scholarly journals Интенсификация теплопередачи в двухфазных системах с капиллярными насосами

2022 ◽  
Vol 92 (1) ◽  
pp. 22
Author(s):  
В.М. Кисеев ◽  
О.В. Сажин
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Analytical Calculation ◽  
Thermal Control ◽  
Two Phase ◽  
Transfer Length ◽  
Loop Heat Pipes ◽  
Heat Transfer Capacity ◽  
Capillary Pumped Loops ◽  
Thermo Physical Properties

Heat transfer in capillary pumped loops (CPL) is carried out by transferring the mass of the circulating coolant in the form of liquid and vapor. Therefore, the hydrodynamics of the phases in the CPL determines their heat transfer capacity (heat flow or the product of the heat flow by the heat transfer length). The influence of structural, hydraulic and thermo-physical properties of capillary structures used as capillary pumps in two-phase thermal control systems (Loop Heat Pipes - LHP) on their heat transfer capacity has been analyzed. Methods of increasing the heat transfer capacity of LHP, due to the use of anisotropic capillary structures with a decrease in pore sizes in the direction of the vaporization zone, have been determined. The conditions of LHP operability and the method of analytical calculation of the temperature field in anisotropic capillary structures for a model with pseudo-convection have been considered. The calculated and experimental data have been compared.

Состояние разработок двухфазных систем терморегулирования космических аппаратов

2021 ◽  
pp. 36-51
Author(s):  
Рустем Юсуфович Турна ◽  
Артем Михайлович Годунов
Keyword(s):  
Heat Transfer ◽  
Control System ◽  
Power Consumption ◽  
High Power ◽  
Single Phase ◽  
Thermal Control ◽  
Two Phase ◽  
Thermal Control System ◽  
Intensification Of Heat Exchange ◽  
Large Heat

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.

Two-Phase Heat Transfer Enhancement on Sintered Copper Microparticle Porous Structure Module Surface

2009 ◽  
Author(s):  
Calvin H. Li ◽  
Ting Li ◽  
Brian Kanney
Keyword(s):  
Heat Transfer ◽  
Porous Structure ◽  
Bubble Dynamics ◽  
Transfer Enhancement ◽  
Enhanced Heat Transfer ◽  
Two Phase ◽  
Sintered Copper ◽  
Theoretical Predictions ◽  
Heat Transfer Capacity ◽  
Two Phase Heat Transfer

An experimental study of the pool boiling two-phase heat transfer on a sintered Cu microparticle porous structure module surface is conducted. Enhanced heat transfer capacity of this module surface has been reported, and the boiling characteristics have been investigated. The bubble dynamics and nucleate size distribution have been compared to the theoretical predictions, and the speculated mechanisms have been discussed.

scholarly journals Retrospective Review of a Two-Phase Mechanically Pumped Loop for Spacecraft Thermal Control Systems

2021 ◽  
Vol 24 (4) ◽  
pp. 27-37
Author(s):  
Gennadiy O. Gorbenko ◽  
◽  
Pavlo H. Gakal ◽  
Rustem Yu. Turna ◽  
Artem M. Hodunov ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Research And Development ◽  
Control Systems ◽  
High Power ◽  
Retrospective Review ◽  
Heat Dissipation ◽  
Space Station ◽  
Thermal Control ◽  
Two Phase ◽  
Large Heat

The main issues associated with the development of two-phase mechanically pumped loops (2-MPL) for thermal control systems of spacecraft with large heat dissipation were formulated back in the early 80s. They have undeniable advantages over single-phase loops with mechanical pumping and two-phase capillary pumped loops at power more than 6 kW and heat transfer distance more than 10 meters. Intensive research and development of such systems started in the USA together with European, Canadian and Japanese specialists due to plans to build new high-power spacecraft and the Space Station Freedom project. In the 90's, S. P. Korolev Rocket and Space Corporation Energia (Russia) was developing a 2-MPL for the Russian segment of the International Space Station with the capacity of 20...30 kW. For this purpose, leading research organizations of the former Soviet Union were involved. In the last two decades, interest in two-phase heat transfer loops has significantly increased because of high-power stationary communications satellites and autonomous spacecraft for Lunar and Martian missions. The paper presents a retrospective review of worldwide developments of 2-MPLs for thermal control systems of spacecraft with large heat dissipation from the early 80's to the present. The participation of scientists and engineers of the Ukrainian National Aerospace University "KhAI" and the Center of Technical Physics is considered. The main directions of research, development results, and scientific and technical problems on the way to the practical implementation of such system are considered. Despite a large amount of research and development work done, there were no practically implemented projects of spacecraft with the high-power thermal control system until recent days. The first powerful stationary satellite with the 2-MPL was SES-17 satellite on the NEOSAT platform by Thales Alenia Space - France. The satellite was successfully launched into space on October 24, 2021 by onboard Ariane 5 launcher operated by Arianespace from the Europe’s Spaceport in Kourou, French Guiana.

Two-Phase Heat Transfer Enhancement on Sintered Copper Microparticle Porous Structure Module Surface

2009 ◽  
Author(s):  
Calvin H. Li ◽  
Ting Li ◽  
Brian Kanney
Keyword(s):  
Heat Transfer ◽  
Porous Structure ◽  
Bubble Dynamics ◽  
Transfer Enhancement ◽  
Enhanced Heat Transfer ◽  
Two Phase ◽  
Sintered Copper ◽  
Theoretical Predictions ◽  
Heat Transfer Capacity ◽  
Two Phase Heat Transfer

An experimental study of the pool boiling two-phase heat transfer on a sintered Cu microparticle porous structure module surface is conducted. Enhanced heat transfer capacity of this module surface has been reported, and the boiling characteristics have been investigated. The bubble dynamics and nucleate size distribution have been compared to the theoretical predictions, and the speculated mechanisms have been discussed.

Minimizing the Wick Thickness in a Planar Microscale Loop Heat Pipe Using Efficient Thermodynamic Design

2011 ◽  
Author(s):  
Navdeep S. Dhillon ◽  
Jim C. Cheng ◽  
Albert P. Pisano
Keyword(s):  
Heat Flow ◽  
Heat Pipe ◽  
Thermal Characteristics ◽  
Heat Pipes ◽  
Working Fluid ◽  
Loop Heat Pipe ◽  
Two Phase ◽  
Loop Heat Pipes ◽  
Evaporator Section ◽  
Compensation Chamber

Theoretical and numerical thermodynamic analysis of the evaporator section of a planar microscale loop heat pipe is presented, to minimize the permissible wick thickness in such a device. In conventional cylindrical loop heat pipes, a minimum wick thickness is required in order to reduce parasitic heat flow, and prevent vapor leakage, into the compensation chamber. By taking advantage of the possibilities allowed by microfabrication techniques, a planar evaporator/compensation chamber design topology is proposed to overcome this limitation, which will enable wafer-based loop heat pipes with device thicknesses on the order of a millimeter or less. Thermodynamic principles governing two-phase flow of the working fluid in a loop heat pipe are analyzed to elucidate the fundamental requirements that would characterize the startup and steady state operation of a planar phase-change device. A three dimensional finite element thermal-fluid solver is implemented to study the thermal characteristics of the evaporator section and compensation chamber regions of a planar vertically wicking micro-columnated loop heat pipe. The use of in-plane thermal conduction barriers to reduce parasitic heat flow into the compensation chamber is demonstrated.

Effect of Increasing Wick Evaporation Area on Heat Transfer Performance for Loop Heat Pipes

2013 ◽  
Vol 711 ◽  
pp. 223-228 ◽  
Author(s):  
Shen Chun Wu ◽  
Jhih Huang Gao ◽  
Zih Yan Huang ◽  
Dawn Wang ◽  
Cho Jeng Huang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Heat Pipe ◽  
Surface Area ◽  
Heat Transfer Performance ◽  
Heat Pipes ◽  
Loop Heat Pipe ◽  
Transfer Performance ◽  
Loop Heat Pipes ◽  
Heat Transfer Capacity

This study investigates the effects of increasing the evaporating area of wick in a loop heat pipe (LHP). This work attempts to improve the performance of the loop heat pipe by increasing the number of grooves and thereby the surface area of the wick. The number of grooves is increased from eight to twelve. Experimental results show that increasing the number of grooves not only increases the surface area of the wick but also enhances LHP performance. When the evaporating surface area increases by 50%, which corresponds to increasing the number of grooves from eight to twelve, the heat transfer capacity increases from 310W to 470W and the thermal resistance is reduced from 0.21°C/W to 0.17°C/W. According to preliminary measurements, increasing the number of grooves in the loop heat pipe is highly promising for improving the heat transfer performance.

scholarly journals АНАЛІЗ ВПЛИВУ ОБСЯГУ ГІДРОАКУМУЛЯТОРУ НА ПРАЦЕЗДАТНІСТЬ ДВОФАЗНОГО КОНТУРУ ТЕПЛОПЕРЕНОСУ СИСТЕМИ ТЕРМОРЕГУЛЮВАННЯ КОСМІЧНОГО АПАРАТУ

2018 ◽  
pp. 24-29
Author(s):  
Павел Григорьевич Гакал ◽  
Геннадий Александрович Горбенко ◽  
Эдем Русланович Решитов ◽  
Рустем Юсуфович Турна
Keyword(s):  
Heat Transfer ◽  
Control System ◽  
Energy Consumption ◽  
Control Systems ◽  
Single Phase ◽  
Thermal Control ◽  
Space Vehicles ◽  
Two Phase ◽  
Thermal Control System ◽  
Two Phase Heat Transfer

The world trend in the development of space vehicles is the expansion of their functionality, which leads to an increase in the power consumption, most of which is allocated in the elements of spacecraft equipment in the form of heat. To remove heat from the equipment elements, transfer it to the heat sink subsystem with subsequent removal to outer space, and also to maintain the required temperature mode of the equipment operation, thermal control systems are used. The increase in the power-to-weight ratio and linear dimensions of new spacecraft in conditions of severe design and weight-and-size limitations leads to a complication and growth of the mass of the system of thermal control of space vehicles. At present, thermal control systems for space vehicles based on single-phase fluid heat transfer loops are used. For space vehicles with an energy consumption of more than 10 kW, thermal control systems based on two-phase heat transfer loops are the most promising. They have a number of advantages in comparison with single-phase thermal control systems: two-phase heat transfer loops can transfer much more heat per unit of flow; the use of heat transfer during boiling allows to maintain the temperature of objects practically on the whole extent of the circuit close to the saturation temperature; the mass of the thermal control system with a two-phase coolant is substantially less than with a single-phase coolant , and the energy consumption of the pump for pumping the coolant is negligible. In this paper, a two-phase heat transfer loop performances are analyzed. The process of increasing the thermal power up to the maximum under conditions of full filling of the accumulator is considered. The study was carried out on an experimental two-phase heat transfer loop with an ammonia. Transient processes associated with an increase in the thermal load from 73 % to 100 % are considered. The obtained data correlate well with the results of the calculation. Based on the results of the analysis, conclusions were made on the operability and stability of the spacecraft thermal control system under these conditions, and recommendations on the choice of the volume of the accumulator are given.

scholarly journals Mathematical modeling of heat transfer in a closed two- phase thermosyphon

2019 ◽  
Vol 21 (3) ◽  
pp. 3-13
Author(s):  
V. I. Maksimov ◽  
A. Е. Nurpeiis
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Heat Flow ◽  
Problem Solution ◽  
Two Phase ◽  
Evaporation Zone ◽  
Characteristic Temperatures ◽  
Simulation Results

We suggested a new approach for describing heat transfer in thermosyphons and determining the characteristic temperatures. The processes of thermogravitation convection in the coolant layer at the lower cap, phase transitions in the evaporation zone, heat transfer as a result of conduction in the lower cap are described at the problem statement. The main assumption, which was used during the problem formulation, is that the characteristic times of steam motion through the thermosyphon channel are much less than the characteristic times of thermal conductivity and free convection in the coolant layer at the lower cap of the thermosyphon. For this reason, the processes of steam motion in the thermosyphon channel, the condensate film on the upper cap and the vertical walls were not considered. The problem solution domain is a thermosyphon through which heat is removed from the energy-saturated equipment. The ranges of heat flow changes were chosen based on experimental data. The geometric parameters of thermosyphon and the fill factors were chosen the same as in the experiments (height is 161 mm, diameter is 42 mm, wall thickness is 1.5 mm, ε=4-16%) for subsequent comparison of numerical simulation results and experimental data. In the numerical analysis it was assumed that the thermophysical properties of thermosyphon and coolant caps do not depend on temperature; laminar flow regime was considered. The dimensionless equations of vortex, Poisson and energy transfer for the liquid coolant under natural convection and the equations of thermal conductivity for the lower cap wall are solved by the method of finite differences. Numerical simulation results showed the relationship between the characteristic temperatures and the heat flow supplied to the bottom cap of thermosyphon. The results of the theoretical analysis are in satisfactory agreement with the known experimental data. 

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