Numerical Study on Heat Transfer Enhanced in a Microcombustor With Staggered Cylindrical Array for Micro-Thermophotovoltaic System

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Haojie Li ◽  
Yanrong Chen ◽  
Yunfei Yan ◽  
Cheng Hu ◽  
Hu Fan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Equivalence Ratio ◽  
Numerical Study ◽  
High Heat ◽  
Stable Combustion ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Study Results ◽  
Ratio Range ◽  
Cylindrical Array

In consideration of high heat transfer efficiency and stable combustion, a new type of microplanar combustor for micro-thermophotovoltaic (micro-TPV) system is proposed, in which the heat transfer is enhanced by staggered cylindrical array. The numerical study results indicate that the temperature of radiation wall of cylindrical-array combustor is higher and more uniform comparing with the conventional-channel combustor, the application of cylindrical-array make the effective radiation of the combustor increase 34.55% and reach to 35.98 W. Moreover, with inlet velocity increase from 4 m/s to 16 m/s, the cylindrical-array combustor shows the better stability of combustion, which the position of the flame moves 4.8 mm in the cylindrical-array combustor and 9.1 mm in the conventional-channel combustor. However, the 0.5–4.5 equivalence ratio range for stable combustion is slightly narrower than 0.4–6.0 in the conventional-channel combustor. To extend the equivalence ratio range, one row of cylindrical array was canceled, and the distribution length of cylindrical array was reduced to 10 mm, After this improvement, the equivalence ratio range is extended to 0.3–5.5, and the negative effect on the flame stability of the cylindrical array is basically eliminated.

Numerical Study on the Effect of Dislocation Relationship on Resistance Characters of the Ceramic Oxidation Bed Based on Fluent Software

2011 ◽  
Vol 347-353 ◽  
pp. 3798-3803
Author(s):  
Yong Qi Liu ◽  
Xiang Chun Chen
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Numerical Study ◽  
High Heat ◽  
Transfer Efficiency ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Fluent Software ◽  
Resistance Loss ◽  
Overall Resistance

As ceramic oxidation bed has high heat transfer efficiency, now, great attention has been given on it. In the oxidation bed, between the honeycomb holes of the fore-and-aft blocks of ceramic honeycombs, there are dislocation relationships. The effect of dislocation relationship on the pressure drop of the oxidation bed was numerically simulated by Fluent software. The results show that, between the two blocks of closely adjacent ceramic honeycombs, when a gap distance of 1mm was left, compared to the situation the gap distance is 0, the overall resistance loss of the oxidation bed reduced vast.

scholarly journals Numerical Study of Flow Maldistribution in Multi-Plate Heat Exchangers Based on Robust 2D Model

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3121 ◽  
Author(s):  
Arkadiusz Brenk ◽  
Pawel Pluszka ◽  
Ziemowit Malecha
Keyword(s):  
Heat Exchangers ◽  
Numerical Study ◽  
High Heat ◽  
Pressure Balance ◽  
Plate Heat ◽  
Pressure Losses ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Wide Range ◽  
Flow Maldistribution

Plate heat exchangers (PHE) are characterized by high heat transfer efficiency and compactness. An exploitation problem of the PHE is related to flow maldistribution, which can make part of the PHE idle, resulting in overheating and damage. Making geometrical modifications to the PHE can help reduce flow maldistribution. Modifications should be kept to a minimum, so as not to complicate the production process. There is a large number of possible geometrical modifications, which simply considers additional obstacles or stream dividers. To test all of them would be impractical and would also take a prohibitively long amount of time to obtain experimental measurements. A typical PHE is characterized by a complex system of channels. Making numerical calculations of its 3D model can be prohibitively time and resource-consuming. The present work introduces a physically consistent methodology of the transformation of a real 3D geometry to its 2D representation. Its main novelty is to assure the same pressure drop balance remains between the 3D and 2D geometries. This is achieved by a preservation of the same cumulative pressure losses in both geometries. The proposed innovative approach levels the pressure balance difference by adding properly designed local geometrical modifications. The developed methodology allowed a wide range of parameter space and various geometrical modifications to be investigated, and revealed geometrical optimizations leading to the improved performance of the PHE. To minimize the influence of other factors, an incompressible and single-phase flow was studied.

Numerical Study of the Heat Transfer in Micro Gas Turbines

2006 ◽  
Vol 129 (4) ◽  
pp. 835-841 ◽  
Author(s):  
T. Verstraete ◽  
Z. Alsalihi ◽  
R. A. Van den Braembussche
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Numerical Study ◽  
Three Dimensional ◽  
High Heat ◽  
Large Temperature ◽  
Radial Compressor ◽  
Micro Gas Turbine ◽  
High Heat Transfer ◽  
The Impact

This paper presents a numerical investigation of the heat transfer inside a micro gas turbine and its impact on the performance. The large temperature difference between turbine and compressor in combination with the small dimensions results in a high heat transfer causing a drop in efficiency of both components. Present study aims to quantify this heat transfer and to reveal the different mechanisms that contribute to it. A conjugate heat transfer solver has been developed for this purpose. It combines a three-dimensional (3D) conduction calculation inside the rotor and the stator with a 3D flow calculation in the radial compressor, turbine and gap between stator and rotor. The results for micro gas turbines of different size and shape and different material characteristics are presented and the impact on performance is evaluated.

Research on the Heat Transfer Characteristics of Receiver in Designed Solar Direct Steam Generation System

2014 ◽  
Vol 472 ◽  
pp. 286-290
Author(s):  
Jing Long Du ◽  
Xiang Huang ◽  
Da Wei Tang
Keyword(s):  
Heat Transfer ◽  
High Heat ◽  
Stable Operation ◽  
Steam Generation ◽  
Generation System ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Direct Steam ◽  
Attractive Option ◽  
Simulation Results

The direct steam generation (DSG) with parabolic collector is an attractive option regarding the economic improvement of parabolic technology for solar thermal electricity generation system. On the basis of theory analysis of flow and heat transfer mechanism in the DSG system, this paper presents the numerical simulation results of one 650 meters loop under different direct normal irradiation values, performance parameters such as water temperature, heat transfer coefficient and dryness of the fluid in the absorber pipe are obtained in the simulation results. This paper shows that fluids parameters are susceptible to the solar direct normal values , high heat transfer efficiency and sensitive control system are the key to ensure DSG systems stable operation.

scholarly journals Enhanced Heat Transfer Characteristics of Graphite Concrete and Its Application in Energy Piles

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Qingwen Li ◽  
Lu Chen ◽  
Haotian Ma ◽  
Chung-Ho Huang
Keyword(s):  
Heat Transfer ◽  
High Heat ◽  
Transfer Efficiency ◽  
Heat Transfer Characteristics ◽  
Enhanced Heat Transfer ◽  
Energy Pile ◽  
Transfer Characteristics ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Energy Piles

The latest research on energy piles demonstrates that most scholars are focusing their attention on optimization by designing more efficient heat exchanger coils, analyzing the heat pump matching parameters, and so on. However, after more than 20 years of development, these traditional methods for improving the heat transfer efficiency of energy piles have reached a bottleneck, and a new approach for the continued enhancement of this technology must be investigated. In this study, powdered graphite with high heat transfer characteristics was included in a concrete mix to create graphite concrete piles with enhanced heat transfer characteristics. The results from theoretical analysis, laboratory testing, and numerical simulation indicate that using graphite to improve the heat transfer efficiency of a concrete material is an effective method for enhancing the thermal efficiency of an energy pile system. The research results also show that the heat transfer coefficient of the concrete exhibits greater improvement when the graphite content is greater than 15% under the same environmental temperature. After studying the performance of the proposed graphite concrete energy pile under different environmental temperatures (10°C, 20°C, 30°C, and 40°C), the results indicate that the working efficiency of the energy pile is better in the summer than in the winter. Finally, parameters such as the cast-in pipe configuration and pile spacing are optimized.

Decreasing the Fouling of Heat Exchanger Plates Using Air Bubbles

2010 ◽  
Vol 297-301 ◽  
pp. 1199-1204 ◽  
Author(s):  
Seung Moon Baek ◽  
Won Sil Seol ◽  
Ho Saeng Lee ◽  
Jung In Yoon
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Environmental Pollution ◽  
High Heat ◽  
Air Bubbles ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Heat Exchanger Plate ◽  
Removal Equipment ◽  
Exchanger Plate

The heat transfer performance of heat exchanger plate decreases as time goes by. The main reason for this phenomenon is the fouling of the heat exchanger plates. To remove the fouling, we have usually cleaned the plate of heat exchanger using chemicals or polishing brush or cloth with hand after stopping the equipment and disassembling the heat exchanger. However, to clean the plate using these methods, the heat exchanger equipment needs to be stopped and disjointed. In addition, it must be re-jointed after cleaning. Especially, the concern of environmental pollution happens in case of using chemicals. Therefore, we need to develop an automatic fouling removal equipment which can continuously keep high heat transfer efficiency and solve the problem of environmental pollution. So, in this paper, we developed and tested the equipment which can clean the fouling on heat exchanger plates automatically per constant period and interval using air bubbles. The total heat transfer coefficient decreased with a slower tendency when using air bubbles compared to the existing methods. There was 10% higher heat transfer effect air bubbles every 10 minutes for 2 hours to remove the fouling ingredients on the heat transfer surface area concerned to the case without air bubbles after 192 hours.

scholarly journals Heat Transfer and Bearing Characteristics of Energy Piles: Review

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6483
Author(s):  
Jinli Xie ◽  
Yinghong Qin
Keyword(s):  
Heat Transfer ◽  
Low Cost ◽  
High Heat ◽  
Heat Pumps ◽  
Transfer Efficiency ◽  
Ground Source Heat Pumps ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Energy Piles ◽  
Composite Energy

Energy piles, combined ground source heat pumps (GSHP) with the traditional pile foundation, have the advantages of high heat transfer efficiency, less space occupation and low cost. This paper summarizes the latest research on the heat transfer and bearing capacity of energy piles. It is found that S-shaped tubes have the largest heat transfer area and the best heat transfer efficiency; that energy piles need to be designed conservatively, such as adjusting the safety coefficient, number and spacing of the piles according to the additional temperature loads; and that unbalanced surface temperature has not been resolved, caused by uneven refrigeration/heating demand in one cycle. A composite energy pile applied to water-rich areas is proposed to overcome the decay of bearing and heat transfer performance. Besides, most of the heat transfer models are borehole-oriented and will fit for energy piles effectively if the models support variable ground temperature boundary conditions.

Numerical Study of the Heat Transfer in Micro Gasturbines

2006 ◽  
Author(s):  
T. Verstraete ◽  
Z. Alsalihi ◽  
R. A. Van den Braembussche
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Numerical Investigation ◽  
Conjugate Heat Transfer ◽  
Numerical Study ◽  
High Heat ◽  
3D Flow ◽  
Radial Compressor ◽  
High Heat Transfer ◽  
The Impact

This paper presents a numerical investigation of the heat transfer inside a micro gasturbine and its impact on the performance. The high temperature difference between turbine and compressor in combination with the small dimensions results in a high heat transfer causing a drop in efficiency of both components. Present study aims to quantify this heat transfer and to reveal the different mechanisms that contribute to it. A conjugate heat transfer solver has been developed for this purpose. It combines a 3D conduction calculation inside the rotor and the stator with a 3D flow calculation in the radial compressor, turbine and gap between stator and rotor. The results for micro gasturbines of different size and shape and different material characteristics are presented and the impact on performance is evaluated.

Research on Trait in Heat Exchange and Flow of Inner Single-Phase Currentin Micro Channel

2012 ◽  
Vol 516-517 ◽  
pp. 408-413 ◽  
Author(s):  
Yue Lian Hu
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Single Phase ◽  
Fluid Dynamic ◽  
High Heat ◽  
Micro Channel ◽  
Heat Transfer Efficiency ◽  
Flow And Heat Transfer ◽  
High Heat Transfer ◽  
Phase Water

During recent years,micro-channel heat transfer technique has been successfully used in many practical situations，and has notable advantages of high heat transfer efficiency and compact configuration.It is an important subject in modern hydrodynamic and heat transfer research field.Computational fluid dynamic program CFX will be used in this article to simulate flow and heat transfer of single-phase water in micro-channel ,flow and temperature felid will be described visually in CFX, and this object is searching a new method to research more flow and heat transfer of single-phase water.

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