Date of Award

2015-01-01

Degree Name

Doctor of Philosophy

Department

Mechanical Engineering

Advisor(s)

Vinod Kumar

Second Advisor

Arturo Bronson

Abstract

High temperature Heat Transfer Fluid (HTF) with Thermal Energy Storage (TES) for the Concentrated Solar Power (CSP) technology can provide a large and relatively cheaper storage option, as opposed to limited and expensive electrical battery storage with PV technology, and hence, it has potential to maintain a constant production when no sunlight is available. Research of material like aluminum, silicon, graphite could be potential candidates to work as thermal energy storage. Currently, nitrate and chloride molten salts are widely used as the TES medium for a CSP plant. However, molten salt, especially chlorides, must be handled carefully at high temperature (800ºC-1200ºC) because of their corrosive nature or decomposition. At high temperature, the electricity generated from a CSP power plant is expected to be cost competitive with conventional sources of power generation system if supplemented with efficient high temperature thermal energy storage (TES) system. In addition, a CSP plant depends only on renewable and clean (i.e., negligible carbon footprint) sources of natural energy resources.

High temperature storage increases power cycle efficiency, which is equivalent to reduce the solar field cost and size, and increases storage energy density. However, the high temperature storage is still not technologically viable at this moment. Our study presents preliminary studies on developing an innovative approach to develop an engineered material that possess high heat capacity and thermal conductivity for temperatures from 700ºC to 1000ºC. The engineered material is achieved by assuming an alloy melt encapsulated in graphite capsules of 10-15mm diameter at approximately 1000ºC. The encapsulated alloy melt uses the enthalpy of fusion/solidification, as well as its heat capacity transfer; it stores and releases heat from 800ºC to 1200ºC during the day time. The storage media uses low-cost, highly-stable solid material (sand, silica) that can be made to behave like a fluid using fluidization and other solid-particle transport mechanism. For charging/discharging processes, air is directly set in contact with the storage media which provides a heat transfer medium for the particles. In the storage mode, stagnant solid particles can be self-insulated to hold the heat. Also for the simulation study, materials falling at an ambient condition will be considered as a main focus.

Language

en

Provenance

Received from ProQuest

File Size

114 pages

File Format

application/pdf

Rights Holder

Arturo Sepulveda Fernandez

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