Thermal performance of latent heat storage for free cooling of buildings in a dry and hot climate: An experimental study

Experimental studies on the Phase Change Material (PCM) storage unit for building ventilation in dry and hot climates were conducted to determine its thermal performance. The PCM unit stored the night time coolness and used it for cooling the hot ambient air during day time. The influence of air flow rate and the inlet air temperature on cold accumulation in PCM during charging process and cold extraction from the PCM during discharging process were analyzed. The air temperatures used for charging of PCM were 20oC, 22oC and 24oC, while during the discharging process, it was at 36oC, 38oC and 40oC. The air flow rates considered for charging of PCM were 4 and 5 m3/hr/kg of PCM. Experimental observations showed that solidification of PCM was more sensitive to the charging air temperature compared to the air flow rate. When the charging air temperature was reduced from 22oC to 20oC, ∼33% less time was needed to completely solidify the PCM. Moreover, when the charging temperature was increased from 22oC to 24oC, ∼52% more time was required by the PCM to complete the solidification process. Changing the air flow rate from 4 m3/hr to 5 m3/hr reduced the solidification time period up to ∼16%.

• Degree of sub cooling plays a vital role during charging of PCM at night time.
• Charging process is more sensitive to air temperature compared to airflow rate.
• At higher discharging air temperature storage is discharged in shorter time period.
• Lower airflow rate through storage can keep hot air within defined comfort range.