Potential of Size Reduction of Flat-plate Solar Collectors When Applying Al2O3 Nanofluid M. Faizal 1, 2, a , R. Saidur 2, b , S.Mekhilef 3, c 1 Engineering Division, ADP, Taylor's University Lakeside Campus, 47500 Selangor, Malaysia 2 Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia 3 Department of Electrical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia a mohdfaizal.fauzan@taylors.edu.my, b saidur@um.edu.my, c saad@um.edu.my Keywords: Al2O3 nanofluid, Flat-plate solar collector, size reduction Abstract. The source of fossil fuel is decreasing. The price increased rapidly. Population and demand of energy increased significantly over the years. Carbon pollution and global warming are becoming major issues. The best way to overcome this problem is by changing to renewable source of energy. One of it is solar thermal energy. However, a solar technology is currently still expensive, low in efficiency and takes up a lot of space. Nanofluid is recognized as a solution to overcome this problem. Due to the high thermal conductivity of nanofluids, the thermal efficiency of a solar collector can be increased and thus decreasing the size of the system. This paper analyzes the efficiency of using the Al 2 O 3 nanofluid as absorbing medium in flat-plate solar collector and estimated the potential of size reduction. When applying the same output temperature of Al 2 O 3 nanofluid as with water, it can be observed that the collector’s size can be reduced up to 24% of its original size. Introduction Commonly, most houses in Malaysia are using Electric Water Heater for shower mainly because the price is cheap and installation is easy. However, the world is facing a huge problem now because of declining source of energy and using the precious electrical energy for heating does not really a good idea since heat can be harnessed directly from the sun. Potentially, Malaysia is located on the equatorial, with hot and humid climate throughout the year and with monthly solar radiation is approximately around 400-600 MJ/m 2 [1]. Solar energy source is sustainable, free, clean and infinite. However, current solar heater is still expensive, low in efficiency and big in size. One of the effective methods to increase the efficiency is to replace the working fluid with nanofluids. Researches on thermal efficiency by applying nanofluids on flat-plate solar collector have been made in the past few years by numerous researchers [2-11]. Experimental investigation conducted by Yousefi, Veysi, Shojaeizadeh and Zinadini [4] on the effect of Al 2 O 3 based nanofluid shown the increase of 28.3% efficiency of flat-plate solar collectors. Lenert and Wang [12] presented a model and experimental study of concentrated solar power application using carbon-coated cobalt (C-Co) nanoparticles and Therminol VP-1 base fluid and concluded that the efficiency is more than 35% with nanofluid and the efficiency will increase with increasing nanofluid height. Lu, Liu and Xiao [13] shown that the application of Copper Oxide (CuO) nanoparticles in evacuated tubular solar collector will significantly enhance the thermal performance of evaporator and evaporating heat transfer coefficient increased by 30% compared to water as working fluid. 5% improvement in efficiency was found out by Otanicar, Phelan, Prasher, Rosengarten and Taylor [14] by using diversity of nanoparticles with water as base fluid for micro-solar-thermal collector. Shin and Banerjee [15] applied novel nanomaterials in molten salts base fluid for concentrated solar power coupled with thermal storage and experienced an enhancement in operational efficiencies. They also concluded that the cost of electricity will be reduced. Taylor, Phelan, Otanicar, Adrian and Prasher [10] used graphite based nanofluid in high flux solar collectors that resulting in 10% increase in efficiency. Advanced Materials Research Vol. 832 (2014) pp 149-153 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.832.149 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 180.200.233.250-15/11/13,03:57:03)