Impact Of Temperature Gradient Research Articles

Simulation study on breakdown evolution of tri-post insulator under electric-mechanical-thermal stresses in 1100 kV HVAC-GIL

Due to the presence of electric-mechanical-thermal stress, inner cracks and reduced adhesion strength between metal and epoxy can cause the breakdown of a tri-post insulator in the GIL. In this study, a simulation model was developed to investigate the breakdown evolution of the tri-post insulator subjected to combined electrical, mechanical, and thermal stresses. Various temperature gradients and defect positions were considered, along with the application of an AC voltage of 1100 kV. At room temperature, the tri-post insulator undergoes considerable residual internal stress of up to 35 MPa, primarily concentrated around the conductor and inserts, thereby accelerating the breakdown process. The temperature gradient across the insulator post has a notable impact on breakdown characteristics. Specifically, when the conductor temperature increases from 25 °C to 125 °C, the breakdown time of the insulator with the HV side defect increases by 83.1 %, while the damaged area reduces by 41.9 %. This is attributed to the release of the residual internal stress and the reduction of strain energy. When the defect is located at the GND side, the breakdown channel forms more rapidly, and the impact of temperature gradient on the breakdown process is weakened, because the tensile stress is high but the temperature is low around the GND inserts. The outcomes of this study are hoped to enhance understanding and enable the prediction of insulation breakdown behaviors in practical projects.

Numerical study on thermal enhancement in magnetohydrodynamic micropolar liquid subjected to motile gyrotactic microorganisms movement and Soret and dufour effects

Motile gyrotactic organism activity in micropolar fluid subjected to simultaneous heat and mass transfer in the presence of thermal diffusion and diffusion thermo effects is modeled. The base fluid is taken as kerosene oil. The immersion of nano-sized particles of C u − T i O 2 kerosene oil makes its rheological characteristics of micropolar fluid because nano-sized particles serve as micro-structures. In this case couple stress, vortex and spin gradient viscosities become significant and simultaneously linear and angular momenta become equally remarkable. So, micropolar theory is the best to model the immersion of nano-structures in the fluid. Similarity variables are used to transform the problems into their dimensionless forms. The mathematical models are solved numerically by applying the finite element method (FEM). The results are validated and numerical experiments are performed to analyze the key parameters of the unknown field variables. In order to analyze the impact of physical parameters on field variables, numerous simulations are performed. The micro-rotation of microparticles and nanoparticles due to fluid deformation motivates fluids particles to rotate faster. Therefore, linear motion is observed to be increased for higher values of vortex viscosity. The curvature parameter has significantly impacted the linear motion of the fluid particles. The impact of the curvature parameter on the movement of nanofluid is lesser than the impact of the curvature parameter on the motion of hybrid nanoparticles. Concentration gradient supports the diffusion of heat in the fluid regime and numerical experiments with variation of Dufour (that measures the effects of concentration gradient on heat diffusion) have shown that concentration gradient is more effective in the case of hybrid nanofluid relative to the mono nanofluid. The angular motion of fluid particles increases when vortex viscosity is increased. Numerical simulations have predicted that the angular motion of particles of hybrid nanofluid has a lesser angular speed than that of the angular motion of particles of mono nanofluid. The Soret number determines the impact of temperature gradient on the diffusion of solute in the fluid. Simulations for various values of Soret number have predicted that the impact of temperature gradient on the diffusion of solute in hybrid nanofluid is stronger than the impact of temperature gradient on the diffusion of solute in mono nanofluid.

Energy analysis of three ventilation systems for a large machining plant

Manufacturing industries play an important role in economic development, but a large amount of energy is consumed in the removal of pollutants and heat generated on the manufacturing floor. An efficient ventilation system is needed for improving indoor air quality and thermal comfort at reduced energy cost. This study studied a displacement ventilation system with diffusers around columns for a machining plant, and compared its energy consumption with that of a perfect mixing ventilation system and the existing ventilation system in the plant. This investigation used computational fluid dynamics (CFD) to determine the vertical air temperature gradient in the plant, and the impact of temperature gradient on energy was estimated by means of building energy simulations (BES). The annual energy cost for the improved displacement ventilation system was 17.5% lower than that for mixing ventilation and 20.3% lower than for the existing ventilation system. However, because a large amount of outdoor air was used in winter, the heating energy consumption with the displacement ventilation was slightly higher than with the other two ventilation systems.

Modelling of impact of temperature gradient on content of polymer ampoule during its forming

Purpose: The aim of the represented study was to model the impact of temperature gradient on content of polymer ampoule during its forming. Design/methodology/approach: The model of polymer ampoules forming is built in SolidWorks software on the basis of finite element method. Using the developed model the study of temperature condition changes is carried out. Numerical modelling was carried out for two types of polymer packaging materials – polypropylene and polyvinylchloride – in similar conditions. Findings: During polymer ampoule forming the highest temperature of liquid is obtained at the bottom of it. The most effective packaging method is to form the ampoule from polypropylene by means of aluminium die. Investigation results have shown that the highest obtained liquid temperature has linear dependence from initial one. Linear coefficients of heating were evaluated for polypropylene (equal to 0.72) and polyvinylchloride (equal to 0.58). Practical implications: Decrease of initial liquid temperature value gives an opportunity to expand the range of products allowed to be packed in polymer ampoules in represented method. Safe conditions for packaging of liquid products in polymer ampoules are formulated, The results of the study may be used to improve the quality of liquid products packaging in polymer ampoules. Originality/value: For the first time the model was developed for determination of liquid heating degree during its packaging in polymer ampoules. The calculations of the temperature distribution are represented for polypropylene and polyvinylchloride ampoules forming by means of aluminium and ceramic dies. The results of the study may be of interest to specialists in the field of polymer packaging manufacturing for food or pharmaceutical industry.

Comparative Analysis of the Efficiency of Fiber Winding Types Used in the Fiber-Optic Gyro Sensor Coil Under Temperature Variation Conditions

Background. The paper is devoted to the study of the effectiveness of different types of coil fiber winding of fiber optic gyro (FOG) in reducing of the impact of Shupe effect under temperature changes. Objective. The objective of the study is to evaluate the effectiveness of different types of FOG fiber coil winding under temperature changes. Methods. Based on the analysis of existing types of winding, and formulae for non-reciprocal phase shift calculation, a method for evaluation of the impact of temperature gradient on coils with different types of winding is created. Method mentioned is applied to 9 different types of coil winding. Results. The dependencies of zero shift vs time for nine types of winding under the impact of axial, radial temperature gradients and combinations thereof are obtained. Conclusion. Overall, use of quadruple windings seems to be optimal; for low precision sensors one can recommend centered unipolar winding while ensuring good thermal and vibration insulation of the coil. The use of pads (or frameless coils) is justified when simple winding is used (e.g., in devices for short-living objects, for automotive industry, etc.), or for high-precision sensors.

Impact of Temperature Gradient on the Indian Major Carp Catla catla Larvae

Catla catla (Family: Cyprinidae) were exposed to 10, 15, 20, 25, 30, 33 and 35 °C following 28 °C acclimation temperature. Temperature change rate was 2 °C/day. Mortality rate of fish was recorded. In 10 °C temperature group, 17 and 65 % mortality was recorded at 14 and 10 °C, respectively. Significantly (P 28 °C), percentage changes of mortality per fall and increase of ΔT = 1 °C was calculated in the log-linear regression model framework. When temperature was reduced from 28 °C, the cumulative mortality increment in each 1 °C fall was e.109 = 1.115 (P 0.05) was obtained for each 1 °C increase of temperature from 28 °C.

Assessment of temperature gradient effects on moisture transfer through thermogradient coefficient

The objective of this paper is to describe moisture transfer through porous material due to temperature gradient. For that purpose, an experimental device was set up to assess moisture flux under isothermal and non-isothermal conditions. This involves placing samples between two compartments with controlled air conditions and monitoring relative humidity and temperature profiles inside the samples over the time. To interpret these results, we proposed to express the mass flux in terms of two driving potentials: water vapor content gradient and temperature gradient. Accordingly, thermogradient coefficient was calculated and discussed. It represents the difference between the moisture fluxes under isothermal and non-isothermal conditions. The impact of temperature gradient on the moisture buffer value (MBV) was also considered through a numerical experiment taking into account thermogradient coefficient. Results show that temperature gradient implies a relative variation of the MBV for about 14%. Thus, it would be better to consider non-isothermal conditions for its assessment.

In Situ Poly Heater—A Reliable Tool for Performing Fast and Defined Temperature Switches on Chip

In this paper, we discuss the calibration procedure and performance of the poly-heater measurement technique for device characterization and reliability issues. We put a particular emphasis on the accessible temperature range, the heating and cooling dynamics, as well as on the impact of temperature gradient between the heater, device, and thermo chuck. In this context, the poly-heater technique provides a reliable solution for fast and arbitrary temperature switches and offers the possibility to reach device temperatures that are far beyond the operating range of conventional thermo-chuck systems.

Impact of Temperature Gradient on Modulus of Asphaltic Concrete Layers

Temperature is one of the most dominant factors that impact the variation in modulus of asphalt concrete (AC) layers. An accurate relationship between temperature and modulus is necessary to successfully characterize asphalt concrete pavements. The variation in modulus is typically related to the average temperature of a layer. However, the temperature gradient within a layer also plays a role in that relationship. The impact of temperature gradient on modulus of AC layers is reported in this paper. A test setup that can simulate the variation in temperature with time of day was developed and used. With the data obtained, a preliminary relationship between temperature gradient and modulus has been developed. The next step of this study is to develop a model that can be used in pavement analysis.