Thermal Performance Model for Spacesuit Waste Heat Rejection Using Water Membrane Evaporators

2010 ◽  
Vol 2 (3) ◽  
Author(s):  
Y. Janeborvorn ◽  
T. P. Filburn ◽  
C. C. Yavuzturk ◽  
E. K. Ungar
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Waste Heat ◽  
Water Channel ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Performance Model ◽  
Heat Transfer Analysis ◽  
Water Evaporation ◽  
Heat Rejection

Hydrophobic, micropore membrane evaporators are studied for use in waste heat rejection in new generation spacesuits developed by the U.S. National Aeronautics and Space Administration (NASA). The waste heat rejection is accomplished via evaporation of liquid water through membrane pores, whereby the hydrophobic membrane allows only water vapor to pass through and retains the liquid phase inside the membrane water channel, allowing the waste heat rejection through the proposed spacesuit water membrane evaporator (SWME) system to be significantly less sensitive to contamination while improving the overall contaminant and system control. Although SWME uses the same heat transport loop as used in current NASA sublimator systems, thus eliminating the need for a separate feedwater system, it permits the system configuration to be simpler and more compact while also eliminating corrosion problems and reducing system freeze-up potential. An improved thermal performance model based on membrane segment energy balances is presented, which is a spacesuit water membrane evaporator for a single circular annulus water channel bounded by two annular vapor channels. The model allows for the investigation of the local heat transfer characteristics along the annulus including temperature gradients in the membrane wall and the water channel using a steady-state approach. The model also accounts for the effects of thermal and hydraulic entry lengths, far field radiation, and energy carried away by the mass of water evaporation. The local heat transfer analysis enables the straightforward calculation of the overall magnitude of heat transfer from the SWME. A model validation is presented via the sum of the squares error analyses between the model predictions and the experimental results.

scholarly journals Numerical heat transfer analysis of micro-scale jet-impingement cooling in a high-pressure turbine vane

2021 ◽  
Author(s):  
Karan Anand
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Heat Transfer Analysis ◽  
Transfer Rates ◽  
Numerical Heat Transfer ◽  
Turbine Vane ◽  
Single Jet

This research provides a computational analysis of heat transfer due to micro jet-impingement inside a gas turbine vane. A preliminary-parametric analysis of axisymmetric single jet was reported to better understand micro jet-impingement. In general, it was seen that as the Reynolds number increased the Nusselt number values increased. The jet to target spacing had a considerably lower impact on the heat transfer rates. Around 30% improvement was seen by reducing the diameter to half while changing the shape to an ellipse saw 20.8% improvement in Nusselt value. The numerical investigation was then followed by studying the heat transfer characteristics in a three-dimensional, actual-shaped turbine vane. Effects of jet inclination showed enhanced mixing and secondary heat transfer peaks. The effect of reducing the diameter of the jets to 0.125 mm yielded 55% heat transfer improvements compared to 0.51 mm; the tapering effect also enhanced the local heat transfer values as local velocities at jet exit increased.

Aero-Thermal Performance of a Winglet at Engine Representative Mach and Reynolds Numbers

2010 ◽  
Author(s):  
D. O. O’Dowd ◽  
Q. Zhang ◽  
L. He ◽  
M. L. G. Oldfield ◽  
P. M. Ligrani ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Shock Wave ◽  
Thermal Performance ◽  
High Speed ◽  
Local Heat Transfer ◽  
Wave Structure ◽  
Local Heat ◽  
Test Facility ◽  
Shock Wave Structure ◽  
Spatially Resolved

This paper presents an experimental and numerical investigation of the aero-thermal performance of an uncooled winglet tip, under transonic conditions. Spatially-resolved heat transfer data, including winglet tip surface and near tip side walls, are obtained using the transient infrared thermography technique within the Oxford High Speed Linear Cascade test facility. CFD predictions are also conducted using the Rolls-Royce HYDRA suite. Most of the spatial heat transfer variations on the tip surface are well-captured by the CFD solver. The transonic flow pattern and its influence on heat transfer are analyzed, which shows that the turbine blade tip heat transfer is greatly influenced by the shock wave structure inside the tip gap. The effect of the casing relative motion is also numerically investigated. The CFD results indicate that the local heat transfer distribution on the tip is affected by the relative casing motion, but the tip flow choking and shock wave structure within the tip gap still exist in the aft region of the blade.

Overall Thermal Performance of a Rectangular Channel With an Array of Elongated Pedestals

2013 ◽  
Author(s):  
S. Huang ◽  
Y. Y. Yan ◽  
J. D. Maltson ◽  
E. Utriainen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Thermal Performance ◽  
Rectangular Channel ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Flow Area ◽  
Coefficient Distribution

Experiments have been conducted to investigate the overall thermal performance of a rectangular channel implemented with an elongated pedestal array. The staggered pedestals were elongated in the spanwise direction in order that the jet flow from between the pedestals impinges at the centre of the pedestals in the downstream row. The average heat transfer coefficient of the pedestal and the local heat transfer coefficient distribution of the bottom channel wall were investigated for different geometrical arrangements. The pressure drop across the pedestal bank was measured. The transient liquid crystal method was used to obtain the local heat transfer coefficient distribution on the bottom channel wall and the lumped capacitance method was used to measure the average heat transfer coefficient of the pedestals in the last two rows of the bank. Five pressure taps were arranged on the centerline of each gap between two pedestal rows to measure the pressure drop. The heat transfer coefficients were measured over the Reynolds number range from 10,000 to 30,000. The minimum flow area to the channel cross-section flow area ratio ranged from 0.149 to 0.333. The effects of pedestal geometry and array distribution were investigated in detail showing the relationship between the pedestal array geometry, heat transfer enhancement and pressure drop. Conclusions were drawn on the effects of geometry and flow conditions on overall thermal performance of the respective channels.

Conjugate heat transfer analysis for laminar flow in pipes having a step change in boundary conditions and wall conductivity

2007 ◽  
Vol 221 (8) ◽  
pp. 919-925 ◽  
Author(s):  
M E Arici ◽  
M E Kaya
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Solid Wall ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Step Change ◽  
Heat Transfer Analysis ◽  
Heated Wall ◽  
Surface Boundary ◽  
Wall Conductivity

The current procedure is to examine the effects of wall axial conduction on heat transfer for laminar flow in pipes. The procedure combines the analytical solution of the problem of the fluid region with a numerical approximation of conduction of the solid wall and has the capability of handling the step change in outer surface boundary condition and wall thermal conductivity. The pipe under investigation is divided into two sections: non-heated and heated ones, and the conductivities of the sections are assumed to be different. The obtained results show that the local heat transfer parameters such as wall and fluid temperatures, and Nusselt number are greatly influenced by the step change in wall conductivity and the partially heated wall arrangement. The results of the present study may have applications in the design of heat transfer devices.

Global and local heat transfer analysis for bicycle helmets using thermal head manikins

2016 ◽  
Vol 53 ◽  
pp. 157-166 ◽  
Author(s):  
Natividad Martínez ◽  
Agnes Psikuta ◽  
René Michel Rossi ◽  
José Miguel Corberán ◽  
Simon Annaheim
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Heat Transfer Analysis ◽  
Bicycle Helmets ◽  
Global And Local

Conjugate Heat Transfer Analysis for Film Cooling Configurations With Different Hole Geometries

2003 ◽  
Author(s):  
Dieter Bohn ◽  
Jing Ren ◽  
Karsten Kusterer
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Secondary Flows ◽  
Heat Transfer Analysis ◽  
Transfer Condition ◽  
Film Cooling Effectiveness

Secondary flows in the cooling jets are the main reason for the degradation of the cooling performance of a film-cooled blade. The formation of kidney vortices can significantly be reduced for shaped holes instead of cylindrical holes. For the determination of the film cooling heat transfer, the design of a turbine blade relies on the conventional determination of the adiabatic film cooling effectiveness and heat transfer conditions for test configurations. Thus, additional influences by the interaction of fluid flow and heat transfer and influences by additional convective heat transfer cannot be taken into account with sufficient accuracy. Within this paper, calculations of a film-cooled duct wall with application of the adiabatic and a conjugate heat transfer condition have been performed for different configurations with cylindrical and shaped holes. It can be shown that the application of the conjugate calculation method comprises the influence of heat transfer on the velocity field within the cooling film. In particular, the secondary flow velocities are affected by the local heat transfer, which varies significantly depending on the local position.

scholarly journals Heat Transfer Analysis and Modification of Thermal Probe for Gas-Solid Measurement

2016 ◽  
Vol 2016 ◽  
pp. 1-7
Author(s):  
Hong Zhang ◽  
Xiangying Qi
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Heat Transfer Analysis ◽  
Transfer Coefficients ◽  
Thermal Probe ◽  
Measuring Range ◽  
Two Phase ◽  
Heat Transfer Coefficients ◽  
Thermal Simulations

The presented work aims to measure the gas-solid two-phase mass flow-rate in pneumatic conveyor, and a novel modified thermal probe is applied. A new analysis of the local heat transfer coefficients of thermal probe is presented, while traditional investigations focus on global coefficients. Thermal simulations are performed in Fluent 6.2 and temperature distributions of the probe are presented. The results indicate that the probe has obviously stable and unstable heat transfer areas. Based on understanding of probe characteristics, a modified probe structure is designed, which makes the probe output signal more stable and widens the measuring range. The experiments are carried out in a special designed laboratory scale pneumatic conveyor, and the modified probe shows an unambiguous improvement of the performance compared with the traditional one.

Heat Transfer Analysis in Mixed Convection

2010 ◽  
Author(s):  
Shan-Fang Huang ◽  
Tai-Yi Ma ◽  
Han-Yang Gu ◽  
Yan-Hua Yang ◽  
Xiao Yan
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Heat Resistance ◽  
Heat Transfer Performance ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Resistance Coefficient ◽  
Heat Transfer Analysis ◽  
Transfer Performance ◽  
Transfer Resistance

Heat transfer is analyzed from a different view in mixed convection in this paper. A concept, namely averaged heat transfer resistance coefficient, is used to describe heat transfer performance. For local position, heat transfer defined by generalized Fourier law is determined by fluid conductance and turbulence heat transfer. On the other hand, heat resistance over the cross section is the integer of the local resistance, where the weight, a function of spatial position, can be expressed by product of local heat transfer and temperature. To enhance heat transfer, it is crucial to reduce the heat resistance where the weight is big, namely near the wall. Heat transfer performance under different buoyancy effect is analyzed by the new. The results show that flow structure and heat transfer are closely connected by a straightforward expression. Heat transfer mechanism of enhancement and deterioration under different stages can be perfectly explained, which can predict heat transfer qualitatively.

Bend Geometries in Internal Cooling Channels for Improved Thermal Performance

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Krishnendu Saha ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Thermal Performance ◽  
Local Heat Transfer ◽  
Outer Wall ◽  
Local Heat ◽  
Internal Cooling ◽  
Cooling Channels ◽  
Baseline Case ◽  
Sharp Turn

The pressure drop and heat transfer in a two pass internal cooling channel with two different bend geometries is experimentally studied with the goal of improving the thermal performance factor (TPF) in the coolant channel. The geometries studied are (1) a baseline U-bend geometry with a rectangular divider wall, (2) a symmetrical bulb at the end of the divider wall, and (3) a combination of the symmetrical bulb and a bow on the opposite outer wall leading to a shaped flow contraction and expansion in the bend. Tests are conducted for four Reynolds number ranging from 10,000 to 55,000. The symmetrical bulb eliminates the separation due to the sharp turn and makes the heat transfer distribution in the bend portion more uniform. This modification reduces the bend pressure drop by 37% and augments the TPF by nearly 29% compared to the baseline case. The combination of bulb and bow case increases the local heat transfer in the bend region significantly, and reduces the bend pressure drop by nearly 27% leading to an augmentation of the TPF of 32% compared to the baseline case. These improvements in TPF point to the benefits of using the improved bend designs in internal cooling channels.

Sign in / Sign up

Export Citation Format

Share Document