Flat Plat Collector performance as a function solar radiation impinging on it surface as a result of variation in time, date and collector orientation

7/30/2019 Flat Plat Collector performance as a function solar radiation impinging on it surface as a result of variation in time

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Solar Thermal Engineering ME 6540

Khalil Raza - Wright State University

1

SOLAR THERMAL ENGINEERING ME - 6540

GRADUATE PROJECT REPORT

Effect of Time, Date and Slope Angle of collector on Solar

Radiation Impinging on Flat Plat Collector

Instructor: Dr. James Menart

By Khalil Raza


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CONTENTS

Abstract

1. Measurement of Solar Radiation1.1 Inputs for Solar Radiation Calculation

1.2 Inputs for Solar Radiation Calculation

2. Effect of Time on Solar Radiation and Flat Plat Collector

3. Effect of Slope Angle on Solar Radiation and Flat Plat3.1 Data for the Solar Radiation while changing the slope angle andkeeping the time and date constant

4. Conclusion

5. References


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Abstract:

Solar energy is clean, free and abundant and it can contribute positively in filling the

energy gap created by oil shortages and its increasing prices. Solar energy can be trapped

in two ways; Solar Thermaltrapping suns heat energy and converting into useful work

and secondly with Solar photovoltaicdirectly converting solar light into electricity. In

this paper, the analysis of flat plat collector has been carried out which is the application

of solar thermal system. Flat plat collectors trap suns thermal energy and these are used

for hot water heating and air conditioning. In this work, flat plat collectors performance

is evaluated by changing different parameters and as the result optimized values of those

parameters are established.

In order to analyze the performance of flat plat collector, one of the important factors is

the useful heat gain, which determines useful work that can be harnessed out of the

collector. To measure the useful heat gain in the flat plat collector, which is the energy,

converted into useful work like heating the water, it is required to calculate the solar

radiation impinging on the collector surface at that location. Hence, the approach towards

measuring the useful heat gain requires calculating first the solar insolation on the tilted

surface. Solar radiation on tilted surface depends on the time, date, location and

orientation of the solar collector. The performance of flat plat collector significantlyvaries with change of time, location and its slope angle. The work is done to measure the

effect of varying time, while keeping the other parameters constant to know the best time

where a collector can gain the maximum amount of heat. Besides, the slope angle or tilt

of solar collector is kept varying to get the optimized angle when the collector will

perform at its best.

All the calculations have been done in MS Excel program that was used for the

homework assignment during this course of Solar Thermal Engineering. In this work, the

radiation has been calculated in the Dayton, OH at 39.78 N and 84.06 W coordinates.

Finally, the results such as absorbed energy by absorbing plate, hourly insolation on tilted

surface and useful heat gain in the collector have been plotted through excel charts as a

function of varying slope angle and time.


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1.Measurement of Solar Radiation:Solar radiation impinging on tilted surface has been measured while the model also

counts the atmospheric effects in the calculation. The solar radiation has been measured

on different dates of year from 6:30 AM to 6:30 PM.

Following data was used to measure the solar radiation:

1.1Inputs for Solar Radiation Calculation:Time: 6:30 AM6:30 PMSlope Angle: 60

Azimuthal Angle: -5 South of East

Latitude: 39.78N and Longitude: 84.06 W

1.2Inputs for Flat Plat Collector:2 sheets of glass cover the collector and each glass plate has aKL of 0.0370

Ambient air temperature = 20oCPlate-to-cover spacing = 0.025 m

Wind speed = 3 m/sCollector is mounted flush to roof of home

House volume = 729 m3Mean plate temperature = 110oC

Plate long wavelength emittance = 0.9

Plate short wavelength emittance = 0.95Glass emittance = 0.88

Back and side insulation thickness = 25 mm

Insulation thermal conductivity = 0.045 W/m-oC

Collector width = 2 mCollector length = 3 m

Non-curve fit chart valuesThis collector has 20 tubes, 0.015 m in diameter running along its length.Plate thickness = 0.0006 m

Plate thermal conductivity = 370 W/m-oC.

Bond conductance = 106 W/m2-oCFluid in tubes = water

Total water flow rate = 0.5 kg/s

Inlet water temperature = 60oC

Mean fluid temperature = 60.56oCMean wall temperature = 61.30oC

2.Effect of Time on Solar Radiation and Flat Plat Collector:Table 1 - For the January 1st, 1995 following results were obtained:Time Hourly

extraterrestri

al radiation Io

Hourly

Insolation on

Tilted Surface

IT

Solar

Radiation

Absorbed by

Absorbing

Plate S

Useful Heat Gain in

Collector

6:30 AM -1.414 0.0000 0 -1152.4157


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7:30 AM -0.4820 0.0000 0.0000 -1152.4157

8:30 AM 0.3970 0.0000 0.0000 -1152.4157

9:30 AM 1.1610 0.0598 0.0382 -1090.5330

10:30 AM 1.7600 0.5431 0.3619 -565.5827

11:30 AM 2.1530 0.2485 0.1601 -892.7133

12:30 PM 2.3120 0.7061 0.4707 -389.0596

1:30 PM 2.2270 0.5474 0.3625 -564.5398

2:30 PM 1.903 0.5560 0.3695 -553.1437

3:30 PM 1.3640 0.5322 0.3563 -574.5814

4:30 PM 0.6440 0.8966 0.6034 1629.1060

5:30 PM -0.2050 -0.4029 -0.2399 545.5203

6:30 PM -1.1280 0.0292 0.0164 1180.7228

Figure 1: Hourly Extraterrestrial Radiation, Hourly Insolation on Tilted Surface and Solar

Radiation Absorbed by Absorbing Plate as a function of time.

Figure 1 shows the quantities as hourly extraterrestrial radiation, hourly Insolation on

tilted surface and energy absorbed by flat plate absorbing plate as a function of time.

Since in the month of January the solar radiation is considerably lower, therefore, the

amount of solar energy is not enough to produce significant work from the collector. Thefollowing graph shows the total useful heat gain during different hours of the day from

the flat plat collectors:

-2.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

4:48 AM 7:12 AM 9:36 AM 12:00 PM 2:24 PM 4:48 PM 7:12 PM

Time

Hourly extraterrestrial radiation Io

Hourly Insolation on Tilted Surface

IT

Solar Radiation Absorbed by

Absorbing Plate S


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Table 2 - For May 5th

, 1995 following results were obtained:Time Hourly

extraterrestrial

radiation Io

Hourly

Insolation on

Tilted Surface

IT

Solar Radiation

Absorbed by

Absorbing Plate S

Useful Heat Gain

in Collector

6:30 AM 0.8147 0.030 0.019238369 -1121.2164

7:30 AM 1.7368 0.2499 0.1660 -883.2283

8:30 AM 2.5990 0.7547 0.4948 -349.9143

9:30 AM 3.3425 1.3987 0.9308 357.0725

10:30 AM 3.9167 1.8407 1.2398 858.1202

11:30 AM 4.2824 2.2164 1.5042 1286.9938

12:30 PM 4.4147 2.8175 1.9356 1986.5519

1:30 PM 4.3046 2.6091 1.7863 1744.4904

2:30 PM 3.9596 2.401 1.6342 1497.7863

3:30 PM 3.4032 1.8091 1.1999 793.5478

4:30 PM 2.6733 1.3388 0.8220 180.5848

5:30 PM 1.8196 0.4899 0.2445 -755.9833

6:30 PM 0.9004 -0.3097 1.1335 685.8587

-1500.0000

-1000.0000

-500.0000

0.0000

500.0000

1000.0000

1500.0000

2000.0000

4:48 AM 7:12 AM 9:36 AM 12:00 PM 2:24 PM 4:48 PM 7:12 PM

Time

Useful Heat Gain in Collector

Useful Heat

Gain in

Collector

Figure 2: Useful Heat Gain in Flat Plat Collector in (Watts) VS Time


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For the month of May, there is considerable solar radiation therefore, the performance issignificantly better here. It can be noticed that amount of Io, IT and S are much better

than the month of January. Each of these quantities is dependent on each other. If the

hourly solar radiation on a tilted surface is more then more energy will be absorbed theabsorbing plate of the solar collector. Consequently, more energy absorbed by the

absorber plate will improve the useful heat gain in the collector. The next graph will

show the Useful Heat Gain as a function time, which is performing well in this month.

-1.0000

0.0000

1.0000

2.0000

3.0000

4.0000

5.0000

4:48 AM 7:12 AM 9:36 AM 12:00 PM 2:24 PM 4:48 PM 7:12 PM

Time

Hourly extraterrestrial radiation

Io

Hourly Insolation on Tilted

Surface IT

Solar Radiation Absorbed by

Absorbing Plate S

Figure 3: Io, IT and S VS Time

-1500.0000

-1000.0000

-500.0000

0.0000

500.0000

1000.0000

1500.0000

2000.0000

2500.0000

4:48 AM 7:12 AM 9:36 AM 12:00 PM 2:24 PM 4:48 PM 7:12 PM

Time


Useful Heat

Gain in

Collector

Figure 4: Useful Heat Gain in Collector VS Time


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Table 3 - For July 17th

, 1995 following results were obtained:Time Hourly

extraterrestrial

radiation Io

Hourly Insolation

on Tilted Surface

IT

Solar Radiation

Absorbed by

Absorbing Plate S

Useful Heat

Gain in

Collector

6:30 AM 0.9192 0.062 0.035832947 -1094.3046

7:30 AM 1.8053 0.3496 0.2288 -781.39198:30 AM 2.6433 0.8582 0.5584 -246.8614

9:30 AM 3.3763 1.4388 0.9520 391.5320

10:30 AM 3.9542 2.0295 1.3702 1069.6981

11:30 AM 4.3377 2.5023 1.7088 1618.7145

12:30 PM 4.5006 2.7967 1.9186 1958.9761

1:30 PM 4.4319 2.8468 1.9504 2010.6295

2:30 PM 4.1361 2.659 1.8048 1774.4833

3:30 PM 3.6335 2.2118 1.4607 1216.3885

4:30 PM 2.9583 1.5441 0.9447 379.5661

5:30 PM 2.1566 0.6792 0.3328 -612.7595

6:30 PM 1.2829 -0.4026 1.4814 1249.9894

-1

0

1

2

3

4

5

0.2 0.3 0.4 0.5 0.6 0.7 0.8

Time

Hourly

extraterrestrialradiation Io

Hourly Insolation

on Tilted Surface

IT

Solar Radiation

Absorbed by

Absorbing Plate S

Figure 5: Io, IT and S at different times in the month of July


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Figure 6: Useful Heat gain in the collector VS Time for the month of July

The month of July receives good amount of solar radiation as in summer the solar

radiations are concentrated and the daylight hours are prolonged1. During the months of

June, July and August the flat plat collector performs meaningfully well than the rest of

the months. Moreover, the best time for obtaining is 11 AM to 1 PM as suggested by the

above graphs. During this period of time the collector gets more concentrated beamradiation which dominant over the diffused and the radiation reflected off the ground.

3. Effect of Slope Angle on Solar Radiation and Flat Plat:Although, time is an important factor that directly affects the performance of flat platcollectors. Along-with time, slope of the solar panel also plays an important role in

collecting the heat from the sun.

3.1Data for the Solar Radiation while changing the slope angle and keeping thetime and date constant:

Date: April 06th, 2011Time: 1:30 PMSlope Angle: Varying from 20 to 44Azimuthal Angle: -5 South of East

Latitude: 39.78N and Longitude: 84.06 W

Whereas the flat plat collector data is same as used for the calculation involving varying

time and date of the year 1995 in the page # 3.

Table 4 - Following results were obtained for April 06th

, 2011Slope, Hourly

Insolation on

Tilted Surface IT

Solar Radiation

Absorbed by

Absorbing Plate S

Useful Heat

Gain in

Collector

20 3.4525 2.407973057 2706.135319

22.00 3.4741 2.424360519 2733.865676

-1500

-1000

-500

0

500

1000

1500

2000

2500

0.2 0.3 0.4 0.5 0.6 0.7 0.8

TIme


Useful Heat

Gain in

Collector


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24.00 3.4921 2.438048839 2757.339386

26.00 3.5066 2.448986092 2776.472774

28.00 3.5174 2.457139974 2791.213944

30.00 3.5247 2.462494425 2801.53731

32.00 3.5284 2.465043529 2807.433709

34.00 3.5284 2.46478537 2808.900456

36.00 3.5249 2.461718646 2805.935853

38.00 3.5177 2.455843601 2798.540705

40.00 3.507 2.447166865 2786.726155

42.00 3.4926 2.435708011 2770.524331

44.00 3.4747 2.421504955 2749.997085

In this calculation, the time is kept same and the slope of the flat plate collector is

changing from 20 to 44. Slope of the angle directly affects the hourly insolation on a

tilted surface that further is dependent factor for the energy absorbed by the absorbingplate and useful heat gain in the collector. It was found that the keeping the slope at 32

and 34 gives the maximum amount of hourly insolation on a tilted surface, which is

approximately 3.5284 MJ/m2 at these two angles. It can also be noticed that the more the

Insolation on tilted surface makes it possible for the collector to absorb the maximumheat energy thus more useful gain in the collector is obtained.

The following graphs have been plotted on the basis of the information given in table 4

2700

2720

2740

2760

2780

2800

2820

20 25 30 35 40 45Slope Angle


Useful Heat Gain in

Collector

Figure 7: Useful Heat Gain VS. Time


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3.44

3.45

3.46

3.47

3.48

3.49

3.5

3.51

3.52

3.53

3.54

20.00 25.00 30.00 35.00 40.00 45.00

Slope Angle

Hourly Insolation on Tilted Surface IT

Hourly Insolation on Tilted

Surface IT

2.4

2.41

2.42

2.43

2.44

2.45

2.46

2.47

20.00 25.00 30.00 35.00 40.00 45.00

Slope Angle

Solar Radiation Absorbed by Absorbing

Plate S

Solar Radiation Absorbed

by Absorbing Plate S

Figure 9: Hourly Insolation on Tilted Surface VS. Time

Figure 8: Solar Radiation Absorbed by Absorbing Plate VS. Time


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4 Conclusion:The results shown in this paper establish the effects of Time and Date on the solar

radiation. It is very much clear that in summers much more solar radiation is expected as

compared to winters. My results have well supported this and also the performance of thecollector varies significantly during different times of the day and in different seasons of

the year. It also showed the slope angle contributes importantly and with proper tilt angle

the solar insolation for an hour on a tilted surface can be increased significantly. That

further makes it possible for the solar collector to absorb maximum heat and as a resultthe useful heat gain is obtained at higher rates.

5.Reference:1 Shining On A Primer on Solar Radiation Data NREL

http://www.nrel.gov/docs/legosti/old/4856.pdf

For the hourly calculation, the value of measured solar radiation on a horizontalsurface was taken from the National Renewable Energy Laboratorys website.http://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3/by_state_and_city.html
http://www.nrel.gov/docs/legosti/old/4856.pdfhttp://www.nrel.gov/docs/legosti/old/4856.pdfhttp://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3/by_state_and_city.htmlhttp://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3/by_state_and_city.htmlhttp://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3/by_state_and_city.htmlhttp://www.nrel.gov/docs/legosti/old/4856.pdf

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Flat Plat Collector performance as a function solar radiation impinging on it surface as a result of variation in time, date and collector orientation