The influence of pressure on the thermal conductivity of liquid He ll

The unusual characteristics of heat transfer in liquid He II have been reported in several recent papers. The very high thermal conductivity of the low-temperature modification of liquid helium was first noted by Keesom and Keesom (1935). It was then found by Allen, Peierls and Uddin (1937) and subsequently verified by Keesom, Keesom and Saris (1938) that the rate of transfer of heat varied with the temperature gradient. The discovery of the momentum transfer accompanying heat flow in He II which was made by Allen and Jones (1938) and the work on mobile surface films of the liquid done by Daunt and Mendelssohn (1938) show that a large part of the heat must be carried by some form of mass transfer. Several ideas and theories to explain the phenomena have been put forward by Kapitza (1938), Jones (1938), Michels, Bijl and de Boer (1938), Tisza (1938) and Keesom and Taconis (1938). The experimental evidence is as yet too meagre to prove or disprove any of the theories. It was with the intention of adding to the data already known concerning the properties of liquid He II that the present research was undertaken. The apparatus which was used is shown in fig. 1. The thermal conductivity was measured by a standard method. A constant supply of heat was supplied to one end of a long capillary containing liquid He II, and the other end was maintained at the constant temperature of the He II bath. Temperatures were observed at two points along the capillary.

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Heat transfer in liquid helium below 1°K

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1955.0195 ◽

1955 ◽

Vol 231 (1187) ◽

pp. 545-555 ◽

Cited By ~ 40

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Heat Flow ◽

Temperature Gradient ◽

Thermal Resistance ◽

Specific Heat ◽

Liquid Helium ◽

Practical Importance ◽

Heat Pulses

The thermal conductivity of liquid helium has been measured between 0.2 and 1.0° K. Below 0.6° K the heat flow is exactly proportional to the temperature gradient and the thermal conductivity is proportional to the specific heat and the diameter of the specimen. Thus the sole mechanism of heat transfer appears to be by phonons which are scattered only at the boundaries of the specimen. These results are in satisfactory accord with previous theoretical discussions and with measurements of the propagation of heat pulses in the liquid. The experiment also afforded the opportunity of making subsidiary measurements of the thermal resistance of the boundary between a metal and liquid helium. Besides being of practical importance, the results show that some modification is called for in the existing theoretical treatments.

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MATERIAL INSULASI TERHADAP EFEK KEHILANGAN PANAS PADA JALUR PIPA PANAS BUMI

PETRO ◽

10.25105/petro.v8i4.6209 ◽

2020 ◽

Vol 8 (4) ◽

pp. 163

Author(s):

Samsol Samsol ◽

Kris Pudyastuti ◽

Nicko Matthe Lie

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

High Temperature ◽

Low Temperature ◽

Heat Loss ◽

Calcium Silicate ◽

Foam Glass ◽

The Other

<p><em>Heat loss which occured because heat transfer from high temperature to low temperature is one of major problem in piping design in geothermal. Insulation used to solve the problem. These analysis carried out in 18 inch pipeline in steam field. Calcium silicate, rockwool, and foam glass is selected as 3 materials in these study. These 3 materials have different thermal conductivity, so ability to withstand heat for each of them is different. This research used to determine the best material to solve heat loss. Rockwool is the best material from the other 2 </em></p>

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Maximizing Heat Transfer Through Joint Fin Systems

Journal of Heat Transfer ◽

10.1115/1.2137764 ◽

2005 ◽

Vol 128 (2) ◽

pp. 203-206 ◽

Cited By ~ 7

Author(s):

A.-R. A. Khaled

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Thermal Performance ◽

Critical Length ◽

The Other ◽

Rigid Fixation ◽

Convection Coefficient ◽

Heat Transfer Characteristics ◽

Cold Side ◽

Transfer Characteristics

Heat transfer through joint fins is modeled and analyzed analytically in this work. The terminology “joint fin systems” is used to refer to extending surfaces that are exposed to two different convective media from its both ends. It is found that heat transfer through joint fins is maximized at certain critical lengths of each portion (the receiver fin portion which faces the hot side and the sender fin portion that faces the cold side of the convective media). The critical length of each portion of joint fins is increased as the convection coefficient of the other fin portion increases. At a certain value of the thermal conductivity of the sender fin portion, the critical length for the receiver fin portion may be reduced while heat transfer is maximized. This value depends on the convection coefficient for both fin portions. Thermal performance of joint fins is increased as both thermal conductivity of the sender fin portion or its convection coefficient increases. This work shows that the design of machine components such as bolts, screws, and others can be improved to achieve favorable heat transfer characteristics in addition to its main functions such as rigid fixation properties.

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Thermal conductivity of sandstones from Biot’s coefficient

Geophysics ◽

10.1190/geo2017-0551.1 ◽

2018 ◽

Vol 83 (5) ◽

pp. D173-D185 ◽

Cited By ~ 2

Author(s):

Tobias Orlander ◽

Eirini Adamopoulou ◽

Janus Jerver Asmussen ◽

Adam Andrzej Marczyński ◽

Harald Milsch ◽

...

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Heat Flow ◽

Cross Section ◽

Geometric Mean ◽

Well Log ◽

Biot’S Coefficient ◽

Model Predictions ◽

The Cross ◽

Rock Texture

Thermal conductivity of rocks is typically measured on core samples and cannot be directly measured from logs. We have developed a method to estimate thermal conductivity from logging data, where the key parameter is rock elasticity. This will be relevant for the subsurface industry. Present models for thermal conductivity are typically based primarily on porosity and are limited by inherent constraints and inadequate characterization of the rock texture and can therefore be inaccurate. Provided known or estimated mineralogy, we have developed a theoretical model for prediction of thermal conductivity with application to sandstones. Input parameters are derived from standard logging campaigns through conventional log interpretation. The model is formulated from a simplified rock cube enclosed in a unit volume, where a 1D heat flow passes through constituents in three parallel heat paths: solid, fluid, and solid-fluid in series. The cross section of each path perpendicular to the heat flow represents the rock texture: (1) The cross section with heat transfer through the solid alone is limited by grain contacts, and it is equal to the area governing the material stiffness and quantified through Biot’s coefficient. (2) The cross section with heat transfer through the fluid alone is equal to the area governing fluid flow in the same direction and quantified by a factor analogous to Kozeny’s factor for permeability. (3) The residual cross section involves the residual constituents in the solid-fluid heat path. By using laboratory data for outcrop sandstones and well-log data from a Triassic sandstone formation in Denmark, we compared measured thermal conductivity with our model predictions as well as to the more conventional porosity-based geometric mean. For outcrop material, we find good agreement with model predictions from our work and with the geometric mean, whereas when using well-log data, our model predictions indicate better agreement.

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Gold in Irish Coal: Palaeo-Concentration from Metalliferous Groundwaters

Minerals ◽

10.3390/min10070635 ◽

2020 ◽

Vol 10 (7) ◽

pp. 635

Author(s):

Liam A. Bullock ◽

John Parnell ◽

Joseph G.T. Armstrong ◽

Magali Perez ◽

Sam Spinks

Keyword(s):

Heat Flow ◽

Low Temperature ◽

Precious Metals ◽

High Heat ◽

Selenium Content ◽

Foreland Basins ◽

High Heat Flow ◽

South Wales ◽

First Time ◽

Very High

Gold grains, up to 40 μm in size and containing variable percentages of admixed platinum, have been identified in coals from the Leinster Coalfield, Castlecomer, SE Ireland, for the first time. Gold mineralisation occurs in sideritic nodules in coals and in association with pyrite and anomalous selenium content. Mineralisation here may have reflected very high heat flow in foreland basins north of the emerging Variscan orogenic front, responsible for gold occurrence in the South Wales Coalfield. At Castlecomer, gold (–platinum) is attributed to precipitation with replacive pyrite and selenium from groundwaters at redox interfaces, such as siderite nodules. Pyrite in the cores of the nodules indicates fluid ingress. The underlying Caledonian basement bedrock is mineralised by gold, and thus likely provided a source for gold. The combination of the gold occurrences in coal in Castlecomer and in South Wales, proximal to the Variscan orogenic front, suggests that these coals along the front could comprise an exploration target for low-temperature concentrations of precious metals.

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Diffusion Layer Theory for Turbulent Vapor Condensation With Noncondensable Gases

Journal of Heat Transfer ◽

10.1115/1.2911397 ◽

1993 ◽

Vol 115 (4) ◽

pp. 998-1003 ◽

Cited By ~ 89

Author(s):

P. F. Peterson ◽

V. E. Schrock ◽

T. Kageyama

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Mass Transfer ◽

Vapor Condensation ◽

Sensible Heat ◽

Transfer Coefficients ◽

Heat Transfer Coefficients ◽

Noncondensable Gas ◽

Noncondensable Gases ◽

Vertical Tubes

In turbulent condensation with noncondensable gas, a thin noncondensable layer accumulates and generates a diffusional resistance to condensation and sensible heat transfer. By expressing the driving potential for mass transfer as a difference in saturation temperatures and using appropriate thermodynamic relationships, here an effective “condensation” thermal conductivity is derived. With this formulation, experimental results for vertical tubes and plates demonstrate that condensation obeys the heat and mass transfer analogy, when condensation and sensible heat transfer are considered simultaneously. The sum of the condensation and sensible heat transfer coefficients becomes infinite at small gas concentrations, and approaches the sensible heat transfer coefficient at large concentrations. The “condensation” thermal conductivity is easily applied to engineering analysis, and the theory further demonstrates that condensation on large vertical surfaces is independent of the surface height.

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Efficient Stabilization of Mono and Hybrid Nanofluids

Energies ◽

10.3390/en13153793 ◽

2020 ◽

Vol 13 (15) ◽

pp. 3793

Author(s):

Sylwia Wciślik

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

New Technologies ◽

Industrial Processes ◽

Challenging Tasks ◽

Future Challenges ◽

Hybrid Nanofluids ◽

Very High ◽

Base Liquid ◽

Conductivity Models

Currently; the transfer of new technologies makes it necessary to also control heat transfer in different industrial processes—both in practical and research—applications. Not so long ago water and ethylene glycol were the most frequently used media in heat transfer. However, due to their relatively low thermal conductivity, they cannot provide the fast and effective heat transfer necessary in modern equipment. To improve the heat transfer rate different additives to the base liquid are sought, e.g., nanoadditives that create mono and hybrid nanofluids with very high thermal conductivity. The number of scientific studies and publications concerning hybrid nanofluids is growing, although they still represent a small percentage of all papers on nanofluids (in 2013 it was only 0.6%, and in 2017—ca. 3%). The most important point of this paper is to discuss different ways of stabilizing nanofluids, which seems to be one of the most challenging tasks in nanofluid treatment. Other future challenges concerning mono and hybrid nanofluids are also thoroughly discussed. Moreover, a quality assessment of nanofluid preparation is also presented. Thermal conductivity models are specified as well and new representative mono and hybrid nanofluids are proposed.

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Heat Transfer From Flames Impinging on Flat and Cylindrical Surfaces

Journal of Heat Transfer ◽

10.1115/1.3686009 ◽

1963 ◽

Vol 85 (1) ◽

pp. 49-54 ◽

Cited By ~ 35

Author(s):

J. E. Anderson ◽

E. F. Stresino

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Experimental Investigation ◽

Low Temperature ◽

Chemical Reaction ◽

Heat Transfer Correlation ◽

Theoretical Reasoning ◽

Combustion Systems

An experimental investigation was made to determine the heat-transfer distribution obtained when a flame impinges on flat and cylindrical surfaces. The combustion systems studied were oxygen-hydrogen, oxygen-propane, oxygen-acetylene, and air-methane with combustion stream velocities varying from 1 ft/sec to 4600 ft/sec. Data taken with cylindrical heat-transfer surfaces are consistent with available heat-transfer correlation for low temperature gases provided the effect of chemical reaction on the thermal conductivity for flame temperatures above 3500 deg R is taken into consideration. Data taken with flat heat-transfer surfaces can be correlated quite well in a generalized curve partially based on theoretical reasoning.

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Analysis of Heat Transfer Mechanism for Shelf Vacuum Freeze-Drying Equipment

Advances in Materials Science and Engineering ◽

10.1155/2014/515180 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 2

Author(s):

Hong-Ping Cheng ◽

Shian-Min Tsai ◽

Chin-Chi Cheng

Keyword(s):

Heat Transfer ◽

Heat Exchange ◽

Low Temperature ◽

Temperature Gradient ◽

Freeze Drying ◽

Heat Transfer Fluid ◽

Processing Temperature ◽

Fluid Temperature ◽

Three Dimension ◽

Flow Rates

Vacuum freeze-drying technology is applicable to the process of high heat-sensitive products. Due to the long drying period and extremely low processing temperature and pressure, the uniform and efficiency of heat transfer fluid temperature in shelf are critical for product quality. Therefore, in this study, the commercial computer fluid dynamics (CFD) software, FLUENT, was utilized for three-dimension numerical simulation of the shelf vacuum freeze-drying process. The influences of different inlet and outlet positions for shelves on the uniformity of the flow rate and temperature were discussed. Moreover, it explored the impacts on the temperature gradient of shelves after heat exchange of different flow rates and low temperature materials. In order to reduce the developing time and optimize the design, the various secondary refrigerants in different plies of shelves were investigated. According to the effect of heat exchange between different flow rates and low temperature layer material shelves on the temperature gradient of shelves surface, the minimum temperature gradient was 20 L/min, and the maximum was 2.5 L/min.

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Thermal Performance of Hybrid-Inspired Coolant for Radiator Application

Nanomaterials ◽

10.3390/nano10061100 ◽

2020 ◽

Vol 10 (6) ◽

pp. 1100

Author(s):

F. Benedict ◽

Amit Kumar ◽

K. Kadirgama ◽

Hussein A. Mohammed ◽

D. Ramasamy ◽

...

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Heat Capacity ◽

Specific Heat ◽

Specific Heat Capacity ◽

Volume Concentration ◽

The Other ◽

Hybrid Nanofluid ◽

Hybrid Nanofluids ◽

Tio2 Nanofluids

Due to the increasing demand in industrial application, nanofluids have attracted the considerable attention of researchers in recent decades. The addition of nanocellulose (CNC) with water (W) and ethylene glycol (EG) to a coolant for a radiator application exhibits beneficial properties to improve the efficiency of the radiator. The focus of the present work was to investigate the performance of mono or hybrid metal oxide such as Al2O3 and TiO2 with or without plant base-extracted CNC with varying concentrations as a better heat transfer nanofluid in comparison to distilled water as a radiator coolant. The CNC is dispersed in the base fluid of EG and W with a 60:40 ratio. The highest absorption peak was noticed at 0.9% volume concentration of TiO2, Al2O3, CNC, Al2O3/TiO2, and Al2O3/CNC nanofluids which indicates a better stability of the nanofluids’ suspension. Better thermal conductivity improvement was observed for the Al2O3 nanofluids in all mono nanofluids followed by the CNC and TiO2 nanofluids, respectively. The thermal conductivity of the Al2O3/CNC hybrid nanofluids with 0.9% volume concentration was found to be superior than that of the Al2O3/TiO2 hybrid nanofluids. Al2O3/CNC hybrid nanofluid dominates over other mono and hybrid nanofluids in terms of viscosity at all volume concentrations. CNC nanofluids (all volume concentrations) exhibited the highest specific heat capacity than other mono nanofluids. Additionally, in both hybrid nanofluids, Al2O3/CNC showed the lowest specific heat capacity. The optimized volume concentration from the statistical analytical tool was found to be 0.5%. The experimental results show that the heat transfer coefficient, convective heat transfer, Reynolds number and the Nusselt number have a proportional relationship with the volumetric flow rate. Hybrid nanofluids exhibit better thermal conductivity than mono nanofluids. For instance, a better thermal conductivity improvement was shown by the mono Al2O3 nanofluids than the CNC and TiO2 nanofluids. On the other hand, superior thermal conductivity was observed for the Al2O3/CNC hybrid nanofluids compared to the other mono and hybrid ones (Al2O3/TiO2).

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