The generalized correlation for the evaluation of the influence of the Stefan flow on the heat transfer coefficient

The analytical equations for the steady-state heat-and-mass transfer in the steam evaporation/condensation processes from the steam-gas mixtures on the planar and spherical surfaces are derived. The vapor flow through the motionless dry gas is considered according to the method proposed by Maxwell for the solution of the diffusion problems. The relationships for the calculation of the coefficients taking into account an increase in the mass output and an increase or a decrease in the heat emission (depending on the directions of the heat-and-mass flows) as a result of the influence of the Stefan flow are presented. The derived relationships can be used to calculate the apparatuses in which the steam evaporation or condensation from the steam-gas mixture occurs (the coolers of the vapor from deaerators, the apparatuses for the deep utilization of the heat of the combustion products, the condensation boilers, etc.). © 2013 Pleiades Publishing, Inc

Effective attraction between oscillating electrons in a plasmoid via acoustic waves exchange

We consider the effective interaction between electrons due to the exchange of virtual acoustic waves in a low temperature plasma. Electrons are supposed to participate in rapid radial oscillations forming a spherically symmetric plasma structure. We show that under certain conditions this effective interaction can result in the attraction between oscillating electrons and can be important for the dynamics of a plasmoid. Some possible applications of the obtained results to the theory of natural long-lived plasma structures are also discussed.Comment: 14 pages in LaTeX2e, two columns, 3 eps figures; minimal changes, some typos are corrected; version published on-line in Proc. R. Soc.

Heat exchange in the microchannel condensers for refrigerating machines

This paper describes the design of an industrial experimental facility designed to explore the prototypes and production samples of air cooled Freon condensers, made of aluminum microchannel tubes with a louvered fins. Theoretical calculations of heat transfer coefficient in microchannel are performed. The obtained results are used to determine technical design characteristics of heat exchangers, as well as to create equipment selection program for the required parameters.В работе описана конструкция промышленной испытательной установки, предназначенной для изучения опытных и серийных образцов конденсаторов фреона с воздушным охлаждением, выполненных из алюминиевых микроканальных труб с развитым оребрением. Приведены теоретические расчеты коэффициентов теплоотдачи в микроканальных конденсаторах. Результаты работы используются для определения конструктивных технических характеристик теплообменных аппаратов, а также с целью создания программы подбора оборудования по требуемым параметрам

TESTING OF THE NEW KOMPOZIT GROUP HEAT EXCHANGERS FOR REFRIGERATING MACHINES

The paper is dealt with the principle of operation of the unit, designed to test the new Kompozit Group compact heat exchangers for refrigerating machines. Data are given about of the results obtained.В работе изложен принцип работы установки, предназначенной для испытаний новых компактных теплообменников Композит Групп для холодильной техники, дан пример полученных результатов

PLATE-FIN EVAPORATOR FOR REFRIGERATING MACHINES «EVA COMPACT»

This paper describes the design of an industrial experimental facility designed to explore the prototypes and production samples of plate-fin heat exchangers. Values of evaporator’s heat capacity are performed. The obtained results are used to determine technical design characteristics of heat exchangers, as well as to create equipment selection program for the required parameters.В работе описана конструкция промышленной испытательной установки, предназначенной для изучения опытных и серийных образцов жидкостных испарителей. Приведены значения тепловой мощности аппарата в разных режимах. Результаты работы используются для определения конструктивных технических характеристик теплообменных аппаратов, а также с целью создания программы подбора оборудования по требуемым параметрам

Testing of the microchannel condensers. Calculation of devices’ heat power

This paper describes the design of a facility designed to explore microchannel Freon condensers. We determined heat power of heat exchangers. Calculations of heat transfer coefficient and comparison with the experimental data are performed. The obtained results are used to determine technical characteristics of heat exchangers, as well as to create equipment selection programs.Описана установка, предназначенная для изучения микроканальных конденсаторов фреона. Приведена тепловая мощность аппаратов, коэффициенты теплопередачи и сравнение с экспериментальными данными. Результаты используются для определения технических характеристик теплообменных аппаратов, создания программ подбора оборудования

Operation of a Plate-Fin Heat Exchanger as a Refrigerating Machines’ Evaporator

This paper describes the design of an industrial experimental facility designed to explore the prototypes and production samples of plate-fin heat exchangers. Values of evaporator’s heat capacity are performed. The obtained results are used to determine technical design characteristics of heat exchangers, as well as to create equipment selection program for the required parameters.В работе описана конструкция промышленной испытательной установки, предназначенной для изучения опытных и серийных образцов жидкостных испарителей. Приведены значения тепловой мощности аппарата в разных режимах. Результаты работы используются для определения конструктивных технических характеристик теплообменных аппаратов, а также с целью создания программы подбора оборудования по требуемым параметрам

Spatial coupling of particle and fluid models for streamers: where nonlocality matters

Particle models for streamer ionization fronts contain correct electron energy distributions, runaway effects and single electron statistics. Conventional fluid models are computationally much more efficient for large particle numbers, but create too low ionization densities in high fields. To combine their respective advantages, we here show how to couple both models in space. We confirm that the discrepancies between particle and fluid fronts arise from the steep electron density gradients in the leading edge of the fronts. We find the optimal position for the interface between models that minimizes computational effort and reproduces the results of a pure particle model.Comment: 4 pages, 5 figure