Numerical Model of Heat Pipes as an Optimization Method of Heat Exchangers

This paper presents research results on heat pipe numerical models as optimization of heat pipe heat exchangers for intensification of heat exchange processes and the creation of heat exchangers with high efficiency while reducing their dimensions. This work and results will allow for the extension of their application in passive and low-energy construction. New findings will provide a broader understanding of how heat pipes work and discover their potential to intensify heat transfer processes, heat recovery and the development of low-energy building engineering. The need to conduct research and analyses on the subject of this study is conditioned by the need to save primary energy in both construction engineering and industry. The need to save primary energy and reduce emissions of carbon dioxide and other pollutants has been imposed on the EU Member States through multiple directives and regulations. The presented numerical model of the heat pipe and the results of computer simulations are identical to the experimental results for all tested heat pipe geometries, the presented working factors and their best degrees of filling.

Intensification of heat exchange by an ultrasound source for milk pasteurization.

The goal of this article is to investigate the effect of ultrasonic vibrations on the process of milk pasteurization. Ultrasound can potentially intensify heat transfer and reduce the formation of thermal sediment (soot deposit) on the walls of heat-exchange devices. The paper presents the results of experimental studies demonstrating the growth rate of thermal sediment on the wall of the heat-exchange apparatus and its amount in the volume of milk under the influence of ultrasonic vibrations and without it.

The influence of the charge shape on heat exchange of a recessed nozzle

The paper deals with the numerical simulation of the flow of thermally conductive viscous gaseous combustion products in the flow paths of a power plant. The influence of the shape of the mass supply surface on the gas dynamics and heat exchange near the recessed nozzle of the power plant is investigated. The coupled problem of heat exchange is solved by the method of control volumes. It is shown that the compensator geometry determines the localization of both the topological features of the flow near the recessed nozzle and the position of local maximums of the heat transfer coefficient. It has been revealed that The use of a channel with a star-shaped cross section and a triangular form of compensator rays leads to an intensification of heat exchange processes near a recessed nozzle.

INTENSIFIED PLATE HEAT EXCHANGE DEVICE IN HEAT SUPPLY SYSTEMS OF THE HOUSING AND COMMUNAL SERVICES OF THE RUSSIAN FEDERATION

Statement of the problem. The problem of intensification of heat exchange processes in a plate heat exchanger on the basis of the HH№ 02 heat exchanger of the Ridan company is discussed. It is essential to carry out an analysis of the existing methods of intensification of heat exchange processes in plate devices according to the results of the analysis to choose the most promising method of intensification of heat exchange process and based on it to develop a patent-protected design of a heat exchange plate. Laboratory tests of the intensified plate heat exchanger with increased turbulence of the coolant are performed. The results of thermal tests on a specialized laboratory installation of the resulting and the serial heat exchanger are presented.Results. The results of the comparison of experimental studies of the intensified plate heat exchanger with the increased turbulence of the heat carrier and the serial plate heat exchanger of identical heat power are shown. The graphs of dependence of the heat transfer coefficient, which is the major characteristic of the operation of heat exchange equipment, on the average temperature pressure are designed. Conclusions. As a result of the laboratory tests in the specialized laboratory of BSTU named after V. G. Shukhov and research at the Voronezh State Technical University established a rise in the heat transfer coefficient due to the increased turbulence of the coolant flow, which causes a decrease in metal consumption and reduces the cost of heat exchange equipment.

Intensified Plate Heat Exchange Device in Heat Supply Systems of the Housing and Communal Services of the Russian Federation

Постановка задачи. Рассматривается задача интенсификации теплообменных процессов в пластинчатом теплообменном аппарате на базе теплообменника НН№ 02 фирмы Ridan . Необходимо выполнить анализ существующих методов интенсификации теплообменных процессов в пластинчатых аппаратах, по результатам анализа выбрать наиболее перспективный метод интенсификации процесса теплообмена и на его основе разработать патентозащищенную конструкцию теплообменной пластины. Выполнить лабораторные испытания интенсифицированного пластинчатого теплообменного аппарата с повышенной турбулизацией теплоносителя. Сравнить результаты теплотехнических испытаний на специализированной лабораторной установке разработанного теплообменника и серийного. Результаты. Приведены результаты сравнения экспериментальных исследований интенсифицированного пластинчатого теплообменного аппарата с повышенной турбулизацией теплоносителя и серийного пластинчатого теплообменника одинаковой тепловой мощности. Построены графики зависимости коэффициента теплопередачи, являющегося основной характеристикой работы теплообменного оборудования, от среднего температурного напора. Выводы. В результате лабораторных испытаний в специализированной лаборатории БГТУ им. В. Г. Шухова и исследований в Воронежском государственном техническом университете установлен прирост коэффициента теплопередачи за счет повышенной турбулизации потока теплоносителя, что приводит к снижению металлоемкости и уменьшению стоимости теплообменного оборудования. Statement of the problem. The problem of intensification of heat exchange processes in a plate heat exchanger on the basis of the HH№ 02 heat exchanger of the Ridan company is discussed. It is essential to carry out an analysis of the existing methods of intensification of heat exchange processes in plate devices according to the results of the analysis to choose the most promising method of intensification of heat exchange process and based on it to develop a patent-protected design of a heat exchange plate. Laboratory tests of the intensified plate heat exchanger with increased turbulence of the coolant are performed. The results of thermal tests on a specialized laboratory installation of the resulting and the serial heat exchanger are presented. Results. The results of the comparison of experimental studies of the intensified plate heat exchanger with the increased turbulence of the heat carrier and the serial plate heat exchanger of identical heat power are shown. The graphs of dependence of the heat transfer coefficient, which is the major characteristic of the operation of heat exchange equipment, on the average temperature pressure are designed. Conclusions. As a result of the laboratory tests in the specialized laboratory of BSTU named after V. G. Shukhov and research at the Voronezh State Technical University established a rise in the heat transfer coefficient due to the increased turbulence of the coolant flow, which causes a decrease in metal consumption and reduces the cost of heat exchange equipment.

Состояние разработок двухфазных систем терморегулирования космических аппаратов

The progress of space technology is leading to more and more energy-equipped spacecraft. The International Space Station already has the capacity of solar panels of more than 100 kW. Autonomous spacecrafts and satellites (including stationary ones) have the capacity of power units of kW, in the nearest future - more than 10 kW. Forced heat transfer using single-phase liquid coolants is still considered as the main method of thermal control on high-power spacecraft (SC). Single-phase mechanically pumped fluid loop is a fully proven means of thermal control of spacecraft with a moderate heat load. A significant disadvantage of such systems is that the coolant temperature varies significantly within the loop. The temperature difference can be reduced by increasing the coolant flow rate, but for this, it is necessary to increase the pump capacity, which inevitably leads to an increase in power consumption, pipeline diameters, and weight of the system as a whole. In the case of spacecraft with high power capacity (more than 5-10 kW) and large heat transfer distances (10 m and more), a two-phase mechanically pumped fluid loop for thermal control is more preferable in terms of weight, the accuracy of thermoregulation, power consumption (and other parameters). The use of a two-phase loop (2PMPL) as a spacecraft thermal control system allows to reduce significantly mass and power consumption for own needs in comparison with a single-phase thermal control system (TCS). The effect is achieved due to the accumulation of transferred heat in the form of latent heat of vaporization and intensification of heat exchange at boiling and condensation of coolant. The article provides a critical review of published works on 2PMPL for spacecraft with high power (more than 5...10 kW) and a large heat transfer distance (more than 10...100 meters) from 1980 up to nowadays. As a result, a list of the main problems on the way of practical implementation of two-phase loops is formed.

Gas–Liquid Two-Phase Flow and Heat Transfer without Phase Change in Microfluidic Heat Exchanger

This work presents an experimental study of the possibility of intensifying in microfluidic heat exchangers (MFHE) by creating a two-phase segmented flow (gas–liquid). Measurements of convective heat transfer were carried out using an MFHE, consisting of six channels 1 × 1 mm. Experimental studies have shown that segmented flow makes it possible to increase the Nusselt number of a laminar flow in MFHE up to 1.67 and reduce thermal resistance up to 1.7 times compared to single-phase flow. At the same time, it was found that the intensification of heat exchange by a two-phase flow is observed only for the range of the volume fraction of gas from 10 to 30%. In addition, the calculation of the thermal performance criterion, including both thermal and hydraulic parameters (friction factor), also confirmed the promise of using the Taylor segmented flow as a method for single-phase heat transfer intensifying in microchannels.

INTENSIFICATION OF HEAT EXCHANGE IN DIABATIC RECTIFICATION COLUMNS

The heat exchange in a diabatic column was investigated during the rectification of an ethanol-water mixture, in which partial condensation of rising vapors on the surface of vertical heat exchange tubes installed vertically along the height of the installation was carried out, as well as the evaporation of intermediate condensate on the surface of horizontal plates. Based on the review of diabatic columns, it is shown that they can reduce the cost of conducting the rectification process. Heat-exchange devices placed on trays of rectification units are considered and ways to intensify heat transfer in them are proposed. It has been established that the most efficient heat removal in heat exchangers of diabatic columns is achieved when using a film flow of a coolant on a heat transfer surface. Heat transfer in a diabatic column is investigated during gravitational flow of surfaces of heat exchange tubes, as well as when organizing an ascending and descending co-current film flow, both in the case of heating and boiling of the coolant. To intensify heat transfer in the coolant film, a helical artificial roughness was installed on the surface of the pipes, made in the form of a wire spiral tightly mounted on the heat transfer surface. The geometric parameters of the helical roughness, such as the distance between the turns of the spiral and the height of the wire, which have the greatest influence on the intensity of heat transfer, have been established. Dependences for determining the value of the heat transfer coefficient are presented and an estimate of the value of the specific heat flux in the diabatic column is given.