p.
37/61
o
Switch ON the burner and set START signal (by the control unit of
the energy consumer) ON as well;
o
Unplug the photosensor by drawing until it is out of the sensor’s
handler and the control board of the burner will analyze this mode
as nominal operation one (i.e. presence of combustion process);
o
In this mode the control board will power the transport auger’s
electric motor and fuel will be transported regularly. The fuel,
which goes off the exhaust side of the flexible hose should be
collected with no scattering in a container for a measured period of
time. For example: the measuring period is 15 minutes (which is ¼
of an hour) and the container’s accumulated fuel mass is 1.0 kg.
The calculation shows that the fuel flow rate is 4 kg/h (practically
the fuel flow rate is determined by dividing the accumulated fuel
mass on the period of time, during which the fuel is transported and
accumulated);
Here is a sample for application of such an approach:
o
Determine the fuel flow rate
( for an hour or less, for example a
shorter period of time – 15 minutes=1/4 hour)- m
fuel
=5.3 kg/h.
Calculate the instant fuel flow rate (m’
fuel
), (divide fuel flow rate per
hour on 3600 , where 1 hour = 3600 seconds) and achieve m’
fuel
=
0.001472 kg/s;
o
Determine/consider the gross calorific value of the fuel
– for example
wood pellets have calorific value H
pellets
= 17.2 MJ/kg = 17200 kJ/kg.
In case other dimension of the calorific value is more convenient to
apply, for example – kWh/kg, then the calculation is as follows :
common wood pellets have gross calorific value of 4.77 kWh/kg
(which is equal to 17.2 MJ/kg);
o
Determine/consider the net efficiency of the system: pellet burner-
heat consumer unit
at nominal thermal capacity mode –
η
system
=89%=0.89. If the net efficiency is not know a priory, a good
initial guess is
η
system
=85%=0.85.
o
Calculate the thermal capacity of the heat consumer unit
-
5
.
22
001472
.
0
*
17200
*
89
.
0
'
*
*
_
fuel
fuel
system
consumer
heat
m
H
P
kW if the
calorific value of the fuel is applied in dimension – MJ/kg. In case that
the calorific value of the fuel is applied in other dimension, for
example kWh/kg, then the calculation is as follows
5
.
22
3
.
5
*
77
.
4
*
89
.
0
*
*
_
fuel
fuel
system
consumer
heat
m
H
P
kW;
o
The same algorithm should be followed for calculating thermal
capacity of the heat consumer in case that the fuel calorific value
differs that cited above or the required thermal capacity of the unit is
lower that the nominal one;
