scholarly journals The calculation of the heat control accumulator volume of two-phase heat transfer loop of a spacecraft thermal control system

2021 ◽  
pp. 15-23
Author(s):  
Artem Hodunov ◽  
Gennady Gorbenko ◽  
Pavel Gakal
Keyword(s):  
Control Systems ◽  
Single Phase ◽  
Operation Mode ◽  
Heat Removal ◽  
Thermal Control ◽  
Working Fluid ◽  
Phase Slip ◽  
Two Phase ◽  
Maximum Heat ◽  
Spacecraft Thermal Control

Spacecraft thermal control systems based on two-phase mechanically pumped loops have advantages in terms of mass and power consumption for auxiliary needs compared to single-phase thermal control systems. However, the disadvantage of two-phase mechanically pumped loops is that when changing the heat load and heat removal conditions, when switching from single-phase to two-phase operation mode and vice versa, the amount of working fluid in the loop changes significantly, which requires the use of a large volume heat-controlled accumulator.  Therefore, determining the minimum required volume of the heat-controlled accumulator for the loop operation is an urgent task due to the need to maintain the performance of the l loop at a minimum and maximum heat loads and minimize the mass of the structure and the working fluid charged. When determining the volume of the heat-controlled accumulator, it is necessary to correctly calculate the mass of the fluid in the loop during the two-phase operation mode. The mass of the fluid depends on the void fraction, which depends significantly on the phase slip. Many models and correlations have been proposed to calculate the phase slip factor. However, they all require justification for the parameters characteristic of spacecraft thermal control systems and weightlessness conditions.   The paper presents the results of ground-based experiments, based on which the verification of different models and correlations for phase slip was performed. The validation of models and correlations for the conditions of weightlessness was performed by comparing the results with the horizontal and vertical orientation of the elements of the experimental setup. The working fluid is ammonia. The experiments showed that the best coincidence of calculation and experience is provided by Chisholm correlation. The discrepancy between the calculated and experimental values did not exceed +/-7% in the entire range of study parameters both for horizontal and vertical orientations, which allow us to recommend the Chisholm correlation for determining the coolant mass in the two-phase mechanically pumped loops for parameters characteristic of spacecraft thermal control systems, including zero-gravity conditions.

Thermal Performance of a Miniature Loop Heat Pipe for Spacecraft Thermal Control System

2007 ◽  
Author(s):  
Hiroki Nagai ◽  
Hosei Nagano ◽  
Fuyuko Fukuyoshi ◽  
Hiroyuki Ogawa
Keyword(s):  
Control System ◽  
Thermal Performance ◽  
High Power ◽  
Thermal Control ◽  
Working Fluid ◽  
Two Phase ◽  
Steady State Condition ◽  
Porous Wick ◽  
Thermal Control System ◽  
Spacecraft Thermal Control

The Loop Heat Pipes (LHPs) are robust, self-starting and a passive two-phase thermal control system that uses the latent heat of vaporization of an internal working fluid to transfer heat from an evaporator (the heat source) to a condenser (the heat sink). The circulation of the working fluid is accomplished by capillary pressure gradients in a fine porous wick with very small pores. LHPs are rapidly gaining acceptance in the aerospace community and several terrestrial applications are emerging as well. In the present study, a miniature LHP is investigated the thermal performance for spacecraft thermal control system. Tests will be conducted including start-up, low power, power ramp up, high power, rapid power change, and rapid sink temperature change. Finally, we want to demonstrate the potential of LHP to become the next-generation heat transfer device to cool terrestrial devices such as advanced electronic which have high power dissipations. First of all, this paper presents the influence of the gravitational forces on the LHP performance. The present tests performed under steady state condition with three different orientations (horizontal, gravity-assisted, anti-gravity).

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 МАЛОИНЕРЦИОННЫЙ ТЕПЛООБМЕННИК АММИАК-АНТИФРИЗ ДЛЯ ИССЛЕДОВАНИЯ ПЕРЕХОДНЫХ ПРОЦЕССОВ В ЭЛЕМЕНТАХ ДВУХФАЗНОЙ СИСТЕМЫ ТЕРМОРЕГУЛИРОВАНИЯ СПУТНИКА

2019 ◽  
pp. 31-38
Author(s):  
Артем Михайлович Годунов ◽  
Евгений Эдуардович Роговой ◽  
Роман Сергеевич Орлов ◽  
Рустем Юсуфович Турна
Keyword(s):  
Heat Exchanger ◽  
Control Systems ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Single Phase ◽  
Thermal Inertia ◽  
Thermal Control ◽  
Inlet Temperature ◽  
Two Phase

Technical progress entails the use of more powerful equipment on satellites. In connection with the growth of heat generation onboard the spacecraft, the task is to develop thermal control systems based on two-phase mechanically pumped fluid loop (2PMPFL). The advantage of such systems is the ability to transport a greater amount of heat, reduced to a unit of flow, than when using circuits with a single-phase coolant. The study of two-phase thermal control systems in terrestrial conditions is difficult because gravity affects the hydraulics and heat transfer of two-phase flows. Particularly difficult is the study of transients. This article presents the results of tests of a recuperative heat exchanger, which allows to study transient processes in 2PMPFL with high accuracy.It was designed and manufactured the heat exchanger of simple “tube in tube” type design. The thermal characteristics of the heat exchanger were determined on the experimental stand, which is a prototype of a closed-type 2PMPFL with ammonia coolant. Single-phase “liquid” modes, two-phase modes with low mass vapor content (up to 0.04), and single-phase transient modes were investigated. It has been experimentally determined that a heat exchanger under given conditions is capable of removing up to 1323 W of heat in a single-phase mode and up to 1641 W of heat - when operating in a two-phase mode. The data obtained in the course of the experiments allowed us to select the most appropriate known correlation for calculating the stationary characteristics of the heat exchanger with an error not exceeding 5%, which is a high indicator of accuracy for engineering calculations.The heat exchanger has low thermal inertia. The conclusion is relevant for the range of parameters: the ammonia temperature at the inlet is 24...60 ⁰C; antifreeze inlet temperature 5… 16 ⁰C; ammonia mass flow rate 8...17 g / s; mass flow rate of antifreeze 1...4 kg/min.Due to the low thermal inertia of the heat exchanger, it can be used to study transients with the rate of change of the coolant temperature at the inlet up to 1.85 K / min. You can use the stationary method of thermal calculation, i.e. calculate the transient process in the quasi-stationary approximation.

Development and Experimental Demonstration of a Shape Memory Alloy-Based Adaptive Two-Phase Radiator for Space Applications

2020 ◽  
Author(s):  
Jared Lilly ◽  
Bethany Hansen ◽  
Ryan Lotz ◽  
Darren Hartl ◽  
Thomas Cognata ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Single Phase ◽  
Thermal Control ◽  
Working Fluid ◽  
Two Phase ◽  
Space Applications ◽  
Regenerative Heat ◽  
Heat Rejection ◽  
Wide Range

Abstract Future space exploration, such as the Artemis program, journeys to Mars, and future lander missions will require thermal control systems (TCSs) with the ability to adapt to a wide range of thermal loads due to vastly fluctuating external temperatures. Current TCSs employ radiators that can achieve a turndown ratio (defined as the ratio of the maximum to minimum heat rejection rates) of 12:1 by utilizing regenerative heat exchangers and a two-fluid-loop system, both of which are heavy and complex. However, future missions will demand radiators that can provide turndown ratios of 12:1 while remaining light, functionally passive, and simply designed. Previous work has investigated using shape memory alloy (SMA) components in single phase radiator prototypes to achieve efficient heat rejection. Preliminary analysis shows that SMA-based radiators can enable turndown ratios as high as 37:1. In this paper, the design, fabrication, and testing of an SMA torque tube driven radiator prototype is discussed. The SMA torque tube is attached to a heat rejecting panel that resembles flat radiator panels currently installed on the International Space Station. As the temperature of the working fluid in the TCS increases, the SMA torque tube actuates and rotates the panel, allowing for more radiative heat rejection to occur. This new design matures the concept past a previous prototype that merely demonstrated actuation under single-phase (e.g., liquid water) flow. The current radiator prototype has been designed to function not only with closed-loop, single-phase fluid flow, but also in conjunction with a two-phase TCS and even as a heat pipe. Both approaches take advantage of phase transformation of the working fluid to improve overall TCS efficiency and decrease complexity. During testing, a heated two-phase working fluid was circulated through the system, resulting in a maximum angular actuation of 67 degrees, thus demonstrating two-phase operation for the first time. These results give confidence that an SMA torque tube-driven radiator can outperform current radiators as development continues.

Two-Phase Flow in Microchannels

2001 ◽  
Author(s):  
G. Hetsroni ◽  
A. Mosyak ◽  
Z. Segal
Keyword(s):  
Heat Sink ◽  
High Speed ◽  
Single Phase ◽  
Flow Boiling ◽  
Electronics Cooling ◽  
Working Fluid ◽  
Microchannel Heat Sink ◽  
Two Phase ◽  
Infrared Radiometry ◽  
Phase Water

Abstract Experimental investigation of a heat sink for electronics cooling is performed. The objective is to keep the operating temperature at a relatively low level of about 323–333K, while reducing the undesired temperature variation in both the streamwise and transverse directions. The experimental study is based on systematic temperature, flow and pressure measurements, infrared radiometry and high-speed digital video imaging. The heat sink has parallel triangular microchannels with a base of 250μm. According to the objectives of the present study, Vertrel XF is chosen as the working fluid. Experiments on flow boiling of Vertrel XF in the microchannel heat sink are performed to study the effect of mass velocity and vapor quality on the heat transfer, as well as to compare the two-phase results to a single-phase water flow.

scholarly journals Heat transfer and entropy generation in a microchannel with longitudinal vortex generators using Nanofluids

2020 ◽  
Author(s):  
Amin Ebrahimi ◽  
Farhad Rikhtegar Nezami ◽  
Amin Sabaghan ◽  
Ehsan Roohi
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Single Phase ◽  
Pure Water ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Working Fluid ◽  
Two Phase ◽  
Rectangular Microchannel ◽  
Important Conclusion

Conjugated heat transfer and hydraulic performance for nanofluid flow in a rectangular microchannel heat sink with LVGs (longitudinal vortex generators) are numerically investigated using at different ranges of Reynolds numbers. Three-dimensional simulations are performed on a microchannel heated by a constant heat flux with a hydraulic diameter of 160 μm and six pairs of LVGs using a single-phase model. Coolants are selected to be nanofluids containing low volume-fractions (0.5%–3.0%) of Al2O3 or CuO nanoparticles with different particle sizes dispersed in pure water. The employed model is validated and compared by published experimental, and single-phase and two-phase numerical data for various geometries and nanoparticle sizes. The results demonstrate that heat transfer is enhanced by 2.29–30.63% and 9.44%–53.06% for water-Al2O3 and water-CuO nanofluids, respectively, in expense of increasing the pressure drop with respect to pure-water by 3.49%–16.85% and 6.5%–17.70%, respectively. We have also observed that the overall efficiency is improved by 2.55%–29.05% and 9.78%–50.64% for water-Al2O3 and water-CuO nanofluids, respectively. The results are also analyzed in terms of entropy generation, leading to the important conclusion that using nanofluids as the working fluid could reduce the irreversibility level in the rectangular microchannel heat sinks with LVGs. No exterma (minimums) is found for total entropy generation for the ranges of parameters studied.

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.

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