scholarly journals Intensive electrocaloric effect in the multilayer capacitor under equilibrium and nonequilibrium thermal conditions

2018 ◽  
Vol 146 ◽  
pp. 51-54 ◽  
Author(s):  
V.S. Bondarev ◽  
I.N. Flerov ◽  
M.V. Gorev ◽  
E.I. Pogoreltsev ◽  
M.S. Molokeev ◽  
...  
Keyword(s):  
Thermal Conditions ◽  
Electrocaloric Effect ◽  
Multilayer Capacitor

scholarly journals Influence of thermal conditions on the electrocaloric effect in a multilayer capacitor based on doped BaTiO3

2017 ◽  
Vol 07 (06) ◽  
pp. 1750041 ◽  
Author(s):  
V. S. Bondarev ◽  
I. N. Flerov ◽  
M. V. Gorev ◽  
E. I. Pogoreltsev ◽  
M. S. Molokeev ◽  
...  
Keyword(s):  
Electric Field ◽  
Thermal Conditions ◽  
Electrocaloric Effect ◽  
Indirect Measurements ◽  
Multilayer Capacitor ◽  
Direct Measurements ◽  
Periodic Electric Field ◽  
Thermal Switches ◽  
Further Development ◽  
Good Agreement

We present the results of studies of thermal expansion, heat capacity, permittivity, polarization and the influence of different thermal conditions on the intensive electrocaloric effect (ECE), [Formula: see text], in a commercial multilayer capacitor based on doped BaTiO3. Investigations in a wide temperature range revealed one anomaly in the behavior of the physical properties at about 290[Formula: see text]K characteristic for the relaxors. Direct measurements showed a high reversibility of ECE under equilibrium thermal conditions. Good agreement was found between the values of [Formula: see text] determined by direct and indirect measurements at the electric field up to 15.4[Formula: see text]kV/cm. Quasi-isothermal conditions lead, firstly, to decrease of large [Formula: see text]0.94[Formula: see text]K obtained in adiabatic conditions under [Formula: see text][Formula: see text]kV/cm to 0.87[Formula: see text]K, and, secondly, the appearance of a difference between the values of [Formula: see text] and [Formula: see text] determined when the electric field is applied and removed. Using this phenomenon and changing the frequency of the periodic electric field, [Formula: see text][Formula: see text]kV/cm, the effect of cooling was obtained equal to [Formula: see text][Formula: see text]K. The results obtained are useful for further development of the electrocaloric refrigeration technique without thermal switches.

Research and Modelling on Electrical and Thermal Mode of LEDs Operation in the Luminaire

2018 ◽  
pp. 155-162 ◽  
Author(s):  
Sergei S. Kapitonov ◽  
Anastasia V. Kapitonova ◽  
Sergei Yu. Grigorovich ◽  
Sergei A. Medvedev ◽  
Taher Sobhy
Keyword(s):  
Thermal Conditions ◽  
Operating Mode ◽  
Thermal Processes ◽  
Thermal Mode ◽  
Crystal Temperature ◽  
Premature Failure ◽  
Model Based

In the article, the electrical and thermal processes in the LED lamp with varied parameters are investigated. Voltage and current measurements on all LEDs of the luminaire are carried out in the nominal operating mode. The power allocated to each LED is determined. The calculation of the LED crystal temperature was carried out using the developed thermal LED model based on the results of the measurements and by using “Multisim” program. It has been established that the temperature of the crystals of individual LEDs in the luminaire differ significantly, which leads to unfavourable thermal conditions for them and an increased likelihood of premature failure.

Tendencies of climatic changes for thermal conditions in the coastal areas of the Okhotsk Sea in last decades

2017 ◽  
Vol 191 ◽  
pp. 176-195 ◽  
Author(s):  
Igor D. Rostov ◽  
Elena V. Dmitrieva ◽  
Alexander A. Vorontsov
Keyword(s):  
Thermal Conditions ◽  
Climatic Changes ◽  
Coastal Areas ◽  
Okhotsk Sea

Numerical and Experimental Modeling of Indoor Air Quality Inside a Conditioned Space with Mechanical Ventilation and DX-Air Conditioner

2020 ◽  
Vol 38 (9A) ◽  
pp. 1257-1275
Author(s):  
Wisam M. Mareed ◽  
Hasanen M. Hussen
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Ventilation System ◽  
Thermal Conditions ◽  
Airflow Rate ◽  
Air Conditioner ◽  
Breathing Zone ◽  
Lecture Room ◽  
Ventilation Performance

 Elevated CO2 rates in a building affect the health of the occupant. This paper deals with an experimental and numerical analysis conducted in a full-scale test room located in the Department of Mechanical Engineering at the University of Technology. The experiments and CFD were conducted for analyzing ventilation performance. It is a study on the effect of the discharge airflow rate of the ceiling type air-conditioner on ventilation performance in the lecture room with the mixing ventilation. Most obtained findings show that database and questionnaires analyzed prefer heights between 0.2 m to 1.2 m in the middle of an occupied zone and breathing zone height of between 0.75 m to 1.8 given in the literature surveyed. It is noticed the mismatch of internal conditions with thermal comfort, and indoor air quality recommended by [ASHRAE Standard 62, ANSI / ASHRAE Standard 55-2010]. CFD simulations have been carried to provide insights on the indoor air quality and comfort conditions throughout the classroom. Particle concentrations, thermal conditions, and modified ventilation system solutions are reported.

Assessment of thermal behavior of a cooling system to reduce thermal fatigue cracks in aluminum injection molds

2020 ◽  
pp. 75-86
Author(s):  
Sergio Antonio Camargo ◽  
Lauro Correa Romeiro ◽  
Carlos Alberto Mendes Moraes
Keyword(s):  
Thermal Fatigue ◽  
Cooling System ◽  
Fatigue Cracks ◽  
Cooling Water ◽  
Thermal Conditions ◽  
Thermal Gradients ◽  
Ansys Software ◽  
Cooling Systems ◽  
Thermal Fatigue Cracks ◽  
Number Of Cycles

The present article aimed to test changes in cooling water temperatures of males, present in aluminum injection molds, to reduce failures due to thermal fatigue. In order to carry out this work, cooling systems were studied, including their geometries, thermal gradients and the expected theoretical durability in relation to fatigue failure. The cooling system tests were developed with the aid of simulations in the ANSYS software and with fatigue calculations, using the method of Goodman. The study of the cooling system included its geometries, flow and temperature of this fluid. The results pointed to a significant increase in fatigue life of the mold component for the thermal conditions that were proposed, with a significant increase in the number of cycles, to happen failures due to thermal fatigue.

Experimental studies of iodine stationary plasma thruster

2019 ◽  
pp. 81-90
Author(s):  
Boris A. Sokolov ◽  
Pavel A. Shcherbina ◽  
Ivan B. Sishko ◽  
Aleksandr V. Shipovskiy Aleksandr ◽  
Aleksandr A. Lyapin ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Thermal Conditions ◽  
Economic Viability ◽  
Electron Drift ◽  
Experimental Facility ◽  
Operational Mode ◽  
Stationary Plasma Thruster ◽  
Stationary Plasma ◽  
Plasma Thruster ◽  
Closed Electron

The paper demonstrates the feasibility of using iodine as propellant for thrusters with closed electron drift and its economic viability. It describes a test setup for running experiments. It provides the results of experimental studies of the stationary plasma thruster using iodine as its propellant with xenon gas-passage hollow cathode, as well as of the operational mode of the thruster where a mixture of xenon and iodine is used. During tests gas dynamic and electrical properties of the thruster were analyzed. Thermal conditions in the iodine storage and supply system were studied. Conclusions were drawn on how the test object could be improved and upgraded. The paper describes the option to use a thermionic non-flow cathode as the compensator cathode for the operation of the iodine thruster. The paper provides the results of an experimental study of the prototype non-flow compensator cathode in diode mode. Based on the results of the studies an experimental facility was built for testing a thruster with non-flow compensator cathode. Key words: cathode, compensator cathode, thruster with closed electron drift, stationary plasma thruster, iodine.

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