kirkpatrick, E. Odic, G. Galli, and Ph Dessante. "Study of partial discharge and breakdown phenomena at triple junctions under various conditions of pressure and temperature." Journal of Physics: Conference Series 2702, no. 1 (February 1, 2024): 012007. http://dx.doi.org/10.1088/1742-6596/2702/1/012007.
Анотація:
Abstract The presence of a triple junction constitutes a potential source of failure in many industrial applications. The reinforcement of the local electric field due to differences in relative permittivity facilitates the formation of partial discharges (PD) which weaken the insulation system and eventually lead to complete breakdown. Additionally, severe environmental conditions (temperature, pressure) associated with certain applications (e. g. nuclear or aeronautical sector) should be considered because of their influence on discharge phenomena occurring at triple junctions. In this study, the behaviour of partial discharge inception voltage (PDIV) and of breakdown (flash-over) voltage (BIV) is compared in the case of a triple junction with an aluminium oxide disc as a solid insulator when the system is heated up to 400 °C. While the PDIV decreases strongly for temperatures above 300 °C, this effect disappears for the BIV. It is proposed that this behaviour is due to the fact that relative permittivity of the aluminium oxide disc increases with temperature at low frequencies, but remains relatively stable at high frequencies, regardless of the temperature.
15
Li, Zhengdai, Jianping Zuo, Yue Shi, Fei Xu, Meilu Yu, and Changning Mi. "An Experimental Study on the Slippage Effects of Sandstone under Confining Pressure and Low Pore Pressure Conditions." Geofluids 2020 (February 24, 2020): 1–17. http://dx.doi.org/10.1155/2020/9296243.
Анотація:
Due to the influences of various factors, such as temperature, stress, and composition, the research regarding rock permeability has been complicated. This study examined the variation laws of sandstone specimens under changing rates of confining and pore pressures after high-temperature heat treatments. The results showed that the free water in the rock volatilized during the low-temperature heat treatments in the range of 100°C to 300°C, with the increase of the heat-treatment temperature above 500°C; the crystal water in the rock is gradually separated out; and the particles in the samples had undergone phase transformations resulting in increased permeability. According to ultrasonic wave velocity test results, the internal cracks of the samples expanded with the increases in the heat-treatment temperatures. In addition, the high-temperature heat treatments were found to improve the accuracy of the direction of the Earth’s stress when using circumferential wave velocity anisotropy methods. Under the influence of slippage effects, as the pore pressure increased, the measured permeability of the samples decreased and the slippage effect occurs in the rock samples with the permeability of 10-3 μm2~10-6 μm2. The experimental results showed that the contribution rate of the slippage effect decreases with the increase of the heat-treatment temperature of the specimen, and the contribution rates of the sandstone slippage effect were generally higher than 5%. Therefore, the impact effects on the permeability of sandstone slippage should be considered in practical engineering processes.
16
MOON, SANGWOON, BOKLAE CHO, SUKMIN CHUNG, CHONGDO PARK, KIJEONG KIM, TAIHEE KANG, and BONGSOO KIM. "THE OPTIMAL FORMATION CONDITION OF CHROMIUM OXIDE THIN FILM ON STAINLESS-STEEL SURFACE." Surface Review and Letters 09, no. 01 (February 2002): 285–91. http://dx.doi.org/10.1142/s0218625x02002208.
Анотація:
We investigated the various oxidation conditions of stainless-steel surface using synchrotron radiation photoemission spectroscopy. Stainless-steel samples are oxidized at 450–550°C in various oxygen partial pressures. Increasing the annealing temperature from 450°C to 550°C, the trivalent chromium concentration in the surface increased and iron oxides decreased. The PES spectra from stainless steels oxidized at 550°C show that there exists the critical oxygen partial pressure, [Formula: see text] Torr. Below this critical pressure, the oxide formed mainly consists of chromium oxide, while the oxide formed mainly consists of iron oxide above the critical pressure. The oxidation behavior is in good agreement with the Ellingham diagram (a free-energy/temperature diagram).
17
Oh, Jihyeon, Dong-Young Kim, Hyunwoo Kim, Oh-Nyoung Hur, and Sung-Hoon Park. "Comparative Study of Carbon Nanotube Composites as Capacitive and Piezoresistive Pressure Sensors under Varying Conditions." Materials 15, no. 21 (October 30, 2022): 7637. http://dx.doi.org/10.3390/ma15217637.
Анотація:
Conducting polymer composites consisting of carbon nanotubes (CNTs) as a conductive filler and polydimethylsiloxane (PDMS) as a polymer matrix were fabricated to investigate their capacitive and piezoresistive effects as pressure sensors. The pressure-sensing behavior and mechanism of the composites were compared in terms of basic configuration with a parallel plate structure. Various sensing experiments, such as sensitivity, repeatability, hysteresis, and temperature dependence according to the working principle, were conducted with varying filler contents. The hysteresis and repeatability of the pressure-sensing properties were investigated using cyclic tensile tests. In addition, a temperature test was performed at selected temperatures to monitor the change in the resistance/capacitance.
18
Valencia, Luisa Maria, and Cristhian Andres Aguirre-Tellez. "Boiling point of volatile liquids at various pressures." Respuestas 22, no. 2 (July 1, 2017): 87. http://dx.doi.org/10.22463/0122820x.1210.
Анотація:
ABSTRACTWater, under normal conditions, tends to boil at a “normal boiling temperature” at which the atmospheric pressure fixes the average amount of kinetic energy needed to reach its boiling point. Yet, the normal boiling temperature of different substances varies depending on their nature, for which substances like alcohols, known as volatile, boil faster than water under same conditions. In response to this phenomenon, an investigation on the coexistence of both gas and liquid phases of a volatile substance in a closed system was made, establishing vapor pressure as the determining tendency of a substance to vaporize, which increases exponentially with temperature until a critical point is reached. Since atmospheric pressure is fixed, the internal pressure of the system was varied to determine its relationship with vapor pressure and thus with the boiling point of the substance, concluding that the internal pressure and boiling point of a volatile liquid in a closed system are negatively proportional.Key words: Pressure, enthalpy of vaporization, temperature.RESUMENEl agua, en condiciones normales, tiende a hervir a una “temperatura de ebullición normal”, en la que la presión atmosférica fija la cantidad media de energía cinética necesaria para alcanzar su punto de ebullición. Sin embargo, la temperatura de ebullición normal de las diferentes sustancias varía en función de su naturaleza, por lo que sustancias como los alcoholes, conocidos como volátiles, hierven más rápido que el agua en las mismas condiciones. En respuesta a este fenómeno, se realizó una investigación sobre la coexistencia tanto de fases gaseosa como líquida de una sustancia volátil en un sistema cerrado, estableciendo la presión de vapor como la tendencia determinante de una sustancia a la vaporización, que aumenta exponencialmente con la temperatura hasta que se alcanza un punto crítico. Dado que la presión atmosférica es fija, se varió la presión interna del sistema para determinar su relación con la presión de vapor y con el punto de ebullición de la sustancia, concluyendo que la presión interna y el punto de ebullición de un líquido volátil en un sistema cerrado son negativamente proporcionales.Palabras clave: Presión, entalpía de vaporización, temperatura.RESUMOA água, em condições normais, tende a ferver a uma «temperatura normal de ebulição» na qual a pressão atmosférica corrige a quantidade média de energia cinética necessária para atingir seu ponto de ebulição. No entanto, a temperatura normal de ebulição de diferentes substâncias varia dependendo da sua natureza, para as quais substâncias como álcoois, conhecidas como voláteis, ferver mais rapidamente do que a água nas mesmas condições. Em resposta a este fenômeno, foi feita uma investigação sobre a coexistência de fases gasosas e líquidas de uma substância volátil em um sistema fechado, estabelecendo pressão de vapor como a tendência determinante de uma substância a vaporizar, que aumenta exponencialmente com a temperatura até chegar a um ponto crítico. Uma vez que a pressão atmosférica é fixa, a pressão interna do sistema foi variada para determinar sua relação com a pressão de vapor e, portanto, com o ponto de ebulição da substância, concluindo que a pressão interna e o ponto de ebulição de um líquido volátil em um sistema fechado são negativamente proporcionais .Palavras-chave: Pressão, entalpia de vaporização, temperatura.
19
Richter, Asta, Roger Smith, Natalia Dubrovinskaia, and Edward Mcgee. "Mechanical properties of superhard materials synthesised at various pressure–temperature conditions investigated by nanoindentation." High Pressure Research 26, no. 2 (June 2006): 99–109. http://dx.doi.org/10.1080/08957950600765269.
20
Lux, B., W. Kalss, R. Haubner, and T. Taniguchi. "Nucleation of c-BN on various substrate materials under high-pressure–high-temperature conditions." Diamond and Related Materials 8, no. 2-5 (March 1999): 415–22. http://dx.doi.org/10.1016/s0925-9635(98)00377-x.
21
Śpiewak, Katarzyna, Grzegorz Czerski, and Karol Bijak. "The Effect of Temperature-Pressure Conditions on the RDF Gasification in the Atmosphere of Steam and Carbon Dioxide." Energies 14, no. 22 (November 10, 2021): 7502. http://dx.doi.org/10.3390/en14227502.
Анотація:
This research aimed to assess the process conditions, temperature and pressure, on the gasification of alternative refuse-derived fuel (RDF) in the atmosphere of steam and carbon dioxide on a laboratory scale using a fixed bed reactor. For this reason, the selected RDF were analysed, including proximate and ultimate analysis, mercury content and ash composition. After that, isothermal gasification measurements using the thermovolumetric method were performed under various temperatures (700, 750, 800, 900 °C) and pressures (0.5, 1, 1.5 MPa), using steam and carbon dioxide as gasifying agents. The obtained results showed that in the entire analysed range, the increase in temperature positively affect both the steam and CO2 gasification of RDF. The formation rates of main components (H2 and/or CO) of the resulting gas, as well as yields of gas components and maximum carbon conversion degrees increase. However, this positive effect was the greater, the lower the process pressure was. In turn, the effect of pressure was more complex. In the case of RDF steam gasification, an increase in pressure had a negative effect on the process, while when using carbon dioxide as a gasifying agent, an improvement of most analysed parameters was observed; however, only at low temperatures, 700–750 °C.
22
Xu, Hao Jie, Juan Qin, Peng Fei Gao, Wei Min Shi, and Lin Jun Wang. "Studies on the Structure and Properties of ZnSb Thin Films Deposited under Various Sputtering Conditions." Key Engineering Materials 748 (August 2017): 143–47. http://dx.doi.org/10.4028/www.scientific.net/kem.748.143.
Анотація:
In this paper ZnSb thin films were prepared by radio frequency magnetron sputteringfrom a stoichiometric Zn4Sb3 target followed by thermal annealing. The influence of sputteringconditions on microstructure, surface morphology, crystallinity and electrical transport propertieswere investigated. For the range of sputtering power of 50 W to 125 W and working pressure of 0.7Pa, it was found that the content of compound ZnSb phase in the films as well as film crystallinitycould be enhanced greatly by increasing the sputtering power, and this effect may be reinforced bydecreasing the working pressure to 0.2 Pa. At 0.7 Pa, A maximum value of 2.99 μW/cmK2 of powerfactor measured at room temperature was obtained at 100 W. The sample prepared at the samepower and lower pressure of 0.2 Pa has a room temperature power factor of 5.46 μW/cmK2 which isalmost doubled.
23
NAKAMURA, Tamotsu, Kazuyoshi KONDO, Hiroshi SASAHARA, and Kazuya NAKAMURA. "Research on pressure welding conditions of various work metals. Effects of contact pressure, surface expansion ratio and temperature." JSME international journal. Ser. 3, Vibration, control engineering, engineering for industry 31, no. 3 (1988): 612–17. http://dx.doi.org/10.1299/jsmec1988.31.612.
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NAKAMURA, Tamotsu, Kazuyoshi KONDO, Hiroshi SASAHARA, and Kazuya NAKAMURA. "Research on pressure welding conditions of various work metals. Effects of contact pressure, surface expansion ratio and temperature." Transactions of the Japan Society of Mechanical Engineers Series C 54, no. 500 (1988): 991–97. http://dx.doi.org/10.1299/kikaic.54.991.
25
Xiao, J., P. Liu, and G. W. Yang. "Nanodiamonds from coal under ambient conditions." Nanoscale 7, no. 14 (2015): 6114–25. http://dx.doi.org/10.1039/c4nr06186a.
Анотація:
Nanodiamonds with a cubic phase and a mean size of 3 nm are synthesized from various types of coal at atmospheric pressure and room temperature using a novel process involving laser ablation in liquid.
26
Huang, Qi, Jocelyn Rodgers, Russell Hemley, and Toshiko Ichiye. "Effects of Pressure and Temperature on the Atomic Fluctuations of Dihydrofolate Reductase from a Psychropiezophile and a Mesophile." International Journal of Molecular Sciences 20, no. 6 (March 22, 2019): 1452. http://dx.doi.org/10.3390/ijms20061452.
Анотація:
Determining the effects of extreme conditions on proteins from “extremophilic” and mesophilic microbes is important for understanding how life adapts to living at extremes as well as how extreme conditions can be used for sterilization and food preservation. Previous molecular dynamics simulations of dihydrofolate reductase (DHFR) from a psychropiezophile (cold- and pressure-loving), Moritella profunda (Mp), and a mesophile, Escherichia coli (Ec), at various pressures and temperatures indicate that atomic fluctuations, which are important for enzyme function, increase with both temperature and pressure. Here, the factors that cause increases in atomic fluctuations in the simulations are examined. The fluctuations increase with temperature not only because of greater thermal energy and thermal expansion of the protein but also because hydrogen bonds between protein atoms are weakened. However, the increase in fluctuations with pressure cannot be due to thermal energy, which remains constant, nor the compressive effects of pressure, but instead, the hydrogen bonds are also weakened. In addition, increased temperature causes larger increases in fluctuations of the loop regions of MpDHFR than EcDHFR, and increased pressure causes both increases and decreases in fluctuations of the loops, which differ between the two.
27
Alandari, J., A. M. Diamy, J. M. Guillerme, J. C. Legrand, and R. I. Ben-Aim. "Rotational Temperature in Helium, Argon, and Oxygen Microwave-Induced Plasmas: Comparison with Translational and Solid Surface Temperatures." Applied Spectroscopy 43, no. 4 (May 1989): 681–87. http://dx.doi.org/10.1366/0003702894202490.
Анотація:
Translational temperature ( Tg), rotational temperature of OH ( Tr), and surface temperature ( Ts are determined in helium, argon, and oxygen plasmas. Measurements are carried out at different pressures and different flow rates as a function of microwave power input by using various methods (line broadening, pressure rise, spectroscopy, thermocouple, pyrometry). The three temperatures depend on the nature of the gas (oxygen < helium > argon) and increase with power input and pressure. Results show that Tg is of the same order of magnitude as Ts. But in all experimental conditions, Tr is always higher than Tg. Therefore, Tr is inadequate for estimating Tg. When no direct determination of Tg is available, Ts seems to give a better estimation of this important parameter.
28
Fischer, Hartmut R., and Al Moghadam. "Testing Various Cement Formulations under Temperature Cycles and Drying Shrinkage for Low-Temperature Geothermal Wells." Materials 16, no. 23 (November 23, 2023): 7281. http://dx.doi.org/10.3390/ma16237281.
Анотація:
Low-enthalpy geothermal wells are considered a sustainable energy source, particularly for district heating in the Netherlands. The cement sheath in these wells experiences thermal cycles. The stability of cement recipes under such conditions is not well understood. In this work, thermal cycling experiments for intermediate- and low-temperature geothermal well cements have been conducted. The samples were cured either under ambient conditions or under realistic pressure and temperature for 7 days. The samples did not show any signs of failure after performing 10 cycles of thermal treatment between 100 °C and 18 °C. We also tested cement formulations under drying conditions. Drying shrinkage is caused by a reduction in the water content of cement, which leads to capillary forces that can damage cement. Such circumstances lead to tensile stresses causing radial cracks. Most samples exhibited cracks under low humidity conditions (drying). Fiber reinforcement, especially using short PP fibers, improved the cement’s resilience to temperature and humidity changes. Such additives can improve the longevity of cement sheaths in geothermal wells.
29
Mahmoudvand, Saba, Behnam Shahsavani, Rafat Parsaei, and Mohammad Reza Malayeri. "Prediction of asphaltene precipitation upon injection of various gases at near-wellbore conditions: A simulation study using PC-SAFT EoS." Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 74 (2019): 63. http://dx.doi.org/10.2516/ogst/2019037.
Анотація:
The depletion of oil reservoirs and increased global oil demand have given impetus to employ various secondary and tertiary oil recovery methods. Gas injection is widely used in both secondary and tertiary modes, though the major problem associated with this process is the precipitation and deposition of asphaltene, particularly at near-wellbore conditions. In-depth knowledge of asphaltene phase behavior is therefore essential for the prediction of asphaltene precipitation. Previous studies reported the impact of gas injection on asphaltene phase behavior, but the knowledge of precipitation of asphaltene as a function of different mole fractions of injected gas is also imperative. In this study, the thermodynamic model of PC-SAFT EoS is used to discern the phase equilibrium of asphaltene by analyzing the asphaltene drop-out curve during gas injection. Asphaltene drop-out curves of two different live oil samples are analyzed by injecting CO2, CH4, and N2 gases at different mole percentages and temperatures. The results revealed that PC-SAFT EoS can serve as a reliable tool for estimating bubble pressure and asphaltene onset pressure for a wide range of temperatures, pressures, and compositions. The simulation results for the injection of CO2, CH4, and N2 also showed that CO2 gas gives minimum asphaltene precipitation. It reduces the size of the drop-out curve or moves it toward higher pressures. CH4 and N2 expand the drop-out curve by raising the upper onset point. CH4 increases the maximum point of the drop-out curve for two types of oil studied (A and B) at two different temperatures. N2 raises the maximum point of oil type “A” by approximately 57% at 395 K, while it has no effect on the maximum point of oil type “B”. In addition, reducing the temperature resulted in either decrease or increase of asphaltene solubility, demonstrating that the impact of temperature on asphaltene precipitation is closely related to the composition of the crude.
30
Sivaramakrishnan, Srikanth, Kanwar Bharat Singh, and Peter Lee. "Influence of Tire Operating Conditions on ABS Performance." Tire Science and Technology 43, no. 3 (September 1, 2015): 216–41. http://dx.doi.org/10.2346/tire.15.430302.
Анотація:
ABSTRACT During its normal service life, a tire is subjected to large variations in operating conditions, such as ambient temperature, inflation pressure, and changes in tread depth. The longitudinal force response of the tire changes significantly because of each of these operating conditions. This, in turn, would directly influence the performance of the antilock braking system (ABS) installed in a vehicle. Current ABS systems are tuned for a vehicle with fixed operating thresholds that do not change. The objective of this study was to understand the influence of a tire's operating conditions on ABS efficiency and the extent of variation it can cause on stopping distance. This was done by obtaining longitudinal-slip characteristics for a given tire at various temperatures, inflation pressures, and tread depth through a traction trailer. These data were then used to simulate an ABS braking maneuver using a half-car vehicle model. The major reasons for the loss in stopping distance performance because of a drop in efficiency under each condition was then analyzed in detail. The latter part of this study explored the potential for improvement in stopping distance that could possibly be achieved through an intelligent ABS system that would use tire-sensed information, such as temperature, pressure, and tread depth to calculate essential tire characteristics in real time using an adaptive magic formula and change its tuning parameters accordingly.
31
Wang, Fakai, Yunpei Liang, Xuelong Li, Lei Li, Jianggong Li, and Yulong Chen. "Orthogonal Experimental Study on Multifactor Conditions for Gas Desorption in Coal." Advances in Civil Engineering 2019 (March 19, 2019): 1–12. http://dx.doi.org/10.1155/2019/3028721.
Анотація:
The isothermal adsorption experiment of coal is an important method to study the mechanism of coal gas desorption. The orthogonal experiment is used to compare the gas desorption mechanism of coal under multifactor conditions, such as the particle size, temperature, pressure, moisture content, and molding pressure. The sensitivity of five factors was used to conduct regression analysis. The sensitivity and influence degree of five factors on the coal gas desorption capacity were analyzed. The results showed the following: (1) the effect of the coal sample particle size, temperature, pressure, moisture content, and molding pressure of coal on the sensitivity of desorption capacity is shown as C (pressure) > B (temperature) > A (particle size) > D (moisture content) > E (molding pressure); (2) the regression analysis of various factors for gas adsorption indicates that the degree of correlation of the multivariate quadratic regression equation is higher compared to that of the multivariate one-time regression equation; and (3) the coal sample particle size, temperature, pressure, moisture content, and type of gas desorption can well represent the gas desorption capacity of a coal sample under various conditions. The smaller the particle size of the coal sample, the higher the ambient temperature, the higher the gas pressure, the lower the moisture content of the coal sample, and the greater the gas desorption per unit mass in 30 min after coal sample gas adsorption equilibrium. The orthogonal test results have important theoretical significance for guiding gas adsorption and desorption tests of coal. For coal and gas outburst prediction, the coal seam gas flow mechanism, coal gas content prediction, and calculation of the mining coal gas emission have important practical significance for gas explosion accident prevention.
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Prikhna, Tetiana, Vladimir Sokolovsky, and Viktor Moshchil. "Bulk MgB2 Superconducting Materials: Technology, Properties, and Applications." Materials 17, no. 11 (June 6, 2024): 2787. http://dx.doi.org/10.3390/ma17112787.
Анотація:
The intensive development of hydrogen technologies has made very promising applications of one of the cheapest and easily produced bulk MgB2-based superconductors. These materials are capable of operating effectively at liquid hydrogen temperatures (around 20 K) and are used as elements in various devices, such as magnets, magnetic bearings, fault current limiters, electrical motors, and generators. These applications require mechanically and chemically stable materials with high superconducting characteristics. This review considers the results of superconducting and structural property studies of MgB2-based bulk materials prepared under different pressure–temperature conditions using different promising methods: hot pressing (30 MPa), spark plasma sintering (16–96 MPa), and high quasi-hydrostatic pressures (2 GPa). Much attention has been paid to the study of the correlation between the manufacturing pressure–temperature conditions and superconducting characteristics. The influence of the amount and distribution of oxygen impurity and an excess of boron on superconducting characteristics is analyzed. The dependence of superconducting characteristics on the various additions and changes in material structure caused by these additions are discussed. It is shown that different production conditions and additions improve the superconducting MgB2 bulk properties for various ranges of temperature and magnetic fields, and the optimal technology may be selected according to the application requirements. We briefly discuss the possible applications of MgB2 superconductors in devices, such as fault current limiters and electric machines.
33
Chen, Shia-Chung, Bi-Lin Tsai, Cheng-Chang Hsieh, Nien-Tien Cheng, En-Nien Shen, and Ching-Te Feng. "Prediction of Part Shrinkage for Injection Molded Crystalline Polymer via Cavity Pressure and Melt Temperature Monitoring." Applied Sciences 13, no. 17 (August 31, 2023): 9884. http://dx.doi.org/10.3390/app13179884.
Анотація:
During an injection molding process, different parts of the molded material are subjected to various thermal–mechanical stresses, such as variable pressures, temperatures, and shear stresses. These variations form different pressure–temperature paths on the pressure–volume–temperature diagram. If these paths cannot converge at a specific target volume value during ejection, it often leads to different levels of shrinkage and associated warping, which pose a significant challenge for molders during mold trials and part quality control. The situation is particularly complicated when molding crystalline polymers because the degree of crystallinity depends on the processing conditions and may vary across different locations. In this study, we propose an innovative and practical approach to improving part shrinkage when molding crystalline polymers. For the first time, we utilized melt temperature profile monitoring rather than the previous mold temperature measurement to detect the crystallization process and determine the time taken to complete the crystallization at different melt and mold temperatures. In addition, we used response surface methodology to build a crystallization time prediction model. The feasibility of the prediction model was verified by determining the warpage of parts molded at various cooling times. Based on this model, we varied the packing pressure, packing time, and melt temperatures to determine the correlation with part shrinkage. Through regression analysis, the time-averaged solidification pressure values can accurately control part shrinkage. Two prediction models provide reasonable accuracy and efficiency for part shrinkage control, as demonstrated by subsequent verification experiments.
34
SZWAJA, Stanisław, Wojciech TUTAK, Karol GRAB-ROGALIŃSKI, Arkadiusz JAMROZIK, and Arkadiusz KOCISZEWSKI. "Selected combustion parameters of biogas at elevated pressure–temperature conditions." Combustion Engines 148, no. 1 (February 1, 2012): 40–47. http://dx.doi.org/10.19206/ce-117050.
Анотація:
Results from tests conducted in several RTD centers lead to conclusion that biogas as a potential fuel for the internal combustion (IC) spark ignited (SI) engine features with its satisfactory combustion predisposition causing smooth engine run without accidental misfiring or knock events. This good predisposition is obtained due to carbon dioxide (CO2) content in the biogas. On the other hand, carbon dioxide as incombustible gas contribute to decrease in the brake power of the biogas fueled engine. To analyze mutual CO2 and CH4 content on biogas burning the combustion parameters as follows: adiabatic combustion temperature, laminar flame speed and ignition delay of biogas with various methane content were determined and presented in the paper. Additionally, these parameters for pure methane were also included in order to make comparison between each other. As computed, ignition delay, which has is strongly correlated with knock resistance, can change several times with temperature increase, but does not change remarkably with increase in methane content. Adiabatic combustion temperature does not also ought to influence on engine performance or increase in engine cooling and exhaust losses due to its insignificant changes. The largest change was observed in laminar flame speed, that can influence on development of the first premixed combustion phase.
35
Samsam-Khayani, Hadi, Binqi Chen, Mirae Kim, and Kyung Chun Kim. "Visualization of supersonic free jet flow structures subjected to various temperature and pressure ratio conditions." Optics and Lasers in Engineering 158 (November 2022): 107144. http://dx.doi.org/10.1016/j.optlaseng.2022.107144.
36
Zhang, Xinyu, Lidong Dai, Haiying Hu, and Chuang Li. "Pressure-Induced Reverse Structural Transition of Calcite at Temperatures up to 873 K and Pressures up to 19.7 GPa." Minerals 13, no. 2 (January 27, 2023): 188. http://dx.doi.org/10.3390/min13020188.
Анотація:
In situ Raman scattering and electrical conductivity experiments have been performed to investigate the structural phase transitions of calcite during the compressed and decompressed processes in a diamond anvil cell at temperatures of 298–873 K and pressures up to 19.7 GPa. Upon compression, calcite (CaCO3-I phase) underwent three structural phase transitions from CaCO3-I to CaCO3-II phases at 1.6 GPa, from CaCO3-II to CaCO3-III phases at 2.2 GPa, and from CaCO3-III to CaCO3-VI phases at 16.8 GPa under room temperature conditions, which were evidenced by the evolution of Raman peaks, as well as the discontinuities in the pressure-dependent Raman shifts and electrical conductivity. Upon decompression, the structural phase transitions from CaCO3-VI to CaCO3-III to CaCO3-II to CaCO3-I phases took place at the respective pressures of 5.4, 1.5, and 0.4 GPa, indicating the reversibility of calcite. Furthermore, an obvious ~11 GPa of pressure hysteresis was detected in the CaCO3-VI to CaCO3-III phase transition, whereas other reverse phase transition pressures were very close to those of compressed results. At three given representative pressure conditions (i.e., 10.5, 12.5, and 13.8 GPa), a series of electrical conductivity experiments were performed at temperature ranges of 323–873 K to explore the temperature-dependent relation of CaCO3-III to CaCO3-VI structural phase transition. With increasing pressure, the transition temperature between CaCO3-III and CaCO3-VI phases gradually decreases, which reveals an obviously negative temperature-pressure relation, i.e., P (GPa) = 19.219 (±1.105) − 0.011 (±0.002) T (K). Our acquired phase diagram of calcite can be employed to understand the high-pressure structural transitions and phase stability for carbonate minerals along various subducting slabs in the deep Earth’s interior.
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Inaguma, Y. "Friction torque characteristics of an internal gear pump." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, no. 6 (April 11, 2011): 1523–34. http://dx.doi.org/10.1177/0954406211399659.
Анотація:
This paper describes the influence of pump operating conditions, such as operating pressures, pump speeds, and oil temperatures, on the friction torque characteristics of internal gear pumps for automobiles. Additionally, it presents a new mathematical model reflecting the influence of the oil temperature on the friction torque. In an internal gear pump, the friction torque was affected by oil temperature as well as operating pressure and pump speed. When the operating pressure was high, the influence of oil temperature on friction torque at a pump speed of less than 1000 r/min was contrary to that at a pump speed of greater than 1000 r/min. It was considered that the friction torque is fundamentally composed of three components: the component dependent on the operating pressure, dependent on the pump speed, and independent of both the operating pressure and the pump speed. However, the component dependent on the operating pressure was affected significantly by not only the pump speed but also the oil temperature. In addition, another factor besides the viscosity of the oil existed in the component dependent on the pump speed. A mathematical model for the friction torque characteristic of the internal gear pump was newly established by adding factors including the oil temperature to the Wilson’s model. The new model was able to represent with accuracy the experimental friction torque characteristic in the internal gear pump under various pump operating conditions.
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Inaguma, Yoshiharu. "A practical approach for analysis of leakage flow characteristics in hydraulic pumps." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 227, no. 5 (August 9, 2012): 980–91. http://dx.doi.org/10.1177/0954406212456933.
Анотація:
This article presents a practical approach to leakage flow analysing for various types of hydraulic pumps. In this study, the influence of pump-operating conditions such as operating pressures, pump speeds and oil temperature on the leakage flow characteristics is investigated and a mathematical model to calculate the leakage flow is proposed. Currently, an external gear, an internal gear or a vane pump is commonly used for an automatic transmission. These pumps have their own leakage flow characteristics, which depend not only on pump-operating conditions but also on structures and dimensions of the pumps. For various pumps having different constructions, the delivery pressure and the oil temperature differently affect the leakage flow characteristics and especially the delivery pressure also changes the clearances causing the leakage flow. A mathematical model for the leakage flow, which takes into account a change in the thickness of clearance according to the delivery pressure, represents accurately the actual leakage flow characteristics in various pumps. Also, it clarifies the influence of the pump-operating conditions on their leakage flow characteristics. In the external and internal gear pumps, the leakage flow would not approach zero due to an existence of the orifice flow leakage almost independent of the viscosity of oil, even at an extremely low oil temperature. This leakage flow influences significantly the volumetric efficiency at a low oil temperature in the gear pumps.
39
Mansour, Adel, and Michael A. Benjamin. "Emissions Performance of the Parker Macrolaminate Premixer Tested Under Simulated Engine Conditions." Journal of Engineering for Gas Turbines and Power 126, no. 3 (July 1, 2004): 465–71. http://dx.doi.org/10.1115/1.1762907.
Анотація:
Single-injector high-pressure rig evaluation of the prototype Parker macrolaminate dual fuel premixer (previously tested at NETL, Mansour et al., 2001) with pressure swirl macrolaminate atomizers was conducted under simulated engine operating conditions running on No. 2 diesel fuel (DF2). Emissions, oscillations and lean blowout (LBO) performance on liquid fuel at high, part and no load operating points (pressures of 160, 100, 120 psig, and inlet temperatures of 690, 570, 590°F, respectively) and various pressure drops (ΔP/P) and air fuel ratio conditions were investigated. The results indicate that the Parker premixer design has the potential to reduce the DF2 NOX emission to below 15 ppmv, 15% O2. At simulated high load conditions with a nominal flame temperature TPZ of 2700°F, the NOX and CO emissions are approximately 10 and 2.5 ppmv at 15% O2, respectively. These NOX results have not been corrected for fuel bound nitrogen (FBN). From the studies of Lee (2000), small amounts of FBN in the liquid fuel generally are completely converted over to fuel NOX under lean premixed conditions. The fuel tested has a nominal 60 ppmw of FBN which converts to an estimated fuel NOX of 4 ppmv at 15% O2. These results compare extremely favorable to existing commercially available premixer technologies tested under similar rig operating conditions. More importantly, the NOX yield for the Parker Macrolaminate premixer appears to be independent of operating conditions (from high to no load and various pressure drop conditions). Variations in combustor pressure, inlet temperature T2 and residence time (τ) or pressure drop (ΔP/P) does not seem to have an effect on the formation of NOX. According to Leonard and Stegmaier (1993), insensitivity of NOX formation to operating conditions is a good indication of high degree of premixing. Additionally, the premixer NOX data is only 1 to 2 ppmv higher than the jet stirred reactor (JSR) results (ran at T2=661°F,PCD=1 atm and TPZ=2762°F with similar DF2) of Lee et al. (2001) further confirming the quality of premixing achieved. Combustion driven oscillations was not investigated by tuning the rig so that oscillations would not be a factor.
40
Singh,, Sanjeev, Abid Z. Hussain,, RU Thombare,, BK Motwani,, and Shweta Singh,. "An in vitro Study to evaluate the Effects of Various Polymerizing Conditions on the Flexural Strength of Autopolymerizing Resins." Journal of Health Sciences & Research 8, no. 1 (2017): 15–19. http://dx.doi.org/10.5005/jp-journals-10042-1042.
Анотація:
ABSTRACT Aim To investigate the effect of variation in temperature and time intervals on the flexural strength of two brands of autopolymerizing resins polymerized at constant pressure. Materials and methods Two autopolymerizing resins RR Cold Cure resin (DPI) and RR-Rapid Repair Powder (Dentsply) were used. A total of 20 samples were fabricated for each group. Samples were polymerized at temperature ranges of 40°, 50°, 60°, and 70°C and at time intervals of 5, 10, and 15 minutes in the customized curing pot, maintaining pressure of 30 psi. Results Flexural strength was verified using universal testing machine using three-point bending test and was then compared with all samples and also with the samples cured in open air (control group). The samples cured at higher temperature, i.e., 60° and 70°C, have shown increased strength than those at 40° and 50°C as well as control group. Time interval of 10 minutes is considered sufficient to increase the strength of the resin, as per the results of this study. Conclusion The samples cured under varied condition of time and temperature but under constant pressure showed increased strength than those cured in open air. Clinical significance The effect of pressure and temperature has been demonstrated, which could be utilized for enhancing the durability of the prosthesis fabricated from autopolymerized resins. How to cite this article Singh S, Hussain AZ, Thombare RU, Motwani BK, Singh S, Mangalekar SB. An in vitro Study to evaluate the Effects of Various Polymerizing Conditions on the Flexural Strength of Autopolymerizing Resins. J Health Sci Res 2017;8(1):15-19.
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Toshiro, Kobayashi, Kamikawa Susumu, Itou Yoshifumi, Kanematsu Hideyuki, and Utsumi Yuichi. "Effect of Deposition and Storage Conditions on the Gas Permeability of SiOx Thin Films." Applied Mechanics and Materials 378 (August 2013): 248–52. http://dx.doi.org/10.4028/www.scientific.net/amm.378.248.
Анотація:
SiOx films (80 nm thick) were vacuum deposited onto a 25-μm-thick polyethylene terephthalate (PET) substrate under various conditions. The effects of chamber pressure, evaporating temperature, and chamber gas composition on the time evolution of the oxygen transmission rate (OTR) were investigated together with changes in the films composition. It was found that the OTR decreases over time when the films are left in air, the rate of the decrease being greater at higher pressures during the formation of the films. However, if the pressure is too high, the OTR immediately reaches a high value after evaporation and does not decrease over time, not even if the films are left in air for a week. It is possible to obtain acceptable low OTR values by employing a moderate operating pressure, a suitable evaporating temperature, and an aging treatment after deposition without using a high-capacity vacuum system and without heat damage of the plastic film substrate.
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Carpenter, Chris. "Inline Setup Provides Automatic Measurement of PVT Behavior of Drilling Fluids." Journal of Petroleum Technology 73, no. 11 (November 1, 2021): 55–56. http://dx.doi.org/10.2118/1121-0055-jpt.
Анотація:
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 204084, “Automatic Measurement of the Dependence on Pressure and Temperature of the Mass Density of Drilling Fluids,” by Eric Cayeux, SPE, NORCE, prepared for the 2021 SPE/IADC International Drilling Conference and Exhibition, originally scheduled to be held in Stavanger, 9–11 March. The paper has not been peer reviewed. The mass density of drilling fluids usually is measured manually with a mud balance. The pressure and temperature dependence of the mass density of the fluid [i.e. its pressure/volume/temperature (PVT) behavior] then is estimated. Variations in the composition of the fluid mix and uncertainties regarding the PVT behavior of each component, however, may lead to inaccuracies. An apparatus that measures the PVT behavior of the drilling fluid contained in a pit directly and automatically has been designed. Inline PVT Measurement The pressure and temperature dependence of drilling fluids can be described by a biquadratic function. However, API Recommended Practice 13D recommends using a linear function of temperature combined with a quadratic form of pressure. Because this process involves six parameters, at least six measurements must be made under different conditions of pressure and temperature. A starting point is to measure the mass density of the fluid under six different pairs of pressures and temperatures. To keep the design of the apparatus as simple as possible, it ideally would not operate under high-pressure and -temperature conditions. Therefore, knowing the range of pressures and temperatures sufficient for taking sample measurements is useful in order to be able to extrapolate the model at higher pressure and temperature conditions with acceptable accuracy. The densitometer’s measurement precision of 0.05 kg/m3 and repeatability of 0.01 kg/m3 is known, so stochastic simulations of the possible measurement error for various spans of investigated pressures and temperatures can be performed. In this study, the authors con-sider that the calibrated PVT model shall be used for a range of pressure of 1000 bar and a range of temperature of 200°C. It is possible to calculate the root mean square of the proportion error between the predicted density value and the “true” value when varying stochastically the systematic bias on the density measurement when the calibration samples are spanning small ranges of pressure and temperature. A possible design for an inline apparatus could be to pump the drilling fluid past a controllable heating element and having a controllable choke downstream of the densitometer apply a pressure while measuring the mass density. The setpoints for the heating element and the choke would be changed six times in order to collect the necessary mass densities to calibrate the PVT model. Changing the temperature of the heating element, however, can require several minutes, and gathering a complete set of calibration measurements may easily take 15 to 30 minutes. An alternative could be to perform six measurements simultaneously. The densitometers can be mounted in series. The configuration could be with six parallel branches or any combinations between series and parallel branches. With two parallel branches, in one branch the temperature of the fluid is not modified, while it is modified in the second branch. For each of the two branches, back pressure is applied at two intermediate positions. This configuration has the advantage of using fewer chokes and pressure sensors (four instead of five).
43
Ge, Yanglin, Tong Lu, Xingong Li, Xiaofeng Hao, Shoulu Yang, Tonghua Lu, Kang Xu, and Xianjun Li. "Changes in Temperature and Vapor-Pressure Behavior of Bamboo Scrimber in Response to Hot-Pressing Parameters." Forests 15, no. 4 (March 28, 2024): 620. http://dx.doi.org/10.3390/f15040620.
Анотація:
This study investigated the heat-transfer behavior of heat-treated and phenolic resin-impregnated bamboo bundle slabs during the hot-pressing process. The significance of these findings lies in their potential to drive advancements in hot-pressing technology, contribute to energy-conservation efforts, and facilitate emission reduction within the bamboo scrimber industry. In this study, the variations in temperature and vapor pressure were investigated during the hot-pressing of bamboo slabs under various conditions, including hot-pressing temperatures (140 °C, 150 °C, 160 °C, and 170 °C), hot-pressing holding times (15 min, 20 min, 25 min, and 30 min), and hot-pressing pressures (4 MPa, 5 MPa, 6 MPa, and 7 MPa). This was achieved using thermocouple sensors and a self-made vapor pressure-monitoring system. The results indicated that higher hot-pressing temperatures significantly increased the heating rate, peak temperature, and core-layer vapor peak pressure of the bamboo bundle slab, with the vapor peak pressure at 170 °C being twice that at 140 °C. Furthermore, extending the holding time had a lesser effect on increasing the peak temperature of the slab but significantly increased the peak vapor pressure in the core layer. Thus, increasing the hot-pressing pressure proved beneficial for slab heating but had a lesser effect on the surface and core-layer peak temperatures. The core-layer vapor pressure of the slab subjected to a hot-press pressure of 7 MPa was 1.8 times higher than that at 4 MPa.
44
Krishnamoorthy, Vijayaragavan, and Sarma V. Pisupati. "Effect of Temperature, Pressure, Feed Particle Size, and Feed Particle Density on Structural Characteristics and Reactivity of Chars Generated during Gasification of Pittsburgh No.8 Coal in a High-Pressure, High-Temperature Flow Reactor." Energies 12, no. 24 (December 14, 2019): 4773. http://dx.doi.org/10.3390/en12244773.
Анотація:
The gasification behavior of coal under high-temperature and high-pressure conditions is important from the perspective of designing and optimizing high efficiency gasifiers and troubleshooting existing gasifiers. The effect of feed particle size, density, temperature, and pressure on char porous structure, morphology, reflectance, and reactivity under conditions relevant to entrained-flow gasification was investigated. The chars were generated over a range of temperatures (1100, 1300, and 1400 °C at 11.3 bar for the −150 + 106 µm fraction), pressures (3.4, 6.2, 11.3, 15.5, and 21.7 bar at 1300 °C for the −150 + 106 µm fraction), for various size fractions (−106 + 75, −150 + 106, −212 + 150, −420 + 212 µm at 1300 °C and 11.3 bar), and density fractions (<1.3, 1.3–1.6, >1.6g/cc for the −106 + 75 µm at 1300 °C and 11.3 bar) of Pittsburgh No.8 bituminous coal using a high-pressure, high-temperature flow reactor (HPHTFR) in a equimolar mixture of CO2 and N2. Chars were characterized for conversion, morphology, thermal swelling ratio, and reactivity using ash tracer technique, oil immersion microscopy, tap density technique, and a thermogravimetric analyzer, respectively, and the results were statistically analyzed to determine for effects by feed particle density, feed particle size, temperature, and pressure. The results showed that the conversion was most affected by temperature, followed by feed particle size, pressure, and feed particle density. In the case of structural characteristics (i.e., thermal swelling ratio and group-I char concentration), feed particle density affected group-I concentration, while both feed particle size and feed particle density affected thermal swelling ratio. Variation in vitrinite content and fragmentation affected the thermal swelling ratio and group-I char concentration. In the case of intrinsic reactivity, particle density showed the largest effect, followed by temperature, particle size, and pressure. An increase in reflectance and temperature was found to inversely affect intrinsic reactivity.
45
Silvestri, G. J., R. L. Bannister, T. Fujikawa, and A. Hizume. "Optimization of Advanced Steam Condition Power Plants." Journal of Engineering for Gas Turbines and Power 114, no. 4 (October 1, 1992): 612–20. http://dx.doi.org/10.1115/1.2906634.
Анотація:
The modern pulverized-coal power plant is the product of continuous design experience and component improvement in the 20th century. In recent years, studies of the effect of high temperatures on turbine materials have led to major worldwide research and development programs on improving the thermal cycle by raising turbine-inlet pressure and temperature. This paper reviews the importance of various parameters in trying to optimize a turbine cycle designed for advanced steam conditions. Combinations of throttle pressure (between 3500 psi [24.1 MPa] and 10,000 psi [70MPa]), throttle and reheat temperature(1000°F [538°C] to 1400°F [760°C]), and number of reheats are explored to establish a realistic turbine cycle design. Assessments and trade-offs are discussed, as applicable. Critical cycle components, feedwater cycle arrangements, and reheat pressure selections are analyzed in establishing an optimized steam turbine-boiler cycle for a 1000 MW turbine-generator. Applicability of results to smaller advanced steam turbines is given. A brief update on the high-temperature Wakamatsu turbine project in Japan is also given.
46
Belovolov, M. I., S. O. Kozelskaya, O. N. Budadin, and V. Yu Kutyurin. "CURRENT STATE OF METHODS AND MEANS OF REGISTRATION OF HIGH TEMPERATURES AND MECHANICAL STRESSES IN STRUCTURES." Kontrol'. Diagnostika, no. 266 (August 2020): 30–43. http://dx.doi.org/10.14489/td.2020.08.pp.030-043.
Анотація:
An analytical review of physically possible methods and available achievements in registering hydrostatic pressure or mechanical stresses using fiber optic fibers and sensors based on them based on published works that can be used in harsh environmental conditions is carried out. The results of the review show that fully distributed or quasidistributed fiber-optic systems for recording hydrostatic pressure or mechanical stress can be implemented on the following physical principles and apparatus with measures to compensate or suppress the influence of temperature: polarizing sensors on birefringent single- mode light guides and OTDR equipment; micro-flexible sensors with OTDR equipment on conventional multimode fibers; measuring systems on fiber Bragg gratings; on discrete sensors, in particular, on sealed fiber Fabry–Perot interferometers; Brillouin distributed sensors on single-mode fibers that are not sensitive to temperature changes. It is shown that single-mode birefringent fibers with hollow holes in the shell and fiber Bragg gratings written in the core have a good linear sensitivity to hydrostatic pressure and a weak dependence on temperature. Lattices in phosphorous-containing single-mode light guides have increased high-temperature properties up to ~500 C and higher. A number of discrete fiber sensors’ structures and pressure recorders are investigated. Various structures of sensitive elements of pressure sensors on sealed fiber Fabry–Perot interferometers and fiber gratings in spherical and cylindrical small-sized cases are investigated. Sensors based on Fabry–Perot fiber interferometers soldered into a glass capillary and protected from water by external high-temperature hermetic coatings showed good linearity in the pressure range of 0…540 ATM at temperatures up to ~200 C. The sensors are efficient at temperatures up to 600 °C and are promising for use in severe and special external conditions. The possibility of compensating the temperature sensitivity by selecting external coatings is shown. Pressure sensors were tested on local areas with microbends and it was shown that they can measure pressures up to ~24 МPа at temperatures up to ~450 C, but to compensate for the dependence of the readings on temperature, it must be measured by an independent sensor. The possibility of independent and simultaneous measurement of hydrostatic pressure and temperature along a single fiber using spontaneous Brillouin scattering is shown. Pressure is measured by the frequency shift of Brillouin scattering, and temperature by its intensity. The operation of the Brillouin recorder in the pressure range 0…34 MРа is demonstrated. The pressure resolution was ~0,2 МРа. New methods are proposed for detecting Brillouin scattering – a heterodyne signal with a high signal-to-noise ratio and based on frequency modulation of a semiconductor single-frequency distributed feedback laser. The measurement range has been increased by more than 10 km and the coordinate resolution has been increased. The Brillouin scattering method is promising for creating distributed systems for measuring hydrostatic pressure or mechanical stress for severe physical conditions, including temperatures of ≥3000 C.
47
Belovolov, M. I., S. O. Kozelskaya, O. N. Budadin, and V. Yu Kutyurin. "CURRENT STATE OF METHODS AND MEANS OF REGISTRATION OF HIGH TEMPERATURES AND MECHANICAL STRESSES IN STRUCTURES." Kontrol'. Diagnostika, no. 266 (August 2020): 30–43. http://dx.doi.org/10.14489/td.2020.08.pp.030-043.
Анотація:
An analytical review of physically possible methods and available achievements in registering hydrostatic pressure or mechanical stresses using fiber optic fibers and sensors based on them based on published works that can be used in harsh environmental conditions is carried out. The results of the review show that fully distributed or quasidistributed fiber-optic systems for recording hydrostatic pressure or mechanical stress can be implemented on the following physical principles and apparatus with measures to compensate or suppress the influence of temperature: polarizing sensors on birefringent single- mode light guides and OTDR equipment; micro-flexible sensors with OTDR equipment on conventional multimode fibers; measuring systems on fiber Bragg gratings; on discrete sensors, in particular, on sealed fiber Fabry–Perot interferometers; Brillouin distributed sensors on single-mode fibers that are not sensitive to temperature changes. It is shown that single-mode birefringent fibers with hollow holes in the shell and fiber Bragg gratings written in the core have a good linear sensitivity to hydrostatic pressure and a weak dependence on temperature. Lattices in phosphorous-containing single-mode light guides have increased high-temperature properties up to ~500 C and higher. A number of discrete fiber sensors’ structures and pressure recorders are investigated. Various structures of sensitive elements of pressure sensors on sealed fiber Fabry–Perot interferometers and fiber gratings in spherical and cylindrical small-sized cases are investigated. Sensors based on Fabry–Perot fiber interferometers soldered into a glass capillary and protected from water by external high-temperature hermetic coatings showed good linearity in the pressure range of 0…540 ATM at temperatures up to ~200 C. The sensors are efficient at temperatures up to 600 °C and are promising for use in severe and special external conditions. The possibility of compensating the temperature sensitivity by selecting external coatings is shown. Pressure sensors were tested on local areas with microbends and it was shown that they can measure pressures up to ~24 МPа at temperatures up to ~450 C, but to compensate for the dependence of the readings on temperature, it must be measured by an independent sensor. The possibility of independent and simultaneous measurement of hydrostatic pressure and temperature along a single fiber using spontaneous Brillouin scattering is shown. Pressure is measured by the frequency shift of Brillouin scattering, and temperature by its intensity. The operation of the Brillouin recorder in the pressure range 0…34 MРа is demonstrated. The pressure resolution was ~0,2 МРа. New methods are proposed for detecting Brillouin scattering – a heterodyne signal with a high signal-to-noise ratio and based on frequency modulation of a semiconductor single-frequency distributed feedback laser. The measurement range has been increased by more than 10 km and the coordinate resolution has been increased. The Brillouin scattering method is promising for creating distributed systems for measuring hydrostatic pressure or mechanical stress for severe physical conditions, including temperatures of ≥3000 C.
48
dos Reis, Jhon Rewllyson Torres, Fabio Furtado Leite, Keshav Sharma, Guilherme Almeida Silva Ribeiro, Welesson Henrique Natanal Silva, Alzir Azevedo Batista, Alexandre Rocha Paschoal, et al. "Raman Spectroscopy on Free-Base Meso-tetra(4-pyridyl) Porphyrin under Conditions of Low Temperature and High Hydrostatic Pressure." Molecules 29, no. 10 (May 17, 2024): 2362. http://dx.doi.org/10.3390/molecules29102362.
Анотація:
We present a Raman spectroscopy study of the vibrational properties of free-base meso-tetra(4-pyridyl) porphyrin polycrystals under various temperature and hydrostatic pressure conditions. The combination of experimental results and Density Functional Theory (DFT) calculations allows us to assign most of the observed Raman bands. The modifications in the Raman spectra when excited with 488 nm and 532 nm laser lights indicate that a resonance effect in the Qy band is taking place. The pressure-dependent results show that the resonance conditions change with increasing pressure, probably due to the shift of the electronic transitions. The temperature-dependent results show that the relative intensities of the Raman modes change at low temperatures, while no frequency shifts are observed. The experimental and theoretical analysis presented here suggest that these molecules are well represented by the C2v point symmetry group.
49
Cheng, Wenjie, Boqin Gu, and Chunlei Shao. "A numerical study on the steady flow in molten salt pump under various conditions for improved hydraulic performance." International Journal of Numerical Methods for Heat & Fluid Flow 27, no. 8 (August 7, 2017): 1870–86. http://dx.doi.org/10.1108/hff-06-2016-0238.
Анотація:
Purpose This paper aims to figure out the steady flow status in the molten salt pump under various temperatures and blade number conditions, and give good insight on the structure and temperature-dependent efficiencies of all pump cases. Finally, the main objective of present work is to get best working condition and blade numbers for optimized hydraulic performance. Design/methodology/approach The steady flow in the molten salt pump was studied numerically based on the three-dimensional Reynolds-Averaged Navier–Stokes equations and the standard k-ε turbulence model. Under different temperature conditions, the internal flow fields in the pumps with different blade number were systematically simulated. Besides, a quantitative backflow analysis method was proposed for further investigation. Findings With the molten salt fluid temperature, sharply increasing from 160°C to 480°C, the static pressure decreases gently in all pump cases, and seven-blades pump has the least backflow under low flow rate condition. The efficiencies of all pump cases increase slowly at low temperature (about 160 to 320°C), but there is almost no variation at high temperature, and obviously seven-blades pump has the best efficiency and head in all pump cases over the wide range of temperatures. The seven-blades pump has the best performance in all selected pump cases. Originality/value The steady flow in molten salt pumps was systematically studied under various temperature and blade number conditions for the first time. A quantitative backflow analysis method was proposed first for further investigation on the local flow status in the molten salt pump. A definition about the low velocity region in molten salt pumps was built up to account for whether the studied pump gains most energy. This method can help us to know how to improve the efficiencies of molten salt pumps.
50
Pashmforoush, Farzad. "Multiphysics simulation of piezoresistive pressure microsensor using finite element method." FME Transactions 49, no. 1 (2021): 214–19. http://dx.doi.org/10.5937/fme2101214p.
Анотація:
In this study, the electro-mechanical behavior of a specially designed highsensitive piezoresistor pressure microsensor was simulated using finite element method, through COMSOL multiphysics software. The mechanical deformation of the diaphragm and the distribution of electrical potential in the piezoresistive were evaluated for various pressure values. In order to determine the influence of the temperature sensitivity parameter, different temperature conditions were investigated. According to the obtained results, by increase of the applied pressure, the resistance of the piezoresistor decreased, while, the sensitivity increased. Also, it was observed that at constant pressure, as the temperature increases, the stress on the diaphragm surface decreases, indicating high stress distribution at the sides and the middle of the diaphragm at low temperatures such as -50 °C. Furthermore, the obtained results demonstrated that temperature variations were not very effective on the potential distribution in the piezoresistor. However, the temperature coefficient of sensitivity demonstrated an increasing tendency with increase of the temperature from -50 °C to 50 °C.