Heat Pipe Performance in Microgravity: Lessons From the Constrained Vapor Bubble, CVB, Capillary Fin Experiment

2012 ◽  
Author(s):  
Joel L. Plawsky ◽  
Peter C. Wayner
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Vapor Bubble ◽  
Capillary Flow ◽  
Space Station ◽  
Internal Heat ◽  
Image Data ◽  
Bubble Nucleation ◽  
Microgravity Environment ◽  
Constrained Vapor Bubble

The Constrained Vapor Bubble (CVB) is a prototype for a wickless heat pipe and was developed into an experiment that was run in the microgravity environment of the International Space Station during 2010. Since the CVB is transparent, we can visualize the flow processes within the device in a way not possible before. Results from the experiment indicate that the CVB operates at higher pressures and temperatures in microgravity, a consequence of radiation being the only mechanism for removing heat from the device. The temperature profile data along the heat pipe and corresponding heat transfer calculations indicate that CVB performance is enhanced in the microgravity environment due to increased capillary flow even though heat transfer to the external environment is diminished by the absence of natural convection. Image data of the liquid profile in the grooves of the heat pipe indicate that the curvature gradient is considerably different from that on Earth and supports the conclusion that capillary flow and internal heat transfer is increased. Operations with the 20 mm version of the device allowed us to view explosive nucleation within the CVB upon device start-up. In this scenario, bubble nucleation occurred spontaneously and periodically at the hot end of the device. The nucleation process sent a shock wave through the pipe that collapsed the original bubble as a new vapor space was generated. The newly formed bubble returned to its original size, shape and location as heat loss from the CVB reestablished the original, pseudo-steady-state temperature and pressure profiles.

The Constrained Vapor Bubble Experiment: Results From the International Space Station

2011 ◽  
Author(s):  
Arya Chatterjee ◽  
Joel L. Plawsky ◽  
Peter C. Wayner ◽  
David F. Chao ◽  
Ronald J. Sicker ◽  
...  
Keyword(s):  
Heat Pipe ◽  
International Space Station ◽  
Vapor Bubble ◽  
Space Station ◽  
Optical Measurements ◽  
Space Environment ◽  
Working Fluid ◽  
Operating Characteristics ◽  
International Space ◽  
Constrained Vapor Bubble

The constrained vapor bubble (CVB) experiment is an experiment in thermal fluid science currently operating on the International Space Station. Flown as the first experiment on the Fluids Integrated Rack on the Destiny module of the US part of the space station, the experiment promises to provide new and exciting insights into the working of a wickless micro heat pipe in the micro-gravity environment. The CVB consists of a relatively simple setup — a quartz cuvette with sharp corners partially filled with pentane as the working fluid. Along with temperature and pressure measurements, the curvature of the pentane menisci formed at the corners of the cuvette can be determined using optical measurements. This is the first time the data collected in space environment is being presented to the public. The data shows that, while the performance of the CVB heat pipe is enhanced due to increased fluid flow, the loss of convection as a heat loss mechanism in the space environment, leads to some interesting consequences. We present some significant differences in the operating characteristics of the heat pipe between the space and Earth’s gravity environments and show that this has important ramifications in designing effective radiators for the space environment.

Constrained Vapor Bubble Heat Pipe Experiment Aboard the International Space Station

2013 ◽  
Vol 27 (2) ◽  
pp. 309-319 ◽  
Author(s):  
Arya Chatterjee ◽  
Joel L. Plawsky ◽  
Peter C. Wayner ◽  
David F. Chao ◽  
Ronald J. Sicker ◽  
...  
Keyword(s):  
Heat Pipe ◽  
International Space Station ◽  
Vapor Bubble ◽  
Space Station ◽  
International Space ◽  
Constrained Vapor Bubble

scholarly journals The Heat-Dissipation and Dehumidification System of the Hybrid Multi-Layer Gravity Heat Pipe Applied to Granary

2019 ◽  
Vol 13 (8) ◽  
pp. 76
Author(s):  
Guoyong Su ◽  
Yu Wu ◽  
Wei Gao
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Dissipation ◽  
Internal Heat ◽  
Internal Temperature ◽  
Transfer Mode ◽  
Working Principle ◽  
Booster Fan ◽  
Working Efficiency ◽  
Dissipation System

Based on the basic working principle and heat transfer characteristics of gravity heat pipe in combination with the grain stack particle's stacking characteristics, this study changes the structure of traditional heat pipe to change the heat transfer mode between the grain stack and the gravity heat pipe so as to improve the grain's heat-dissipation rate and heat-dissipation efficiency. Generally, this system can satisfy the internal heat dissipation requirements of grain stack only under the action of a non-power fan driven by the air in the atmosphere and the temperature difference between inside and outside of the fan. When the internal temperature sensor of the grain stack detects that the internal temperature of the grain stack is high only under the action of the non-power fan, the pipeline booster fan will be started. At the same time, when the gas exchange occurs between the internal gas in grain stack and the external air, the dehumidification and drying of the grain stack can be realized through the gas drying device of the product. Through theory and simulation, this paper conducts a comparative analysis on the variation law of grain stack's temperatures under the action of gravity heat pipe and no gravity heat pipe so as to explore the heat-dissipation system's working efficiency of the new structure gravity heat pipe. The gravity heat pipe and the non-power fan in the system are all green products, which makes this design product have better heat-dissipation effect and less energy consumption.

Modeling for Fluid Flow and Heat Transfer in Closed Loop Pulsating Heat Pipe

2020 ◽  
pp. 1-34
Author(s):  
Radhakanta Sarangi ◽  
Satya Prakash Kar ◽  
Abhilas Swain ◽  
Lalit Kumar Pothal
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Vapor Bubble ◽  
Closed Loop ◽  
Working Fluid ◽  
Vapour Bubble ◽  
Pulsating Heat Pipe ◽  
Time Step ◽  
Liquid Plug ◽  
Evaporation And Condensation

Abstract Numerical modelling of multi turn Closed Loop Pulsating Heat Pipe (CLPHP) is presented in this paper for ethanol as working fluid. Modelling is carried out for 1mm and 2mm ID PHP for different number of turns, different orientations and at constant wall temperature boundary conditions. Momentum and heat transfer variations with time are investigated numerically solving the one dimensional governing equations for vapor bubble and liquid plugs. Evaporation and condensation takes place by heat transfer through liquid film present around the vapour bubble. The code takes into account the realistic phenomena such as vapour bubble generation, liquid plug merging and super heating of vapor bubbles above its saturation temperature. During merging of liquid plugs, a time step adaptive scheme is implemented and this minimum time step was found to be 10−7 s. Nature of flow is investigated by momentum variation plot. Model results are compared with the experimental results from literature for nine different cases. Maximum variation in heat transfer for all these cases is found to be below ±34%. Keywords: Closed Loop Pulsating Heat Pipe, Liquid Plug, Plug momentum, Vapor Bubble, Heat Transfer, Thin Film Evaporation and Condensation

Temperature Response of Heat Transport in a Micro Heat Pipe

1999 ◽  
Vol 121 (2) ◽  
pp. 438-445 ◽  
Author(s):  
G. P. Peterson ◽  
H. B. Ma
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transport ◽  
Capillary Flow ◽  
Temperature Drop ◽  
Temperature Response ◽  
Axial Direction ◽  
Vapor Flow ◽  
Micro Heat Pipe

A detailed mathematical model for predicting the heat transport capability and temperature gradients that contribute to the overall axial temperature drop as a function of heat transfer in a micro heat pipe has been developed. The model utilizes a third-order ordinary differential equation, which governs the fluid flow and heat transfer in the evaporating thin film region; an analytical solution for the two-dimension heat conduction equation, which governs the macro evaporating film region in the triangular corners; the effects of the vapor flow on the liquid flow in the micro heat pipe; the flow and condensation of the thin film caused by the surface tension in the condenser; and the capillary flow along the axial direction of the micro heat pipe. With this model, the temperature distribution along the axial direction of the heat pipe and the effect on the heat transfer can be predicted. In order to verify the model presented here, an experimental investigation was also conducted and a comparison with experimental data made. This comparison indicated excellent correlation between the analytical model and experimental results, and as a result, the analysis provides a better understanding of the heat transfer capability and temperature variations occurring in micro heat pipes.

HEAT TRANSFER AND FLUID FLOW IN A NONISOTHERMAL CONSTRAINED VAPOR BUBBLE

2000 ◽  
Vol 181 (1) ◽  
pp. 203-223 ◽  
Author(s):  
J. HUANG ◽  
M. KARTHIKEYAN ◽  
P. C. WAYNER ◽  
J> L. PLAWSKY
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Vapor Bubble ◽  
Constrained Vapor Bubble

The Constrained Vapor Bubble Fin Heat Pipe in Microgravity

2011 ◽  
Vol 50 (15) ◽  
pp. 8917-8926 ◽  
Author(s):  
Arya Chatterjee ◽  
Peter C. Wayner ◽  
Joel L. Plawsky ◽  
David F. Chao ◽  
Ronald J. Sicker ◽  
...  
Keyword(s):  
Heat Pipe ◽  
Vapor Bubble ◽  
Constrained Vapor Bubble

Heat Transfer Characteristic of Flat Trapezoid Grooved Micro Heat Pipes

2014 ◽  
Vol 609-610 ◽  
pp. 1526-1531 ◽  
Author(s):  
Yan Xia Yang ◽  
Xiao Dong Wang ◽  
Yi Luo ◽  
Liang Liang Zou
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Capillary Flow ◽  
Transfer Characteristic ◽  
Fluid Distribution ◽  
Working Fluid ◽  
Transfer Performance ◽  
Maximum Heat ◽  
Micro Heat Pipe

To study the heat transfer performance of micro heat pipe, theoretical analysis of flat plate micro heat pipe with trapezoid cross section are presented in this paper. A one-dimensional stationary mathematical model for micro heat pipe grooved capillary flow using finite volume method (FVM) was established. The micro heat pipe had vapor space connect with each other and the influences of shear stress between vapor and fluid in the working process were described in the model which made the model more precisely. The axial variation of working fluid distribution in the heat pipe, pressure difference between vapor and liquid, and velocity of vapor and liquid were analyzed. In addition, the maximum heat transport capacity of micro heat pipe was calculated. The simulation results showed good agreement with the experiment results, and it could predict the heat transfer performance accurately, which was useful to micro heat pipe structural design.

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