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Thermal Energy Storage (thermal + energy_storage)
Selected AbstractsExperimental Investigation of Performances of Microcapsule Phase Change Material for Thermal Energy StorageCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 2 2010G. Fang Abstract Performances of microcapsule phase change material (MPCM) for thermal energy storage are investigated. The MPCM for thermal energy storage is prepared by a complex coacervation method with gelatin and acacia as wall materials and paraffin as core material in an emulsion system. A scanning electron microscope (SEM) was used to study the microstructure of the MPCM. In thermal analysis, a differential scanning calorimeter (DSC) was employed to determine the melting temperature, melting latent heat, solidification temperature, and solidification latent heat of the MPCM for thermal energy storage. The SEM micrograph indicates that the MPCM has been successfully synthesized and that the particle size of the MPCM is about 81 ,m. The DSC output results show that the melting temperature of the MPCM is 52.05,°C, the melting latent heat is 141.03 kJ/kg, the solidification temperature is 59.68,°C, and the solidification latent heat is 121.59 kJ/kg. The results prove that the MPCM for thermal energy storage has a larger phase change latent heat and suitable phase change temperature, so it can be considered as an efficient thermal energy storage material for heat utilizing systems. [source] Characterization of granular phase changing composites for thermal energy storage using the T-history methodINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2010M. A. Rady Abstract The present article reports on the characterization of granular phase changing composites using the T-history method. Further modifications and improvements of the method are employed to handle granular materials undergoing phase change over a temperature range. The accuracy of the T-history method is shown to be limited by the assumption of temperature-independent specific heats and the difficulty of determining the limits of solid and liquid phases. The concept of enthalpy and its relationship with temperature has been employed in the analysis to overcome these difficulties. Enthalpy,temperature and apparent heat capacity curves similar to those obtained using DSC have been developed. These characteristic curves are necessary for accurate design, modeling, and optimization of latent heat thermal energy storage systems. Experiments have been also carried out to measure the transient temperature distribution inside a cylindrical packed bed using phase changing granulates. Analysis of temperature variation along the bed shows good agreement with the measured phase change characteristics. Copyright © 2009 John Wiley & Sons, Ltd. [source] Ground water level influence on thermal response test in Adana, TurkeyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2008. Bozda Abstract For optimum design of borehole thermal energy storage (BTES) and ground sources heat pump (GSHP) applications, determination of underground thermal properties is required. The design and economic feasibility (number and depth of boreholes) of these systems need thermal conductivity of geological structure, , (W,m,1,K,1), and thermal resistance of ground heat exchanger, R (K,W,1,m). Thermal properties measured in laboratory experiments do not coincide with data of in situ conditions. Therefore, in situ thermal response test equipment has been developed and used in Canada, England, Germany, Norway, U.K., U.S.A. and Sweden to ensure precise designing of BTES systems. This paper describes the results and evaluations of the Adana continual thermal response test measurements. Copyright © 2007 John Wiley & Sons, Ltd. [source] Energetic and exergetic analysis of a domestic water tank with phase change materialINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2008C. Solé Abstract Although water is a cheap and effective medium for thermal energy storage, other options are currently being studied, to increase the storage density or to reduce the cost of the storage. The authors have been developing a system which combines the advantages of stratified sensible heat storage and latent, phase change heat storage; i.e. a hot water storage tank with stratification where a phase change material (PCM) is included into a spiral tube installed in the top of the tank. The PCM used was a granular PCM,graphite compound of about 90 vol.% of sodium acetate trihydrate and 10 vol.% graphite. This paper presents the results of an experimental investigation of the performance of the new storage concept, and of a conventional hot water storage tank for comparison. The data are further analysed with respect to the energetic and exergetic performance of the two systems. Copyright © 2007 John Wiley & Sons, Ltd. [source] Heat transfer enhancement of fatty acids when used as PCMs in thermal energy storageINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2008Muhsin Mazman Abstract Phase change materials (PCM) used in latent heat storage systems usually have very low thermal conductivities. This is a major drawback in maintaining the required heat exchange rate between PCM and heat transfer fluid. This paper investigates the enhancement of the heat transfer between PCM and heat transfer fluid, using high thermal conductivity as additives like stainless steel pieces, copper pieces and graphite,PCM composite material. In the experiments, palmitic,lauric acid (80:20) (PL) and stearic,myristic acid (80:20) (SM) were used as PCMs. Test results show that heat transfer enhancement of copper pieces was better at 0.05 Ls,1 flow rate compared to 0.025 Ls,1. Using copper as an additive increased the heat transfer rate 1.7 times for melting and 3.8 times for freezing when flow rate was 0.050 Ls,1. Decreasing the flow rate from 0.050 to 0.025 Ls,1, increased the melting times 1.3 times and freezing times 1.8 times, decreasing heat transfer rates accordingly. The best result of heat transfer enhancement was observed for the PCM,graphite composite. However, changing the flow rate did not affect the heat transfer rate when graphite was used as additive. Copyright © 2007 John Wiley & Sons, Ltd. [source] Experimental investigation of an adsorptive thermal energy storageINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2007B. Dawoud Abstract A zeolite-water adsorption module, which has been originally constructed for an adsorption heat pump, has been experimentally investigated as an adsorptive thermal energy storage unit. The adsorber/desorber heat exchanger contains 13.2 kg of zeolite 13X and is connected to an evaporator/condenser heat exchanger via a butterfly valve. The flow rate of the heat transfer fluid in the adsorber/desorber unit has been changed between 0.5 and 2.0 l min,1, the inlet temperature to the evaporator between 10 and 40°C. It turned out that the higher the flow rate inside the adsorber/desorber unit the faster and more effective is the discharge of heat. However, at lower flow rates higher discharge temperatures are obtained. Storage capacities of 2.7 and 3.1 kWh have been measured at the evaporator inlet temperatures of 10 and 40°C, respectively, corresponding to thermal energy storage densities of 80 and 92 kWh m,3 based on the volume of the adsorber unit. The measured maximum power density increases from 144 to 165 kWh m,3 as the flow rate in the adsorber increases from 0.5 to 2 l min,1. An internal insulation in form of a radiation shield around the adsorber heat exchanger is recommended to reduce the thermal losses of the adsorptive storage. Copyright © 2006 John Wiley & Sons, Ltd. [source] On the technical feasibility of gas turbine inlet air cooling utilizing thermal energy storageINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2006Y. H. Zurigat Abstract The potential of using thermal energy storage (TES) in the form of ice or chilled water to cool gas turbine inlet air is evaluated for a remote oil field location in the Sultanate of Oman using local hourly typical meteorological year weather data. It is found that under the conditions investigated seasonal TES in chilled water storage tanks or ice bins for the location considered is prohibitively expensive and thus not recommended. Application of partial TES option shows that the cool storage does not result in any noticeable reduction in the chiller size. Hence, TES whether seasonal, partial, or full storage is not a viable option for the considered location, especially in the absence of time-of-use utility rate structure. Copyright © 2005 John Wiley & Sons, Ltd. [source] A feasibility study of using thermal energy storage in a conventional air-conditioning systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2004M. M. Hussain Abstract An Erratum has been published for this article in International Journal of Energy Research 2004; 28 (13): 1213. This paper deals with the simulation of thermal energy storage (TES) system for HVAC applications. TES is considered to be one of the most preferred demand side management technologies for shifting cooling electrical demand from peak daytime hours to off peak night hours. TES is incorporated into the conventional HVAC system to store cooling capacity by chilling ethylene glycol, which is used as a storage medium. The thermodynamic performance is assessed using exergy and energy analyses. The effects of various parameters such as ambient temperature, cooling load, and mass of storage are studied on the performance of the TES. A full storage cycle, with charging, storing and discharging stages, is considered. In addition, energy and exergy analysis of the TES is carried out for system design and optimization. The temperature in the storage is found to be as low as 6.4°C after 1 day of charging without load for a mass of 250 000 kg. It is found that COP of the HVAC system increases with the decrease of storage temperature. Energy efficiency of the TES is found to be 80% for all the mass flow rate of the discharging fluid, whereas exergy efficiency varies from 14 to 0.5%. This is in fact due to the irreversibilities in a TES process destroy a significant amount of the input exergy, and the TES exergy efficiencies therefore become always lower than the corresponding energy efficiencies. Copyright © 2004 John Wiley & Sons, Ltd. [source] Thermal energy storage systems as a key technology in energy conservationINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2002Ibrahim DincerArticle first published online: 27 MAY 200 Abstract In this study we deal with the methods and applications of describing, assessing and using thermal energy storage systems, as well as economical, energy conservation and environmental aspects of such systems. The energetic and environmental impacts of thermal energy storage (TES) systems are discussed and highlighted with a number of illustrative examples. The main emphasis is laid on sensible TES, since it is internationally accepted as the most economical and practical energy storage technique. An energy and exergy modelling is presented for TES systems as a key component in the above-mentioned aspects. Illustrative examples are also given to practically demonstrate how exergy analysis provides a more realistic and meaningful assessment than the conventional energy analysis of the efficiency and performance of a sensible heat storage system. It is believed that the results will be useful to engineers and designers seeking to improve and optimize TES systems. Copyright © 2002 John Wiley & Sons, Ltd. [source] Role of Mn of PEG in the morphology and properties of electrospun PEG/CA composite fibers for thermal energy storageAICHE JOURNAL, Issue 3 2009Changzhong Chen Abstract As an aim toward developing novel class of form-stable polymer-matrix phase change materials for thermal energy storage, ultrafine composite fibers based on cellulose acetate and polyethylene glycol (PEG) with five different molecular weight (Mn) grades were prepared by electrospinning. The effects of Mn of PEG on morphology, thermal properties and mechanical properties of the composite fibers were studied by field emission scanning electron microscopy, differential scanning calorimetry, and tensile testing, respectively. It was found that the composite fibers were smooth and cylindrical shape, with the average diameters ranging from about 1000 to 1750 nm which increased with Mn of PEG. Thermal analysis results showed that the composite fibers imparted balanced thermal storage and release properties in different temperature ranges with the variation of Mn of PEG. Thermal cycling test indicated that the prepared composites had excellent thermal stability and reliability even they were subjected to 100 heating-cooling thermal cycles. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Experimental Investigation of Performances of Microcapsule Phase Change Material for Thermal Energy StorageCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 2 2010G. Fang Abstract Performances of microcapsule phase change material (MPCM) for thermal energy storage are investigated. The MPCM for thermal energy storage is prepared by a complex coacervation method with gelatin and acacia as wall materials and paraffin as core material in an emulsion system. A scanning electron microscope (SEM) was used to study the microstructure of the MPCM. In thermal analysis, a differential scanning calorimeter (DSC) was employed to determine the melting temperature, melting latent heat, solidification temperature, and solidification latent heat of the MPCM for thermal energy storage. The SEM micrograph indicates that the MPCM has been successfully synthesized and that the particle size of the MPCM is about 81 ,m. The DSC output results show that the melting temperature of the MPCM is 52.05,°C, the melting latent heat is 141.03 kJ/kg, the solidification temperature is 59.68,°C, and the solidification latent heat is 121.59 kJ/kg. The results prove that the MPCM for thermal energy storage has a larger phase change latent heat and suitable phase change temperature, so it can be considered as an efficient thermal energy storage material for heat utilizing systems. [source] | ||||||||||