Thermal analysis of a conceptual loop heat pipe for solar central receivers

• Published in: Energy (Oxford) Vol. 158; pp. 709 - 718
• Main Authors: Liao, Zhirong, Xu, Chao, Ren, Yunxiu, Gao, Feng, Ju, Xing, Du, Xiaoze
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2018; Elsevier BV
• Subjects: Central receiver; Computer simulation; Evaporation; Heat; Heat flux; Heat pipes; Heat transfer; Heat transfer coefficients; Irradiation; Loop heat pipe; Loop heat pipes; Mathematical models; Numerical analysis; Numerical simulation; Pipes; Power plants; Radiation; Solar energy; Solar power; Solar power tower plant; Temperature gradients; Thermal analysis; Thermal cycling; Three dimensional models; Vapors; Working fluids; Central receiver; Numerical simulation; Solar power tower plant; Loop heat pipe
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2018.06.069

This study presents a novel loop heat pipe central receiver for the solar power tower (SPT) plant. For the first study, the evaporator section of the proposed receiver is simulated by a three-dimensional numerical model to study the flow, heat transfer and the evaporation phenomenon of the working fluid. In addition, effects of the outlet boundary pressure at the vapor groove and the solar irradiation heat flux on the absorbing surface are analyzed. The results show that most of the working fluid vaporizes at the liquid/vapor interface close to the casing. The heat transferred from the casing to the vapor working fluid is negligible, and thus the vapor temperature in the groove can be assumed to be constant in simulating the whole loop heat pipe central receiver. A lower temperature difference between the liquid/vapor interface and the compensation chamber is beneficial for obtaining more heat energy transferred to the vapor working fluid. It is also found that the evaporation heat transfer coefficient changes obviously with the absorbed solar heat flux. The findings of present work can be used as a reference to the modelling and design of the whole loop heat pipe central receiver in the next step. •A novel loop heat pipe central receiver for solar power tower plant is proposed.•A 3D model is used to simulate the evaporator section of the proposed receiver.•Most of the liquid working fluid vaporizes at the wick surface close to the casing.•The evaporation heat transfer coefficient varies obviously with the solar flux.•The change of the casing thermal resistance should not be ignored.