k h aluminum fin, and water tank (T^) durmg the test ^
(Fig. 8). The thermocouple readings are recorded with an I
OMEGA HH309A thermometer with aScuracy ±0.2%.
The repeatability and accuracy of measurements are examined by monitoring the solar irradiation using a
SP-Lite2 Pyranometer (directional error (up to 80° with
1000 W/m2 beam) less than 10 W/m2) during the c6Ssea^,ve
tive days of experiment. A sample of recorded data has
been plotted in Fig. 9.
Among the efficient phase change materials tested in
phase-I, Tritriacontane paraffin and Erythritol are chosen
for the second phase of the experiment to study their effect on the storage capacity in both normal and on-demand operation by keeping the collectors initially stagnated for an extended period of time before water flow circulation.
In "normal operation", water is continuously circulating
through the manifold during the day. "On-demand operation" (stagnation mode) is unique to our SWH systems with PCM. The PCM inside the evacuated tube collector acts as a storage medium for releasing heat at a later time t^