Encapsulated Nitrates Phase Change Material Selection for Use as Thermal Storage and Heat Transfer Materials at High Temperature in Concentrated Solar Power Plants

Gustavo Cáceres,Karina Fullenkamp,Krzysztof Naplocha,Anna Dmitruk,Macarena Montané

doi:10.3390/en10091318

Abstract

In the present paper, the finite element method is used to perform an exhaustive analysis of the thermal behavior of encapsulated phase change materials (EPCMs), which includes an assessment of several materials in order to identify the best combination of PCM and shell material in terms of thermal energy storage, heat transfer rate, cost of materials, limit of pressure that they can support and other criteria. It is possible to enhance the heat transfer rate without a considerable decrease of the thermal energy storage density, by increasing the thickness of the shell. In the first examination of thermomechanical coupling effects, the technical feasibility can be determined if the EPCM dimensions are designed considering the thermal expansion and the tensile strength limit of the materials. Moreover, when a proper EPCM shell material and PCM composition is used, and compared with the current storage methods of concentrated solar power (CSP) plants, the use of EPCM allows one to enhance significantly the thermal storage, reaching more than 1.25 GJ/m3 of energy density.

Highlights

Worldwide, high dependence on fossil fuels and the increased energy demand have set two challenges for society: (1) to identify environmentally friendly energy sources, and (2) to develop more efficient methods and technologies, in order to satisfy the high energy demands
Results obtained from model calculation are presented divided in: (1) thermo-mechanical analysis of the shell materials and (2) thermal analysis for the entire encapsulated phase change materials (EPCMs)
The results show that considering just the cost of materials and cost of tanks, it will be necessary to incur a total cost of 34,150,053 ($USD) instead of 44,281,791.09 ($USD), which implies a 30% cost reduction when the EPCM (LiNO3 /KNO3 /NaNO3 covered by iron) is used instead of traditional sensible storage

Summary

Introduction

High dependence on fossil fuels and the increased energy demand have set two challenges for society: (1) to identify environmentally friendly energy sources, and (2) to develop more efficient methods and technologies, in order to satisfy the high energy demands. To achieve these targets, renewable energy generation technologies have become a key factor by allowing exploitation of cleaner and abundant energy sources. In the case of concentrated solar power (CSP) plants, the intermittency problem is addressed with the use of thermal energy storage (TES) systems [1,2,3,4]. According to Ma et al [1], CSP plants integrated with TES can provide utility-scale, dispatchable electricity to the power grid

Objectives

Results

Conclusion