Design Calculations of the Limiting Characteristics of Heat Pipes for Cooling Active Phased Antenna Arrays

WSEAS TRANSACTIONS ON APPLIED AND THEORETICAL MECHANICS ◽

10.37394/232011.2021.16.15 ◽

2021 ◽

Vol 16 ◽

pp. 142-149

Author(s):

S. Radaev

Keyword(s):

Antenna Arrays ◽

Operating Temperature ◽

Algorithm Design ◽

Saturation Temperature ◽

Heat Pipes ◽

Counter Flow ◽

Phased Antenna Arrays ◽

Capillary Limit ◽

Design Calculations ◽

Viscous Limit

The article provides an algorithm for calculating the limiting characteristics of heat pipes for cooling active phased antenna arrays at a given saturation temperature. The maximum transmitted power is determined taking into account the limitations of the heat pipes operation by the capillary limit, by boiling (transition to film boiling, boiling limit), by the sonic limit at which the speed of steam reaches the speed of sound (sonic limit), by the entrainment of droplets liquid coolant from the surface of the wick with a counter flow of steam (entertainment limit) and viscous limit, which is realized at low temperatures (viscous limit). It is shown that an increase in the thickness of the wick and its porosity may be necessary to increase the capillary limit of heat pipes, while an increase in the thickness of the wick increases the thermal resistance of the tube and, accordingly, can lead to overheating of the cooled elements. Based on the above algorithm, design calculations for two types of heat pipes have been carried out. The dependences of various limits of the heat pipe on the operating temperature are plotted. Based on the above algorithm, calculations were performed for two types of heat pipes.

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Mathematical Modeling of Heat and Mass Transfer in Heat Pipes in a One-Dimensional Formulation when Cooling Active Phased Antenna Arrays

International Journal of Mechanics ◽

10.46300/9104.2021.15.23 ◽

2021 ◽

Vol 15 ◽

pp. 196-203

Author(s):

S. Radaev

Keyword(s):

Mass Transfer ◽

Heat Pipe ◽

Heat And Mass Transfer ◽

Antenna Arrays ◽

Saturation Temperature ◽

Heat Pipes ◽

Equilibrium Temperature ◽

One Dimensional ◽

Phased Antenna Arrays ◽

The Mathematical Model

The work proposes test one-dimensional models of heat and mass transfer in heat pipes during cooling of active phased antenna arrays, which can be used in processing the test results of flat heat pipes in order to determine their performance characteristics and identify the parameters required for modeling in a more complex setting (for example, in flat and taking into account the presence of several localized sources of heat supply). To take into account the influence of the heat release power on the equilibrium temperature inside the heat pipe, the model has been added to take into account the dependence of the steam saturation temperature on the pressure, which is realized inside the steam pipeline when the heat pipe is heated. Numerous calculations carried out made it possible to refine the mathematical model. In particular, a significant effect on the temperature distribution along the heat pipe is shown, taking into account the dependence of the steam saturation temperature on the pressure in the parawire. It is shown that the introduction of standard functions for the characteristics of the coolant (water) in the liquid and vapor state, as well as taking into account the capillary pressure on temperature, makes it possible to refine the resulting solution.

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Operational Limitations of Heat Pipes With Silver-Water Nanofluids

Journal of Heat Transfer ◽

10.1115/1.4024616 ◽

2013 ◽

Vol 135 (11) ◽

Cited By ~ 7

Author(s):

Lazarus Godson Asirvatham ◽

Rajesh Nimmagadda ◽

Somchai Wongwises

Keyword(s):

Silver Nanoparticles ◽

Heat Pipe ◽

Heat Load ◽

Operating Temperature ◽

Particle Diameter ◽

Heat Pipes ◽

Working Fluid ◽

Limit Value ◽

Capillary Limit ◽

Nanoparticles Concentration

The paper presents the enhancement in the operational limits (boiling, entrainment, sonic, viscous and capillary limits) of heat pipes using silver nanoparticles dispersed in de-ionized (DI) water. The tested nanoparticles concentration ranged from 0.003 vol. % to 0.009 vol. % with particle diameter of <100 nm. The nanofluid as working fluid enhances the effective thermal conductivity of heat pipe by 40%, 58%, and 70%, respectively, for volume concentrations of 0.003%, 0.006%, and 0.009%. For an input heat load of 60 W, the adiabatic vapor temperatures of nanofluid based heat pipes are reduced by 9 °C, 18 °C, and 20 °C, when compared with DI water. This reduction in the operating temperature enhances the thermophysical properties of working fluid and gives a change in the various operational limits of heat pipes. The use of silver nanoparticles with 0.009 vol. % concentration increases the capillary limit value of heat pipe by 54% when compared with DI water. This in turn improves the performance and operating range of the heat pipe.

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