3.2. Empirical and semi-empirical models
Due to the complex geometry and internal transport mechanisms,
empirical and semi-empirical models are often applied to
describe the thermodynamic behavior of scroll expanders. The
empirical models describe the direct relationship between the
performance parameters and operating parameters. They ignored
the physical fundamentals of the working process. However, some
types of empirical models have no tolerance beyond the extrapolated
calibration range, especially when the models are complex
and nonlinear. The semi-empirical models consist of a series of
thermodynamic equations deduced from mass, energy and momentum
conversations. Critical parameters are determined according
to the experimental results. The empirical and semiempirical
models are valid within a specific operation range.