A source-sink approach for computation of intensity of low-potential underground heat non-stationary extraction

2020 ◽  
Vol 5 ◽  
pp. 28-36
Author(s):  
Dmitry Saponenko ◽  
Boris Semenov
Keyword(s):  
Heat Transfer ◽  
Heat Removal ◽  
Heat Extraction ◽  
Transfer Resistance ◽  
Intensity Estimation ◽  
Linear Heat ◽  
Ground Types ◽  
Single Pipe ◽  
Source Sink ◽  
Stationary Heat Transfer

A new methodology for estimation of changing intensity characteristics of non-stationary heat transfer in underground heat extraction by a single-pipe upright heat exchanger is presented in this paper. Major trends in changing of a heat removal volume, linear heat transfer coefficient, linear heat transfer resistance, and heat sink radius have been estimated for specific ground types. Also a generalized one-factor linear semilogarythmic equation has been developed for specific ground types, along with an appropriate approximating function intended to simplify the underground heat extraction intensity estimation methodology.

scholarly journals Development of technology to ensure minimal thermal resistance between mating surfaces while simulating outer space conditions

2019 ◽  
Vol 3 (4) ◽  
pp. 216-221
Author(s):  
E. A. Starostin ◽  
A. P. Lebedev ◽  
M. S. Moskovskih ◽  
E. P. Maslov
Keyword(s):  
Heat Transfer ◽  
Outer Space ◽  
Heat Removal ◽  
Thermal Control ◽  
Electronic Equipment ◽  
Thermal Mode ◽  
Transfer Scheme ◽  
Transfer Resistance ◽  
Radio Electronic

The transition to the leaky design of the instrument compartment of the spacecraft inevitably leads to additional thermal loads on the components of the onboard electronic equipment due to a change in the heat transfer scheme. The thermal mode of operation of the onboard radio-electronic equipment of the spacecraft is one of the important factors for ensuring the long term active existence of the spacecraft. Ensuring the long term of active existence of spacecraft is the most important scientific, engineering and economic task, the solution of which requires a deep systematic approach at all stages of the creation and operation of onboard electronic equipment of the spacecraft. The strategic objective for ensuring the long term of the spacecraft’s active existence is the implementation at all stages of the life cycle of onboard radio-electronic equipment of the highest achievable reliability indicators through the using of modern design and technological solutions, as well as effective methods for its design and production. This article presents the results of experimental work to reduce heat transfer resistance between onboard electronic equipment and the spacecraft’s thermal control system. As a result of the work, the main data were obtained on improving the heat sink efficiency of the energy-converting equipment of the spacecraft, the effectiveness of measures to ensure heat removal of the onboard radio-electronic equipment of the spacecraft was confirmed.

scholarly journals MATHEMATICAL MODELING OF HEAT TRANSMISSION THROUGH THE ENCLOSURE CONSTRUCTION

2020 ◽  
pp. 29-39
Author(s):  
A. Grazhdankin ◽  
V. Ivanchenko ◽  
A. Pis'menskiy
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Temperature Distribution ◽  
Dissimilar Materials ◽  
Building Envelope ◽  
Transfer Resistance ◽  
Space Planning ◽  
Air Temperatures ◽  
The Mathematical Model ◽  
Stationary Heat Transfer

Currently, the main direction of energy saving in mass construction is the energy efficiency of structural and space-planning solutions of buildings and structures. To evaluate the thermotechnical qualities of the enclosure, it is necessary to know the value of the heat transfer resistance and the temperature in any plane of the enclosure at given air temperatures on one and the other side of the enclosure. To understand and describe the processes of heat transfer, as well as to determine the temperature distribution inside the enclosing structures, Tabunshchikov Y.A. and Brodach M.M. derived a mathematical model of heat transfer through the enclosing structure. When considering one-dimensional heat transfer perpendicular to the wall surface at the internal borders between dissimilar materials of the building envelope, it is assumed that the temperature functions T (x) and the heat flow Q (x) are continuous. The article presents an analytical and numerical solution of a boundary value problem for stationary heat transfer through a multilayer enclosing structure, as well as a comparison of the obtained solution with the current regulatory documentation. An experimental study is conducted in the laboratory to compare the theoretical, obtained in the mathematical model of heat transfer given in the article, and the experimental temperature distribution, which shows greater convergence of the results and confirms the validity of the mathematical model.

INFLUENCE OF HEAT TREATMENT OF MOUNTAIN MASSIVE ON TEMPERATURE MODE OF GEOTHERMAL CIRCULATION SYSTEM

2018 ◽  
pp. 44-50
Author(s):  
Yu. P. Morozov
Keyword(s):  
Heat Transfer ◽  
Operating Time ◽  
Fluid Motion ◽  
Coolant Temperature ◽  
Circulation System ◽  
Thermal Processes ◽  
Temperature Mode ◽  
Heat Influx ◽  
Stationary Heat Transfer

Based on the solution of the problem of non-stationary heat transfer during fluid motion in underground permeable layers, dependence was obtained to determine the operating time of the geothermal circulation system in the regime of constant and falling temperatures. It has been established that for a thickness of the layer H <4 m, the influence of heat influxes at = 0.99 and = 0.5 is practically the same, but for a thickness of the layer H> 5 m, the influence of heat inflows depends significantly on temperature. At a thickness of the permeable formation H> 20 m, the heat transfer at = 0.99 has virtually no effect on the thermal processes in the permeable formation, but at = 0.5 the heat influx, depending on the speed of movement, can be from 50 to 90%. Only at H> 50 m, the effect of heat influx significantly decreases and amounts, depending on the filtration rate, from 50 to 10%. The thermal effect of the rock mass with its thickness of more than 10 m, the distance between the discharge circuit and operation, as well as the speed of the coolant have almost no effect on the determination of the operating time of the GCS in constant temperature mode. During operation of the GCS at a dimensionless coolant temperature = 0.5, the velocity of the coolant is significant. With an increase in the speed of the coolant in two times, the error changes by 1.5 times.

scholarly journals Numerical Investigation on the Influence of Surface Flow Direction on the Heat Transfer Characteristics in a Granite Single Fracture

2021 ◽  
Vol 11 (2) ◽  
pp. 751
Author(s):  
Xuefeng Gao ◽  
Yanjun Zhang ◽  
Zhongjun Hu ◽  
Yibin Huang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Rate ◽  
Flow Direction ◽  
Heat Extraction ◽  
Geothermal System ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Heat Transfer Capacity

As fluid passes through the fracture of an enhanced geothermal system, the flow direction exhibits distinct angular relationships with the geometric profile of the rough fracture. This will inevitably affect the heat transfer characteristics in the fracture. Therefore, we established a hydro-thermal coupling model to study the influence of the fluid flow direction on the heat transfer characteristics of granite single fractures and the accuracy of the numerical model was verified by experiments. Results demonstrate a strong correlation between the distribution of the local heat transfer coefficient and the fracture morphology. A change in the flow direction is likely to alter the transfer coefficient value and does not affect the distribution characteristics along the flow path. Increasing injection flow rate has an enhanced effect. Although the heat transfer capacity in the fractured increases with the flow rate, a sharp decline in the heat extraction rate and the total heat transfer coefficient is also observed. Furthermore, the model with the smooth fracture surface in the flow direction exhibits a higher heat transfer capacity compared to that of the fracture model with varying roughness. This is attributed to the presence of fluid deflection and dominant channels.

Investigation Into Thermal Stress Characteristics of Pipe-in-Pipe Under High Temperature Condition

2018 ◽  
Author(s):  
Si-Hwa Jeong ◽  
Min-Gu Won ◽  
Nam-Su Huh ◽  
Yun-Jae Kim ◽  
Young-Jin Oh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
High Temperature ◽  
Temperature Distribution ◽  
Heat Transfer Analysis ◽  
Piping System ◽  
Curved Pipe ◽  
High Temperature Condition ◽  
Single Pipe ◽  
Radiation Conditions

In this paper, the thermal stress characteristics of the pipe-in-pipe (PIP) system under high temperature condition are analyzed. The PIP is a type of pipe applied in sodium-cooled faster reactor (SFR) and has a different geometry from a single pipe. In particular, under the high temperature condition of the SFR, the high thermal stress is generated due to the temperature gradient occurring between the inner pipe and outer pipe. To investigate the thermal stress characteristics, three cases are considered according to geometry of the support. The fully constrained support and intermediate support are considered for case 1 and 2, respectively. For case 3, both supports are applied to the actual curved pipe. The finite element (FE) analyses are performed in two steps for each case. Firstly, the heat transfer analysis is carried out considering the thermal conduction, convection and radiation conditions. From the heat transfer analysis, the temperature distribution results in the piping system are obtained. Secondly, the structural analysis is performed considering the temperature distribution results and boundary conditions. Finally, the effects of the geometric characteristics on the thermal stress in the PIP system are analyzed.

Predicting heat extraction due to boiling in the cooling channels during the pressure die casting process

2000 ◽  
Vol 214 (3) ◽  
pp. 465-482 ◽  
Author(s):  
L D Clark ◽  
I Rosindale ◽  
K Davey ◽  
S Hinduja ◽  
P J Dooling
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Die Casting ◽  
Casting Process ◽  
Nucleate Boiling ◽  
Heat Extraction ◽  
Film Boiling ◽  
Cooling Channels ◽  
Die Casting Process ◽  
Pressure Die Casting

The effect of boiling on the rate of heat extraction by cooling channels employed in pressure die casting dies is investigated. The cooling effect of the channels is simulated using a model that accounts for subcooled nucleate boiling and transitional film boiling as well as forced convection. The boiling model provides a continuous relationship between the rate of heat transfer and temperature, and can be applied to surfaces where forced convection, subcooled nucleate boiling and transitional film boiling are taking place in close proximity. The effects of physical parameters such as flow velocity, degree of subcooling, system pressure and bulk temperature are taken into account. Experimental results are obtained using a rig that simulates the pressure die casting process. The results are compared with the model predictions and are found to show good agreement. Instrumented field tests, on an industrial die casting machine, are also reported. These tests show the beneficial effects of boiling heat transfer in the pressure die casting process, including a 75 per cent increase in the production rate for the test component.

scholarly journals Simultaneous impacts of Joule heating and variable heat source/sink on MHD 3D flow of Carreau-nanoliquids with temperature dependent viscosity

2019 ◽  
Vol 8 (1) ◽  
pp. 356-367 ◽  
Author(s):  
J. V. Ramana Reddy ◽  
V. Sugunamma ◽  
N. Sandeep
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Joule Heating ◽  
Uniform Space ◽  
Weissenberg Number ◽  
Physical Parameters ◽  
Temperature Dependent ◽  
3D Flow ◽  
Temperature Dependent Viscosity ◽  
Source Sink

Abstract The 3D flow of non-Newtonian nanoliquid flows past a bidirectional stretching sheet with heat transfer is investigated in the present study. It is assumed that viscosity of the liquid varies with temperature. Carreau non-Newtonain model, Tiwari and Das nanofluid model are used to formulate the problem. The impacts of Joule heating, nonlinear radiation and non-uniform (space and temperature dependent) heat source/sink are accounted. Al-Cu-CH3OH and Cu-CH3OH are considered as nanoliquids for the present study. The solution of the problem is attained by the application of shooting and R.K. numerical procedures. Graphical and tabular illustrations are incorporated with a view of understanding the influence of various physical parameters on the flow field. We eyed that using of Al-Cu alloy nanoparticles in the carrier liquid leads to superior heat transfer ability instead of using only Aluminum nanoparticles. Weissenberg number and viscosity parameter have inclination to exalt the thermal field.

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