Identification of Solar Collector Dynamics Using Physical Model-Based Approach

A system dynamics model of flat-plate solar collectors was derived and identified here. A nonlinear physical model was first derived from a two-node concept and energy conservation principle. The model was then approximated by the linear perturbation equations which were Laplace transformed and solved to lead to a distributed model in terms of the transfer functions. A model reduction was further employed to yield a linear time-invariant model with parameters as functions of steady-state operating conditions. The model parameters were identified by a dynamic test with step inputs at various operating conditions using frequency response analysis and model fitting in frequency domain. The identified parameters were then fitted to a function of steady-state mass flowrate m_w. Thus, the model can describe the system dynamics behavior under various operating conditions through the identified parameters. The simulations using the model were shown to agree very well with the test results.