A mathematical model for anti-freezing and cooling analysis of solar collector system

•A dynamic thermal–hydraulic coupling model for collector system was established.•The model can calculate temperature distribution of the dynamic cooling process.•The solution method can accurately and quickly solve the new model.•The accuracy of the model was verified experimentally. The robust and accurate evaluation of the temperature distribution of the solar collector system during the cooling process is instrumental for a reasonable and effective system anti-freezing. Thus, it is necessary to establish a proper and comprehensive model of the solar collector system. This paper presents an unsteady multi-node, thermal and hydraulic coupling model of the solar collector system. The model was established based on the analysis of the flow and heat transfer processes of the fluid in the collector system loop and following the finite difference method. The coupling model was solved by adopting an iterative method, and the model accuracy was verified by experiments. The results showed that solving the collector system model using Ferrera's method was more than 148 times faster than that using Fsolve function, and the maximum difference between the two calculation results was only 0.53 ℃. The cooling process of the centralized solar collector system was analyzed, and the results showed that the system fluid temperature distribution was related to the flow rate distribution and the cooling time. With the cooling process, the temperature distribution of the solar collector gradually became uniform.