Design integration of novel porous ceramic evaporative cooling systems

Vallejo, Juan (2018) Design integration of novel porous ceramic evaporative cooling systems. PhD thesis, University of Nottingham.

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Abstract

The rise in demand of air conditioning is unsustainable. Concerns over the subsequent greenhouse emissions and global climate change led to a recent rise of interest by professionals in the building sector in the application of ancient cooling techniques in contemporary architecture to reduce energy demand and deliver healthy and comfortable environments. Despite the successful progress, further research is still needed to make passive cooling systems appealing to a wider audience and to address the limitations found in previous work.

This research responded to this context by focusing on the design and manufacture of a novel cooling system that combined the principles of passive cooling with the inherited use of ceramics in architecture to create an aesthetic and optimised wetted Porous Ceramic Cooling (PCC) screen that improves comfort conditions in indoor, transitional and outdoor spaces. The optimisation focused in the geometrical characteristics of the ceramic element and in the water supply method. This process was informed by a continuous performance monitoring that evaluated cooling and hydraulic capacity of several prototypes under a wide range of ambient conditions. In addition, new steady state and computational fluid dynamic (CFD) models were developed to assist in the sizing and performance prediction of PCC systems in early and late design stages.

The resulting system consisted of tubular-shaped samples arranged over a vertical plane. Water was supplied using a top-drip irrigation system and engraved water channels uniformly distributed the fluid over the ceramic surface to induce evaporation when exposed to an airstream. Experimental and computational studies confirmed the significant impact of geometry on the evaporation rate, highlighting the proportional and inversely proportional relationship of the ceramic effective surface area (ESA) and drag coefficient (Cd) respectively. Air temperature reductions up to 2°C were observed under the warmer and dryer hours of the monitored period (DBT-WBT greater than 12°C) and a competitive average water consumption of 2-4 l/m2·day was obtained. Furthermore, the developed numerical models demonstrated their effectiveness in assisting the design process of PCC systems, allowing estimate airstream velocities, achieved temperature reduction, humidity increase and water consumption prior to manufacture. It is hoped that this research will contribute to a wider application of passive evaporative cooling techniques in architecture.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Gillott, Mark
Chilton, John
Keywords: evaporative cooling, porous ceramic, passive, architecture, calculation tool
Subjects: N Fine Arts > NA Architecture
T Technology > TH Building construction > TH7005 Heating and ventilation. Air conditioning
Faculties/Schools: UK Campuses > Faculty of Engineering > Built Environment
Item ID: 55217
Depositing User: Vallejo, Juan
Date Deposited: 15 Apr 2019 09:47
Last Modified: 07 May 2020 13:32
URI: http://eprints.nottingham.ac.uk/id/eprint/55217

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