Numerical and experimental investigation on the thermochemical gasification potential of Cocoa pod husk (Theobroma Cacoa) in an open-core gasifier


Thermochemical conversion is a promising technology to generate producer gas (PG) from different types of agroforestry biomass residues. To use an existing open-core biomass gasifier for different feedstocks available in a agroforestry region, its viability must be studied systematically. Cocoa pod husk (CPH) is one of the promising agricultural wastes, widely available in tropical farmlands of hilly regions. In this study, a commercial 115 kWth biomass gasifier is used in both numerical and experimental methods to find the potential of CPH as a feedstock. The moisture of CPH is varied from 5 to 25%, and the performance of gasifier is investigated for ER between 0.20 and 0.40. The results show that compositions of CO, H2 and CH4 in PG are 20–24%, 12.0–16.5% and 2.0–3.2%, respectively, for the tested conditions. The best equivalence ratio and moisture content are identified as 0.25 and 5%, respectively. The calorific value, conversion efficiency and cold gas efficiency are found as 6.13 MJ/Nm3, 82% and 68%, respectively. The predicted performance parameters and temperature distribution are compared with experimental values and literature. Thus, CPH is identified as a promising feedstock for an open-core gasifier.

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A r :

Arrhenius rate (s1)


Carbon conversion efficiency (%)


Computational fluid dynamics


Constituent gases


Cold gas efficiency (%)


Coco Pod Husk


Calorific Value (MJ Nm−3)


Combustion zone

E a :

Activation energy (J k mol−1)


Equivalence ratio


Producer gas


Pyrolysis zone


Root mean square


Reduction zone

\(C_{x\varepsilon }\) :

Model constants

\(D_{i,m}\) :

Mass diffusion coefficient for species ‘i’ in the mixture (m2 s−1)

\(\vec{F}\) :

Body forces (Nm−3)

\(\vec{g}\) :

Acceleration due to gravity (ms−2)

\(G_{b}\) :

Buoyancy turbulence kinetic energy (m2 s2)

\(G_{{\text{k}}}\) :

Gradient turbulence kinetic energy (m2 s2)

\(\overrightarrow {{J_{i} }}\) :

Diffusion flux of species i

P :

Static pressure (Pa)

\(R_{{i{\text{r}}}}\) :

Homogeneous reaction rate of species i (kg m−3 s−1)

\({\text{R}}_{{{\text{i}},{\text{r}}}}\) :

Homogeneous reaction rate (kg m−3 s−1)

\(S_{h}\) :

Source term (Wm−1)

\(S_{k} ,S_{e}\) :

User-defined source terms

S m :

MASS added to the phase (kg)

\(\vec{v}\) :

Velocity (ms−1)

Y i :

Mass fraction of the species i (%)

Y m :

Overall dissipation turbulence rate

\({\uprho }\) :

Density (kg m−3)

\({\upmu }\) :

Dynamic viscosity (kg m−1 s−1)

\({\upvarepsilon }\) :

Turbulent dissipation rate (m2 s−3)

k :

Turbulent kinetic energy (m2 s2)

\({\upsigma }_{{\text{k}}}\) :

Turbulent Prandtl number

\({\uplambda }_{{{\text{eff}}}}\) :

Effective conductivity


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Correspondence to Murugan Paradesi Chockalingam.

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Gunasekaran, A.P., Chockalingam, M.P., Padmavathy, S.R. et al. Numerical and experimental investigation on the thermochemical gasification potential of Cocoa pod husk (Theobroma Cacoa) in an open-core gasifier. Clean Techn Environ Policy (2021).

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  • Agricultural waste
  • Carbon conversion efficiency
  • Cocoa pod husk
  • Gasifier
  • Producer gas
  • Species transport model