Frank Bruno

A chilled ceiling panel using PCM is developed. Study has research on its thermal performance and analysis on heat transfer mechanism. Phase change process of PCM has three stages, solid Mushy and Liquid. Mathematic model is built for the cool room and simulation is made to evaluate the thermal performance. Contact thermal resistance and conduction shape factor are taken into

Jet impingement is effective at improving the heat transfer between air and a heated surface. Studies have shown that jet impingement can marginally improve the thermal efficiency of a glazed collector. However, little attention has been placed on applying jet impingement to ...

Designing a cost-effective phase change thermal storage system involves two challenging aspects: one is to select a suitable storage material and the other is to increase the heat transfer between the storage material and the heat transfer fluid as the performance of the system is limited by the poor thermal conductivity of the latent heat storage material. When used for

... Lakes SA 5095 - Mawson Lakes – Adelaide, Australia 1 edward.halawa@unisa.edu.au, 2 frank.bruno@unisa.edu.au, 3 wasim.saman@unisa ... Monthly space heating (SH) loads were estimated using an Australian building energy rating software, AccuRate (Hearne website, 2006 ...

Abstract An engine driven high-pressure micro-compressor has been developed which employs a unique driving principle. Its advantages make it ideal for supplying high-pressure gaseous fuel to direct injection gas engines. Possible arrangements of the compressor ...

ABSTRACT Thermal energy storage allows improved dispatch-ability of power from a concentrated solar power plant and increases its annual capacity factor. The selection of an appropriate heat transfer fluid (HTF) is important for designing a cost-effective thermal storage system and to improve the cycle efficiency of the power plant. The current state-of-the-art HTF for tower power plants is molten salts, which have the drawback of having low degradation temperature and high melting temperatures respectively. Alternative HTFs under investigation allow for a much larger range of operation, and can offer other cost and performance advantages. In this study, a comparison of six gaseous and liquid HTFs was carried out to determine their suitability for use in a high temperature thermal storage unit with flat slabs of phase change materials. The comparison is in terms of their thermo-physical properties, heat transfer characteristics between the flat plates and the total delivered electrical energy to the grid. Using a validated mathematical model of phase change material in thin slabs, the HTF outlet temperature, heat transfer rate and liquid fraction profiles were predicted when using different HTFs at a constant heat capacity rate for both charging and discharging processes. For the capacity rate considered, liquid sodium was identified as the best HTF, delivering the highest electrical energy to the grid, achieving 99.4% relative to the ideal case. Solar salt achieved a value of 93.6%, while the gaseous fluids of atmospheric air, air at 10 bar, s-CO2 at 100 bar and steam at 10 bar achieved between 87.9% and 91.3% of the ideal delivered electricity. Gaseous fluids have the advantage of being able to be used as the working fluid in the power block. This study shows that gaseous fluids are comparable to liquid HTFs in PCM storage facilities.

... Due to the simple construction and high ratio of surface area to volume of the flat container, this geometry has been investigated numerically and experimentally ( [Ismail and Gon??alves, 1999] , [Simard and Lacroix, 2003] , [Zalba et al., 2004] , [Halawa et al., 2010] , [Halawa and ...

ABSTRACT This paper investigates the dynamic thermal behavior of phase change material (PCM) melting in a rectangular enclosure at various inclination angles. Lauric acid as a PCM with high Prandtl number (Pr ≈ 100) is used. The enclosure is heated isothermally from one side while the other walls are thermally insulated. Experiments were performed with hot wall temperatures of 55, 60 and 70 °C (3.6×108⩽Ra⩽8.3×108)(3.6×108⩽Ra⩽8.3×108) for different inclination angles of 0°, 45° and 90°. Image processing of melt photographs along with recorded temperatures were used to calculate the melt fractions, Nusselt numbers and the local interfacial heat transfer rates at the solid–liquid interface. Qualitative time-dependent natural convection flow structures were deduced indirectly from the instantaneous shape of the solid–liquid interface which were confirmed by quantitative data from temperature measurements. The results reveal that the enclosure inclination has a significant effect on the formation of natural convection currents and consequently on the heat transfer rate and melting time of the PCM. As the inclination angle is decreased from 90° to 0°, the convection currents in the enclosure increases and chaotic flow structures appear. When melting commences in the horizontally inclined enclosure, the solid–liquid interface line becomes wavy which implies the formation of Benard convection cells in the liquid PCM. For the same hot wall temperatures, a decrease in inclination angle leads to a considerable enhancement in energy transport from the hot wall of the enclosure to the PCM. It is found that the heat transfer enhancement ratio for the horizontal enclosure is more than two times higher than that of the vertical enclosure.

ABSTRACT An experimental validation for a computational fluid dynamics (CFD) and an effectiveness-number of transfer units (ε-NTU) model for tubes in a large phase change material (PCM) tank has been conducted. The inlet and outlet heat transfer fluid (HTF) temperatures as well as twelve temperature locations in the PCM tank were compared with the CFD results. The average effectiveness of the phase change process of each experimental point was also compared with results from the CFD as well as the ε-NTU models. From this study, it was concluded that the CFD model and the ε-NTU model developed can accurately predict the behaviour of the thermal storage system during the freezing process. There are however, discrepancies in the melting process due to the exclusion of the effect of natural convection in the models. Using the experimental results, an effective thermal conductivity has been determined to account for buoyancy for various distances of tubes. The paper gives details of the CFD model of the phase change thermal storage system, and presents results from the CFD model, experiments and ε-NTU model.