Experimental investigation of molten salt nanofluid for solar thermal energy application

Donghyun Shin, Debjyoti Banerjee

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

20 Scopus citations

Abstract

The overall efficiency of a Concentrated Solar Power (CSP) system is critically dependent on the thermo-physical properties of the Thermal Energy Storage (TES) components and the Heat Transfer Fluid (HTF). Higher operating temperatures in CSP result in enhanced thermal efficiency of the thermodynamic cycles that are used in harnessing solar energy (e.g., using Rankine cycle or Stirling cycle). Particlularly, high specific heat capacity (Cp) and high thermal conductivity (k) of the HTF and TES materials enable reduction in the size and overall cost of solar power systems. However, only a limited number of materials are compatible for the high operating temperature requirements (exceeding 400° C) envisioned for the next generation of CSP systems. Molten salts have a wide range of melting point (200° C-500° C) and are thermally stable up to 700° C. However, thermal property values of the molten salts are typically quite low (Cp is typically less than ∼2J/g-K and k is typically less than ∼1 W/m-K). To obviate these issues the molten salts can be doped with nanoparticles - resulting in the synthesis / formation of nanomaterials (nanocomposites and nanofluids). Nanofluids are colloidal suspensions formed by doping with minute concentration of nanoparticles. Nanofluids were reported for anomalous enhancement in their thermal conductivity values. In this study, molten salt-based nanofluids were synthesized by liquid solution method. A differential scanning calorimeter (DSC) was used to measure the specific heat capacity values of the proposed nanofluids. The observed enhancement in specific heat is then compared with predictions from conventional thermodynamic models (e.g. thermal equilibrium model or "simple mixing rule"). Transmission Electron Microscopy (TEM) is used to verify that minimal aggregation of nanoparticles occurred before and after the thermocycling experiments. Thermocycling experiments were conducted for repeated measurements of the specific heat capacity by using multiple freeze-thaw cycles of the nanofluids/ nano-composites, respectively. This study demonstrates the feasibility for using novel nanomaterials as high temperature nanofluids for applications in enhancing the operational efficiencies as well as reducing the cost of electricity produced in solar thermal systems utilizing CSP in combination with TES.

Original languageEnglish
Title of host publicationASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011
PublisherAmerican Society of Mechanical Engineers
ISBN (Print)9780791838921
DOIs
StatePublished - 2011
EventASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 - Honolulu, HI, United States
Duration: Mar 13 2011Mar 17 2011

Publication series

NameASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011

Conference

ConferenceASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011
Country/TerritoryUnited States
CityHonolulu, HI
Period03/13/1103/17/11

Fingerprint

Dive into the research topics of 'Experimental investigation of molten salt nanofluid for solar thermal energy application'. Together they form a unique fingerprint.

Cite this