Numerical And Experimental Characterisation Of The Flow And Heat Distribution Of A Cross-Draft Combustor
Bibliographic record
Abstract
Traditional biomass cookstoves, which remain prevalent in many developing regions, are characterised by inefficient combustion processes that contribute to elevated pollutant emissions and reduced thermal efficiency [1].On the other hand, traditional experimental evaluations using physical prototypes can be time-consuming, costly, and limited in scope.The complexity of airflow and heat transfer in cookstoves further challenges accurate experimental analysis [2], [3].Computational Fluid Dynamics (CFD) has emerged as a powerful tool to overcome these limitations as it enables detailed visualisation and analysis of flow, heat transfer, and combustion processes [4], [5].The study evaluates the fluid flow and heat transfer in a semi-continuous coal cookstove, focusing on internal draft mechanisms that support combustion.The cookstove is equipped with (i) a hopper that acts as a fuel container, facilitating the semi-continuous feeding of fuel into the combustion chamber; (ii) Grate positioned at 25 aiding in ash removal and aiding in movement of fuel towards the combustion zone; (iii) The combustion chamber, (iv) the heat exchanger for gas circulation; and (v) Chimney.The design of the stove aligns with similar models previously reported in the literature [6]- [8].The geometry was constructed in Siemens NX and imported into STAR-CCM+ for CFD simulation.A segregated flow solver was used for steady-state analysis.The coal bed was treated as a porous medium to account for flow resistance and heat transfer within the packed structure.Combustion heat release was modelled using a volumetric heat source embedded within the porous zone.Experimentally, 1.5 kg of coal (gross calorific value: 24.9 MJ/kg) was ignited using paraffin-soaked pine woodchips, followed by adding an additional 7 kg of coal for semi-continuous feeding.The primary air supply was varied between highpower (HP, air gap: 5.5 cm) and low-power (LP, air gap: 0.5 cm) settings.Temperature data were recorded using K-type thermocouples, and water for the water boiling test and fuel mass changes were measured via a Combix load cell system.Grate shaking was applied periodically (every 30 minutes for HP and every 60 minutes for LP) to mitigate ash accumulation and fuel stagnation.The experimental results yielded thermal efficiencies of 10.1 1.9% and 13.5 2.6%, and firepower values of 6.6 1.5 kW and 3.4 0.6 kW for HP and LP settings, respectively.The highest temperatures for both conditions were observed at the bottom of the hopper, with the HP run achieving significantly higher peak temperatures, which were corroborated by the CFD simulations.By integrating experiments with a CFD model, this research bridges the gap between traditional combustion studies and sustainable energy applications, providing an understanding of heat transfer mechanisms within cooking stoves and aiding in the development of cleaner and more efficient cooking solutions from coal resources.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".