Effect of roughness geometry on heat transfer and friction characteristics of PCM storage unit for night coolness storage in summer season

• Main Authors: Shukla Shailndra Kumar, Singh Satish K.
• Format: Article
• Language: English
• Published: VINCA Institute of Nuclear Sciences 2013-01-01
• Series: Thermal Science
• Subjects: PCM; storage unit; air temperature; comfort temperature; NTU; night coolness; artificial roughness
• Online Access: http://www.doiserbia.nb.rs/img/doi/0354-9836/2013/0354-98361200023S.pdf

This paper presents a theoretical analysis of thermal storage unit using phase change material (PCM) as storage medium. Storage unit consists of parallel rectangular channels for the air flow which are separated by phase change storage material. The purpose of storage unit is to absorb the night coolness and to provide cooled air at comfort temperature during day time in summer season. MATLsimulation tool has been used to compute the air temperature variation with location as well as time, charging and discharging time of storage unit. Phase change material used for analysis is selected in such a way that it’s Melting point lies between comfort temperature and minimum night ambient temperatures. The air flow rate needed for charging of PCM is approximately four times greater than the flow rate required during day time to achieve comfort temperature for approximately eight hours, due to limited summer night time (only eight hours). The length of storage unit for which NTU value is greater than or equal to five will give the exit air temperature equal to PCM temperature for the case of latent heat utilization. It is found that artificial roughness on the duct surface effectively reduces the length of storage unit in the cost of some extra pressure drop across the duct.