Abstract
New design of system for providing cold air within the building was recommended in this study. Mixture of TiO2 (with fraction of 0.04) and RT25 was applied as NEPCM and three-lobed ducts were filled with them. Air become warmer outside the building owing to sun radiation and with moving along the channel, its temperature reduces because of melting procedure. Homogeneous model for NEPCM has been incorporated in equations of paraffin zone which contain laminar flow. Also, the range of inlet velocity contains the turbulent flow at air flow with Re = 6e3 to 1e4. The temperature of inlet air (Tin) was assumed as another active parameter. Irreversibility of system has been analyzed, too. Testing the exactness of procedure of modeling was applied according to previous published work and good accommodation has been reported. To decline the computing price, size of grid and time step were analyzed to find the optimized values. With adding TiO2 particles, the temperature of paraffin enhances and speeds of charging increases. At t = 5hr, dispersing nano-powders makes temperature and LF to grow around 0.19% and 0.79%, respectively. The required time declines around 31.26% and 40.78% with rise of Re and Tin.
•New design of system for providing cold air within the building was studied.•Mixture of TiO2 (with fraction of 0.04) and RT25 was applied as NEPCM.•The temperature of inlet air (Tin) was assumed as another active parameter.•The required time declines around 31.26% with rise of Re.•At t = 5hr, dispersing nano-powders makes temperature to grow around 0.19%.