Papers by Keyword: Thermal Energy Storage

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Authors: G. Murali, K. Mayilsamy, B.Mubarak Ali
Abstract: Thermal Energy Storage (TES) has become extremely important in the recent years since it balances the energy demand and improves the efficiency of the solar systems. It is important that the thermal energy storage systems have the necessary characteristics to improve the performance of the storage. Usage of Phase Change Materials (PCM) for energy storage provides a great benefit but, their low thermal conductivity becomes a major drawback. This can be compensated with the use of phase change material in an appropriate design for successful functioning of the system. This review article summarizes the recent designs of thermal energy storage systems containing Phase Change Material that have been adopted for efficient energy storage.
Authors: Janis Kazjonovs, Jana Vecstaudz, Janis Locs, Diana Bajare, Aleksandrs Korjakins
Abstract: This paper reviews a modeling study on PCM/timber composite materials and their incorporation in building materials, particularly in passive applications. Commercially available paraffin PCMs (RT21 and RT27) were incorporated in timber for increasing its thermal mass. In order to evaluate PCM/timber composite material behavior in building, computer simulation was performed. The obtained results showed that by using this technique it is possible to increase the thermal mass and reduce cooling loads in summer conditions.
Authors: Martina Jurigova, Maria Minarova, Ivan Chmúrny
Abstract: Thermal energy is necessary of many reasons. The most basic and most obvious includes food preparation and delivery of heat. Thermal energy storage is actually a temporary storage at high temperatures, respectively at low temperatures. It is an advanced technology, which can reduce environmental impact and it can facilitate more efficient and cleaner energy system. Nowadays, these systems have ability to retain thermal energy for a period of three months or more. The aim of design of these systems is to keep the thermal energy in summer period and to use it for heating in winter period. The role of such storage systems is to accumulate the heat, to balance temperature differences and to achieve the most effective use of the collected energy. This paper is focused on thermal analysis of system, which contains concrete tank. It is a system with water as a storage medium and the cooling of the water was monitored for 30 days.
Authors: M. Gajendiran, N. Nallusamy
Abstract: A massive deployment of solar thermal technology is required in those industries which use large quantities of low temperature hot water for the economic operation. With the rise in fuel cost and scarcity now, there is a significant research, development and application in solar industrial process heating. Due to the unavailability of solar energy during non sunny days and diurnal changes throughout the day, storage of thermal energy is inevitable. Recent developments nationally and internationally may rekindle new applications of solar thermal energy use by industry. This paper reviews the application of solar industrial process heating in paper industry.
Authors: Jaroslav Jerz, Peter Tobolka, Martin Nosko, Tomáš Dvorák
Abstract: The development of efficient materials for heat storage has become recently a popular research topic as amount of energy gained from solar power depends significantly on day and night cycle. That's why the right choice of material for heat storage directly affects the utilization efficiency of solar thermal energy. Research on heat storage materials nowadays focuses on phase change materials (PCMs) enabling repeatedly utilize the latent heat of the phase transition between the solid and liquid phase. Most currently used PCMs have low thermal conductivity, which prevents them from overcoming problem of rapid load changes in the charging and discharging processes. To overcome this obstacle and to obtain excellent heat storage possibility, various techniques have been proposed for enhancing the thermal conductivity of PCMs, such as adding metallic or nonmetallic particles, in-corporating of porous or expanded materials, fibrous materials, macro-, micro-, or nanocapsules, etc.The authors of this study report particularly the huge potential of oxide nanoadditives, such as titania (TiO2), alumina (Al2O3), silica (SiO2) and zinc oxide (ZnO), that are even in small quantities (up to 3 wt.%) able significantly to enhance the heat storage characteristics of conventional PCMs. Moreover, the microstructure of the granules produced by recycling of aluminum scrap refers to the possibility of their utilizing for the purpose of low cost solutions enabling to increase the thermal conductivity of PCMs. The above mentioned technical solutions are therefore the important keys to successful commercialization of materials for latent heat storage in future building industry.
Authors: Huan Liu, Yan Rong Tang, Ya Fei Guo, Shi Qiang Wang, Tian Long Deng
Abstract: Energy demand to ensure a comfortable environment for humans has increased worldwide, especially in the application of phase change material (PCM) for resident living. In this paper, the current applications of PCMs including solar water-heating system, solar cooker and residential building aspects were presented, and the suggestions for future works were also discussed.
Authors: Yao Lin Lin, Wei Yang, Ming Sheng Liu
Abstract: The paper presents the study on the control optimization of the central cooling plant system including thermal chilled water energy storage (TES) tank in a high-tech building consists of office area, clean room and lab space. The optimized control sequences were implemented on the cooling tower staging, cooling tower fan/condenser water pump/primary chilled water pump staging and speed control, chiller staging, TES pump speed and TES modulation valves control, and secondary chilled water loop differential pressure control. The proposed control effectively resolved the problem of fluctuation in the secondary chilled water supply temperature during charging cycle and temperature increase during the discharging cycle. The number of primary chilled water pumps, condenser water pumps and cooling tower fans were also reduced to minimum after the optimization. Implementation of optimized control sequences is predicted to have an annual electricity savings of 856,125 kWh, which is about 20% of the total central plant energy consumption.
Authors: N.A.M. Amin, Azizul Mohamad, R. Daud, M.S. Abdul Majid, Mohd Afendi, Frank Bruno, Martin Belusko
Abstract: The application of phase change material (PCM) for thermal energy storage (TES) has become one of the viable solutions in energy saving achievable with renewable thermal systems. Packed bed of spheres has been used as TES to enlighten the encapsulated PCM availability in space within the TES system. In order to minimise the high manufacturing cost, the simulation on the TES model is proposed. In accordance to that, a model of TES containing a PCM sphere has been studied in this paper. A commercialised computational fluid dynamics (CFD) software is used to simulate the TES model and the result is then compared experimentally, thus validating the simulation model. The model has been validated for both charging and discharging processes. It is also found that with the use of the CFD model, one could determine the effective thermal conductivity of the PCM at different temperatures.
Authors: R. Sudheer, K. Narayan Prabhu
Abstract: In recent years phase change materials have emerged to be ideal energy storage materials for their higher energy density over sensible heat storing materials. Use of phase change materials (PCM) have been successfully implemented at lower temperature applications with various organic compounds. On the other hand, high temperature applications have been solely dominated by various salts, their eutectics and mixtures as phase change materials. This work discusses the suitability of metals and alloys for thermal energy storage applications as the phase change material. Metals offer superior thermal conductivities with considerable energy density compared to salts. Here, two alloys namely, Sn-0.3Ag-0.7Cu (SAC) solidifying over 212-224°C and ZA8 (Zn-8%Al) solidifying over 378-405°C have been studied. Thermal analysis of PCMs using Computer Aided Cooling Curve Analysis (CA-CCA) and DSC technique were performed to predict the solidification path. In addition to this, Newtonian technique was employed to estimate the latent heat of fusion for these phase change materials. Cooling rate curves and Fraction Solid curves offered a better insight into their ability to receive and discharge heat over the concerned temperature range.
Authors: Rungrudee Boonsu, Sukruedee Sukchai
Abstract: The research was performed on thermal energy storage prototype in Thailand. Concrete was used as the solid media sensible heat material in order to fulfill local material utilization which is easy to handle and low cost. Saturated steam was used for heat transfer fluid. The thermal energy storage prototype was composed of pipes embedded in a concrete storage block. The embedded pipes were used for transporting and distributing the heat transfer medium while sustaining the pressure. The heat exchanger was composed of 16 pipes with an inner diameter of 12 mm and wall thickness of 7 mm. They were distributed in a square arrangement of 4 by 4 pipes with a separation of 80 mm. The storage prototype had the dimensions of 0.5 x 0.5 x 4 m. The charging temperature was maintained at 180°C with the flow rates of 0.009, 0.0012 and 0.014 kg/s whereas the inlet temperature of the discharge was maintained at 110°C. The performance evaluation of a thermal energy storage prototype was investigated in the part of charging/discharging. The experiment found that the increase or decrease in storage temperature depends on the heat transfer fluid temperature, flow rates, and initial temperature. The energy efficiency of the thermal energy storage prototype at the flow rate of 0.012 kg/s was the best because it dramatically increased and gave 41% of energy efficiency in the first 45 minutes after which it continued to rise yet only gradually. Over 180 minutes of operation time, the energy efficiency at this flow rate was 53% and the exergy efficiency was 38%.
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