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F2.2 ` Against pitch' installations

F2.2 ` Against pitch' installations

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77

FIGURE F1

FIGURE F2
‘WITH PITCH’ INSTALLATION

‘AGAINST PITCH’ INSTALLATION

AS/NZS 3500.4.2:1997

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AS/NZS 3500.4.2:1997
78

FIGURE F3
‘CROSS PITCH’ INSTALLATION

79

AS/NZS 3500.4.2:1997

APPENDIX G

SOLAR HOT WATER SYSTEMS SUGGESTED COMPONENT SIZES
(UNRATED SYSTEMS)
(Informative)
G1 GENERAL The data presented in this Appendix should be read in conjunction
with the text of the Standard.

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G2 ANTICIPATED SOLAR FRACTION The anticipated solar fraction (f ) listed in
Table G1 is for typical solar hot water systems installed in houses and incorporating a
well-designed flat plate collector with a well-insulated container having a draw-off
capacity not less than 80% container storage volume. However, the values for storage
container capacity and collector area do not necessarily relate to any particular
commercially available close-coupled systems. All data presented in this Appendix
correspond to the average requirements of a four-person household.
G3 SOLAR RADIATION DATA Basic solar radiation data is given in Figures G1
and G2 for Australia and Figure G3 for New Zealand. For more comprehensive details of
solar radiation in Australia, reference should be made to the Australian Solar Radiation
Data Handbook, published by the Department of Resources and Energy, Canberra and the
National Institute of Water and Atmospheric Research Ltd., Wellington, New Zealand for
further information.

AS/NZS 3500.4.2:1997

80

TABLE

G1

SUGGESTED COMPONENT SIZES
(UNRATED SYSTEMS)
1

2

3

4

5

Angle of
inclination

Area

Container
storage

Anticipated
solar
fraction (f)

degrees

m2

L

percent

Adelaide
Alice Springs
Auckland

35 (35)
32 (24)
35 (37)

4
4
4

315
315
360

74
94
65

Brisbane
Christchurch
Canberra

29 (27)
35 (43.5)
33 (35)

4
4
4

315
360
315

81
60
67

Darwin
Hobart
Invercargill

15 (12)
42 (43)
20 (40)

3
5
4

270
360
360

97
65
56

Melbourne
Perth
Sydney

38 (38)
33 (32)
34 (34)

5
4
4

360
315
315

67
77
76

Wellington

35 (41)

4

360

60

Collector

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Location

NO TES:
1 Column 2:

Nominal angle of inclination of flat plate collector to
horizontal (see Clause 5.4.1.4). Latitude angle is shown in
parentheses.

2 Column 3:

Collector aperture area expressed in square metres. This
area is for optimum conditions of collector inclination and
orientation. For non-optimum conditions, the solar fraction
will be reduced (see Appendix I) and a greater area may be
required.

3 Column 5:

Anticipated average annual solar energy fraction (f)
expressed as a percentage of total hot water energy
delivered, i.e. —
E − EP
× 100
f = wh
Ewh

where

Ewh

= hot water energy delivered at water heater outlet
(mass × specific heat capacity × temperature
differential)

Ep

= total supplementary energy purchased for water
heating

4 The actual solar fraction will vary with household hot water use patterns
and with weather variations from year to year. The figures given should
be accurate to within 5% for normal situations.

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81

FIGURE G1
AS/NZS 3500.4.2:1997

CONTOURS OF ANNUAL MEAN DAILY SOLAR RADIATION ON
A HORIZONTAL SURFACE (MJ/m 2.d)

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AS/NZS 3500.4.2:1997

82

FIGURE G2 ANNUAL MEAN DAILY SOLAR RADIATION ON A NORTH FACING
SURFACE INCLINED AT THE LATITUDE ANGLE, (MJ/m 2.d)

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83

FIGURE G3
AS/NZS 3500.4.2:1997

CONTOURS OF ANNUAL MEAN DAILY SOLAR RADIATION ON
A HORIZONTAL SURFACE (MJ/m 2.d)

AS/NZS 3500.4.2:1997

84

APPENDIX H

ESTIMATION OF SHADING OF COLLECTORS
(Informative)

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H1 GENERAL In order to be able to assess whether or not collectors will be subject
to shading during the year, it is necessary to know the solar altitude for the installation
location when the sun is at its lowest, i.e. in midwinter. As most of the useful solar
radiation is received within 3 h either side of solar noon for any system installed at or
near the recommended orientation and inclination, any significant shading of collectors in
these hours, i.e. 9.00 a.m. to 3.00 p.m. standard time, will affect the performance of such
a system, and should be avoided in locating the unit. Table H1 lists the solar altitude at
midwinter for various locations in Australia and New Zealand. By checking the solar
altitude, as observed at the lower edge of the collectors, the installer can determine
whether or not nearby buildings, trees or other obstructions will cast a shadow on the
collector, For example, if a building, observed from the base of the collectors, is above
the midwinter solar altitude, then that building will cast a shadow on the collectors.

TABLE

H1

SOLAR ALTITUDE AT MIDWINTER
Solar altitude, degrees

Latitude,
degrees

9.00 a.m.

Noon

3.00 p.m.

Darwin
Brisbane
Perth

12
27
32

33.5
23.4
19.8

54.5
39.5
34.5

33.5
23.4
19.8

Sydney
Adelaide/Canberra
Auckland

34
35
37

18.3
17.6
16.1

32.5
31.5
29.5

18.3
17.6
16.1

Melbourne
Devonport
Wellington

38
41
41

15.4
13.2
13.2

28.5
25.6
25.5

15.4
13.7
13.2

Hobart
Christchurch
Invercargill

43
43.5
46

11.7
11.2
9.0

23.6
23.0
20.0

11.7
11.2
9.0

City

H2 SUN LOCATER The midwinter solar altitude may be checked using a commercial
‘sun locater’. However, a simple solar altitude sight may be constructed from the diagram
in Figure H1 for Australia and Figure H2 for New Zealand. The diagram may be glued to
cardboard, or preferably reproduced to a larger scale on cardboard, and then cut out and
assembled. An assembled sight is shown in Figure H3.
The solar altitude sight is used by aligning the arrow due north, using a compass or map,
and with the base of the sight horizontal, sighting the 9.00 a.m., noon and 3.00 p.m.
positions of the winter sun, from a viewpoint near the base of the solar collectors. Any
objects which can be seen above the sight will cast a shadow on the collector in winter.
The use of the solar altitude sight is shown in Figure H3.

85

AS/NZS 3500.4.2:1997

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H3 APPROXIMATE METHOD OF DETERMINING SOLAR ALTITUDE In the
absence of a solar altitude sight, the midwinter solar altitude can be estimated by eye,
using the fact that a closed fist extended at arm’s length from the head subtends
approximately 10° at the eye (see Figure H4), as follows:
(a)

Select a viewpoint close to the lower edge of the collectors, and face due north.

(b)

Extend one arm with the index finger in line between your eye and the true horizon.

(c)

Make a closed fist with your other hand, place it upright on top of the extended
index finger; this gives a solar altitude of 10°.

(d)

Place the second fist on top of the first, which gives 20°, and so on. Then, using
Table H1, estimate the altitude of the noon sun in midwinter and note any likely
shading.

(e)

Repeat this procedure facing N-E and N-W to estimate the midwinter solar altitude
at 9.00 a.m. and 3.00 p.m., respectively, using the data from Table H1.

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AS/NZS 3500.4.2:1997

FIGURE H1

86

MIDWINTER SOLAR ALTITUDE SIGHT (AUSTRALIA)

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87

FIGURE H2
AS/NZS 3500.4.2:1997

MID-WINTER SOLAR ALTITUDE SIGHT (NEW ZEALAND)