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Title: Heat transfer enhancement using rotating metallic porous media
Author: Al Husseny, Adel Ahmed Niameh Mehdy
ISNI:       0000 0004 7429 6676
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2016
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The present research is dedicated to numerically optimise the heat transfer enhancement achieved by means of utilising rotating metallic porous media. Three systems that play a crucial role in power generation systems are examined. The first is the cooling passages used to dissipate the heat generated within the rotor conductors in electrical generators, the second is the double pipe-heat exchanger, and the last is the rotary thermal regenerator. In all of the systems under consideration, the main objective is to improve the overall performance achieved and to determine the optimum values of the parameters affecting it. Concerning the first system examined, an enhancement way is proposed through filling such rotating cooling passages either fully or partially with open-cell metal foams. A compound heat transfer enhancement is utilised in the second system through applying an axial rotation to a double-pipe heat exchanger occupied with open-cell metal foams structures. The enhancement process carried out using the third system is examined through proposing an effective and less-costly way to simulate and design rotary regenerators based on a porous medium approach. The developing three-dimensional convective fluid flow across the porous media utilised in all the systems investigated is considered laminar and incompressible. Both thermal dispersion and rotational effects, including centrifugal buoyancy and Coriolis force, are taken into account in the first and second systems, while they are neglected in the latter. The momentum equations are mathematically formulated using the generalised model with considering that fluid and solid phases are in a local thermal non-equilibrium. The governing equations are discretised based on the finite volumes method and then solved iteratively using the SIMPLE algorithm, where an in-house FORTRAN code has been developed to investigate the first system, while the other two systems have been simulated using the STAR-CCM+ CFD commercial code. Inspecting the worth of using metal foams to enhance the heat dissipated by the rotating channels reveals the potential of this proposal to outperform the turbulent flow in rotating clear channels, which confirms that this enhancement way is practically justified and efficient. Moreover, the overall system performance achieved using the compound enhancement employed in the second system is incomparable, i.e. OSP=O(102). The porous medium approach, on the other hand, has been found to be sufficient to accurately simulate the convective flow across the third system. Hence, it can be utilised as an effective and more economical alternative to design such sort of heat exchangers rather than the traditional experimental or numerical ways. The resulted data reveal that heat transfer can be improved considerably by manipulating the design factors including the operating conditions as well as the geometrical and thermal characteristics of the porous medium used. However, care must be taken to avoid unnecessary expenses resulting from potential augmentation in pressure drop.
Supervisor: Turan, Ali ; Nasser, Adel Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available