Flat-plate cryostat for measurements of multilayer insulation thermal conductivity

Cryogenics ◽  
1985 ◽  
Vol 25 (10) ◽  
pp. 593-595 ◽  
Author(s):  
T. Hałaczek ◽  
J. Rafałowicz
Keyword(s):  
Thermal Conductivity ◽  
Flat Plate ◽  
Multilayer Insulation

scholarly journals Repeatability Measurements of Apparent Thermal Conductivity of Multilayer Insulation (MLI)

2017 ◽  
Vol 278 ◽  
pp. 012195 ◽  
Author(s):  
M Vanderlaan ◽  
D Stubbs ◽  
K Ledeboer ◽  
J Ross ◽  
S Van Sciver ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Apparent Thermal Conductivity ◽  
Multilayer Insulation

Experimental and Statistical Analysis of MgO Nanofluids for Thermal Enhancement in a Novel Flat Plate Heat Pipes

2017 ◽  
Vol 17 (01n02) ◽  
pp. 1760018 ◽  
Author(s):  
P. Pandiaraj ◽  
A. Gnanavelbabu ◽  
P. Saravanan
Keyword(s):  
Thermal Conductivity ◽  
Flat Plate ◽  
Volume Fraction ◽  
Heat Pipes ◽  
Influential Factors ◽  
Working Fluid ◽  
Particle Fraction ◽  
Solution Ph ◽  
Plate Heat ◽  
Xrd Techniques

Metallic fluids like CuO, Al2O3, ZnO, SiO2 and TiO2 nanofluids were widely used for the development of working fluids in flat plate heat pipes except magnesium oxide (MgO). So, we initiate our idea to use MgO nanofluids in flat plate heat pipe as a working fluid material. MgO nanopowders were synthesized by wet chemical method. Solid state characterizations of synthesized nanopowders were carried out by Ultraviolet Spectroscopy (UV), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) techniques. Synthesized nanopowders were prepared as nanofluids by adding water and as well as water/ethylene glycol as a binary mixture. Thermal conductivity measurements of prepared nanofluids were studied using transient hot-wire apparatus. Response surface methodology based on the Box–Behnken design was implemented to investigate the influence of temperature (30–60[Formula: see text]C), particle fraction (1.5–4.5 vol.%), and solution pH (4–12) of nanofluids as the independent variables. A total of 17 experiments were accomplished for the construction of second-order polynomial equations for target output. All the influential factors, their mutual effects and their quadratic terms were statistically validated by analysis of variance (ANOVA). The optimum stability and thermal conductivity of MgO nanofluids with various temperature, volume fraction and solution pH were predicted and compared with experimental results. The results revealed that increase in particle fraction and pH of MgO nanofluids at certain points would increase thermal conductivity and become stable at nominal temperature.

Potential of Size Reduction of Flat-Plate Solar Collectors when Applying Al2O3 Nanofluid

2013 ◽  
Vol 832 ◽  
pp. 149-153 ◽  
Author(s):  
Mohd Faizal ◽  
Rahman Saidur ◽  
Saad Mekhilef ◽  
M Faizal
Keyword(s):  
Thermal Conductivity ◽  
Flat Plate ◽  
Solar Collector ◽  
Fossil Fuel ◽  
Size Reduction ◽  
Solar Thermal Energy ◽  
Absorbing Medium ◽  
Renewable Source ◽  
Original Size ◽  
Flat Plate Solar Collector

The source of fossil fuel is decreasing. The price increased rapidly. Population and demand of energy increased significantly over the years. Carbon pollution and global warming are becoming major issues. The best way to overcome this problem is by changing to renewable source of energy. One of it is solar thermal energy. However, a solar technology is currently still expensive, low in efficiency and takes up a lot of space. Nanofluid is recognized as a solution to overcome this problem. Due to the high thermal conductivity of nanofluids, the thermal efficiency of a solar collector can be increased and thus decreasing the size of the system. This paper analyzes the efficiency of using the Al2O3nanofluid as absorbing medium in flat-plate solar collector and estimated the potential of size reduction. When applying the same output temperature of Al2O3nanofluid as with water, it can be observed that the collectors size can be reduced up to 24% of its original size.

scholarly journals Modeling the conjugate problem of heat transfer at hot jet impingement onto a cooled surface

2021 ◽  
Vol 2119 (1) ◽  
pp. 012157
Author(s):  
V V Lukashov ◽  
V S Naumkin
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Flat Plate ◽  
Gas Flow ◽  
Jet Impingement ◽  
Conjugate Problem ◽  
Heat Fluxes ◽  
The Other ◽  
Local Maxima ◽  
The Impact

Abstract The paper solves the problem of thermal conductivity inside a flat plate under the impact of a hot jet of nitrogen impinging from one side and cooled by a gas flow from the other side. In this formulation of the problem, there may be local maxima and minima of the temperature inside the plate, caused by an uneven distribution of heat fluxes along the plate.

scholarly journals Numerical study of magnetohydrodynamic free convective heat transfer flow along a vertical flat plate with temperature dependent thermal conductivity

2010 ◽  
Vol 6 (1) ◽  
pp. 16-29 ◽  
Author(s):  
M. M. Rahman ◽  
M. A. Alim
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Flat Plate ◽  
Temperature Dependent ◽  
Implicit Finite Difference ◽  
Transfer Flow ◽  
Temperature Dependent Thermal Conductivity ◽  
Vertical Flat Plate

The present numerical work describes the effect of the magnetohydrodynamic (MHD) free convective heat transfer flow along a vertical flat plate with temperature dependent thermal conductivity and heat conduction. The governing equations reduce to local non-similarity boundary layer equations using suitable transformation have been integrated by employing an implicit finite difference method together with the Keller box technique. Comparison with previously published work is performed and excellent agreement is observed. Profiles of the dimensionless velocity and temperature distributions as well as the local skin friction coefficient and surface temperature distribution are shown graphically for various values of the magnetic parameter M, thermal conductivity variation parameter g and Prandtl number Pr.Keywords: Implicit finite difference method, free convection flow, vertical flow, vertical flat plate, temperature dependent thermal conductivityDOI: 10.3329/jname.v6i1.2654Journal of Naval Architecture and Marine Engineering Vol.6(1) 2009 16-29

Effect of Thermal Conductivity on Heat Transfer From a Flat Plate With Combined Impingement and Film Cooling

2012 ◽  
Author(s):  
Rajesh Kumar Panda ◽  
B. V. S. S. S. Prasad
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Flat Plate ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Turbulence Modeling ◽  
The Other ◽  
Air Jets ◽  
Volume Method ◽  
Interaction Surface

The effect of solid thermal conductivity on conjugate heat transfer from a flat plate with combined impingement and film cooling is studied both experimentally and computationally. One side of the plate is exposed to hot mainstream, while the other side experiences impinging air jets. A geometric configuration with multiple staggered rows of cylindrical film holes and a matrix of impingement holes is considered. In the experiments a thermo-chromic liquid crystal (TLC) technique is used to measure the surface temperature. For the purpose of computations, the physical domain is meshed with very fine sized hexahedral and tetrahedral grids suitable for the finite volume method. Grid refinement is carried out using GCI method and SST κ-omega RANS equations are used for turbulence modeling. Three blade materials: A - with k = 0.2W/m K, B - with k = 1.5W/m K and C - with k = 15W/m K and three blowing ratios, M = 0.6, 1.0 and 1.6 are considered for the conjugate heat transfer study. A good agreement of effectiveness distribution on the interaction surface is found between the measured and the computations. On the interaction surface, heat flux values are the lowest for material A and progressively increase with increasing thermal conductivity. However the effectiveness values vary significantly for material A in the stream-wise direction. The Nusselt number on the other hand differs only slightly among different materials.

Sign in / Sign up

Export Citation Format

Share Document