Sinusoidal response measurement procedure for the thermal performance assessment of PCM by means of dynamic heat flow meter apparatus

Abstract

The implementation, in Building Performance Simulations (BPS) tools, of robust models capable of simulating the thermophysical behaviour of a Phase Change Material (PCM) represents a fundamental step for an appropriate thermal evaluation of buildings that adopt PCM-enhanced envelope components. Reliable and robust measuring procedures are essential, at a material and component level, to provide experimental data for the empirical validation of software tools. The traditional laboratory tests that are generally used for the validation of models present some limitations, because PCMs are usually subjected to conditions that may be very different from the real boundary conditions of the building components in which PCMs are applied. Furthermore, in many experimental full-scale mockups, the relatively small quantity of installed PCM and the combination of several thermal phenomena do not allow software tools to be tested in a reliable way. In this paper, an experimental procedure, based on a modified Heat Flow Meter Apparatus, has been developed to test the behaviour of PCM-enhanced components; the procedure, which is based on the measurement of the sinusoidal response, has been set up to provide data for the comparison and testing of numerical models and of BPS tools. Moreover, general indications and guidelines are provided to solve some issues related to building specimens that contain bulk PCM in order to obtain a more accurate measurement of their performance.// The experimental results presented in this paper were obtained from two different bulk PCMs (organic and inorganic). It was found that it is important to evaluate different PCM typologies and different thermophysical boundary conditions, including partial and full phase transitions, to test simulation codes that implement PCM modelling functions. In fact, some phenomena, such as hysteresis and subcooling effects are more evident when partial phase transition takes place. The results related to the characterization of the thermal conductivity of a paraffin-based PCM have shown a significant increase (up to 42%) of the equivalent thermal conductivity from a solid to a liquid state, with an upward heat flux, thus highlighting that further investigations and improvements are needed to measure the equivalent thermal conductivity in the different PCM phases.

An Explicit Finite Element Method for Thermal Simulations of Buildings with Phase Change Materials

“…Therefore, more layer splitting could be more challenging to control and predict. For example, Fantucci et al [33] mentioned the possible air-pocket generation because of the volume shrinkage of PCM, which could be avoided by bending the alveolar polycarbonate container used to fill PCM. In a future study, we will further consider air pockets.…”

“…Their study also emphasizes the importance of the different thermal properties received during the heating and cooling process. Fantucci et al [33] also studied the specific heat at heating and cooling for two different PCMs, one organic paraffin and one inorganic salt hydrate. The latter showed a hysteresis effect in the transition temperature, while the first showed almost the same transition temperature at heating and cooling.…”

On the Melting Process of the Phase Change Material in Horizontal Rectangular Enclosures

“…Besides the influence of orientation and aspect ratio of containers, heating the different sides of the rectangular enclosure also plays an important role in the melting process of PCM. For instance, by using a heat flow meter apparatus, Fantucci et al [25] have measured a significant change of equivalent thermal conductivity of the PCM between the upper and the below-heated samples. The difference was mainly attributed to the convection occurring in the below-heated sample.…”

An engineering‐oriented variable water flow air‐conditioning system terminal flow rate estimation method based on component flow resistance characteristics

“…[11][12][13][14][15][16][17][18][19] In the past few years, numerous types of water flowmeters have been invented, made available, and studied to meet various needs. [20][21][22][23] To determine the measurement errors caused during their installation, Martim et al 24 compared the flow rate as measured by an electromagnetic flowmeter under different installation conditions. Other studies 25,26 indicated that gas-liquid two-phase flows could be measured by a Coriolis flowmeter or electromagnetic flowmeter.…”

“…Water flow rate plays a critical role not only in VWFAC systems but also in other thermal engineering systems 11‐19 . In the past few years, numerous types of water flowmeters have been invented, made available, and studied to meet various needs 20‐23 . To determine the measurement errors caused during their installation, Martim et al 24 compared the flow rate as measured by an electromagnetic flowmeter under different installation conditions.…”