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Measurement of global and direct normal solar energy radiation in Seri Iskandar and comparison with other cities of Malaysia
Journal Pre-proof Measurement of global and direct normal solar energy radiation in Seri Iskandar and comparison with other cities of Malaysia Sanan T. Mohammad, Hussain H. Al-Kayiem, Mohammed A. Aurybi, Ayad K. Khlief PII:
S2214-157X(19)30431-9
DOI:
https://doi.org/10.1016/j.csite.2020.100591
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CSITE 100591
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Case Studies in Thermal Engineering
Received Date: 27 October 2019 Revised Date:
16 January 2020
Accepted Date: 17 January 2020
Please cite this article as: S.T. Mohammad, H.H. Al-Kayiem, M.A. Aurybi, A.K. Khlief, Measurement of global and direct normal solar energy radiation in Seri Iskandar and comparison with other cities of Malaysia, Case Studies in Thermal Engineering (2020), doi: https://doi.org/10.1016/j.csite.2020.100591. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Ltd.
Author statement Sanan T. Mohammad: Conceptualization, Methodology, Prof Dr. Hussain H. Al-Kayiem: Writing- Reviewing and Editing, Mohammed A. Aurybi: Data curation, Writing- Original draft preparation. Ayad K. Khlief : Visualization, Investigation.
1
Measurement of global and direct normal solar energy radiation in Seri
2
Iskandar and comparison with other cities of Malaysia
3
Sanan T. Mohammad1, 2, Hussain H. Al-Kayiem1* , Mohammed A. Aurybi1 and Ayad K.
4
Khlief1
5
1
Mechanical Engineering Department, Universiti Teknologi PETRONAS, 32610 Bandar Seri Iskandar, Perak, Malaysia
6 2
7
* [email protected]
8 9
Dura thermal power plant, Iraq Ministry of Electricity, Baghdad *
Abstract
10
Potential solar data are an essential tool for successful solar design and application. However,
11
because of the limited availability of solar radiation stations, spatial resolution is affected
12
whenever an attempt to construct a solar radiation map is made. In this paper, actual solar data
13
were acquired in Universiti Teknologi PETRONAS (UTP), Seri Iskandar, Malaysia
14
(4°24´latitude, 100°58´E longitude, 24 m altitude). The measurements of global solar radiation
15
and direct normal radiation were gathered and analyzed for the whole of 2018. In addition to
16
solar data collection, real-time solar radiation, high accuracy, and related meteorological data
17
were also obtained. With one-minute recorded average values the everyday and monthly solar
18
radiation averages were determined. A record of 1068.10 W/m2 as maximum daily global solar
19
radiation and 915 W/m2 for direct normal radiation was observed on 9 September 2018.
20
Discussions on daily and monthly average clearness index differences are also elaborated in this
21
paper. The acquired data were compared with corresponding data obtained from other selected
22
Malaysian cities and the widely usable data resource, the NASA solar energy model and surface
23
meteorology. Investigation of the data indicated that Seri Iskandar obtains an ample amount of
24
global solar radiation, indicating the strong potential for the use of solar energy.
25
Keywords: clearness index; direct normal irradiation; global radiation; Pyranometer; Solar
26
energy.
27
1
28 29
1- Introduction.
30
Obtaining accurate information on the intensity of solar radiation at a given location is essential
31
for the development of solar energy-based projects. This information is utilized in the design,
32
cost analysis, and calculation of the efficiency of a project. As crucial as the assessment of the
33
humidity and temperature data collection for a specific period, assessment of the clearness index
34
of an area is also essential in the feasibility of a solar-driven project [1, 2]. Studies have also
35
shown that insolation, which refers to the incidental solar radiation measured as irradiance (or
36
energy per time unit area or per unit area) is also an important factor [3, 4]. Solar energy is one
37
of the most valuable sources of energy capable of supplying additional energy to the world in the
38
upcoming decades. A study carried out by [5] stated that the monthly average of daily solar
39
radiation in Malaysia is recorded as 4000–5000 Wh/m2. The monthly average of sunshine ranges
40
from four to eight hours or about 2200 hours of sunshine a year [6]. Malaysia’s geographical
41
position provides the opportunity to have abundant solar energy with rich resources such as
42
natural gas. With respect to developing renewable energy technologies in the Malaysian region,
43
the country has the opportunity to utilize this natural energy resource effectively, while ensuring
44
a clean environment. The usage of photovoltaic devices, which is concentrated solar power
45
(CSP) technology, has become more suitable for rural electrification. Moreover, water pumping
46
from walls forms cathodic protection for the pipelines as well as for telecommunications, and for
47
building facades. Solar thermal devices have multiple uses, including sea-water desalination,
48
crop drying, and water heating. Hence, applying the usage of solar energy in the region has
49
significant potential. Global solar radiation distribution has been measured through various
50
regions of Malaysia. Being one of the developing countries, solar radiation measurements are
51
not easily accessible because of high equipment and maintenance costs and calibration
52
requirements of measurement equipment. Several researchers have suggested that an alternative
53
solution towards the stated difficulties is to use a modeling approach for solar radiation [7-14].
54
A number of studies have reported global solar radiation measurements in Malaysian cities [15-
55
23]. Consequently, several models have been proposed and tested to estimate solar energy
56
potential.
2
57
A study by [16] estimated solar radiation in Malaysia for three major cities: Kuala Lumpur,
58
Penang, and Kota Bharu, while using an Angstorm-type regression equation to estimate clear
59
date radiation at the location stated. Sopian and Othman (1992) [17] used a simplified Angstrom
60
model to calculate the monthly average solar radiation on horizontal surfaces in areas including
61
Kuching, Kota Kinabalu, Kota Bharu, Senai, Bayan Lepas, Kuala Lumpur, Petaling Jaya, and
62
Bandar Baru Bangi. Azhari et al. (2008) [22] used two statistical methods to forecast the monthly
63
average daily solar radiation based on meteorological factors, including sunshine hours, relative
64
humidity, total rainfall, and wind speed at Lapangan Terbang Sultan Abdul Aziz Shah Subang.
65
The study employed satellite images to predict solar energy as an alternative method presented
66
by [23] who used the Box-Jenkins method to provide a prediction of global solar radiation at
67
Bangi. Global solar radiation at University Malaysia Terengganu was measured from the year
68
2004 to 2010 by [24]. The study found that the highest monthly mean global solar radiation
69
values on a 24-hour basis were recorded at 314.9 W/m2 and 7556 Wh/m2/day. In the state of
70
Terengganu, the largest value of hourly average solar radiation intensity was recorded at 1139
71
W/m2.
72
A study by Filho et al. (2016) [25] demonstrated the observational characteristics and empirical
73
modeling to estimate the diffused, global, and direct solar radiation in Rio de Janeiro, whereas
74
Wattan and Janjai (2016) [26] investigated 14 radiation models in two cities in Thailand, namely
75
Nakhon Pathom and Ubon Ratchathani, and conducted an analysis of the predicted diffused sky
76
radiation. Another recent study presented the estimation of solar radiation through satellite
77
pictures processing or horizontal ground-based surface measurements with devices, such as
78
pyranometer, at meteorological stations [27-28].
79
Although solar radiation data have been reported in various regions in Malaysia, reliable
80
and year-long global radiation data are still required for the Perak region. Solar data are required
81
to support a project of solar trough power plant model in UTP. Such solar data are essential for
82
the proper design and implementation of the concentration solar power plant (CSPP) in this
83
region in Malaysia.
84
Hence, the objectives of this paper are as follows:
85
(i) To provide and discuss in-site measured global and direct solar radiation to determine the
86
region’s ability for the establishment of CSPPs. 3
87
(ii) To discuss the measured data and compare the mean of 22-year satellite data from the
88
NASA surface meteorology and solar energy model (http://eosweb.larc.nasa.gov/sse/) [29].
89
(iii) To compare the measured global solar radiation with other cities in Malaysia to demonstrate
90
the solar energy potential of the Seri Iskandar region in Perak state.
91
(iv) To predict and discuss the clearance index.
92 93
2- Climate data of study area.
94
Malaysia is situated in the equatorial region and has a tropical climate that is usually warm and
95
humid during the entire year. The diurnal deviation can differ at various locations. Seri Iskandar
96
is located close to Ipoh City at 4° 24' 0" N 100.58° ' 0" E within the state of Perak. In particular,
97
Seri Iskandar has a tropical rainforest climate and the temperature remains almost the same with
98
negligible change. The average temperature of the city is around 30°C. Seri Iskandar also
99
witnesses a high rate of precipitation during the year with an average monthly rainfall of 200 mm
100
(7.9 in) and an average yearly rainfall of 2,427.9 mm (95.59 in). October has the most rainfall,
101
with an average of 297.2 mm (11.70 in) and January is the driest month, with an average rainfall
102
of 132.3 mm (5.21 in) [30]. According to the measurement of global solar radiation in the solar
103
research center at UTP, Ipoh receives an average of 7.0 h of sunshine per day.
104 105
3-Experimental setup and procedure.
106
The measurement station is located at UTP Seri Iskandar, Perak (4°24´latitude, 100°58´E
107
longitude, 24 m altitude), Malaysia. This study was carried out for an entire year (January–
108
December 2018). The direct normal irradiation (DNI) and global solar radiation measurement
109
instruments were set at 5 m above ground level. An EKO Pyrheliometer was used to measure
110
the direct normal irradiation (DNI). The EKO Pyrheliometer is situated at the solar side zone of
111
UTP as displayed in Fig .1(a). This instrument can record maximum irradiance values up to
112
2,000 W/m2 at a typical accuracy of ±0.005%. Its dimensions are (430(W) x 380(D) x 440(H)
113
mm). A two-CMP 11 Pyranometer was also used to measure global solar radiation as shown in
114
Fig .1(b). It was mounted on the roof to avoid being in the shade. Both devices were cleaned 4
115
periodically to check for differences between their readings. Global solar radiation data from the
116
two devices were compared, but no significant differences were noticed. The CMP 11
117
Pyranometer is highly sensitive and hence, data from this machine were used. From the raw data
118
stored for every minute, the mean, maximum, and minimum hourly values were calculated. From
119
the hourly data set, daily and monthly statistics of the solar radiation data were prepared.
120
(a)
121
(b)
122
Fig. 1. (a) EKO Pyrheliometer sun tracking device, (b) CMP 11 Pyranometer in UTP
123
The monthly average daily clearness index was calculated by taking the ratio of the measured
124
global solar insolation to the calculated extraterrestrial horizontal insolation [31]. The values of
125
the monthly average daily extraterrestrial radiation (Ho) were calculated for days, thereby
126
providing the average for each month.
127
Ho was calculated from the following equation [11]:
128
sin sin
cos cos sin
(1)
129
where Isc is the solar constant (=1367 W m−2),
refers to the latitude of the site,
represents the
130
sun declination and ws refers to the mean sunrise hour angle for the given month.
and ws can be
131
computed by the following equations [11,23]:
132 133
23.45 sin 360
284 /365#
,
(2)
where n is the day number of the year starting from 1 January.
5
$ 1
134 135
0.0033 cos
cos ,- − tan
&'( ) &'*
+
(3)
tan
(4)
136
The clearance index could be predicted as follows:
137
1
138
4. Results and discussion.
139
The data clearly show that the average daily and maximum global radiations are higher during
140
the drier seasons and lower during the high rain season. Fig. 2 describes the daily average and
141
daily maximum global solar radiation for the entire year. The graphs demonstrate that the daily
142
maximum global radiation of 1068 W/m2 was recorded on 9 September 2018, and the highest
143
daily average solar radiation of 399 W/m2 was recorded on 4 April 2018. The average daily
144
energy input for the entire year was 20.29 MJ/m2/day, which is consistent with the global solar
145
map [32]. Fig. 2 also demonstrates the downward excursions throughout the year, especially in
146
October, November, and December. These excursions might be because of rain events and
147
higher air mass during these months. The higher air mass caused a reduction in clear sky data by
148
absorption along the longer path length.
2
(5)
23
Global solar radiation[W/m2]
1200 1000 800 600 400 200 0 0
50
100
150
200
250
300
350
400
Day of the year Average
Max
149 150
Fig. 2. Daily averages and daily recorded peaks of global solar radiations throughout the year
151
2018. 6
152
The daily average and maximum direct normal solar irradiation for 2018 are displayed in Fig 3.
153
The highest 24-hour based daily average direct normal solar irradiation of 298.9W/m2 was
154
recorded on 4 April 2018. Maximum direct normal solar irradiation was recorded around 915
155
W/m2 on 9 September 2018. In addition, the amount of direct normal solar irradiation is
156
considerably high particularly from January to July 2018. However, starting August 2018, the
157
line pattern dropped gradually until January next year. More fluctuations and intra-daily
158
variability characterization are observed to occur in the direct normal beam for all months
159
because of cloud covers in Malaysia.
Direct normal irradiation[W/m2]
1200 1000 800 600 400 200 0 0
50
100
150
200 250 Day of the year
Average
300
350
400
Max
160 161
Fig. 3. Daily averages and daily recorded peaks of direct normal irradiations throughout the year
162
2018.
163 164
Fig 4 shows the daily averages for each month, and peak daily global solar radiation for the
165
entire year. The highest monthly average of daily radiation was recorded in February 2018 as
166
282 W/m2/day. Meanwhile, the highest peak in solar radiation was recorded as 1068 W/m2
167
during the month of September. November had the lowest monthly average recordings of solar
168
radiation of 209.2 W/m2/day. Lastly, the error bars in the monthly average mean values of
169
global solar radiation are less than 5%, indicating that significant values were observed
170
throughout the seasonal variation. 7
172
radiation. Long sunshine duration with mostly clear skies led to the high availability of solar
173
energy in these months. Minimum global solar radiation is observed during the rainy season
174
months of August–December because of the heavy fog and precipitation that usually occur
175
during these months. 1200
300
1000
250
800
200
600
150
400
100
200
50
0
0 1
2
3
4
5
6
7
8
9
10
11
12
Average global radiation (W/m2/day)
The dry season months of January–July has high solar energy potential in terms of global solar
Global solar radaition (W/m2)
171
Month of the year Max global radiation
Average global radiation
176 177
Fig. 4. Monthly averages and monthly peaks of daily total global solar radiation.
178
Large time-series data comparison carried out using data from the NASA satellite from
179
[29] to measure the monthly daily values of global solar radiation for Seri Iskandar (MJ/m2/day)
180
and (Assadi et al., 2014) [33] can be found in Table 1. The recorded measurements correlated
181
with the 22-year average global solar radiation of the NASA Surface meteorology and Solar
182
Energy (SSE) model. The SSE Web Mapping Application and Services contain geospatially
183
enabled solar-, meteorology-, and cloud-related parameters formulated for assessing and
184
designing renewable energy systems. The measurements are also compared with the three-year
185
average data obtained by [33].
186
representable.
Hence, the measurements recorded in the year 2018 are
187 188 189 8
190
Table 1 Monthly mean daily values of global solar radiation for Seri Iskandar. Months
Global radiation, H (MJ/m2/day)
Relative differences between the measured and NASA (%)
Relative differences between the measured and Assadi et al (%)
9.3
11
Present measurement
NASA SSE model (22-year average)
January
19.33
17.52
Assadi et al (Average 2010– 2012) 17.18
February
21.37
19.72
20.45
7.7
4.3
March
20.23
19.04
19.29
5.8
4.6
April
19.51
18.97
19.88
2.7
1.8
May
19.21
17.74
18.54
7.6
3.4
June
18.59
17.46
18.53
6.4
1
July
18.34
17.31
18.42
5.6
0.43
August
16.36
16.84
18.46
2.9
12
September
17.47
16.81
18.32
3.7
4.8
October
15.20
16.09
17.63
5.8
15
November
15.08
14.79
16.82
1.9
11.5
December
15.13
14.58
15.48
3.6
2.3
Annual
17.98
17.23
18.25
4.1
1.5
191 192
The table shows that the measured values of the ground-based global solar radiation at Seri
193
Iskandar city are slightly higher than those predicted by the NASA SSE elevation model. The
194
highest value was observed for February as 21.37 MJ/m2-day, whereas the minimum value was
195
observed for the month of November as 15.08 MJ/m2-day. In the month of November, ground-
196
based and NASA data show equal values of global solar radiation with relative differences
197
percentage of 1.9%. The annual average value of global solar radiation for ground-based data is
198
17.98 MJ/m2-day, which is higher than NASA measurements at 17.23 MJ/m2-day.
199
The ground-based solar radiation measurement data obtained under the present study was
200
compared with Assadi et al. (2014) [33] as presented in Table 1. The measured values of the
201
ground-based global solar radiation at Seri Iskandar city are slightly lower than those predicted 9
203
ground-based is 17.98 MJ/m2 /day which is lower than the measurements of 18.25 MJ/m2 /day
204
with annual relative difference percentage of 1.5%.
205
The daily averages of each month and peak daily direct normal solar radiations for 2018 are
206
based on data measured at the solar research site (SRS) as shown in Fig 5. The figure shows that
207
August had the lowest monthly average of daily solar radiation of 120W/m2/day. September had
208
the highest daily peak in direct solar radiation at 915 W/m2. Data from February had the highest
209
monthly average of daily radiation of 191 W/m2/day. 1200
250
1000
200
800
150
600 100
400
50
200 0
Average direct normal irradiation(W/m2/day)
by the model of Assadi et al. (2014). The annual average value of global solar radiation for
Direct normal irradiation (W/m2)
202
0 1
2
3
4
5
6
7
8
9
10
11
12
Month of the year Max direct normal irradiation
Average direct normal irradiation
210 211
Fig. 5. Monthly averages and monthly peaks daily total direct normal irradiation DNI.
212
Table 2 shows the comparison with the monthly mean of the daily values of direct normal solar
213
irradiation for Seri Iskandar (MJ/m2/day) and the NASA SSE model time-series data [29]. Two
214
differences were observed in the measurements:
215
(1) The NASA SSE model measured values for 22 years while the current study measured values
216
for one year, and
217
(2) Weather conditions that vary from year to year have led to minor differences in
218
measurements related to 22-year average global solar radiation data of the NASA SSE model.
219
The measured values of the direct normal irradiance (DNI) at Seri Iskandar city are slightly
220
higher those predicted by the NASA SSE elevation model as observed from Table 2. The 10
221
minimum value was observed for the month of November at 8.6 MJ/m2-day. The highest value
222
was observed for the month of February at 14.92 MJ/m2-day. In the month of August, ground-
223
based and NASA measurements had equal values of DNI with relative differences percentage of
224
0.09 %. The annual average value of DNI for ground-based is 12.08 MJ/m2-day, which is higher
225
than the NASA measurements at 10.99 MJ/m2-day.
226
Table 2: Monthly mean daily values of direct normal solar radiation for Seri Iskandar. Months
Direct normal irradiation, H
Relative differences
(MJ/m2/day)
between the measured
Present
NASA SSE
measurement
model (22-year
and NASA (%)
average) January
13.67
12.91
5.5
February
14.92
13.972
6.3
March
14.19
12.42
12.4
April
14.02
13.71
2.2
May
13.45
12.88
4.2
June
13.21
11.91
9.8
July
12.71
11.44
9.9
August
10.27
10.26
0.09
September
11.47
8.96
21
October
9.72
7.812
19.6
November
8.60
8.42
2
December
8.79
7.23
17.7
Annual
12.08
10.99
8.9
227 228
The reasons behind the differences in present data and those already available can be
229
attributed to two reasons. First, the present data represent measurement of global and direct
230
normal solar energy radiation for one year only, whereas NASA satellite comprised a 22-year
231
average and that of Assadi et al. (2014) [33] spanned two years (2010–2012). Second, the present
232
data are measurements on the ground. However, NASA satellite elevation on earth provides 11
233
results close to reality with error ratio. Assadi et al. (2014) presented a model prediction by
234
MATLAB program that slightly equal to the present data. These reasons validate the solar
235
radiation measurements and confirm the potential of solar energy for the region. Therefore, the
236
ground-based measurements can be utilized to improve the world solar radiation database.
237
The daily values of the monthly mean of Seri Iskandar global solar radiation were
238
compared with several cities in Malaysia (shown in Table 3) as reported by Sopian and Othman
239
(1992) and Muzathik (2013). The table shows clearly that the average monthly global radiation
240
over the course of the year was comparatively good for Seri Iskandar. The annual mean global
241
radiation for recorded for Seri Iskandar was also close to that obtained for the other cities.
242
The monthly average global radiation over the course of the year is comparatively higher for
243
Kota Kinabalu, although in the dry season months, several Malaysian cities had higher values.
244
The peak radiation month in Kota Kinabalu is April (21.64 MJ/m2 day) and the month with the
245
lowest radiation was in January (17.71 MJ/m2 /day). The annual mean global radiation for Seri
246
Iskandar was good as compared with the Malaysian cities. The total annual global solar radiation
247
received in Seri Iskandar on a horizontal surface is about 17.91 MJ/ m2/day. More than 63% of
248
this total is contributed by the dry season months (January to July) and about 37% in August to
249
December. The global solar radiations in the major cities of Malaysia are approximately the
250
same within 7.5%.
251 252 253 254 255 256 257 258
12
259
Table 3: Monthly mean daily values of global solar radiation for Seri Iskandar and other cities
260
for one year (Muzathik, 2013) [24]. Global radiation (MJ/m2/day)
Months
Relative
Seri
Kuala
Kuching
Kota
Kota
differences
Iskandar
Terengganu
(2013)
Kinabalu
Bharu
Between Seri
(2018)
(2013)
(2013)
(2013)
Iskandar And Kota Kinabalu (%)
January
19.33
17.91
12.02
17.71
16.26
8.3
February
21.37
21.60
13.35
19.36
17.72
9.4
March
20.23
21.40
15.39
20.97
19.72
3.6
April
19.51
23.64
13.07
21.64
19.74
10.7
May
19.21
20.34
13.42
20.16
18.23
4.9
June
18.59
17.42
16.28
19.11
17.10
2.8
July
18.34
19.43
16.57
19.41
17.17
5.5
August
16.36
19.15
15.14
19.44
17.42
18.8
September
17.47
20.20
15.79
18.20
18.12
4.1
October
15.20
16.40
15.23
19.21
17.09
26
November
15.08
16.24
14.92
18.08
13.28
19.8
December
15.13
13.38
12.56
18.00
12.15
18.9
Annual
17.91
18.92
14.48
19.27
17.00
7.5
Average 261 262
The daily variation of the clearness index throughout the year in Seri Iskandar is shown
263
in Fig. 6. The figure shows that the variation is within range from 0.2 and 0.9. A variety of
264
conditions contributed to the fluctuation of values throughout the rainy season and clear skies.
265
Fig 7 shows the monthly average clearness index, which varies between 0.45 and 0.55; based on
266
these data, 0.50 as the average clearness index value was approximately measured. During the
13
267
rainy season, both the clearness index and global solar radiation were recorded to be low. When
268
the clearness index is low, the solar radiation energy is reduced dramatically.
Clearness index [K=H/Ho]
1 0.8 0.6 0.4 0.2 0 0
50
100
150
200
250
300
350
400
Day of the year
269
Fig. 6. Daily average clearness index (K) variation. H is the total solar radiation and Ho is the
271
extraterrestrial solar radiation.
Clearness Index
270
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 1
2
3
4
5
6
7
8
9
10
11
12
Month of the year
272 273
Fig. 7. Monthly average clearness index.
274
Sopian and Othman (1992) and Muzathik (2013) [17,24] have reported the monthly
275
clearness indices of Malaysian cities, such as Kuala Terengganu, Kuching, Kota Kinabalu, and
276
Kota Bharu and have identified Malaysian cities with higher solar energy potential areas, which 14
277
is why we compared these data with the Seri Iskandar monthly mean clearness index (see Table
278
4). The comparison provides evidence that the monthly average clearness index over the course
279
of the year is good for Seri Iskandar, although Kota Kinabalu experiences higher monthly mean
280
clearness index values at certain months. With respect to the current comparison of the climate
281
conditions in various cities, clearness index, direct normal irradiation, and global radiation, Seri
282
Iskandar has been demonstrated to utilize the greatest solar energy.
283
Table 4: Monthly averaged clearness index of Seri Iskandar and other cities compared with data
284
obtained by [17, 24], and NAS SSE [29]
Months
January
Monthly averaged insolation clearness index, K (0–1) NASA SSE Seri model Kuala Kota Iskandar Kuching (22-year Terengganu Kinabalu (measured) average) 0.52 0.48 0.54 0.35 0.55
Kota Bharu 0.51
February
0.55
0.51
0.62
0.38
0.57
0.52
March
0.54
0.51
0.57
0.41
0.56
0.53
April
0.53
0.51
0.64
0.36
0.59
0.54
May
0.52
0.49
0.54
0.37
0.53
0.48
June
0.51
0.5
0.48
0.48
0.53
0.48
July
0.49
0.49
0.53
0.45
0.51
0.45
August
0.47
0.46
0.53
0.41
0.51
0.46
September
0.48
0.45
0.53
0.43
0.50
0.50
October
0.47
0.44
0.44
0.41
0.53
0.47
November
0.45
0.42
0.49
0.41
0.53
0.39
December
0.46
0.43
0.42
0.36
0.54
0.37
Annual
0.50
0.47
0.53
0.40
0.54
0.47
Average 285 286
Malaysia is a tropical country with one season of weather all around the year. Figure (8) shows
287
the temperature with average global radiation. the average temperature in Malaysia is around 32
288
⁰
C in the day and around 26 ⁰C in the night with a very small change around the year. There is an 15
289
agreement on the design temperatures of the HVAC system and other solar systems assuming 32
290
⁰
C in the daytime and 26 ⁰C in the night time.
35
350
30
300
25
250
20
200
15
150
10
100
5
50
0
0 0
2
4
6
8
10
12
14
Average global radiation(W/m2/day)
Temperature(⁰C)
291
Month of the year T_amb
Average global radiation
292
Fig. 8. Monthly average temperature
293 294 295
Figure (9) describe wind speed during all seasons. Sometimes the result is high the wind speed
296
and sometimes low the wind speed. Again, it is probably caused by the cloudy sky which clouds
297
sometimes suddenly come and disappears. In the rainy season, normally the intensity of the
298
cloud is higher than the dry season. That is why more high wind speed is observed in the rainy
299
season.
16
350
3
300
2.5
250
2
200
1.5
150
1
100
0.5
50
0
0 0
2
4
6
8
10
12
14
Average global radiation(W/m2/day)
Wind speed(m/s)
3.5
Month of the year Wspd
Average global radiation
300
Fig. 9. Monthly average wind speed
301 302 303
4 Conclusions.
304
The Solar Thermal Research Center (STARC) of UTP has decided to implement various solar
305
research projects, hence, this study presents the potential for a project utilizing the global solar
306
radiation and direct normal irradiation of solar energy at Seri Iskandar city, Malaysia. A key for
307
meteorological parameters and its implications is solar radiation and weather conditions. These
308
data are crucial in the design of solar thermal systems (such as solar collectors, desalination
309
systems, and dryers), PV-systems, environment-conscious buildings, and HVAC designs, as well
310
as in the applied aspects of solar radiation, such as human-environment interactions and
311
dynamics of agricultural and biological systems. Data have been used in the design of the CSPP
312
model in STARC. The total solar radiation recorded at Seri Iskandar throughout the period of a
313
year exhibited better potential as compared with other cities in Malaysia. With respect to the
314
data obtained, solar radiation was found to be greater in its average values during the dry season
315
(January to July) as compared with the rainy season (August to December). The current
316
measurement data were compared with NASA SSE model results and are in good agreement. In
317
addition to solar radiation data, the clearness index was also predicted using meteorological data
318
and currently measured data. These data are in good agreement. The predicted clearness index
319
for Seri Iskandar was within values ranging from 0.45–0.55, with yearly average of 0.50. The 17
320
acquired solar data evidently show that Seri Iskandar town gains ample amount of solar radiation
321
and is a good location for solar application and utilization.
322
It is hoped that this study would be of interest to researchers and designers of solar thermal
323
systems. However, further investigations for long term meteorological data from different cities
324
in Malaysia are required to obtain more effective results.
325
Acknowledgment
326
We acknowledge the utmost support from Universiti Teknologi PETRONAS, Malaysia. We also
327
would like to express our appreciation to the Ministry of Higher Education-Malaysia for the
328
financial support of the CSP project under the MyRA grant and utilization of instruments under
329
the [FRGS/1/2015/TK10/UTP/03/2] grant.
330 331 332
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Nomenclature monthly mean extraterrestrial horizontal solar radiation (MJ/m2-day)
409 410 411
is the global solar insolation on a horizontal surface at any location on any given day(MJ/m2day) .
412
solar constant (=1367 W m−2)
413
latitude of the site (degrees)
414
angle of declination (degrees)
415
day of the year
416
mean monthly sunset hour angle (degrees)
21
Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
S2214-157X(19)30431-9
DOI:
https://doi.org/10.1016/j.csite.2020.100591
Reference:
CSITE 100591
To appear in:
Case Studies in Thermal Engineering
Received Date: 27 October 2019 Revised Date:
16 January 2020
Accepted Date: 17 January 2020
Please cite this article as: S.T. Mohammad, H.H. Al-Kayiem, M.A. Aurybi, A.K. Khlief, Measurement of global and direct normal solar energy radiation in Seri Iskandar and comparison with other cities of Malaysia, Case Studies in Thermal Engineering (2020), doi: https://doi.org/10.1016/j.csite.2020.100591. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Ltd.
Author statement Sanan T. Mohammad: Conceptualization, Methodology, Prof Dr. Hussain H. Al-Kayiem: Writing- Reviewing and Editing, Mohammed A. Aurybi: Data curation, Writing- Original draft preparation. Ayad K. Khlief : Visualization, Investigation.
1
Measurement of global and direct normal solar energy radiation in Seri
2
Iskandar and comparison with other cities of Malaysia
3
Sanan T. Mohammad1, 2, Hussain H. Al-Kayiem1* , Mohammed A. Aurybi1 and Ayad K.
4
Khlief1
5
1
Mechanical Engineering Department, Universiti Teknologi PETRONAS, 32610 Bandar Seri Iskandar, Perak, Malaysia
6 2
7
* [email protected]
8 9
Dura thermal power plant, Iraq Ministry of Electricity, Baghdad *
Abstract
10
Potential solar data are an essential tool for successful solar design and application. However,
11
because of the limited availability of solar radiation stations, spatial resolution is affected
12
whenever an attempt to construct a solar radiation map is made. In this paper, actual solar data
13
were acquired in Universiti Teknologi PETRONAS (UTP), Seri Iskandar, Malaysia
14
(4°24´latitude, 100°58´E longitude, 24 m altitude). The measurements of global solar radiation
15
and direct normal radiation were gathered and analyzed for the whole of 2018. In addition to
16
solar data collection, real-time solar radiation, high accuracy, and related meteorological data
17
were also obtained. With one-minute recorded average values the everyday and monthly solar
18
radiation averages were determined. A record of 1068.10 W/m2 as maximum daily global solar
19
radiation and 915 W/m2 for direct normal radiation was observed on 9 September 2018.
20
Discussions on daily and monthly average clearness index differences are also elaborated in this
21
paper. The acquired data were compared with corresponding data obtained from other selected
22
Malaysian cities and the widely usable data resource, the NASA solar energy model and surface
23
meteorology. Investigation of the data indicated that Seri Iskandar obtains an ample amount of
24
global solar radiation, indicating the strong potential for the use of solar energy.
25
Keywords: clearness index; direct normal irradiation; global radiation; Pyranometer; Solar
26
energy.
27
1
28 29
1- Introduction.
30
Obtaining accurate information on the intensity of solar radiation at a given location is essential
31
for the development of solar energy-based projects. This information is utilized in the design,
32
cost analysis, and calculation of the efficiency of a project. As crucial as the assessment of the
33
humidity and temperature data collection for a specific period, assessment of the clearness index
34
of an area is also essential in the feasibility of a solar-driven project [1, 2]. Studies have also
35
shown that insolation, which refers to the incidental solar radiation measured as irradiance (or
36
energy per time unit area or per unit area) is also an important factor [3, 4]. Solar energy is one
37
of the most valuable sources of energy capable of supplying additional energy to the world in the
38
upcoming decades. A study carried out by [5] stated that the monthly average of daily solar
39
radiation in Malaysia is recorded as 4000–5000 Wh/m2. The monthly average of sunshine ranges
40
from four to eight hours or about 2200 hours of sunshine a year [6]. Malaysia’s geographical
41
position provides the opportunity to have abundant solar energy with rich resources such as
42
natural gas. With respect to developing renewable energy technologies in the Malaysian region,
43
the country has the opportunity to utilize this natural energy resource effectively, while ensuring
44
a clean environment. The usage of photovoltaic devices, which is concentrated solar power
45
(CSP) technology, has become more suitable for rural electrification. Moreover, water pumping
46
from walls forms cathodic protection for the pipelines as well as for telecommunications, and for
47
building facades. Solar thermal devices have multiple uses, including sea-water desalination,
48
crop drying, and water heating. Hence, applying the usage of solar energy in the region has
49
significant potential. Global solar radiation distribution has been measured through various
50
regions of Malaysia. Being one of the developing countries, solar radiation measurements are
51
not easily accessible because of high equipment and maintenance costs and calibration
52
requirements of measurement equipment. Several researchers have suggested that an alternative
53
solution towards the stated difficulties is to use a modeling approach for solar radiation [7-14].
54
A number of studies have reported global solar radiation measurements in Malaysian cities [15-
55
23]. Consequently, several models have been proposed and tested to estimate solar energy
56
potential.
2
57
A study by [16] estimated solar radiation in Malaysia for three major cities: Kuala Lumpur,
58
Penang, and Kota Bharu, while using an Angstorm-type regression equation to estimate clear
59
date radiation at the location stated. Sopian and Othman (1992) [17] used a simplified Angstrom
60
model to calculate the monthly average solar radiation on horizontal surfaces in areas including
61
Kuching, Kota Kinabalu, Kota Bharu, Senai, Bayan Lepas, Kuala Lumpur, Petaling Jaya, and
62
Bandar Baru Bangi. Azhari et al. (2008) [22] used two statistical methods to forecast the monthly
63
average daily solar radiation based on meteorological factors, including sunshine hours, relative
64
humidity, total rainfall, and wind speed at Lapangan Terbang Sultan Abdul Aziz Shah Subang.
65
The study employed satellite images to predict solar energy as an alternative method presented
66
by [23] who used the Box-Jenkins method to provide a prediction of global solar radiation at
67
Bangi. Global solar radiation at University Malaysia Terengganu was measured from the year
68
2004 to 2010 by [24]. The study found that the highest monthly mean global solar radiation
69
values on a 24-hour basis were recorded at 314.9 W/m2 and 7556 Wh/m2/day. In the state of
70
Terengganu, the largest value of hourly average solar radiation intensity was recorded at 1139
71
W/m2.
72
A study by Filho et al. (2016) [25] demonstrated the observational characteristics and empirical
73
modeling to estimate the diffused, global, and direct solar radiation in Rio de Janeiro, whereas
74
Wattan and Janjai (2016) [26] investigated 14 radiation models in two cities in Thailand, namely
75
Nakhon Pathom and Ubon Ratchathani, and conducted an analysis of the predicted diffused sky
76
radiation. Another recent study presented the estimation of solar radiation through satellite
77
pictures processing or horizontal ground-based surface measurements with devices, such as
78
pyranometer, at meteorological stations [27-28].
79
Although solar radiation data have been reported in various regions in Malaysia, reliable
80
and year-long global radiation data are still required for the Perak region. Solar data are required
81
to support a project of solar trough power plant model in UTP. Such solar data are essential for
82
the proper design and implementation of the concentration solar power plant (CSPP) in this
83
region in Malaysia.
84
Hence, the objectives of this paper are as follows:
85
(i) To provide and discuss in-site measured global and direct solar radiation to determine the
86
region’s ability for the establishment of CSPPs. 3
87
(ii) To discuss the measured data and compare the mean of 22-year satellite data from the
88
NASA surface meteorology and solar energy model (http://eosweb.larc.nasa.gov/sse/) [29].
89
(iii) To compare the measured global solar radiation with other cities in Malaysia to demonstrate
90
the solar energy potential of the Seri Iskandar region in Perak state.
91
(iv) To predict and discuss the clearance index.
92 93
2- Climate data of study area.
94
Malaysia is situated in the equatorial region and has a tropical climate that is usually warm and
95
humid during the entire year. The diurnal deviation can differ at various locations. Seri Iskandar
96
is located close to Ipoh City at 4° 24' 0" N 100.58° ' 0" E within the state of Perak. In particular,
97
Seri Iskandar has a tropical rainforest climate and the temperature remains almost the same with
98
negligible change. The average temperature of the city is around 30°C. Seri Iskandar also
99
witnesses a high rate of precipitation during the year with an average monthly rainfall of 200 mm
100
(7.9 in) and an average yearly rainfall of 2,427.9 mm (95.59 in). October has the most rainfall,
101
with an average of 297.2 mm (11.70 in) and January is the driest month, with an average rainfall
102
of 132.3 mm (5.21 in) [30]. According to the measurement of global solar radiation in the solar
103
research center at UTP, Ipoh receives an average of 7.0 h of sunshine per day.
104 105
3-Experimental setup and procedure.
106
The measurement station is located at UTP Seri Iskandar, Perak (4°24´latitude, 100°58´E
107
longitude, 24 m altitude), Malaysia. This study was carried out for an entire year (January–
108
December 2018). The direct normal irradiation (DNI) and global solar radiation measurement
109
instruments were set at 5 m above ground level. An EKO Pyrheliometer was used to measure
110
the direct normal irradiation (DNI). The EKO Pyrheliometer is situated at the solar side zone of
111
UTP as displayed in Fig .1(a). This instrument can record maximum irradiance values up to
112
2,000 W/m2 at a typical accuracy of ±0.005%. Its dimensions are (430(W) x 380(D) x 440(H)
113
mm). A two-CMP 11 Pyranometer was also used to measure global solar radiation as shown in
114
Fig .1(b). It was mounted on the roof to avoid being in the shade. Both devices were cleaned 4
115
periodically to check for differences between their readings. Global solar radiation data from the
116
two devices were compared, but no significant differences were noticed. The CMP 11
117
Pyranometer is highly sensitive and hence, data from this machine were used. From the raw data
118
stored for every minute, the mean, maximum, and minimum hourly values were calculated. From
119
the hourly data set, daily and monthly statistics of the solar radiation data were prepared.
120
(a)
121
(b)
122
Fig. 1. (a) EKO Pyrheliometer sun tracking device, (b) CMP 11 Pyranometer in UTP
123
The monthly average daily clearness index was calculated by taking the ratio of the measured
124
global solar insolation to the calculated extraterrestrial horizontal insolation [31]. The values of
125
the monthly average daily extraterrestrial radiation (Ho) were calculated for days, thereby
126
providing the average for each month.
127
Ho was calculated from the following equation [11]:
128
sin sin
cos cos sin
(1)
129
where Isc is the solar constant (=1367 W m−2),
refers to the latitude of the site,
represents the
130
sun declination and ws refers to the mean sunrise hour angle for the given month.
and ws can be
131
computed by the following equations [11,23]:
132 133
23.45 sin 360
284 /365#
,
(2)
where n is the day number of the year starting from 1 January.
5
$ 1
134 135
0.0033 cos
cos ,- − tan
&'( ) &'*
+
(3)
tan
(4)
136
The clearance index could be predicted as follows:
137
1
138
4. Results and discussion.
139
The data clearly show that the average daily and maximum global radiations are higher during
140
the drier seasons and lower during the high rain season. Fig. 2 describes the daily average and
141
daily maximum global solar radiation for the entire year. The graphs demonstrate that the daily
142
maximum global radiation of 1068 W/m2 was recorded on 9 September 2018, and the highest
143
daily average solar radiation of 399 W/m2 was recorded on 4 April 2018. The average daily
144
energy input for the entire year was 20.29 MJ/m2/day, which is consistent with the global solar
145
map [32]. Fig. 2 also demonstrates the downward excursions throughout the year, especially in
146
October, November, and December. These excursions might be because of rain events and
147
higher air mass during these months. The higher air mass caused a reduction in clear sky data by
148
absorption along the longer path length.
2
(5)
23
Global solar radiation[W/m2]
1200 1000 800 600 400 200 0 0
50
100
150
200
250
300
350
400
Day of the year Average
Max
149 150
Fig. 2. Daily averages and daily recorded peaks of global solar radiations throughout the year
151
2018. 6
152
The daily average and maximum direct normal solar irradiation for 2018 are displayed in Fig 3.
153
The highest 24-hour based daily average direct normal solar irradiation of 298.9W/m2 was
154
recorded on 4 April 2018. Maximum direct normal solar irradiation was recorded around 915
155
W/m2 on 9 September 2018. In addition, the amount of direct normal solar irradiation is
156
considerably high particularly from January to July 2018. However, starting August 2018, the
157
line pattern dropped gradually until January next year. More fluctuations and intra-daily
158
variability characterization are observed to occur in the direct normal beam for all months
159
because of cloud covers in Malaysia.
Direct normal irradiation[W/m2]
1200 1000 800 600 400 200 0 0
50
100
150
200 250 Day of the year
Average
300
350
400
Max
160 161
Fig. 3. Daily averages and daily recorded peaks of direct normal irradiations throughout the year
162
2018.
163 164
Fig 4 shows the daily averages for each month, and peak daily global solar radiation for the
165
entire year. The highest monthly average of daily radiation was recorded in February 2018 as
166
282 W/m2/day. Meanwhile, the highest peak in solar radiation was recorded as 1068 W/m2
167
during the month of September. November had the lowest monthly average recordings of solar
168
radiation of 209.2 W/m2/day. Lastly, the error bars in the monthly average mean values of
169
global solar radiation are less than 5%, indicating that significant values were observed
170
throughout the seasonal variation. 7
172
radiation. Long sunshine duration with mostly clear skies led to the high availability of solar
173
energy in these months. Minimum global solar radiation is observed during the rainy season
174
months of August–December because of the heavy fog and precipitation that usually occur
175
during these months. 1200
300
1000
250
800
200
600
150
400
100
200
50
0
0 1
2
3
4
5
6
7
8
9
10
11
12
Average global radiation (W/m2/day)
The dry season months of January–July has high solar energy potential in terms of global solar
Global solar radaition (W/m2)
171
Month of the year Max global radiation
Average global radiation
176 177
Fig. 4. Monthly averages and monthly peaks of daily total global solar radiation.
178
Large time-series data comparison carried out using data from the NASA satellite from
179
[29] to measure the monthly daily values of global solar radiation for Seri Iskandar (MJ/m2/day)
180
and (Assadi et al., 2014) [33] can be found in Table 1. The recorded measurements correlated
181
with the 22-year average global solar radiation of the NASA Surface meteorology and Solar
182
Energy (SSE) model. The SSE Web Mapping Application and Services contain geospatially
183
enabled solar-, meteorology-, and cloud-related parameters formulated for assessing and
184
designing renewable energy systems. The measurements are also compared with the three-year
185
average data obtained by [33].
186
representable.
Hence, the measurements recorded in the year 2018 are
187 188 189 8
190
Table 1 Monthly mean daily values of global solar radiation for Seri Iskandar. Months
Global radiation, H (MJ/m2/day)
Relative differences between the measured and NASA (%)
Relative differences between the measured and Assadi et al (%)
9.3
11
Present measurement
NASA SSE model (22-year average)
January
19.33
17.52
Assadi et al (Average 2010– 2012) 17.18
February
21.37
19.72
20.45
7.7
4.3
March
20.23
19.04
19.29
5.8
4.6
April
19.51
18.97
19.88
2.7
1.8
May
19.21
17.74
18.54
7.6
3.4
June
18.59
17.46
18.53
6.4
1
July
18.34
17.31
18.42
5.6
0.43
August
16.36
16.84
18.46
2.9
12
September
17.47
16.81
18.32
3.7
4.8
October
15.20
16.09
17.63
5.8
15
November
15.08
14.79
16.82
1.9
11.5
December
15.13
14.58
15.48
3.6
2.3
Annual
17.98
17.23
18.25
4.1
1.5
191 192
The table shows that the measured values of the ground-based global solar radiation at Seri
193
Iskandar city are slightly higher than those predicted by the NASA SSE elevation model. The
194
highest value was observed for February as 21.37 MJ/m2-day, whereas the minimum value was
195
observed for the month of November as 15.08 MJ/m2-day. In the month of November, ground-
196
based and NASA data show equal values of global solar radiation with relative differences
197
percentage of 1.9%. The annual average value of global solar radiation for ground-based data is
198
17.98 MJ/m2-day, which is higher than NASA measurements at 17.23 MJ/m2-day.
199
The ground-based solar radiation measurement data obtained under the present study was
200
compared with Assadi et al. (2014) [33] as presented in Table 1. The measured values of the
201
ground-based global solar radiation at Seri Iskandar city are slightly lower than those predicted 9
203
ground-based is 17.98 MJ/m2 /day which is lower than the measurements of 18.25 MJ/m2 /day
204
with annual relative difference percentage of 1.5%.
205
The daily averages of each month and peak daily direct normal solar radiations for 2018 are
206
based on data measured at the solar research site (SRS) as shown in Fig 5. The figure shows that
207
August had the lowest monthly average of daily solar radiation of 120W/m2/day. September had
208
the highest daily peak in direct solar radiation at 915 W/m2. Data from February had the highest
209
monthly average of daily radiation of 191 W/m2/day. 1200
250
1000
200
800
150
600 100
400
50
200 0
Average direct normal irradiation(W/m2/day)
by the model of Assadi et al. (2014). The annual average value of global solar radiation for
Direct normal irradiation (W/m2)
202
0 1
2
3
4
5
6
7
8
9
10
11
12
Month of the year Max direct normal irradiation
Average direct normal irradiation
210 211
Fig. 5. Monthly averages and monthly peaks daily total direct normal irradiation DNI.
212
Table 2 shows the comparison with the monthly mean of the daily values of direct normal solar
213
irradiation for Seri Iskandar (MJ/m2/day) and the NASA SSE model time-series data [29]. Two
214
differences were observed in the measurements:
215
(1) The NASA SSE model measured values for 22 years while the current study measured values
216
for one year, and
217
(2) Weather conditions that vary from year to year have led to minor differences in
218
measurements related to 22-year average global solar radiation data of the NASA SSE model.
219
The measured values of the direct normal irradiance (DNI) at Seri Iskandar city are slightly
220
higher those predicted by the NASA SSE elevation model as observed from Table 2. The 10
221
minimum value was observed for the month of November at 8.6 MJ/m2-day. The highest value
222
was observed for the month of February at 14.92 MJ/m2-day. In the month of August, ground-
223
based and NASA measurements had equal values of DNI with relative differences percentage of
224
0.09 %. The annual average value of DNI for ground-based is 12.08 MJ/m2-day, which is higher
225
than the NASA measurements at 10.99 MJ/m2-day.
226
Table 2: Monthly mean daily values of direct normal solar radiation for Seri Iskandar. Months
Direct normal irradiation, H
Relative differences
(MJ/m2/day)
between the measured
Present
NASA SSE
measurement
model (22-year
and NASA (%)
average) January
13.67
12.91
5.5
February
14.92
13.972
6.3
March
14.19
12.42
12.4
April
14.02
13.71
2.2
May
13.45
12.88
4.2
June
13.21
11.91
9.8
July
12.71
11.44
9.9
August
10.27
10.26
0.09
September
11.47
8.96
21
October
9.72
7.812
19.6
November
8.60
8.42
2
December
8.79
7.23
17.7
Annual
12.08
10.99
8.9
227 228
The reasons behind the differences in present data and those already available can be
229
attributed to two reasons. First, the present data represent measurement of global and direct
230
normal solar energy radiation for one year only, whereas NASA satellite comprised a 22-year
231
average and that of Assadi et al. (2014) [33] spanned two years (2010–2012). Second, the present
232
data are measurements on the ground. However, NASA satellite elevation on earth provides 11
233
results close to reality with error ratio. Assadi et al. (2014) presented a model prediction by
234
MATLAB program that slightly equal to the present data. These reasons validate the solar
235
radiation measurements and confirm the potential of solar energy for the region. Therefore, the
236
ground-based measurements can be utilized to improve the world solar radiation database.
237
The daily values of the monthly mean of Seri Iskandar global solar radiation were
238
compared with several cities in Malaysia (shown in Table 3) as reported by Sopian and Othman
239
(1992) and Muzathik (2013). The table shows clearly that the average monthly global radiation
240
over the course of the year was comparatively good for Seri Iskandar. The annual mean global
241
radiation for recorded for Seri Iskandar was also close to that obtained for the other cities.
242
The monthly average global radiation over the course of the year is comparatively higher for
243
Kota Kinabalu, although in the dry season months, several Malaysian cities had higher values.
244
The peak radiation month in Kota Kinabalu is April (21.64 MJ/m2 day) and the month with the
245
lowest radiation was in January (17.71 MJ/m2 /day). The annual mean global radiation for Seri
246
Iskandar was good as compared with the Malaysian cities. The total annual global solar radiation
247
received in Seri Iskandar on a horizontal surface is about 17.91 MJ/ m2/day. More than 63% of
248
this total is contributed by the dry season months (January to July) and about 37% in August to
249
December. The global solar radiations in the major cities of Malaysia are approximately the
250
same within 7.5%.
251 252 253 254 255 256 257 258
12
259
Table 3: Monthly mean daily values of global solar radiation for Seri Iskandar and other cities
260
for one year (Muzathik, 2013) [24]. Global radiation (MJ/m2/day)
Months
Relative
Seri
Kuala
Kuching
Kota
Kota
differences
Iskandar
Terengganu
(2013)
Kinabalu
Bharu
Between Seri
(2018)
(2013)
(2013)
(2013)
Iskandar And Kota Kinabalu (%)
January
19.33
17.91
12.02
17.71
16.26
8.3
February
21.37
21.60
13.35
19.36
17.72
9.4
March
20.23
21.40
15.39
20.97
19.72
3.6
April
19.51
23.64
13.07
21.64
19.74
10.7
May
19.21
20.34
13.42
20.16
18.23
4.9
June
18.59
17.42
16.28
19.11
17.10
2.8
July
18.34
19.43
16.57
19.41
17.17
5.5
August
16.36
19.15
15.14
19.44
17.42
18.8
September
17.47
20.20
15.79
18.20
18.12
4.1
October
15.20
16.40
15.23
19.21
17.09
26
November
15.08
16.24
14.92
18.08
13.28
19.8
December
15.13
13.38
12.56
18.00
12.15
18.9
Annual
17.91
18.92
14.48
19.27
17.00
7.5
Average 261 262
The daily variation of the clearness index throughout the year in Seri Iskandar is shown
263
in Fig. 6. The figure shows that the variation is within range from 0.2 and 0.9. A variety of
264
conditions contributed to the fluctuation of values throughout the rainy season and clear skies.
265
Fig 7 shows the monthly average clearness index, which varies between 0.45 and 0.55; based on
266
these data, 0.50 as the average clearness index value was approximately measured. During the
13
267
rainy season, both the clearness index and global solar radiation were recorded to be low. When
268
the clearness index is low, the solar radiation energy is reduced dramatically.
Clearness index [K=H/Ho]
1 0.8 0.6 0.4 0.2 0 0
50
100
150
200
250
300
350
400
Day of the year
269
Fig. 6. Daily average clearness index (K) variation. H is the total solar radiation and Ho is the
271
extraterrestrial solar radiation.
Clearness Index
270
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 1
2
3
4
5
6
7
8
9
10
11
12
Month of the year
272 273
Fig. 7. Monthly average clearness index.
274
Sopian and Othman (1992) and Muzathik (2013) [17,24] have reported the monthly
275
clearness indices of Malaysian cities, such as Kuala Terengganu, Kuching, Kota Kinabalu, and
276
Kota Bharu and have identified Malaysian cities with higher solar energy potential areas, which 14
277
is why we compared these data with the Seri Iskandar monthly mean clearness index (see Table
278
4). The comparison provides evidence that the monthly average clearness index over the course
279
of the year is good for Seri Iskandar, although Kota Kinabalu experiences higher monthly mean
280
clearness index values at certain months. With respect to the current comparison of the climate
281
conditions in various cities, clearness index, direct normal irradiation, and global radiation, Seri
282
Iskandar has been demonstrated to utilize the greatest solar energy.
283
Table 4: Monthly averaged clearness index of Seri Iskandar and other cities compared with data
284
obtained by [17, 24], and NAS SSE [29]
Months
January
Monthly averaged insolation clearness index, K (0–1) NASA SSE Seri model Kuala Kota Iskandar Kuching (22-year Terengganu Kinabalu (measured) average) 0.52 0.48 0.54 0.35 0.55
Kota Bharu 0.51
February
0.55
0.51
0.62
0.38
0.57
0.52
March
0.54
0.51
0.57
0.41
0.56
0.53
April
0.53
0.51
0.64
0.36
0.59
0.54
May
0.52
0.49
0.54
0.37
0.53
0.48
June
0.51
0.5
0.48
0.48
0.53
0.48
July
0.49
0.49
0.53
0.45
0.51
0.45
August
0.47
0.46
0.53
0.41
0.51
0.46
September
0.48
0.45
0.53
0.43
0.50
0.50
October
0.47
0.44
0.44
0.41
0.53
0.47
November
0.45
0.42
0.49
0.41
0.53
0.39
December
0.46
0.43
0.42
0.36
0.54
0.37
Annual
0.50
0.47
0.53
0.40
0.54
0.47
Average 285 286
Malaysia is a tropical country with one season of weather all around the year. Figure (8) shows
287
the temperature with average global radiation. the average temperature in Malaysia is around 32
288
⁰
C in the day and around 26 ⁰C in the night with a very small change around the year. There is an 15
289
agreement on the design temperatures of the HVAC system and other solar systems assuming 32
290
⁰
C in the daytime and 26 ⁰C in the night time.
35
350
30
300
25
250
20
200
15
150
10
100
5
50
0
0 0
2
4
6
8
10
12
14
Average global radiation(W/m2/day)
Temperature(⁰C)
291
Month of the year T_amb
Average global radiation
292
Fig. 8. Monthly average temperature
293 294 295
Figure (9) describe wind speed during all seasons. Sometimes the result is high the wind speed
296
and sometimes low the wind speed. Again, it is probably caused by the cloudy sky which clouds
297
sometimes suddenly come and disappears. In the rainy season, normally the intensity of the
298
cloud is higher than the dry season. That is why more high wind speed is observed in the rainy
299
season.
16
350
3
300
2.5
250
2
200
1.5
150
1
100
0.5
50
0
0 0
2
4
6
8
10
12
14
Average global radiation(W/m2/day)
Wind speed(m/s)
3.5
Month of the year Wspd
Average global radiation
300
Fig. 9. Monthly average wind speed
301 302 303
4 Conclusions.
304
The Solar Thermal Research Center (STARC) of UTP has decided to implement various solar
305
research projects, hence, this study presents the potential for a project utilizing the global solar
306
radiation and direct normal irradiation of solar energy at Seri Iskandar city, Malaysia. A key for
307
meteorological parameters and its implications is solar radiation and weather conditions. These
308
data are crucial in the design of solar thermal systems (such as solar collectors, desalination
309
systems, and dryers), PV-systems, environment-conscious buildings, and HVAC designs, as well
310
as in the applied aspects of solar radiation, such as human-environment interactions and
311
dynamics of agricultural and biological systems. Data have been used in the design of the CSPP
312
model in STARC. The total solar radiation recorded at Seri Iskandar throughout the period of a
313
year exhibited better potential as compared with other cities in Malaysia. With respect to the
314
data obtained, solar radiation was found to be greater in its average values during the dry season
315
(January to July) as compared with the rainy season (August to December). The current
316
measurement data were compared with NASA SSE model results and are in good agreement. In
317
addition to solar radiation data, the clearness index was also predicted using meteorological data
318
and currently measured data. These data are in good agreement. The predicted clearness index
319
for Seri Iskandar was within values ranging from 0.45–0.55, with yearly average of 0.50. The 17
320
acquired solar data evidently show that Seri Iskandar town gains ample amount of solar radiation
321
and is a good location for solar application and utilization.
322
It is hoped that this study would be of interest to researchers and designers of solar thermal
323
systems. However, further investigations for long term meteorological data from different cities
324
in Malaysia are required to obtain more effective results.
325
Acknowledgment
326
We acknowledge the utmost support from Universiti Teknologi PETRONAS, Malaysia. We also
327
would like to express our appreciation to the Ministry of Higher Education-Malaysia for the
328
financial support of the CSP project under the MyRA grant and utilization of instruments under
329
the [FRGS/1/2015/TK10/UTP/03/2] grant.
330 331 332
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Nomenclature monthly mean extraterrestrial horizontal solar radiation (MJ/m2-day)
409 410 411
is the global solar insolation on a horizontal surface at any location on any given day(MJ/m2day) .
412
solar constant (=1367 W m−2)
413
latitude of the site (degrees)
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angle of declination (degrees)
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day of the year
416
mean monthly sunset hour angle (degrees)
21
Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.