Nano-enhanced Phase Change Material for thermal management of BICPV

S Sharma,L Micheli,W Chang,A.A Tahir,K.S Reddy,T.K Mallick

doi:10.1016/j.apenergy.2017.09.076

Abstract

Building-Integrated Concentrated Photovoltaics (BICPV) is based on Photovoltaic (PV) technology which experience a loss in their electrical efficiency with an increase in temperature that may also lead to their permanent degradation over time. With a global PV installed capacity of 303GW, a nominal 10°C decrease in their average temperature could theoretically lead to 15GW increase in electricity production worldwide. Currently, there is a gap in the research knowledge concerning the effectiveness of the available passive thermal regulation techniques for BICPV, both individually and working in tandem. This paper presents a novel combined passive cooling solution for BICPV incorporating micro-fins, Phase Change Material (PCM) and Nanomaterial Enhanced PCM (n-PCM). This work was undertaken with the aim to assess the unreported to date benefits of introducing these solutions into BICPV systems and to quantify their individual as well as combined effectiveness. The thermal performance of an un-finned metallic plate was first compared to a micro-finned plate under naturally convective conditions and then compared with applied PCM and n-PCM. A designed and fabricated, scaled-down thermal system was attached to the electrical heaters to mimic the temperature profile of the BICPV. The results showed that the average temperature in the centre of the system was reduced by 10.7°C using micro-fins with PCM and 12.5°C using micro-fins with n-PCM as compared to using the micro-fins only. Similarly, the effect of using PCM and n-PCM with the un-finned surface demonstrated a temperature reduction of 9.6°C and 11.2°C respectively as compared to the case of natural convection. Further, the innovative 3-D printed PCM containment, with no joined or screwed parts, showed significant improvements in leakage control. The important thermophysical properties of the PCM and the n-PCM were analysed and compared using a Differential Scanning Calorimeter. This research can contribute to bridging the existing gaps in research and development of thermal regulation of BICPV and it is envisaged that the realised incremental improvement can be a potential solution to (a) their performance improvement and (b) longer life, thereby contributing to the environmental benefits.

Highlights

To address the concerns related to environmental sustainability, increasing energy costs and depleting fossil fuel resources, renewable energy technologies have been at the forefronts of energy research
This paper presents a novel combined passive cooling solution for Building-Integrated Concentrated Photovoltaics (BICPV) incorporating micro-fins, Phase Change Material (PCM) and Nanomaterial Enhanced PCM (n-PCM)
The results showed that the average temperature in the centre of the system was reduced by 10.7 °C using micro-fins with PCM and 12.5 °C using micro-fins with n-PCM as compared to using the micro-fins only

Summary

Introduction

Afins CP H HL hfins hflat I kp kn,PCM kn L m n ρ Qin area of micro-fins (m2) specific heat of PCM (J kg−1 K−1). Height of micro-fins (m) latent heat of PCM (J kg−1). PCMs are materials used for heat absorption, storage and recovery and are often employed in renewable energy systems due to the intermittent and unpredictable nature. They are analogous to heat batteries and contribute to the applied system for rationalising and uniformly spreading the use of energy over a period of time. PCMs are preferred where higher storage densities are required, entailing a smaller volume of material with high latent heat [47]. The sensible heat effect is often negligible compared to the latent heat during phase transformations, to calculate purely the latent heat Eq (2) [48] can be used.

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