Thermal storage efficiency enhancement for solar air heater using a combined SHSm and PCM cylindrical capsules system : experimental investigation

Abstract EN

The present work aims to enhance the thermal storage efficiency and thermal behavior for solar air heater integrated with cylindrical capsules system.

The cylindrical capsule has diameter 50 mm and length 600 mm, placed in the cross flow of airstream.

In this experimental study, a high specific heat of latent heat storage materials (PCM-paraffin wax) were invested to increase the stored ability for sensible heat storage materials (pure sand).

Three cases are tested under constant incident irradiation 1000Wm-2, in the first case cylindrical capsules packed with pure sand, second case cylindrical capsules packed with compound (sand+10% PCM) and third case cylindrical capsules packed with compound (sand+20% PCM) , for both natural convection and forced convection with different mass flow rates (0.5 , 1.132 kg/min).

The experimental results indicated that the compound (sand + 20 %PCM) gives the best thermal storage duration (380 min),with increase in outlet air temperature by approximately 5.6 % in forced convection with (0.5 kg/min) compared with pure sand (240 min).

For forced convection with (1.132 kg / min), compound (sand + 20 %PCM) gives (355 min) thermal storage duration with increase in outlet air temperature by approximately 9.2 % compared with pure sand (220 min).

Increase of mass flow rate leads to decrease the outlet air temperature period time of the discharge process.