The computation procedure is outlined in Fig. 4. Temperature
initialization is required at the start of the simulation. Then at
the start of each simulation time-step, the Tank 340 model is first
set to the required stratification condition based on the ambient
temperature and wind speed from the weather data file. The inlet
temperature Tin to the collector tubing is taken from the lowest
water temperature node of the stratified tank. The instantaneous
collector system efficiency is then determined by equation (5),
with the inputs of I and Ta. ˙Qcol is computed using Eq. (4). The heat
absorption rate ˙Qin at each tube of the solar collector is determined
by equation (6). The mass flow rate m˙ from the tube to the tank is
determined by equation (15). From Eq. (2),