Thermal Analysis and Optimization Potential of Clamp Kilns for Fired Clay Brick Production
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Author
Date
2023Type
- Master Thesis
ETH Bibliography
yes
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Abstract
Fired clay bricks are the primary building material in Malawi, traditionally produced in small-scale clamp ovens. However, the country’s construction sector faces significant challenges. Malawi experiences rapid growth and has one of the highest rates of urbanization globally, resulting in a high demand for building materials. Unfortunately, wood, the predominant fuel for clay brick production, is increasingly scarce due to the depletion of natural forests over the past decades.
Despite the existence of more efficient technologies, clamp kilns are likely to continue being used in rural areas of Malawi for years to come due to their advantageous properties, including ease of use and low investment costs. However, there is a lack of quantitative analysis on their efficiency in the available literature. Therefore, the goal of this Master’s Thesis is to investigate the optimization potential of clamp kilns.
To achieve this, an experimental setup was designed to measure temperatures at 16 different points during a firing period in a small brick clamp located in Chembe, Malawi. These temperature measurements were used to assess the quality of bricks produced in various sections of the kiln. The results served as a basis for identifying areas within the clamp where the brick quality was insufficient.
In order to simulate the impact of different kiln layouts on brick quality and fuel consumption, a thermal simulation using the Finite Element Method was developed. A 3D model of the kiln was analyzed, and the temperature measurements were used as a reference to validate the accuracy of the model.
Based on the temperature measurements, it was observed that surface heat losses adversely affect brick quality. To address this issue, different layouts with increased width and length were simulated. The results showed that by increasing the width and length of the kiln, the proportion of insufficiently fired bricks could be reduced by 40.5%, while the fuelwood demand decreased by 20%. Thus, increasing the width and length of the kiln proved to be a simple way to save fuelwood and improve brick quality using clamp kiln technology. However, increasing the height of the oven did not yield beneficial results due to poor heat transfer to the top layers.
Even though the utilization of clamp kiln technologies can be improved, there are inherent flaws in their design that hinder the uniform firing of clay bricks and result in heat losses. These issues, such as the intermittent nature of the firing process and the fixed position of the fired bricks, are addressed in the design of more advanced kiln types. Therefore, efforts to industrialize Malawi’s brick sector are important in order to reduce the environmental impact of the country’s construction industry. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000666850Publication status
publishedPublisher
ETH ZurichOrganisational unit
09746 - Tilley, Elizabeth / Tilley, Elizabeth
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yes
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