Particle Image Velocimetry (PIV) experimental study on the buoyant flow fields within a thermal chimney system for geothermal power plant

Yu, G. , Zagaglia, D. , Green, R. and Yu, Z. (2020) Particle Image Velocimetry (PIV) experimental study on the buoyant flow fields within a thermal chimney system for geothermal power plant. International Journal of Green Energy, 17(15), pp. 951-960. (doi: 10.1080/15435075.2020.1809428)

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Abstract

To enhance the air-cooling process in geothermal power plants for economical utilization of the exhaust steam from expansion, a natural-draft thermal chimney design was proposed and studied here in this paper. In view of the necessity of accurate velocity field measurements which would provide further insight into the physics behind the evolving plumes above heated horizontal cylinders, Particle Image Velocimetry (PIV) was employed to experimentally investigate the buoyant flow in the thermal chimney system. Two configurations have been tested to understand the flow induced by the horizontally heated cylinders inside the thermal chimney. Firstly, flow field above a single row of cylinders was tested while they were isothermally heated to simulate of an air-cooled condenser. After that, a second row of cylindrical heaters (air-heater) was added above the first row to enhance the buoyant flow, aiming at enhancing the air side flow of the air-cooled condenser. Flow characteristics and velocity enhancement were studied for both configurations. The results show that significant flow unsteadiness occur near the cylindrical heaters because of the non-steady crossing flows between adjacent cylinders, and the unsteadiness attenuates in the downstream. The effects of cylinder row distance, surface temperature as well as downstream distance on the flow field were then analyzed. Flow velocity is increased by the air-heater as the buoyancy force is enhanced, proving the idea of flow enhancement of the thermal chimney configuration. It is also observed that the velocity fluctuation, turbulent kinetic energy and vorticity change significantly after adding the second row of heaters. The present study provides further insight into natural convection flow theory of heated cylinders for a Rayleigh number range of 1.3E4 to 2.2E4, which is fundamental for the flow enhancement designing of the proposed natural-convection-driven cooling system.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Green, Dr Richard and Yu, Dr Guopeng and Zagaglia, Dr Daniele and Yu, Professor Zhibin
Authors: Yu, G., Zagaglia, D., Green, R., and Yu, Z.
College/School:College of Science and Engineering > School of Engineering > Aerospace Sciences
College of Science and Engineering > School of Engineering > Systems Power and Energy
Journal Name:International Journal of Green Energy
Publisher:Taylor & Francis
ISSN:1543-5075
ISSN (Online):1543-5083
Published Online:06 October 2020
Copyright Holders:Copyright © 2020 The Authors
First Published:First published in International Journal of Green Energy 17(15): 951-960
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
300663Geothermally Sourced Power and Freshwater Generation for Eastern AfricaZhibin YuEngineering and Physical Sciences Research Council (EPSRC)EP/P028829/1ENG - Systems Power & Energy
190699National Wind Tunnel FacilityFrank CotonEngineering and Physical Sciences Research Council (EPSRC)EP/L024888/1ENG - Aerospace Sciences