DISTRIBUTION OF TOTAL AND DIFFUSE SOLAR RADIATION AT LAHORE, PAKISTAN

Transcription

1 Journal of Scientific Research Vol. XXXX No. 1, June, 2010 ISSN DISRIBUION OF OAL AND DIFFUSE SOLAR RADIAION A LAHORE, PAKISAN M. Akhlaque Ahme* Firoz Ahme** an Wasim Akhtar*** * Basic an Applie Science, Sir Sye University of Engineering an echnology Karachi, Pakistan. ** Department of Physics, University of Karachi, Karachi, Pakistan. *** Usman Institute of echnology, Karachi, Pakistan. Abstract: In this research work the solar raiation for Lahore ( Latitue31.56)has been stuie for efficient utilization of solar energy employing sunshine hour ata. he results obtaine exhibit the variation of irect an iffuse raiation at Lahore. he iffuse raiation is maximum in the month of July an minimum uring the month of April, May an June. he K t Value inicates the clear sky uring the month of January, February, April, May an September to December. Where as uring the month of Jun to August the sky is mostly clouy which is the monsoon months. From the estimate results it is foun that with the exception of monsoon months solar energy can be utilize very efficiently through out the year. Key Wors: Diffuse Raiation, Lahore, Solar Raiation, Sky Conition. Introuction Global solar raiations are available in At present Pakistan is facing serious Pakistan but iffuse solar raiation are energy problem ue to increase eman not measure experimentally in any of energy, high cost of energy import an meteorological station of the country. high population growth. he rural sector herefore it is rather important to which comprises seventy percent of evelop methos to estimate the global population is epenent on the use of an iffuse solar raiation using none commercial energy resources. o climatological parameters. Several overcome this problem one has to empirical formula have been evelope evelop alternate energy resources. to calculate the global solar raiation Wiely use renewable resources are using various parameters. hese solar an win energy which has shown parameters are Sunshine hours (1) the prospects an potential for efficient relative humiity an sunshine hour (2), utilization. the eclination angle an altitue(3).etc. Detail information about the availability Besies these many other workers have of solar raiation on horizontal surfaces reporte the estimation of global an is essential for the optimum esign an iffuse solar raiation employing stuy of solar energy conversion system. various climatological parameters. (4). he commercial an efficient application In the present work the solar raiation of solar energy seems inevitable because have been one for Lahore using of abunant sunshine available sunshine ata to utilize solar energy. throughout the year. Solar raiation ata are available for most part of the worl he Lahore city has an area of 461 acres. but is not available for many countries It is locate at latitue N an which can not affor the measuring longitue east. It is the capital of instrument an technique involve. Punjab province having a population of 1-For Proof an Corresponence: M. Akhlaque Ahme

2 M. Akhlaque Ahme 65 million people. estimate by an empirical formula which co-relates the iffuse solar raiation his work will help the energy strategist component H to the aily total raiation an planners to utilize the solar energy H. he co-relation equqtion which is potential to solve the energy crises of the wiely use are given below.(7,8) province. H /H = K (Page,Jk 1964) (7) Methos of preiction H /H = K (K ) 2- In the present work the H/H, the 3 O 3.108(K) (Liu & Joren) (8 ) monthly global solar raiation falling on a horizontal surface at particular location an the monthly mean aily raiation on horizontal surface in the absence of atmosphere is given by the following expression.(4,5) 38 Where H is the monthly mean of aily iffuse solar raiation an K = H/H O is the clearness inex. Results an Discussion he input parameters for the estimation H/H 0 = a + b(n/n) (1) of monthly average aily global solar raiation at Lahore, Pakistan are shown Where n is the monthly mean aily no. of in table:1 sunshine hour an N is the ay length at particular location an a an b are the From table1. it is observe that sunshine climatological etermine regression uration of Lahore is between 60 to 80% constant. n/n is also calle the possible through out the year. Employing these percentage of sunshine hour. parameters the regression constant 'a' an 'b' are evaluate. Inserting these values in he regression constant a an b have equations (1) the monthly average aily been obtaine from the relationship global solar raiation H is estimate. he given as (6) an also confirme by Frere value of Ho, H, H b an D for Lahore is et.al metho (Fere et.al 1980) as given shown in Figure (1). able 2 gives the below. calculate values for Ho, H, K t an H for Lahore. It also shows the ratio. D/H an a= cosö (n/N) (2) D/Ho. It inicates that the value of b= cosö (n/N) (3) iffuse raiation to extraterrestrial raiation is not more than 16% with the he value H 0 may be etermine by the exception of July which is 19%. following experession. Diffuse solar raiation H 0=24/Ð I SC ([ cos (360n/365)] he iffuse solar raiation for Lahore is [cosö cosä sinw s +2ðws /360 sinö estimate by Liu an Joren, Page sinä] (4) metho, as no station in Pakistan Where I SC is the solar constant, Ö is the measures Diffuse solar raiation. From latitue of the area, ä is the solar the estimate result it is seen that eclination an ws is the sunset hour contribution of iffuse solar raiation is angle. very low throughout the year with the = sin[360*248+n/365] (5) exception of monsoon months, i,e from Cos w S = -tanö tan ä (6) Jun to August. he Liu & Joren metho preicts lower values then the Page co- Preiction of iffuse solar raiation relation. he contribution of iffuse he iffuse solar raiation H can be

3 Distribution of total an Diffuse Solar Raiation raiation is blow 35%.(9,10) he availability of irect raiation is therefore encouraging from utilization point of view. he transmission of D/H O is between 14 an 19 percent where as of D/H is between20 an 33 percent which means that presence of clou is only in January an July an mostly the sky is clear which is very favorable conition for solar energy utilization. 39 Statistical Distribution of Global Solar Raiation January - April 61% May - June 65% July - August 60% September - December 68% Variation of Direct an Diffuse Solar Raiation here is a large variation in the intensities of irect an iffuse solar raiation ue to Fig: (1) represents a plot of monthly clou. his has been inicate in fig(2). variation of Extraterrestrial, total, irect he result inicates that uring the an iffuse solar raiation at Lahore, months of April to June are quit Pakistan. In case of irect raiation a ip appreciable. he percentage of iffuse is seen in the month of July for Lahore. raiation contribution to global is low in he transmission through atmosphere K the month of July. he presence of irect along with the percent of iffuse raiation for the month of April, May raiation is shown in Fig(3). he sky is June will be very useful for utilizing it for fairly clear throughout the year except for solar concentrater,solar cookers an the month of July. solar furnaces. he Angstrom moel for the etermination of the global solar Sky Conition at Lahore raiation an Liu an Joran moel for he transparency of the atmosphere is the estimation of iffuse solar raiation inicate by fraction of Extraterrestrial exhibit the valiity of estimation for the raiation that reaches the earth surface as location uner stuy. global solar raiation. It is the measure of the egree of the clearness of the sky Conclusion which is given as below. he result obtaine inicates that the solar energy utilization has bright K = H / H O (9) prospects in Lahore, Pakistan. he Where K is the clearness inex. H is the estimate values of global an iffuse raiation reveals that solar raiation can global solar raiation an Ho the be very efficiently use to compensate Extraterrestrial insulation. As shown in for the energy eficits. For the estimation figure (3) the sky at Lahore is very clear of iffuse raiation lieu an Joran an throughout the year with exception of page methos are in goo agreement. he July. experimental ata of global an iffuse solar raiation is not available for Statistical Distribution Lahore, Pakistan,so estimation has to be Statistical istribution of global solar one employing sunshine hour of the raiation inicates that availability of location. global solar raiation at Lahore is 65% uring the month of May- June an 68% Acknowlegement uring the month of September to he authors are please to acknowlege December. In the monsoon perio it is to Pakistan Merological Deppt. Karachi 60% office for proviing the sunshine hour ata for this work.

4 M. Akhlaque Ahme References Narosa Publishing House, New 1. Angstrom, A. Solar an terrestrial Dehli, Inia,1977. raiation Q.J.R. Met. Soc , Page, J.K. he estimation of monthly mean values of aily short 2. Gopinathan, K.K. A new moel for wave raiation on vertical an estimating total solar raiation. incline surface from sunshine Solar an Win technology. 5. recors of latitue 40 egree N to 40 (1) , egree S. Proc. Of UN-Conf. on New Sources of Energy. l:4 paper 3. Liu, Y.H an Joran, R.C. he inter s/ ,1964. relationship an characteristic istribution of irect, iffuse an 8. Sabbagh, J. A., Sayigh, A.A.M. an t o t a l s o l a r r a i a t i o n f r o m El. Salam, E.M.A. Estimation of the metrological ata. t o t a l s o l a r r a i a t i o n f r o m meteorological ata. 4. Rey, S. J. An empirical metho for the estimation of net raiation 9. ogral, I.. an Hasan, ogrul. intensity Solar Energy Global solar raiation over urkey. 292,1971. Comparison of preicte an measure ata Renewable Energy. 5. Ahme Akhlaque M an Ahma , Firoz, Estimation of Global an Diffuse Solar raiation for 10. Ahma, Firoz an Ulfat Intikhab. Hyeraba, Sinh. Pakistan. Journal Emperical moel for the correlation of Basic an Applie Science, of Monthly Average Daily Global 5:2,73-77, Solar Raiation with hours of sunshine on a horizontal surface at 6. iwari G.N an Suleja, Sangeeta. Karachi, Pakistan. urkish J. Solar hermal Engineering System, Physics ,

5 Distribution of total an Diffuse Solar Raiation able:1 Input parameter for estimation of monthly Global Solar raiation at Lahore, Pakistan. Monthly sunshine hours n Monthly average ay length N January February March April May June July August September October November December n/n percentage of possible sunshine hour 41

6 M. Akhlaque Ahme Ho mjm 2 able 2: Calculate Solar raiation ata for Lahore H K=H/Ho H /H LJ H /H page H Page mjm 2 H LJ D= D/H D/Ho H +H January February March April May June July August September October November December Fig:1 Aplot of the monthly variation of total,irect an iffuse solar raiation for Lahore(Latitue 31.34) Pakistan Langly/ay H0 H Hb D Jan. Feb. March April May June July Augu. Sept. Oct. Nov. Dec. 42

7 Distribution of total an Diffuse Solar Raiation Fig:2 Shows the variation of irect an iffuse raiation for Lahore, Pakistan Raiation Mj/ Direct Diffuse 5 0 Jan. Feb. March April May June July Augu. Sept. Oct. Nov. Dec. Fig:3 Behaviour of the clouness inex Kt,D/H an D/H0 uring a year for Lahore, Pakistan Ratios Kt D/H D/H Jan. Feb. March April May June July Augu. Sept. Oct. Nov. Dec. 43