scholarly journals Numerical Investigation on Two-Phase Flow Heat Transfer Performance and Instability with Discrete Heat Sources in Parallel Channels

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4408
Author(s):  
Changming Hu ◽  
Rui Wang ◽  
Ping Yang ◽  
Weihao Ling ◽  
Min Zeng ◽  
...  
Keyword(s):  
Heat Source ◽  
Heat Transfer Performance ◽  
Source Distribution ◽  
Phase Flow ◽  
Heat Sources ◽  
Two Phase ◽  
Discrete Heat Sources ◽  
Discrete Heat Source ◽  
Parallel Channels ◽  
Heat Source Distribution

With the rapid development of integrated circuit technology, the heat flux of electronic chips has been sharply improved. Therefore, heat dissipation becomes the key technology for the safety and reliability of the electronic equipment. In addition, the electronic chips are distributed discretely and used periodically in most applications. Based these problems, the characteristics of the heat transfer performance of flow boiling in parallel channels with discrete heat source distribution are investigated by a VOF model. Meanwhile, the two-phase flow instability in parallel channels with discrete heat source distribution is analyzed based on a one-dimensional homogeneous model. The results indicate that the two-phase flow pattern in discrete heat source distribution is more complicated than that in continuous heat source distribution. It is necessary to optimize the relative position of the discrete heat sources, which will affect the heat transfer performance. In addition, compared with the continuous heat source, the flow stability of discrete heat sources is better with higher and lower inlet subcooling. With a constant sum of heating power, the greater the heating power near the outlet, the better the flow stability.

scholarly journals The influence of heat source distribution on the space cooling load oriented to local thermal requirements

2019 ◽  
pp. 1420326X1989163
Author(s):  
Chao Liang ◽  
Arsen Krikor Melikov ◽  
Xianting Li
Keyword(s):  
Heat Source ◽  
Source Distribution ◽  
Thermal Plume ◽  
Cooling Load ◽  
Heat Sources ◽  
Local Cooling ◽  
Thermal Requirements ◽  
Space Cooling ◽  
Airflow Field ◽  
Heat Source Distribution

Existing studies have shown that the space cooling load oriented to local thermal requirements is significantly influenced by different heat source distributions. However, numerical methods have been mainly used in the analysis based on a fixed airflow field and ignoring the thermal plume. Here, an experiment in a chamber with mixing ventilation was conducted. The heat sources were simulated by metal barrels and an oil-filled radiator, 13 types of heat source distributions were designed and the local cooling load (LCL) was used as the evaluation index. The results show that (1) the LCL is equal to the total amount of heat sources at the steady state in a room with mixing ventilation only if the heat sources are also distributed uniformly; (2) the LCL decreases with a decrease in the intensity of heat sources, achieving a decrease rate of 47.4%–70.8% in the experiment with different intensities; (3) the LCL is 9.2%–22.3% lower than the total amount of heat sources when these are located near the exhaust diffuser or far away from the target zone; (4) owing to its smaller surface area, the LCL with an oil-filled radiator is 7% lower than that with five metal barrels.

scholarly journals Forced Convection through Discrete Heat Sources and Simple Thermal Model – A Numerical Study

2019 ◽  
Vol 4 (6) ◽  
pp. 1397-1406
Author(s):  
Kartikaswami Hasavimath ◽  
Kishan Naik ◽  
Banjara Kotresha ◽  
N. Gnanasekaran
Keyword(s):  
Heat Source ◽  
Forced Convection ◽  
Thermal Model ◽  
Conjugate Heat Transfer ◽  
Numerical Study ◽  
Vertical Channel ◽  
Heat Sources ◽  
Discrete Heat Sources ◽  
Discrete Heat Source ◽  
Bottom Heat

In this work a forced convection through discrete heat sources and simple thermal model placed inside the vertical channel is analyzed numerically. The problem considered for the investigation comprises of a vertical channel with distinct heat source assembly located at the center of the channel. The novelty of the present work is to replace the discrete heat source assembly by a simple thermal model to obtain uniformly distributed temperature and streamlines. A conjugate heat transfer investigation is carried out because the problem domain consists of aluminum solid strips as well as Bakelite strips in discrete heat source assembly which are replaced by a aluminum solid in case of simple thermal model. The numerically obtained data are initially compared with experimental data for the purpose of validation. The temperature of each discrete sources decrease with increase in inlet velocity of the fluid and bottom heat source is able to take higher heat load. The results in terms excess temperature obtained for both discrete heat source and simple thermal model is presented and discussed.

Optimal Distribution of Heat Sources in Convergent Channels Cooled by Laminar Forced Convection

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
E. Jassim ◽  
Y. S. Muzychka
Keyword(s):  
Heat Source ◽  
Leading Edge ◽  
Constructal Theory ◽  
Source Distribution ◽  
Heat Sources ◽  
Optimal Distribution ◽  
Convergent Channel ◽  
Freestream Velocity ◽  
Heat Source Distribution ◽  
Laminar Forced Convection

The constructal theory is applied to the flow in a convergent channel. The primary goals of this work are to analyze the heat source distribution and generalize the formula concerning such configurations, to study the spacing between consecutive elements, and to verify the analysis by comparing the proposed configuration with numerical simulations. The results show that nonuniform distributions enhance the performance of the system by allowing the heat source element to work near its maximum condition. Furthermore, the optimal distribution occurs when the heat sources are placed closer to each other near the leading edge of the channel. While the literature shows that the spacing between any consecutive element increases as the sources move downstream from the leading edge, the present results proved that such conclusions are restricted, depending on the ratio of outlet to inlet freestream velocity. Accordingly, the spacing has a maximum value when the exit freestream velocity is more than twice that of the inlet. For design issues, the study also addresses the minimum heat required to achieve optimal system performance. The results show that the amount of heat needed by the system to work close to its optimal performance varies exponentially with the convergent angle and increases with the increase in the heating element’s width. The comparison of the present distribution of the heat source elements with a regular one (fixed spacing) is performed numerically to demonstrate the efficiency of the proposed configuration. The results show that the present model forces the system to work more efficiently than the uniform distribution.

scholarly journals Assessing Heavy Industrial Heat Source Distribution in China Using Real-Time VIIRS Active Fire/Hotspot Data

2018 ◽  
Vol 10 (12) ◽  
pp. 4419 ◽  
Author(s):  
Caihong Ma ◽  
Jin Yang ◽  
Fu Chen ◽  
Yan Ma ◽  
Jianbo Liu ◽  
...  
Keyword(s):  
Economic Development ◽  
Heat Source ◽  
Infrared Imaging ◽  
Mainland China ◽  
Processing System ◽  
Source Distribution ◽  
Heavy Industry ◽  
Rapid Urbanization ◽  
Active Fire ◽  
Heat Source Distribution

Rapid urbanization and economic development have led to the development of heavy industry and structural re-equalization in mainland China. This has resulted in scattered and disorderly layouts becoming prominent in the region. Furthermore, economic development has exacerbated pressures on regional resources and the environment and has threatened sustainable and coordinated development in the region. The NASA Land Science Investigator Processing System (Land-SIPS) Visible Infrared Imaging Radiometer (VIIRS) 375-m active fire product (VNP14IMG) was selected from the Fire Information for Resource Management System (FIRMS) to study the spatiotemporal patterns of heavy industry development. Furthermore, we employed an improved adaptive K-means algorithm to realize the spatial segmentation of long-order VNP14IMG and constructed heat source objects. Lastly, we used a threshold recognition model to identify heavy industry objects from normal heat source objects. Results suggest that the method is an accurate and effective way to monitor heat sources generated from heavy industry. Moreover, some conclusions about heavy industrial heat source distribution in mainland China at different scales were obtained. Those can be beneficial for policy-makers and heavy industry regulation.

Experimental Study of Linear and Radial Two-Phase Heat Transport Devices Driven by Electrohydrodynamic Conduction Pumping

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Matthew R. Pearson ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Heat Source ◽  
Capillary Pressure ◽  
Heat Transport ◽  
Radial Direction ◽  
Heat Pipes ◽  
Working Fluid ◽  
Phase Flow ◽  
Transport Capacity ◽  
Two Phase ◽  
Capillary Phenomenon

Heat pipes are well known as simple and effective heat transport devices, utilizing two-phase flow and the capillary phenomenon to remove heat. However, the generation of capillary pressure requires a wicking structure and the overall heat transport capacity of the heat pipe is generally limited by the amount of capillary pressure generation that the wicking structure can achieve. Therefore, to increase the heat transport capacity, the capillary phenomenon must be either augmented or replaced by some other pumping technique. Electrohydrodynamic (EHD) conduction pumping can be readily used to pump a thin film of a dielectric liquid along a surface, using electrodes that are embedded into the surface. In this study, two two-phase heat transport devices are created. The first device transports the heat in a linear direction. The second device transports the heat in a radial direction from a central heat source. The radial pumping configuration provides several advantages. Most notably, the heat source is wetted with fresh liquid from all directions, thereby reducing the amount of distance that must be travelled by the working fluid. The power required to operate the EHD conduction pumps is a trivial amount relative to the heat that is transported.

scholarly journals Convection in an internally heated stratified heterogeneous reservoir

2019 ◽  
Vol 870 ◽  
pp. 67-105 ◽  
Author(s):  
Angela Limare ◽  
Claude Jaupart ◽  
Edouard Kaminski ◽  
Loic Fourel ◽  
Cinzia G. Farnetani
Keyword(s):  
Heat Source ◽  
Scaling Laws ◽  
Lower Layer ◽  
Thermal Structure ◽  
Internal Heat ◽  
Source Distribution ◽  
Heat Sources ◽  
Homogeneous Fluid ◽  
Earth’S Mantle ◽  
Lower Fluid

The Earth’s mantle is chemically heterogeneous and probably includes primordial material that has not been affected by melting and attendant depletion of heat-producing radioactive elements. One consequence is that mantle internal heat sources are not distributed uniformly. Convection induces mixing, such that the flow pattern, the heat source distribution and the thermal structure are continuously evolving. These phenomena are studied in the laboratory using a novel microwave-based experimental set-up for convection in internally heated systems. We follow the development of convection and mixing in an initially stratified fluid made of two layers with different physical properties and heat source concentrations lying above an adiabatic base. For relevance to the Earth’s mantle, the upper layer is thicker and depleted in heat sources compared to the lower one. The thermal structure tends towards that of a homogeneous fluid with a well-defined time constant that scales with $Ra_{H}^{-1/4}$, where $Ra_{H}$ is the Rayleigh–Roberts number for the homogenized fluid. We identified two convection regimes. In the dome regime, large domes of lower fluid protrude into the upper layer and remain stable for long time intervals. In the stratified regime, cusp-like upwellings develop at the edges of large basins in the lower layer. Due to mixing, the volume of lower fluid decreases to zero over a finite time. Empirical scaling laws for the duration of mixing and for the peak temperature difference between the two fluids are derived and allow extrapolation to planetary mantles.

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