EXPERIMENTAL AND NUMERICAL STUDY ON NATURAL AIR COOLING OF A REMOTE RADIO UNIT

In this paper, a numerical study of three-dimensional (3D) natural convection air-cooling of two identical heat sources, simulating electronic components, mounted in a rectangular enclosure was carried out. The governing equations were solved by using the finite-volume method based on the SIMPLER algorithm. The effects of Rayleigh number Ra, spacing between heat sources d, and aspect ratios Ax in x-direction (horizontal) and Az in z-direction (transversal) of the enclosure on heat transfer were investigated. In steady state, when d is increased, the heat transfer is more important than when the aspect ratios Ax and Az are reduced. In oscillatory state, the critical Rayleigh numbers Racr for different values of spacing between heat sources and their aspect ratios, at which the flow becomes time dependent, were obtained. Results show a strong relation between heat transfers, buoyant flow, and boundary layer. In addition, the heat transfer is more important at the edge of each face of heat sources than at the center region.

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Experimental and numerical study of an earth-to-air heat exchanger for air cooling in a residential building in hot semi-arid climate

Energy and Buildings ◽

10.1016/j.enbuild.2016.04.071 ◽

2016 ◽

Vol 125 ◽

pp. 109-121 ◽

Cited By ~ 52

Author(s):

Mohamed Khabbaz ◽

Brahim Benhamou ◽

Karim Limam ◽

Pierre Hollmuller ◽

Hassan Hamdi ◽

...

Keyword(s):

Heat Exchanger ◽

Numerical Study ◽

Residential Building ◽

Arid Climate ◽

Air Cooling ◽

Semi Arid

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COMPARATIVE ANALYSIS OF MAGNETIC SYSTEMS OF PERMANENT MAGNET MOTORS FOR TRAM

Tekhnichna Elektrodynamika ◽

10.15407/techned2021.05.027 ◽

2021 ◽

Vol 2021 (5) ◽

pp. 27-37

Author(s):

V.V. Grebenikov ◽

◽

R.V. Gamaliia ◽

S.A. Dadychyn ◽

◽

...

Keyword(s):

Permanent Magnet ◽

Electric Drive ◽

High Speed ◽

Permanent Magnets ◽

Numerical Study ◽

Thermal Calculation ◽

Air Cooling ◽

Electric Motors ◽

Magnetic Systems ◽

Low Speed

A numerical study of eight configurations of magnetic systems of electric motors with permanent magnets for driving a tram was carried out. The permanent magnet electric motor can be used as a high-speed electric drive to replace the existing DC electric drive of a tram, and as a low-speed gearless electric drive of a new generation tram. The most promising configurations of magnetic systems of electric motors with permanent magnets for tram drive have been determined. By varying the geometrical and winding parameters of each of the investigated models of electric motors, the mechanical characteristics are determined, at which the given torque and power are achieved in the entire range of the rotor speed. Also, a thermal calculation was performed taking into account the urban driving cycle of high-speed electric motors with air cooling by a fan and low-speed ones in liquid cooling mode. The calculation of the characteristics of the investigated electric motors was carried out in the Simcentre MotorSolve software package. References 13, figures 8, tables 3.

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Investigation of Applicability of Transporting Water Mist for Cooling Turbine Blades

Volume 5A: Heat Transfer ◽

10.1115/gt2014-25818 ◽

2014 ◽

Cited By ~ 5

Author(s):

Ting Wang ◽

Reda Ragab

Keyword(s):

High Pressure ◽

Gas Turbine ◽

Numerical Study ◽

Particle Diameter ◽

Water Mist ◽

Cover Plate ◽

Air Cooling ◽

Real Gas ◽

Rotating Blades ◽

Cooling Passage

This paper presents a numerical study to investigate the feasibility of transporting water mist to the rotating blades of a high pressure turbine. The idea of using mist film cooling to enhance conventional air cooling has been proven to be a feasible technique under laboratory conditions. However, there are challenges in implementing this scheme for real gas turbine systems. The first challenge is how to transport the mist to the rotating blades and the second challenge is delivering the mist to the injection holes and getting the particles to survive within the harsh gas turbine environment. Both a zero-dimensional mist evaporation analytical model and a 3D computational fluid dynamics (CFD) scheme are employed for analysis. In the CFD simulation, the Lagrangian-Eulerian method is used along with the discrete phase model (DPM) to track the evaporation process of each individual water droplet. For transporting the mist to the blades, the high-pressure water mist is injected into the stream of cooling air extracted from the compressor through two different passages. The first passage passes through the rotor cover-plate cavity before entering the blade base. The second passage passes through a diaphragm box on the base of the second vane, then tangentially through a cooling passage in the rotating shaft, and eventually to the blade base. The results show that it is feasible to transport the mist from the turbine casing to the blade through both passages, provided that droplets with sufficient particle diameter and mist loading are used. The shorter passage, through the nozzle diaphragm, alleviates a lot of challenges facing the passage through the blade cavity, and seems to be more practical. A side benefit of transporting mist through the internal passages is the additional cooling of the pre-swirler and rotor cover plates. The results are encouraging for implementing the mist cooling technique under real gas turbine conditions.

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