161 ISSN 0003-701X, Applied Solar Energy, 2017, Vol. 53, No. 2, pp. 161–166. © Allerton Press, Inc., 2017. Innovative Sensible Heat Transfer Medium for a Moving Bed Heat Exchanger in Solar Central Receiver Power Plants 1 Louy Qoaider a, *, Qahtan Thabit a , and Suhil Kiwan b a German Jordanian University, School of Applied Technical Sciences, Amman, Jordan b Jordan University of Science and Technology, Irbid, Jordan *e-mail: Louy.Qoaider@gju.edu.jo Received April 28, 2017 AbstractRenewable energies are gaining importance due to the steadily increasing scarcity of fossil fuels, the ongoing climate change and last but not least the risks which accompany the use of nuclear power. In this growing market, solar thermal power plants offer a centralized, potentially load following electricity produc- tion. To serve this need, the integration of thermal energy storage systems is essential. The Moving Bed Heat Exchanger MBHX storage concept for CSP systems using sensible heat transfer medium aims at using a low cost solid storage media. This concept requires intermediate bulk cycles to transfer heat between the solar field and the storage material (the bulk). Heat Transfer Fluids (HTF) such as synthetic oils (mobiltherm 603) are typically used. In this work, granular materials such as sand and rocks are studied to present an additional HTF to represent an efficient and cost-effective alternative. Low cost solid particulates can store and trans- port heat at temperatures over 1000°C. For the purpose of heat recovery, a moving bed heat exchanger (MBHX) is applied and tested. In this study, the dense granular mass is gravity-driven through a heat exchanger. The performance of the MBHX with the utilization of Sand, Basalt, and a Mixture of Sand and Basalt as a granular material was experimentally investigated. It is found that the effectiveness of the MBHX using a mixture of 50% sand and 50% basalt improved by 30% compared to using sand alone. DOI: 10.3103/S0003701X1702013X 1. INTRODUCTION Storage of solar energy is one of the challenges, which could ensure the future development of Con- centrating Solar Power (CSP) plants [1]. When Ther- mal Energy Storage (TES) is integrated in a CSP plant it represents the main differences between CSP and other renewable energy technologies i.e. its inherent capacity to store heat for periods of time for later con- version to electricity when clouds block the sun or after sunset. There are three types of implementing this TES approach, based on the “nature” of heat to be stored: sensible, latent and thermochemical heat. Many novel types of power plants driven by renewable energy sources depend on thermal energy storage (TES) as a central component. Such large-scale, high- temperature TES typically have to provide storage capacities up to 3 GW h for a discharge duration between 4 and 12 full-load hours. For example, for electricity generation from concentrating solar power (CSP), TES opens up opportunities for the reduction of specific costs and increased system efficiency. They also allow continuous operation beyond sunshine hours and smoothening out of fluctuations in daily solar radiation. Furthermore, TES increases the oper- ational flexibility of the plant and thus provides new options for economically optimized combined heat and power (CHP) operation. One of the most import- ant technologies of CSP is central receiver tower plant. Unlike linear concentrating systems (troughs), which reflect light onto a focal line, the central receiver sys- tems send concentrated light onto a remote central receiver. TES systems correct the mismatch between supply and demand of thermal energy. In the medium to high temperature range (100~1000°C), only limited storage technology is commercially available and a strong effort is needed to develop a range of storage technologies which are efficient and economical for the very specific requirements of the different applica- tion sectors. Heat transfer fluid (medium) and storage medium are represent the core of these systems. Cur- rent research deals with the use of granular material as sensible heat storage inventory and heat transfer medium in central receiver systems (CRS) [2]. Ther- mal energy storage (TES) based on a flowable granular material made of ceramics or natural stones allows for a load following operation of a central receiver solar power plant at high process temperatures (>600°C). A Moving Bed Heat Exchanger (MBHX) is a promising technology option for this component. 1 The article is published in the original. SOLAR POWER PLANTS