Rhus Chinensis - Inspired Vertical Hierarchical Structure for Solar - Driven All - Weather Co - Harvesting of Fresh Water, Clean Salts, and Authigenic Electricity.

Review of the heat transfer enhancement for phase change heat storage devices

Advanced 3D-printed phase change materials

Thermal conductivity enhancement on phase change materials for thermal energy storage: A review

Latent heat storage and efficient heat transport technology helps to utilize the intermittent solar energy for continuous and near isothermal applications. However, many latent heat storages face challenges of storage charging, heat retaining, and discharging the stored heat. This paper tries to address the challenges of heat transportation and storage charging-discharging issues. The heat transportation from the receiver over some distance, from outside to the kitchen, is carried out with a stainless pipeline and water as heat transfer fluids. However, the charging-discharging process is carried by conduction method with the help of fins. In addition, the stored heat is retained for about one-two days by using aerogel insulation. The latent heat is stored in a phase change material (PCM), nitrate salt (mixture of 60% NaNO 3 and 40% KNO 3 ), which melts at 222oC and has 109 J/g specific heat of fusion. The storage has the capacity of storing up to 250oC heat and supply this heat isothermally during baking in the liquid-solid phase transition. However, the sensible heat stored in the solid and liquid form of the PCM is used to perform additional applications that do not require uniform heat which includes bread baking, kita (large pancake) baking and water boiling. The low thermal conductivity of PCM is enhanced by using extended aluminum fins that are attached to the baking plate and extruded inward to the storage. In this paper, two-phase loop thermosyphon of steam is used to manage the long distance heat transportation required between the receiver (outside) and the storage (inside a house). The steam in the thermosyphon flow has restricted to a maximum working temperature of 250oC. Steam is selected for its highest heat capacity, availability and stable nature. It carries heat from the collector focus point and condenses in a coiled pipe imbedded in aluminum plate placed on top of the storage. Many fins are solidly attached to this plate to conduct the heat down to the PCM inside the storage during charging. This design configuration avoids pressure development inside the PCM storage and the charging-discharging temperature is recorded in three zones (top, middle and bottom) of the storage. The experimental and numerical results show that the heat transportation, retention and charging-discharging methods are effective. Keywords : Solar energy, PCM storage, Latent heat storage, Two-phase thermosyphon.

Latent heat storage and efficient heat transport technology helps to utilize the intermittent solar energy for continuous and near isothermal applications. However, many latent heat storages face challenges of storage charging, heat retaining, and discharging the stored heat. This paper tries to address the challenges of heat transportation and storage charging-discharging issues. The heat transportation from the receiver over some distance, from outside to the kitchen, is carried out with a stainless pipeline and water as heat transfer fluids. However, the charging-discharging process is carried by conduction method with the help of fins. In addition, the stored heat is retained for about one-two days by using aerogel insulation. The latent heat is stored in a phase change material (PCM), nitrate salt (mixture of 60% NaNO 3 and 40% KNO 3 ), which melts at 222oC and has 109 J/g specific heat of fusion. The storage has the capacity of storing up to 250oC heat and supply this heat isothermally during baking in the liquid-solid phase transition. However, the sensible heat stored in the solid and liquid form of the PCM is used to perform additional applications that do not require uniform heat which includes bread baking, kita (large pancake) baking and water boiling. The low thermal conductivity of PCM is enhanced by using extended aluminum fins that are attached to the baking plate and extruded inward to the storage. In this paper, two-phase loop thermosyphon of steam is used to manage the long distance heat transportation required between the receiver (outside) and the storage (inside a house). The steam in the thermosyphon flow has restricted to a maximum working temperature of 250oC. Steam is selected for its highest heat capacity, availability and stable nature. It carries heat from the collector focus point and condenses in a coiled pipe imbedded in aluminum plate placed on top of the storage. Many fins are solidly attached to this plate to conduct the heat down to the PCM inside the storage during charging. This design configuration avoids pressure development inside the PCM storage and the charging-discharging temperature is recorded in three zones (top, middle and bottom) of the storage. The experimental and numerical results show that the heat transportation, retention and charging-discharging methods are effective. Keywords : Solar energy, PCM storage, Latent heat storage, Two-phase thermosyphon.

Thermal performance study of a solar-coupled phase changes thermal energy storage system for ORC power generation

Flexible engineering of advanced phase change materials

Modern heating systems for buildings need a supply temperature of approximately 35 C. Standard heat storage systems do not work very efficiently with small supply temperature differences, because of the low sensible heat storage capacity. In contrast to the sensible heat storage a phase change material (PCM) storage system uses the phase change process to store energy at small temperature differences [3], [4], [5]. In this paper a thermo hydraulic model of a PCM storage is developed and implemented by using Modelica, so that dynamic modelling is possible. To show the advantages of latent heat storage (LHS) the PCM storage model has been combined to build a standard heat pump system model with a PCM storage instead of a sensible water storage and the overall system is analysed.

Solar cooling and heating plants: An energy and economic analysis of liquid sensible vs phase change material (PCM) heat storage

Based on the energy storage problem for solar energy utilization and the advantages of spiral groove tube heat exchanger, spiral groove tubes were used in the solar energy phase change heat storage. The thermal storage process of heat reservoir was simulated numerically. Firstly, the simulation method and the reliability of the used model are verified experimentally with smooth tube. Using spiral groove tube as water flow pipe and phase change material as heat storage medium, The three-dimensional model of heat storage was built by Gambit software and the grids were divided by ICEM. The heat storage process in the spiral groove tube and smooth tube heat storage were numerically simulated and the heat transfer enhancing effect was investigated. The influence of structural parameters such as groove pitch and groove depth on the heat storage process is simulated numerically and the influence rules are analyzed. The results show that the convective heat transfer intensity and heat transfer capability are enhanced when the smooth tubes are substituted by spiral groove tubes in the phase change heat storage and the heat storage time becomes shorter. In the range of this paper, the optimal structural parameters of spiral groove tube is groove pitch p=7mm and groove depth e=0.4mm.

Design and functionality of a segmented heat-storage prototype utilizing stable supercooling of sodium acetate trihydrate in a solar heating system

Phase-change heat storage device is the key equipment for the heating technology's application of solar heating technology, industrial waste, etc. Based on the analysis of the characteristics of the current phase-change heat storage device, the capillary phase-change material heat storage tank was proposed. And with a composite phase change materials, whose thermal properties were tested and the results showed that the composite phase change material meets the requirements of solar heating technology. Meanwhile, the effect of water flow and temperature to the capillary phase-change material heat storage tank were investigated and the optimum flow was got, which provides credible data for the design of the capillary phase-change material heat storage tank.

The preliminary version of an analysis of activities in research, development, and demonstration of low temperature thermal energy storage (TES) technologies having applications in renewable energy systems is presented. Three major categories of thermal storage devices are considered: sensible heat; phase change materials (PCM); and reversible thermochemical reactions. Both short-term and annual thermal energy storage technologies based on prinicples of sensible heat are discussed. Storage media considered are water, earth, and rocks. Annual storage technologies include solar ponds, aquifers, and large tanks or beds of water, earth, or rocks. PCM storage devices considered employ salt hydrates and organic compounds. The sole application of reversible chemical reactions outlined is for the chemical heat pump. All program processes from basic research through commercialization efforts are investigated. Nongovernment-funded industrial programs and foreign efforts are outlined as well. Data describing low temperature TES activities are presented also as project descriptions. Projects for all these programs are grouped into seven categories: short-term sensible heat storage; annual sensible heat storage; PCM storage; heat transfer and exchange; industrial waste heat recovery and storage; reversible chemical reaction storage; and models, economic analyses, and support studies. Summary information about yearly funding and brief descriptions of project goals and accomplishmentsmore » are included.« less

In this review we aim at providing an up-to-date and comprehensive overview on the use of additives within selected Phase Change Materials (PCMs) from both an experimental and more theoretical perspective. Traditionally, mostly focusing on short-term thermal energy storage applications, the addition of (nano)fillers has been extensively studied to enhance unsatisfactory thermo-physical properties in PCMs, in order to overcome limiting aspects such as low thermal conductivity possibly leading to unacceptable long charging and/or discharging periods and inefficient heat-storage systems. On the other hand, here we focus on the most important PCMs for long-term thermal energy storage (i.e. spanning from classical solid-to-liquid to more recent solid-to-solid PCMs) and make an effort in shedding light on the role played not only by additives but also (and importantly) by additivation protocols on the resulting thermo-physical and stability properties. While introducing and connecting to general advantages related to additivation in classical PCMs for thermal energy storage, we discuss specifically the use of additives in sugar alcohols and sodium acetate trihydrate, as well as in novel emerging classes of PCMs capable of undergoing solid-to-solid transitions and showing promising features for long-term heat storage materials. We highlight outstanding issues in the use of additives for property enhancement in PCMs and expect that the present work can contribute to expand the current understanding and field of application of the less mature PCMs for thermal energy storage, especially as far as long term applications are concerned.

For the thermal environment and the warming requirement of Vehicle, carry out experiment study on heat storage characteristic of phase change materials (PCM) encapsulated by Spherical stack. heat storage and release experiment process , changing factors such as medium flow rate and melting point which impact on PCM heat transfer characteristics , melting rate and response time have been analyzed. The results show that within the scope of experiment high medium flow rate is conducive to promote PCM melting rate and heat storage. In the experiments process, high melting point of PCM storage heat grade is high, but the low melting point of PCM is more suitable for vehicle motor, batteries in low temperature waste heat recovery. At the same time, multi-melting point PCM storage device with spheres piled encapsulated delamination mixed stowage was better satisfy the different condition of waste heat recovery and utilization than single melting point of PCM.