Experimental Study Of Enhanced Heat Transfer In Transversally Corrugated Tube With Molten Salt

Now, Concentrating Solar Power is becoming the hot spot for investment in thefield of renewable energy.Heat transfer and thermal storage is considered to be the keytechnology in the high temperature utilization of solar energy. Acting as the heattransfer and heat storage materials, the characteristics of the working fluid influencedthe whole system’s efficiency and intending application deeply. Molten salts with a lotof advantages such as low cost, wide range of service temperature, large heat capacity,low viscosity, low vapor pressure and good chemical stability, have been consideredas an extremely potential medium for heat transfer and storage in concentrating solarthermal power plants and nuclear power plants. But the research on the enhanced heattransfer with molten salt is little, so it is necessary to study it.By the support of the National"973"project,firstly,experimental data on transitionconvective heat transfer with two kinds of molten salts in a circular tube was analysed.The average forced convective heat transfer coefficients of molten salts weredetermined by least-squares method. Finally, heat transfer correlation of transitionflow with molten salts in a circular tube was obtained and good agreement wasobserved between the experimental data of molten salts and the well-known Hausenequation and Gnielinski equation.Secondly, the experimental system was modified to conduct the experimentalstudy of forced convection heat transfer and the resistance measurement in three kindsof transversally corrugated tubes. By data processing, the heat transfer coefficient ofmolten salt-oil, the heat transfer coefficient of moltern salt side, the Nusselt number,the resistance coefficient and the intensification ratio under different conditions wereobtained.Three different experimental correlations and a general experimentalcorrelation cosidering structure factor were fitted. The results showed that:the changelaw of the heat transfer with the Re of the transversally corrugated tubes is similar tothe smooth tube but it is better than the smooth tube.The experimental data agree wellwith the experimental correlations with the maximum error being-11.8%; theresistance coefficient of the transversally corrugated tubes is bigger than the smoothtube s’and the resistance coefficient has an inverse relationship with the P andRe.The transversally corrugated tube with P=9is the optimal intensifier tube.