Assessment of energy production and energy balance for the adaptation of wind micro-aggregates at a comparative analysis.
Dubau, Calin ; Catas, Adriana
Abstract: The work intends to make a synthetic presentation of an
assessment method of the production of energy and energy balance in the
conditions of adaptation of wind micro-aggregates at a comparative
analysis, by determining certain energy parameters which are used in
design calculations, obtaining the total production of energy kwh/year.
Key words: energy assessment, turbine, electric generator, energy
balance, system
1. INTRODUCTION
In the process of assessment of a turbine, the installation point
represents a pair of values ([P.sub.ai], [v.sub.i]) for which the system
is dimensioned, where [P.sub.ai] represents the largest power at which
the system may work.
The turbine's energy balance refers to determining certain
energy parameters, which are used in the design calculation, for the
adaptation of wind aggregates to the requirements of a comparative
analysis (Dubau, 2007; Bej, 2003).
2. MATERIAL AND METHOD
For assessments during the design were used three positions of
powers (Gyulai, 2000, 2003), that is:
--valorized power by the turbine's blading ([P.sub.pal]);
--power at spindle (coupling between turbine and generator)
([P.sub.arb]);
--electric power at the generator's marker stones ([P.sub.eb])
For the dynamic behaviour of the group of machines were identified
the curves for the engine moment of the turbine and for the resistant
moment of the electric generator.
For these analyzed were used experimental programs.
In the area of maximum powers the three levels of powers had the
following orientative values:
[P.sub.eb] [congruent to] 2500 W, [P.sub.arb] [congruent to] 2800
W, [P.sub.pal] [congruent to] 3000 W.
The power at markers stones at the nominal point has the value of
2000 W, and the nominal speed is of 250 rpm, and in an accepted
functioning field we have for n = 40 ... 500 rpm.
The power installed at the electric generator's marker stones
was established at 2500W and this was based on the results of an
economic efficiency study.
By correlating the performances of the three dimensions of turbines
with the electric generator, where the level of limited power ws
considered at the level of 3 kW (at the turbine's spindle),
different limitation speeds are accepted. The management system shall
select the speed in relation to the admitted electric power in the
generator's winding.
The parameters which define the turbine's gauge are the
diameter (D) and the height of the blading (H). In these conditions, the
exposed area is calculated with the formula A = D.H and the relation of
power at the spindle is
[P.sub.a] = [C.sub.Pa] x [rho] x [v.sup.3]/2 x D x H, (1)
where [rho] is the air's density which depends on the altitude of the sea level and the air's temperature; v--air speed depends on
time and elevation of the place; [C.sub.pa] depends on the
characteristic number
[lambda] = peripheral x speed/wind x speed (2)
3. RESULTS AND DISSCUSIONS
The assessment of energy production and the energy balance for the
three dimensions of the turbine have the following determined values
such as:
3.1 The assessment of energy production and the energy balance in
the case of Turbine T 32
We have the parameters: Turbine T 32 ([[lambda].sub.o] = 3), S =
4,5 [m.sup.2] D = 1,5 m; Location's offer: [v.sub.m] = 6 m/s,
Const. k = 0,73; Air density: [rho] = 1,225 kg/[m.sup.3].
The assessment of energy production is shown in Table 1.
3.2 The assessment of energy production and energy balance in the
case of Turbine T 33
We have the parameters: Turbine T33 ([[lambda].sub.o] = 3), S = 6
[m.sup.2] D = 2 m; Location's offer: [v.sub.m] = 5 m/s, Const. k =
0,73; Air density: [rho] = 1,225 kg/[m.sup.3].
The assessment of energy production is shown in Table 2.
3.3 The assessment of energy production and energy balance in the
case of Turbine T 34
We have the parameters: Turbine T34 ([[lambda].sub.o] = 3), S = 7,5
[m.sup.2] D = 2,5 m; Location's offer: [v.sub.m] = 4 m/s, Const. k
= 0,73; Air density: [rho] = 1,225 kg/[m.sup.3].
The assessment of energy production is shown in Table 3.
These tables emphasize assessments of production of energy and
energy banalce for the three types of turbine, offering in this manner
the possibility of adaptation of turbines to the specific requirements.
In the Figure 1 we can notice the correlation between the
performances of the turbine with the generator performance.
[FIGURE 1 OMITTED]
4. CONCLUSIONS
By analyzing these results presented in relation to the energy
reports regarding the adaptation of turbines to the specific
requirements, the conclusions are as follows:
--it is necessary a better corellation of performances of the two
machines (turbine and generator) with the objective of maximizing the
product ([C.sub.p] * [[eta].sub.G]).
--the size of turbine's area exposed, with the condition of
complying to the restrictions imposed.
--optimal management of the aggregate through controlling the speed
(variable for [C.sub.pmax] and constant for limitation of power).
--verification of energy calculation for the favourable variability
of the location's offer (const. k = 0, 73).
5. REFERENCES
Bej, A. (2003). Wind turbines, "Power" collection,
Politehnica Publishing House, ISBN 973-625-098-9, pp. 43-44, Timisoara,
Romania
Dubau, C. (2007). Using wind microagregate in complex systems,
Politehnica Publishing House, ISSN: 1842-4937, ISBN: 978-973-625-408-6,
pp. 150-157, Timisoara, Romania
Gyulai, Fr. (2000). Specialization course in sustainable energy technologies. Modules: Installations Wind and Wind Units, Timisoara
Gyulai, Fr. (2003). Contributions on horizontal axis wind turbine
theory, The 5th International Conference on Hydraulic Machinery and
Hydrodynamics, Timisoara, Romania
Gyulai, Fr. (2003). Vocational Traning in Sustainable Energy-Course
Wind Energy
Tab. 1. The assessment of energy production and the energy
balance in the case of Turbine T 32
F
V [hours/ [P.sub.T] n
[m/s] year] [C.sub.P] [W] [rpm]
2 934 0,45 10 76
3 103 0,45 35 115
4 103 0,45 79 153
5 969 0,45 156 191
6 858 0,45 267 229
7 723 0,45 425 267
8 583 0,45 636 306
9 452 0,45 905 344
10 338 0,45 1242 382
11 244 0,45 1651 420
12 170 0,45 2143 458
13 115 0,45 2726 497
14 75 397 3000 472
15 48 322 3000 411
16 29 266 3000 391
17 18 222 3000 379
18 10 187 3000 367
19 6 159 3000 363
20 3 136 3000 357
Prod. of
energy at
marker
V [[eta].sub.G] stones
[m/s] [%] [P.sub.G] [W] [kWh/an]
2 6 0,6 0,6
3 8 2,8 2,9
4 20 15,8 16,4
5 32 49,9 48,4
6 56 149,5 128,3
7 76 323.0 233,5
8 81 515,2 300,4
9 86 778,3 351,8
10 88 1093,0 369,4
11 89 1469,4 358,5
12 90 1928,7 327,9
13 90 2453,4 282,1
14 90 2700,0 202,5
15 90 2700,0 129,6
16 90 2700,0 78,3
17 90 2700,0 48,6
18 90 2700,0 27,0
19 90 2700,0 16,2
20 90 2700,0 8,1
Total energy [kWh/year]: 2930,5
Tab. 2. The assessment of energy production and energy
balance in the case of Turbine T 33
F
V [hours/ [P.sub.T] n
[m/s] year] [C.sub.P] [W] [rpm]
2 1186 0,45 13 57
3 1194 0,45 46 86
4 1097 0,45 105 115
5 943 0,45 208 143
6 768 0,45 356 172
7 598 0,45 567 201
8 446 0,45 848 229
9 321 0,45 1207 258
10 223 0,45 1655 286
11 150 0,45 2200 315
12 98 0,45 2857 344
13 62 0,37 3000 292
14 39 0,29 3000 274
15 23 0,24 3000 261
16 14 0,19 3000 252
17 8 0,16 3000 244
18 4 0,14 3000 241
19 1 0,11 3000 233
20 0 0 0 --
Prod. Of
energy at
V [[eta].sub.G] [P.sub.G] marker stones
[m/s] [%] [W] [kWh/an]
2 7 0,9 1,l
3 35 16,1 19,2
4 63 66,2 72,6
5 78 162,2 152,9
6 79 281,2 215,9
7 84 476,3 284,8
8 85 720,8 321,5
9 86 1038,0 333,2
10 88 1456,4 324,8
11 90 1980,0 297,0
12 90 2571,3 252,0
13 88 2640,0 163,7
14 88 2640,0 103,0
15 87 2610,0 60,0
16 88 2640,0 37,0
17 87 2610,0 20,9
18 86 2580,0 10,3
19 86 2580,0 2,6
20 -- --
Total energy [kWh/year]: 2672,5
Tab. 3. The assessment of energy production and energy
balance in the case of Turbine T 34
F
V [hours/ [P.sub.T] n
[m/s] year] [C.sub.P] [W] [rpm]
2 1450 0,45 17 46
3 1289 0,45 57 69
4 1057 0,45 132 92
5 818 0,45 260 115
6 604 0,45 445 138
7 428 0,45 709 160
8 294 0,45 1060 183
9 195 0,45 1509 206
10 126 0,45 2069 229
11 80 0,45 2751 252
12 49 378 3000 215
13 29 297 3000 204
14 17 238 3000 193
15 9 193 3000 183
16 5 159 3000 177
17 2 133 3000 182
18 0 0 0 --
Prod. of
energy
marker
V [[eta].sub.G] stones
[m/s] [%] [P.sub.G] [W] [kWh/an]
2 6 1,0 1,5
3 40 22,8 29,4
4 70 92,4 97,7
5 80 208,0 170,1
6 82 364,9 220,4
7 86 609,7 261,0
8 86 911,6 268,0
9 87 1312,8 256,0
10 87 1800,0 226,8
11 97 2393,4 191,5
12 85 2550,0 125,0
13 83 2490,0 72,2
14 83 2490,0 42,3
15 82 2460,0 22,1
16 81 2430,0 12,2
17 82 2460,0 4,9
18 -- -- --
Total energy [kWh/year]: 2001,1