Experimental and numerical investigations of the optical and thermal aspects of a PCM-glazed unit

This paper reports on the thermal and optical characterisation of PCM (phase change material) RT27 using the T-history method and spectrophotometry principles, respectively, and the experimental and numerical performance evaluation of a PCM-glazed unit. Various relationships describing the variations in the extinction, scattering and absorption coefficients within the phase change region were developed, and were validated in a numerical CFD model. The results show that: (i) during rapid phase changes, the transmittance spectra from the PCM are unstable, while under stable conditions visible transmittance values of 90% and 40% are obtained for the liquid and phases, respectively; (ii) the radiation scattering effects are dominant in the solid phase of the PCM, while radiation absorption dominates in the liquid phase; (iii) the optical/radiation performance of PCM can be successfully modelled using the liquid fraction term as the main variable; (iv) the addition of PCM improves the thermal mass of the unit during phase change, but risks of overheating may be a significant factor after the PCM has melted; (v) although the day-lighting aspects of PCM-glazed units are favourable, the change in appearance as the PCM changes phase may be a limiting factor in PCM-glazed units

New insight on passive ice making and seasonal storage of the Iranian Yakhchal and their potential for contemporary applications

The Yakhchals of Iran are a type of ancient structure and system used to produce, harvest and store ice for cooling uses later in the year. In this paper, the authors present an explanation of how Yakhchals are understood to have operated and then go on to present analyses of aspects of the ice making and storage processes. A transient 1D heat transfer model is used to predict how much ice could be made over the course of a year. A second transient heat transfer simulation is used to predict the amount of ice that could be retained (not melt) over the storage season. Finally, the potential for a modern day application of passive ice making and storage for space cooling in an ultra-low energy office is explored

Unidentified Spaces

Musical Recordin