No abstract

No abstract

No abstract

No abstract

The availability of hot water is essential for overnight industrial and domestic use. Integrating the solar heater with thermal energy storage showed a promising result on hot water production when sunlight is not present. In the present work, an outdoor experimental investigation of a flat plate solar collector was carried out with PCM and nano-enhanced PCM. The phase change material (PCM) used in this experiment is paraffin wax. However, 1% weight fraction of 20nm copper nanoparticles was added to improve the properties of the compound. Three cases have been investigated, namely, without PCM, with PCM and with nanoenhanced PCM (nano-PCM). It was found that at the operational mode of 0.5 kg/min and at a 10º inclination angle, with PCM and nano-PCM, hot water at 40.2ºC and 40.8ºC was produced the following morning. However, without the PCM case hot water was produced at 35.2ºC. The system was enhanced by 6.9% and 8.4% respectively when PCM and nano-PCM were used.

ABSTRCT:For decades, it has been a challenging task for brake engineers to reduce or totally eliminate squeal that emanates from brake systems. Despite the large number of proposals that have been implemented in tackling disc brake squeal, very few solutions are totally effective to reduce or suppress it. This paper presents an approach to tackle disc brake squeal through chamfered and slotted pad. A three-dimensional FE model of an actual disc brake system is developed. The baseline FE model is first simulated using complex eigenvalue and transient analysis to predict squeal and compared to the squeal tests data obtained in the brake dynamometer. A reasonable correlation is found between these results. Then, three different pad modifications are proposed, simulated and tested. It is shown that pad with chamfers and diagonal slot can totally suppress squeal both in prediction and squeal test.

Clinical wastes generated from hospitals and other health care institutions have increased globally, partly because of COVID-19 pandemic. Appropriate handling and disposal of this wastes is important because of their impact on human and environment. One approach is the use this wastes as composite fillers in phase change material (PCM) added into concrete and mortars used in built sector. This study investigates silicon catheter waste (SCW) and latex glove waste (LGW) as fillers mix with PCM cement mortar and evaluates the thermal performance. To determine a viable inclusion method for the cement mortar varying weight (2.5, 5.0, 7.5, and 10.0)% of PCM mixed with SCW and LGW were used as replacement of the composite aggregates. Characterization of the encapsulate PCM cement mortar and thermal analysis under elevated temperatures, compressive strength test, water absorption, porosity, and density was conducted. The microstructural analysis and thermal behavior of the modified specimens after 28 days was tested under dynamic ambient condition. From the result the quality of the cement mortar reduced from excellent to poor as the loading concentration increased from 0 to 10%. The addition of the PCM SCW and PCM LGW to the cement mortar reduced the compressive strength by 38% and 40%, respectively. The density value reduced by 3.2% and 6.8% under elevated temperature and the water absorption increased by 56% and 39%. The morphology of PCM cement mortar mixed with SCW and LGW showed less void spaces with increased homogenous formation.No thermal decomposition was observed in the PCM cement mortar with the addition of the SCW and LGW at elevated temperatures. The SCW and LGW fillers increased the thermal conductivity of the PCM mortar by 14% and 18%, and prolonged the surface temperature by 5 hours by an average of 5 C and 7 C, respectively. In addition, the SCW and LGW fillers mixed with PCM cement mortar was found to enhance the thermal performance by 65% compared with the typical cement mortar. There are huge potential on their application in building and construction industry.

Utilizing the Phase change material or PCM as thermal storage in solar research has been widely focused. Some researches embedded metal and non-metal Nanoparticles into the PCM to investigate the effect on the thermal properties of the mixtures. In this study, copper nanoparticles are dispersed into paraffin wax to form Nanoparticles-PCM mixture. Three samples have been prepared: Sample 1 is paraffin wax only, Sample 2 is 1% 20nm copper powder + 150 ml paraffin wax, and Sample 3 is 2% 20nm copper powder + 150 ml paraffin wax. Differential Scanning Calorimeter is used to analyse the melting point, solidification point and specific heat of mixture. Transmission Electron Microscopy is used to identify the shape and size of 20nm copper powder. The study showed that thermal conductivity of Nanoparticles-PCM mixture was increased as well as the sensible heat. However, there is reduction in the melting point and heat flow to melt the Nanomaterials but latent heat of fusion was increased. 20nm copper powder is proven to be suspended in the paraffin wax.