SIMULATION OF LIQUID FLAT-PLATE SOLAR COLLECTORS OPERATION IN UNSTEADY STATES

The mathematical model of a liquid flat-plate solar collector dynamics is presented. It is a one-dimensional model with distributed parameters. The proposed model is based on solving equations describing the energy conservation for the glass cover, air gap between cover and absorber, absorber, working fluid, and insulation. To solve these equations, the implicit finite-difference scheme is suggested. The thermo-physical properties of the air gap, absorber, and working fluid are computed in on-line mode. The transient heat transfer coefficients are also computed in real-time. The efficiency of the method is confirmed by experimental verification. Comparing the measurement results of the transient fluid temperature at the collector outlet with computational results, satisfactory convergence is found. The presented model is suitable for collectors working in a parallel or in a serpentine tube arrangement with single or double covers.