2.2. Phase-II: Normal vs. stagnation operation
In the second phase of the experiment, a standard Apricus collector is used to facilitate the comparison of the
performance of identical commercial evacuated tubes sunultaneously with and without phase change materials.
The commercial Apricus solar collector has 10 evacuated
tubes which four tubes are left untouched (no PCM), three
tubes are filled with Tritriacontane paraffin (2 kg per tube), and three tubes with Erythritol baggies (1.4kg per tube) and silicon oil. Total latent heat capacity of PCM integrated tubes are almost equal due to the higher latent heat capacity of the Erythritol compared with paraffin. Each setup includes an immersion pump inside the storage tanks with 40 L capacity to circulate the water in the system and a flow meter that controls the water flow-rate entering the manifold.
Several thermometers record the temperature mside each evacuate tube (T^n) which are attached to the