Thermal analysis of a micro solar thermal collector designed for methanol reforming Xiaoguang Gu a,⇑ , Robert A. Taylor a,b , Qiyuan Li a , Jason A. Scott c , Gary Rosengarten d a School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney 2052, Australia b School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, Sydney 2052, Australia c School of Chemical Engineering, The University of New South Wales, Sydney 2052, Australia d School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Melbourne 3053, Australia Received 3 June 2014; received in revised form 25 November 2014; accepted 23 December 2014 Communicated by: Associate Editor Jayanta Kumar Nayak Abstract A solar powered micro-reactor for hydrogen production is analysed in this study. A small, portable (4 W), compound parabolic concentrator (CPC)-based collector was designed and manufactured to provide heat for a methanol reforming (endothermic) chemical reaction. The designed collector consists of a small, flat, double-sided selective-surface receiver in a vacuum package. To our knowledge, the design represents the first time that a high vacuum package (<10 2 Pa) has been combined with a CPC for this purpose. Our previous optical and thermal models predicted that 78% of incident solar flux could be concentrated to the flat receiver with a concentration ratio of 1.75. In this paper, the collector’s performance was assessed for different volumetric flow rates (liquid flow rates at the inlet ranging from 0 to 350 lL/min) with and without a vacuum to validate the theoretical analysis of our previous work. Results showed that the experimental temperature measurements without a vacuum were well matched with the theoretical values. Additionally, it was shown that the temperature can be dramatically increased in a vacuum environment. In the vacuum experimental configuration, a stagnation temperature of 327 °C was found for an irradiance of 1000 W/m 2 . Temperature measurements for flow rates ranging from 0 to 100 lL/ min also agreed with the theoretical model. Overall, this system represents a compact, portable solar collector which is capable of achiev- ing high operational temperatures without tracking. Ó 2015 Elsevier Ltd. All rights reserved. Keywords: Solar energy; Methanol reforming; CPC; High temperature 1. Introduction In the last few decades, numerous ways of using renew- able energy sources have been developed, motivated by the fact that society cannot permanently depend on conven- tional fossil fuel resources (Birgersson et al., 2012; Hong et al., 2005; Otanicar et al., 2012). An excellent potential solution is to harness solar energy – a vast, relatively untapped resource (Mojiri et al., 2013). A wide range of photovoltaic and solar thermal devices have been devel- oped in recent years (Crisostomo et al., 2014; Huang et al., 2001; Taylor et al., 2012) along with numerous meth- ods to improve the performance of solar thermal collectors, such as new working fluids (Boerema et al., 2013; Khullar et al., 2012; Taylor et al., 2011b). Additionally, the use of nano-particles as novel receivers is under constant develop- ment (Gulati et al., 2013; Otanicar et al., 2010, 2011; http://dx.doi.org/10.1016/j.solener.2014.12.030 0038-092X/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: School of Mechanical and Manufacturing Engineering, The University of New South Wales, High Street, 2052, Australia. Tel.: +61 (0) 416249230. E-mail address: xiaoguang.gu@unsw.edu.au (X. Gu). www.elsevier.com/locate/solener Available online at www.sciencedirect.com ScienceDirect Solar Energy 113 (2015) 189–198