Design Optimisation of Compound Parabolic Concentrator (CPC) for Improved Performance R. Abd-Rahman, M. M. Isa, H. H. Goh

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1 Tokyo Japan May 2-2, 21, 1 () Part XXIII Design Optiisation of Copound Parabolic Concentrator (CPC) for Iproved Perforance R. Abd-Rahan, M. M. Isa, H. H. Goh Abstract A copound parabolic concentrator (CPC) is a well known non-iaging concentrator that will concentrate the solar radiation onto receiver (PV cell). This is also will lead to the decreases of concentration ratio but it will be negligible. In this paper, the flux distribution of untruncated and truncated 2-D hollow copound parabolic trough concentrator (hcptc) design is presented. The untruncated design has initial height, H=13. with concentration ratio, C_(2-D)=. This paper presents the optical siulation of copound parabolic trough concentrator using raytracing software TracePro. Results showed that, after the truncation, the height of CPC reduced % fro initial height with the geoetrical concentration ratio only decrease 1%. Thus, the cost of reflector and aterial dielectric usage can be saved especially at anufacturing site. Keywords Copound parabolic trough concentrator, optical odelling, ray-tracing analysis. T I. INTRODUCTION HEdeand for alternative energy is increasing in any countries around the world [1]. Power utility copany, governent agencies as well as acadeic institutions have put extensive efforts in exploring the potential of renewable energy for iproved electric power generation [2], [3]. This issued can overcoe by using solar energy since it offers unliited potential as a clean renewable energy. Solar energy is one of the ost popular energy resources that can be harvested through device such as photovoltaic (PV) cell and directly convert the solar irradiance into electricity [], []. However, the cost of PV aterial is relatively expensive which requires high investent cost. Due to the high costs of PV odules, the use of a device called solar concentrator is highly desirable [2], []. It allows the collection of sunlight fro a large area and focus onto a sall area of the receiver which will harness the power fro the sun to generate the electricity. Concentrating photovoltaic (CPV) is a third generation in solar energy technology [], [], []. It used optical devices like irrors or lens to concentrate solar radiation onto photovoltaic (PV) cell. The ais of CPV are reducing the R. Abd-Rahan is with the Electrical and Electronic Engineering, UniversitiTun Hussein Onn, Parit Raja, BatuPahat, Johor, Malaysia (phone: -3-3; fax: -3-;(e-ail: rahisha@ uth.edu.y). M. M. Isa, was with the Electrical and Electronic Engineering, UniversitiTunHusseonOnn, Parit Raja, BatuPahat, Johor, Malaysia (eail: urniza1@gail.co). H. H. Goh is with the Electrical and Electronic Engineering, UniversitiTun Hussein Onn, Parit Raja, BatuPahat, Johor, Malaysia (phone: ; fax: -33; (e-ail: hhgoh@ uth.edu.y). syste cost in PV technology by replacing the nuber of expensive PV cell used with inexpensive optics and also perforance iproveent. There are any proposed types of solar concentrator based on their applications. A copound parabolic concentrator (CPC) is one of well-known noniaging type s solar concentrator [], [1]. The theory of optics is related with the creation of iage fro an initial object. For non-iaging optical syste is defined where the optical syste has to take the light fro the light source, instead of an object. Then, it concentrated to any point of receiver, instead of an iage. CPC is coposed by cobining two parabolas either translation or rotation operation, preier invested by Prof. Winston [11]-[13]. It can be either syetrical or asyetrical design. However, the acceptance angle of CPC will be decrease when reaching higher concentration. To overcoe this proble, truncation is a way to increase the acceptance angle but also lead decreasing geoetrical concentration ratio. Truncation can be defined as reoving the entry aperture which is the top part of CPC. Then, the cost of aterial usage and reflector can be saved especially at anufacturing site. Therefore, this research focuses on designing an optiized copound parabolic concentrator (CPC) by truncation and analysed using raytracing software. II. DESIGN PRINCIPLE In this work, TracePro ray-tracing software had been used to analyse the flux distribution of solar radiation onto the CPC surface [1]. The design of full and truncated 2D-CPC depending on the height and acceptance angles which relative to concentration ratio as shown in Fig.1. One of disadvantage of CPC is tall and narrow height copared to its diaeter or collecting entry aperture area. Therefore, for the econoic purpose, the initial height of CPC needs to be iniized and this will lead in saving the cost of reflector or dielectric aterial usage. This is can refer as truncation process where the entry aperture of CPC structure can be reoved. Norally, 1/3 to ½ fro the top of full height CPC can be truncated but also affect the concentration ratio value. Although the result will reduce the concentration ratio but it will be negligible. As previous explanation, the iportant of truncations refer to the results in the reduction of height of the CPC with sall reduce in concentration value. The diension of final 2D-CPC can be constructed with following equations (Equation 1 to Equation ) below: The height of full CPC 323

2 Tokyo Japan May 2-2, 21, 1 () Part XXIII 1 (1) The height to aperture ratio of concentrator The truncated height of CPC 1 cos (2) Half entry aperture for a truncated CPC where: a': half side of exit aperture θ_a: full half acceptance angle ɸ_T: truncated half acceptance angle (3) () concentration ratio also will be decreases. Due to this, the truncation of height of CPC has significantly affected the geoetrical concentration ratio. Based on the graph, at starting point geoetrical concentration ratio equal to, the slope of truncated height decrease sharply curve in range fro 13. to 11 height, resulting in large decrease of concentration ratio. When the concentration ratio equal to 3., the slope of the graph begins oderately curve in decreasing for each truncation height and consequential lower decrease in geoetrical concentration ratio. Due to this, the truncated height, H_T of 2D-CPC is selected as 1.23 after truncation and giving new concentration ratio equal to 3.. Therefore, the geoetrical concentration ratio only decreases 1% fro initial value, to 3. when the initial height truncated fro 13. to 1.23 copared to larger decrease in concentration ratio with sae aount truncation (.1) of height/concentration variations below 3.. For exaple, the truncated height of 1.23 to 1. gives the large decrease of concentration ratio by % fro 3. to Truncated height, HT Truncated geoetrical concentration ratio, CgT Fig.2 Variation truncated height over the geoetrical concentration ratio for 2D-CPC The ray trace diagra for untruncated and truncated CPC design are shown in Fig.3 and Fig.3 when the incident rays at noral incidence ( ) to the entry aperture of CPC. It can be seen that, the top surface of CPC did not uch intercept solar radiation copared to the botto surface (yellow box). Fig. 1Coparison initial CPC and truncated 2D-CPC odel III. RESULTS AND ANALYSIS Fig.2 shows a graph of variation of the truncated height, HT over the geoetrical concentration ratio for a half acceptance angle, θa = 1. for 2-D CPC. In this case, the full height for initial CPC design is 13. with the geoetrical concentration ratio equal to. It can be seen that, as the truncated height of CPC decreases, the geoetrical 323

Tokyo Japan May 2-2, 21, 1 () Part XXIII 3 Much interce pt solar radiatio n 1 3. Tru ncat ion Fig.

Those reflectors (R1 and R2) have an area of 211.² each and received 1W/² of power density fro grid source. The incident flux on the overall surface is easured as.13w, which is.% of the source eitted.

3 Tokyo Japan May 2-2, 21, 1 () Part XXIII 3 Much interce pt solar radiatio n 1 3. Tru ncat ion Fig. 3 Ray trace diagra at noral incidence angle ( ) Initial CPC design Truncated CPC design At the incidence angle, the flux distribution for overall reflector 1 (R1) and reflector 2 (R2) surface present in Fig. and Fig. respectively. Based onfig. and Fig., it illustrated the 2-D irradiance ap while for Fig. and Fig. show it profile. The blue line indicates the incident flux on horizontal axis while green line for vertical axis and also the location of top (right side) and botto (left side) of CPC surface. Those reflectors (R1 and R2) have an area of 211.² each and received 1W/² of power density fro grid source. The incident flux on the overall surface is easured as.13w, which is.% of the source eitted. On this figure, when the incidence angle is, both ap clearly shows that the irradiance flux distribution of solar radiation ore unifor at the botto surface copare to the top surface (yellow box) entry aperture of CPC. This is because the top surface of CPC did not intercept uch of solar radiation. Irradiance (W/²) size () Fig. Flux distribution on overall surface for reflector 1 (R1) 2- D irradiance ap Profile 323

4 Tokyo Japan May 2-2, 21, 1 () Part XXIII 1 3 Irradiance (W/²) size () Fig. Flux distribution on overall surface for reflector 2 (R2) 2- D irradiance ap Profile For the truncated design, flux distribution at the incidence angle for overall reflector 1 (R1) and reflector 2 (R2) surface present in Fig. and Fig.. Irradiance (W/²) size () Fig. Flux distribution on overall surface for reflector 1 (R1) 2-D irradiance ap Profile Based on both figures, the Fig. and Fig. illustrated the 2-D irradiance ap while the Fig. and Fig. show it profile. The blue line indicates the incident flux on horizontal axis while green line for vertical axis and also the location of top (right side) and botto (left side) of CPC surface. This reflector has an area of 1121.² and received 1W/² of power density fro grid source. The incident flux on the overall surface is easured as 3.21W, which is 2.3% of the source eitted. It is clearly shows that the irradiance flux distribution of solar radiation ore unifor; % fro overall surface of CPC copared to previous analysis for initial design. 32

5 Tokyo Japan May 2-2, 21, 1 () Part XXIII ACKNOWLEDGMENT The authors would like to thank to Ministry of Higher Education, Malaysia (KPT) and Research and Innovation Centre, UTHM for financially supporting this research under the Research Acculturation Grant Schee (RAGS) grant Vot.No.R23. Irradiance (W/²) size () Fig. Flux distribution on overall surface for reflector 2 (R2) 2-D irradiance ap Profile REFERENCES [1] Electricity Supply Application Handbook. 3rd ed. 212: TenagaNasionalBerhad. [2 ] Muhaad-Sukki, F., et al., Solar concentrators. International Journal of Applied Sciences(IJAS), 21. 1(1). [3] Sukki, F.M., et al., Solar Concentrators In Malaysia: Towards The Developent Of Low Cost Solar Photovoltaic Systes.JurnalTeknologi, 212. (1): p. 3. [] Jha, A.R., Solar Cell Technology and Application. th ed. 21: CRC Press. [] Renewable Energy Technologies: Cost Analysis Series, in Solar Photovoltaic212. [] Swanson, R.M., The proise of concentrators.progress in Photovoltaics Research and Applications, 2. (1): p [] Caeron, A., Tracking the CPV global arket: Ready to fulfil its potential, in Renewable Energy World Magazine211. [] McConnell, R., V. Fthenakis, and V. Fthenakis, Concentrated Photovoltaics.Third Generation Photovoltaics, 212. [] Swanson, R.M., Photovoltaic concentrators. Handbook of photovoltaic science and engineering [1] Winston, R., J.C. Miñano, and P. Benitez, Noniaging optics. 2: Elsevier Acadeic Press, pp [11] Figari, A., Soe features of the copound parabolic concentrator, 211, FOTONICA. [12] Mansi G. Sheth, D.P.K.S., Design and Developent of Copound Parabolic Concentrating Solar Collector with Flat Plate Absorber. International Journal of Innovative Research in Science,Engineering and Technology, 213. Vol.2(). [13] MansiG.Sheth, P.A.T., Developent of 2D Copound Parabolic Concentrating Solar Collector for Its Different Surface Teperature Analysis. International Journal of Research in Advent Technology, January 21. 2(1). [1] Gregory, G.G. and R.J. Koshel. Modeling the operating conditions of solar concentrator systes.inphotonics Europe. 2. International Society for Optics and Photonics. IV. CONCLUSION Untruncated and truncated 2-D hollow copound parabolic trough concentrators had been described and analyze using the ray-tracing software TracePro. The optiu design of truncated CPC is chosen depending on height, entry aperture and geoetrical concentration ratio paraeters. Irradiance flux distribution also had been analyzed for both cases (untruncated and truncated). It is clearly shows that the irradiance flux distribution of solar radiation ore unifor at the botto surface copares to the top surface entry aperture of CPC. This is because the top surface of CPC did not intercept uch of solar radiation. Furtherore, after the truncation, the height of CPC reduced % fro initial height with the geoetrical concentration ratio only decrease 1%. Thus, the cost of reflector and aterial dielectric usage can be saved especially for anufacturing site. 321

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