Heat Transfer Optimization of end Winding Rotor Generator by the Use of Modified Axial Spacer: A Case Study

Abstract In this paper, transient analysis on heat transfer across the residential building roof having various materials like wood wool, phase change material and weathering tile is performed by numerical simulation technique. 2-dimensional roof model is created, checked for grid independency and validated with the experimental results. Three different roof structures are included in this study namely roof with (i). Concrete and weathering tile, (ii). Concrete, phase change material and weathering tile and (iii). Concrete, phase change material, wood wool and weathering tile. Roof type 3 restricts 13% of heat entering the room in comparison with roof having only concrete and weathering tile. Also the effect of various roof layers’ thickness in the roof type 3 is investigated and identified that the wood wool plays the major role in arresting the entry of heat in to the room. The average reduction of heat is about 10 % for an increase of a unit thickness of wood wool layer.

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Investigation of Heat Transfer for Shell-Tube Fuel-Cooled Heat Exchanger

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.378.459 ◽

2013 ◽

Vol 378 ◽

pp. 459-465

Author(s):

Ya Guo Lu ◽

Peng Fei Zhu

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Relative Error ◽

Absolute Error ◽

Heat Transfer Characteristics ◽

Shell Side ◽

Transfer Characteristics ◽

Aero Engine ◽

The Absolute

A calculate method based on ε-NTU model for heat transfer characteristics of shell-tube fuel-cooled heat exchanger of aero-engine lubrication system was built. The heat convection coefficient was obtained by a dimensionless curve (Re~StPr2/3), which was detailed introduced as well. A case study was executed at last. The absolute error of the outlet lubrication of the tube side and the shell side between the value of calculation and experiment was less than ±10°C, and the relative error was less than 6.5%. The absolute error of the heat transferred between calculation and experiment was less than ±0.9kW, and the relative error was less than 7.4%. It indicates that the mothod is available for the investigation of heat transfer characteristics of shell-tube fuel-cooled heat exchanger.

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Heat Transfer Optimization of NEXA Ballard Low-Temperature PEMFC

Energies ◽

10.3390/en14082182 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2182

Author(s):

Artem Chesalkin ◽

Petr Kacor ◽

Petr Moldrik

Keyword(s):

Heat Transfer ◽

Fuel Cell ◽

Low Temperature ◽

Stable Condition ◽

Energy System ◽

Proton Exchange ◽

Cfd Modeling ◽

Heat Distribution ◽

Operation Conditions ◽

Heat Transfer Optimization

Hydrogen is one of the modern energy carriers, but its storage and practical use of the newest hydrogen technologies in real operation conditions still is a task of future investigations. This work describes the experimental hydrogen hybrid energy system (HHS). HHS is part of a laboratory off-grid system that stores electricity gained from photovoltaic panels (PVs). This system includes hydrogen production and storage units and NEXA Ballard low-temperature proton-exchange membrane fuel cell (PEMFC). Fuel cell (FC) loses a significant part of heat during converting chemical energy into electricity. The main purpose of the study was to explore the heat distribution phenomena across the FC NEXA Ballard stack during load with the next heat transfer optimization. The operation of the FC with insufficient cooling can lead to its overheating or even cell destruction. The cause of this undesirable state is studied with the help of infrared thermography and computational fluid dynamics (CFD) modeling with heat transfer simulation across the stack. The distribution of heat in the stack under various loads was studied, and local points of overheating were determined. Based on the obtained data of the cooling air streamlines and velocity profiles, few ways of the heat distribution optimization along the stack were proposed. This optimization was achieved by changing the original shape of the FC cooling duct. The stable condition of the FC stack at constant load was determined.

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