Introduction
Methods
The principles of construction of the research stand
-
Temperature:
-
At several points inside the bed;
-
Ambient;
-
Of air flowing into the bed;
-
Of air flowing out of the bed;
-
Water at the inlet and outlet of the cooling system
-
-
Air humidity at the inlet and outlet of the bed;
-
Air flow at the inlet and outlet of the bed;
-
Water flow in the cooling system;
-
Time;
-
Charge weight measurement;
-
Measurement of the post-process compost mass;
-
Run-off mass;
-
Electric current power in the system of the air heating pumped into the bed;
-
Concentration of gases in the air leaving the compost heap: carbon dioxide and ammonia.
-
Temperature––DALLAS 18B201 sensors, accuracy class: 0.25 °C;
-
Air flow––air thermal flow meters MCF008 manufactured by Yamatake, accuracy ±3 % FS, flow rate range from 0 to 200 l min−1, analogue output 4–20 mA;
-
Water flow in the cooling system––flow meter KAMSTRUP multi 3.5 type MULTICAL 401, measurement range 0.0035–3.5 m3 h−1;
-
Measurement of the power of the electric heater of air at the bioreactor inlet––digital meter manufactured by Lumel, type N30P, which enables measurement of basic electric quantities, including power and active energy, as well as time, analogue output––programmable 0–10 V, active energy––measurement from 0 to 9999999.9 kWh within an accuracy of ± 5 %, time measurement within an accuracy of up to 1 s per 24 h;
-
Humidity measurement––humidity meter, manufactured by AZ Instruments, model AZ 8829R, measurement range 0–100 % RH, recording frequency from 1 s to 2 h;
-
mass measurement––digital scales;
Fuzzy controlling
Fuzzy control of the composting process
-
Temperature inside the bioreactor (T)––enables the assessment of heat removal process;
-
Aeration rate (V N )––too little aeration slows down the process, causing a drop in temperature inside the heap; too much aeration results in drying the composting material and the simultaneous loss of heat to air, which lowers the temperature inside the heap
-
Heat removal rate (V Q )––too-strong heat removal causes a drop in temperature inside the heap below the optimum temperature; heat removed at too low a level reduces the efficiency of the process.
-
Aeration rate (V N );
-
Heat removal rate (V Q ).
Input | Output | ||||
---|---|---|---|---|---|
v
N
(V) |
v
Q
(V) |
T (°C) |
v
N
(V) |
v
Q
(V) | |
1 | 0 | 0 | 80 | 1 | 9 |
2 | 3 | 5 | 80 | 2 | 9 |
3 | 3 | 5 | 34 | 6 | 1 |
4 | 3 | 9 | 30 | 5 | 6 |
5 | 7 | 8 | 30 | 5 | 9 |
6 | 7 | 8 | 25 | 8 | 1 |
7 | 1 | 8 | 25 | 5 | 1 |
8 | 8 | 1 | 25 | 8 | 0 |
Preparation of experiment
Results and discussion
Series number | X11 | X12 | X13 | X21 | X22 | X23 | X24 | X31 | X32 | X33 | Y11 | Y12 | Y13 | Y21 | Y22 | Y23 | Y24 | Y31 | Y32 | Y33 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Control series without fuzzy control | |||||||||||||||||||
2 | Control series without fuzzy control | |||||||||||||||||||
3 | 30 | 50 | 54 | 50 | 54 | 56 | 60 | 56 | 60 | 80 | 0 | 3 | 5 | 3 | 5 | 6 | 8 | 6 | 8 | 10 |
4 | 30 | 45 | 52 | 50 | 55 | 55 | 62 | 54 | 62 | 80 | 0 | 3 | 5 | 3 | 5 | 6 | 8 | 6 | 8 | 10 |
5 | 30 | 50 | 54 | 50 | 54 | 56 | 60 | 56 | 60 | 80 | 0 | 2 | 5 | 2 | 4 | 7 | 9 | 5 | 8 | 10 |
6 | 30 | 50 | 54 | 50 | 50 | 51 | 60 | 56 | 60 | 80 | 0 | 3 | 4 | 3 | 5 | 6 | 8 | 5 | 9 | 10 |
Control algorithm
Control system
-
The temperature inside the bed for cases 3–6 fluctuated around the value set as the optimum, and caused changes in variables distribution ithat were accompanied by a change in the characteristics of the regulation system. This proves the effectiveness of the control and regulation system.
-
In the next step, the energy balance will be made for the entire process, which will enable optimisation of the control system in accordance with the adopted criteria (the choice of the most beneficial variable distribution and change, if any, of the rules in the rules base).