PCM Layer Thickness Research Articles

Economic optimization of PCM and insulation layer thickness in residential buildings

As suggested by previous studies, in economic optimization of buildings equipped with phase change materials, insulation layer and PCM highly affect each other’s performance. To consider these effects, in the present study, the thickness of the insulation and PCM layer of a residential building are optimized simultaneously. Coupled with EnergyPlus as the thermal simulation tool, genetic algorithm is applied to optimize the thicknesses for different climatic regions of Iran. Tehran, Isfahan, Shiraz, Bandar Abbas, Yazd, and Tabriz were selected for optimization. The fitness function is the total cost of the building throughout its operation years. In each city, the optimum PCM and insulation layer thicknesses are obtained with different present worth factors each accounting for a different scenario regarding the economic outlook of the country. Results show that the optimum PCM thickness is zero for all cases. On the other hand, the optimum insulation thickness varies significantly by region and PWF. While in southern parts of the country it was approximately zero, in cold regions, the optimum thickness was more than 6cm. Moreover, results show that with current economic situation of the country, insulation layers are far more cost effective than phase change materials.

Characterization of the optical properties of a PCM glazing system

The optical char acteristics of an advan ced glazin g sy stem are p resented in this p ap er. The investigated glazin g sy stem is based on the incorp oration of a p araffin-based Phase Change M aterial (PCM) into a transp arent comp onent, made of two extra-clear glass p anes and a cavity where the PCM lay er is p laced.Due to the highly scattering p rop erty of the sy stem (when the PCM is in solid state), the use of a lar ge integr ating sp here equip ment (75 cm diameter) is necessary to obtain reliable results.The sp ectral transmission, reflection and absorp tion coefficients of the PCM glazin g sy stem are measured b etween 400 and 2000 nanometers, and the integr ated valu es are calcu lated accordin g to the relevant standards. The optical p rop erties are determined with a maximu m relative error of 4% (on the sum of the transmission, reflection and absorption coefficients), when the PCM lay er is either in comp lete solid state or liqu id state. The average error for all the op tical p rop erties is 2%.Different thicknesses of the PCM lay er are used in order to assess the dep endency of the optical p rop erties on the PCM lay er thickness. The angular dep endency is also investigated for beam angle up to 45 deg.