Enhanced heat transfer performances of molten salt receiver with spirally grooved pipe

• Spirally grooved tube is a very effective way for solar receiver enhancement.
• Heat absorption model of receiver is proposed with general heat transfer correlation.
• Spirally groove tube increases absorption efficiency and reduces wall temperature.
• Operating temperature of molten salt remarkably increases with groove height.
• Heat absorption performance is promoted for first and second thermodynamics laws.

The enhanced heat transfer performances of solar receiver with spirally grooved pipe were theoretically investigated. The physical model of heat absorption process was proposed using the general heat transfer correlation of molten salt in smooth and spirally grooved pipe. According to the calculation results, the convective heat transfer inside the receiver can remarkably enhance the heat absorption process, and the absorption efficiency increased with the flow velocity and groove height, while the wall temperature dropped. As the groove height increased, the heat losses of convection and radiation dropped with the decrease of wall temperature, and the average absorption efficiency of the heat receiver can be increased. Compared with the heat receiver with smooth pipe, the heat absorption efficiency of heat receiver with spirally grooved pipe e/d = 0.0475 can rise for 0.7%, and the maximum bulk fluid temperature can be increased for 31.1 °C. As a conclusion, spirally grooved pipe can be a very effective way for heat absorption enhancement of solar receiver, and it can also increase the operating temperature of molten salt.