Abstract:
This dissertation was divided into two parts. The first part was to investigate
the significance of porous media with the mathematical model for selecting
appropriately porous media in the porous burner. The second part was to conduct
the experiment of the biomass porous burners with rotation of the combustion
chamber. For the mathematical model, the governing equations were performed
numerically using an implicit finite difference method. The porous media was
assumed by a one-dimensional model, uniformly irradiated by blackbody radiation
having the ability of absorption and emission. The scattering effect, however, is not
taken into account in the calculation. The temperature profiles of solid and
gaseous phase as well as the derivative of the net radiative heat flux of
materials were predicted. The input air velocity is in the range of 0.50 to 1.25
m/s. ASUS 304 stainless wire-mesh are used as porous media in which porosity
are 0.82, 0.79, 0.77 and 0.72 having pores per inch (PPI) of 8, 12, 16 and 20,
respectively. The optical thickness is in the range of 1.25 to 11.35. From the
results of calculations by mathematical models, it can be concluded that
, s and had the highest value at = 0.72 (PPI = 20), = 11.35 (0.040m) which will be
used as a condition for further experimental studies. In the experiment part, the
combustion chamber had an outer diameter of 150 mm and a length of 407 mm.
The burner was divided into two important zones. The first zone was the supplying
of pellet biomass mixing with the air into the chamber (Injection zone). The second
zone was a combustion chamber which a driving system of the rotation was
installed. The rotating speed was examined in four levels: 0, 0.5, 1.0 and 1.5 rpm.
The supplying fuel rate (QF) was also done in three levels: 7.00, 9.46 and 11.92 kW.
The supplying air rate (QA) had three levels: 0.0056, 0.0083 and 0.0111 m3
/s. The 304 stainless steel was used as porous media. The layer of porous media (H) and pores
per inch (PPI) were 6 layers and 12, respectively. The combustion behavior such as
temperature change (T), exhaust gas (CO and NOx) and combustion efficiency (.C)
were investigated. From the experiment, it was found that the level of T was raised
from the increasing from 0 to 1.0 rpm but the T was dropped at = 1.5 rpm. The
level of T was increased with QF and QA due to the quantity of fuel and air supplied
into the system had sufficient leading to obtaining better combustion. However, the
level of the exhaust gas of CO and NOX became, respectively, the lowest and highest
at the condition of QF = 9.46 kW and QA = 0.0111 m3
/s. Moreover, the maximumc in all experiments of the dissertation gave 95.5 % at the conditions of = 1.5 rpm,
QF = 9.46 kW and QA = 0.0111 m3
/s.