196,039 research outputs found
Alternative experimental characterization of phase change material plasterboard using two-step temperature ramping technique
No full textThe increasing energy demand for heating and cooling is leading to the development of new strategies for reducing energy consumption and greenhouse gas emissions. Phase change materials applied on the building envelope can act as a heat modulation passive cooling strategy, reducing the energy requirement. An essential aspect for an effective application of PCM is the knowledge of its thermo-physical properties, namely heat conductivity, specific heat and latent heat. Differential scanning calorimetry (DSC) is one of the most used techniques, but the characteristics of the sample necessary for the test make it unsuitable for all those inhomogeneous or composite materials for which a small sample may not be representative of their properties. Alternative and unconventional tests have been developed to overcome this limitation and estimate experimentally one or more thermal properties of a selected material. In the research presented here, a new low-cost experimental set up was developed for the experimental estimation of the thermal conductivity, the specific heat and the latent heat of a plaster containing granular phase change materials through both steady-state as well as unsteady-state tests. The estimated values were then used in the numerical modelling of the experimental set up. A good agreement in thermal response between the experimental and the simulated values validates the proposed experimental estimation method.CO 2022 Elsevier B.V. All rights reserved
Addition of granular phase change materials (PCMs) and graphene to a cement-based mortar to improve its thermal performances
No full textThe addition of phase change materials (PCMs) into building materials represents a valid strategy towards the improvement of their thermal performance and therefore of the indoor comfort. However, when paraffin PCMs are used, the thermal conductivity of the mixture inevitably decreases due to the PCM low thermal conductivity. The research here presented focused on the addition of granular paraffin PCM into a cement-based mortar to improve its thermal storage capacity, and of hydrophobic graphene to counterbalance the reduction in thermal conductivity. Experimental tests at laboratory scale and numerical simulations were carried out to compare the behavior of two equivalent radiant floor samples in terms of temperatures and heat fluxes. Lower temperature fluctuations and delayed minimum temperatures were observed in the mortar with PCM and graphene, if compared to the Reference one. Eventually, in order to investigate the possibility of using the new mortar in case of building refurbishment, a floor with the enhanced mortar lowered 1 cm was simulated and then compared to the reference one. Results showed that the surface of the lowered floor reached the same maximum temperature with the system on and up to 3 K higher with the system off
Conflict solving through magic in the Germanic language area: the case of charms against thieves
No full textExperimental investigation of a cement-based mortar enhanced with granular phase change materials (PCMs) and graphene
No full textThe addition of phase change materials (PCMs) into building materials represents a valid strategy towards the improvement of the thermal performance and therefore of the indoor comfort. However, when paraffin PCMs are added to increase the building component thermal capacity, the overall thermal conductivity inevitably decreases due to the PCM low thermal conductivity. The research here presented focused on the addition of granular paraffin PCM into a cement-based mortar to improve the thermal storage capacity, and of graphene to counterbalance the reduction of the thermal conductivity. Experimental tests at laboratory scale were carried out at the TekneHub Laboratory at the University of Ferrara (Italy), where two equivalent samples of radiant floor were realized and installed in a room with constant temperature and were monitored in terms of temperatures and heat fluxes. Results confirm the effect of PCM in keeping the floor at a higher temperature than the reference case and therefore delaying the cooling
An application of multi-source heat pump system
No full textThe HVAC sector has seen in recent years the growing interest in using the so-called multi-source heat pump systems. This type of system aims to enhance the energy performances of the heat pump technology leading to a significant saving of primary energy. As already known in this field, the heat pump represents the best solution in terms of potential for the environmental decarbonization, energy efficiency and exploitation of renewable energies. The common heat pump systems usually exploit the air, water, or the ground as heat source and sink. The multi-source heat pump system uses different heat sources in one system. This approach could lead, for example, to the reduction of the ground heat exchangers field size which represents one of the main investment issues in GSHP system applications. In fact, sun and air can be used as alternative source to the ground during the middle season or when they are available and convenient, while the ground could be used during the peak periods of the seasons keeping good energy performances of the system. The present work summarises the results of a real large-scale experimental plant used for the air conditioning of a 100 m2 snack bar located in Ferrara, Italy. The energy and thermal behaviour of the plant has been monitored for one year. The data about the operating conditions in summer and winter has been analysed to evaluate the contribution of the different sources and the global efficiency of the system
Radiant floor enhanced with two PCMs for space heating and cooling: A large-scale experimental investigation
No full textWhen integrated in radiant floor systems, PCMs provide efficient energy storage and release in the heating period as well as effective buffering of internal gains in the cooling season. Despite a large number of studies has been examining the thermal performance of radiant floors with PCMs, most of the works conducted a numerical analysis. Only a few studies experimentally investigated PCM integrated radiant floor systems, and they were limited at laboratory scale. In addition, nearly all the works focused exclusively on space heating. A radiant floor heating and cooling system enhanced with PCMs was experimentally analysed at large-scale by the University of Ferrara within the H2020 European project IDEAS. The system was composed of two types of PCMs, one for heating and one for cooling, installed in a 100 m2 building demonstrator. Analysis of the monitoring data showed that the system can maintain the heating and cooling setpoint temperatures even in hard weather conditions and that the turning on of the system can be effectively postponed thanks to the PCM effect
An application of multi-source heat pump system
No full textThe HVAC sector has seen in recent years the growing interest in using the so-called multi-source heat pump systems. This type of system aims to enhance the energy performances of the heat pump technology leading to a significant saving of primary energy. As already known in this field, the heat pump represents the best solution in terms of potential for the environmental decarbonization, energy efficiency and exploitation of renewable energies. The common heat pump systems usually exploit the air, water, or the ground as heat source and sink. The multi-source heat pump system uses different heat sources in one system. This approach could lead, for example, to the reduction of the ground heat exchangers field size which represents one of the main investment issues in GSHP system applications. In fact, sun and air can be used as alternative source to the ground during the middle season or when they are available and convenient, while the ground could be used during the peak periods of the seasons keeping good energy performances of the system. The present work summarises the results of a real large-scale experimental plant used for the air conditioning of a 100 m2 snack bar located in Ferrara, Italy. The energy and thermal behaviour of the plant has been monitored for one year. The data about the operating conditions in summer and winter has been analysed to evaluate the contribution of the different sources and the global efficiency of the system
Development of a numerical model of CaCl2 hydration and dehydration reaction for thermochemical energy storage
No full textPeriodical variations experienced by buildings' energy demand and supply might be tackled by means of Thermal Energy Storage (TES) systems. Among these, thermochemical heat storage (TCHS) by means of thermochemical material (TCM) is one of the most promising, allowing the greatest energy storage density per unit volume, negligible heat losses and longterm storage. As part of the Horizon Europe project "ECHO", a preliminary 2D model of the TCHS system was developed with the software COMSOL Multiphysics as a tool to support the real-scale prototype design, anticipating the behaviour of the system, as well as the implementation of the control algorithm. The model was implemented to work in both charge (dehydration) and discharge (hydration) without having to change the reaction kinetics equation from time to time, only based on the instant-by-instant boundary conditions. This ability to switch from hydration to dehydration and vice versa at any time makes it possible to estimate the performance of the TCM even in the event of not being completely hydrated or dehydrated, and also to establish some relationship between the TCM charging and discharging times
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
- …
