The following data were obtained from a study dealing with the behavior of a solar energy water heater system. A commercial selective surface, single cover collector with a well-insulated storage tank was theoretically modeled. Seventeen computer runs were made, using this theoretical model. The runs were made in accordance with a 24 factorial design with an added center point where the four "variables" were four dimensionless groups corresponding to (1) the total daily insolation, (2) the tank storage capacity, (3) the water mass flow rate through the absorber, and (4) the "intemtittency" of the input solar radiation. For each of these 17 runs two response values were calculated, the collection efficiency (y₁) and the energy delivery efficiency (y₂). Analyze the following results, where L. M, and H designate low, medium, and high values, respectively for the groups.

The motivation for this work was the fact that the theoretical model was too complicated to allow for ready appreciation of the effects of various variales on the responses of interest. This factorial design approach provided the kind of information that was desired.