Validation of a Transient Simulation Program (TRNSYS)

Although a Transient Simulation Program (TRNSYS) has become a widely used model for simulating a solar energy system, there has not been extensive work done in validating this model with actual data. The approach used to validate this model consisted of a modular buildup of components with validation for each module. Extreme care was taken in choosing the necessary parameters to model each component. Where parameters were not given, they were either derived or reasonable values were selected based upon general conditions prevailing in Central Florida or conditions which are generally true for certain solar hot water systems. The intent of this approach was to avoid forcing the model to fit experimental data. Such forcing can cause present results to correlate favorably, but gives no assurances for model performance in future simulations which may be made for varying conditions or completely different systems. TRNSYS compared favorably with experimental data. The average error for an entire 8 hour simulation with 15 minute intervals was only 3.39 percent for the entire tank and collector combination. The model\u27s major deviations were in the start-up collector outlet temperature and rapid changing in actual hot water demand which the model could not match primarily in amplitude and not phase