3-D NUMERICAL SIMULATION OF HEAT TRANSFER ENHANCEMENT IN A RECEIVER TUBE OF SOLAR PARABOLIC TROUGH COLLECTOR WITH TWISTEDTAPE INSERTS AND MWCNT-NANOFLUID

摘要

For a concentrated solar power's collector (CSP), having high convection's heat transfer coefficient is a major factor for optimum energy transfer from sun to heat transfer fluid. In this investigation, heat transfer enhancement of multi-walled carbon nanotube (MWCNT)/heat transfer's oil nanofluid in the receiver tube of a solar parabolic trough that equipped with the typical twisted-tape (TT) studied numerically. Twisted-tape generates swirling flow and make the flow more turbulent and enhance heat transfer rate between the heat transfer fluid and inner surface of receiver tube. Three dimensional numerical simulation is made with three different volume fractions of 0.05%, 0.1% and 0.2% and twisted-tape with twist ratio (TR=y/w) of 2.67 that y is twist length and w is tape width. Flow regime is turbulent and non-uniform solar wall heat flux is assumed as thermal boundary conditions. Absorbed solar radiation on receiver and glass tubes are determined for the noon hour of the first day of summer by SolTrace software. Results show significant enhancement in Nusselt number (Nu) and pressure drop (ΔP) for the tube with TT insert and MWCNT nanofuid, comparing with plain tube without nanofluid.