Phase change thermal energy storage (TES) is a promising technology due to the large heat capacity of phase change materials (PCM) during the phase change process and their potential thermal energy storage at nearly constant temperature. Although a considerable amount of research has been conducted on medium and low temperature PCMs in recent years, there has been a lack of a similar systematic and integrated study on high temperature PCMs and high temperature thermal energy storage processes. Analyzing the available literature, this review evaluates the selection principles of PCMs and introduces and compares the available popular material selection software options. The thermophysical property data of high temperature PCMs is comprehensively summarized, including high temperature molten salts and metal alloys. Several heat transfer and performance enhancement techniques are summarized and discussed as potential alternative methods to overcome poor thermal conductivity when using high temperature molten salt as the PCM. The common thermophysical property measurement methods used in literature are also summarized and compared. This review gives a broad overview of material selection, innovation and investigation of thermophysical properties for high temperature PCM development, and will be a helpful reference for the design of high temperature phase change TES systems.

Selection principles and thermophysical properties of high temperature phase change materials for thermal energy storage: A review

Phase Change Materials (PCM) have been widely used in different applications. PCM is recognized as one of the most promising materials to store solar thermal energy in the form of latent heat. Utilization of PCMs for solar energy storage compensates for the intermittent characteristic of this energy source. Mathematical modeling and numerical simulation of solar energy storage systems provide useful information for researchers to design and perform experiments with a considerable saving in time and investment. This paper is focused on modeling and simulation of PCM based systems that are used in different solar energy storage applications. A thorough literature review is performed to investigate and compare the results and accuracy of different mathematical models, numerical methods and thermodynamic analysis of using different PCMs in different solar systems. Moreover, the potential research areas in numerical simulations and thermodynamic analysis of solar systems based on PCMs are determined considering the existing gaps in the literature. Although the main idea of using PCMs is storing thermal energy for different applications, PCMs can be used for other purposes such as cooling photovoltaic panels. Past studies have shown that utilization of PCMs in photovoltaic panels can improve the performance of panels by decreasing the average panel temperature by 9.7%. The results of simulations also showed that for each climate a specific PCM with a melting temperature should be used to reach the most uniform temperature distribution.

A review on modeling and simulation of solar energy storage systems based on phase change materials

In this work, technologies related to the storage of solar energy, utilizing the latent heat content of phase change materials for the production of domestic hot water are reviewed. Many researchers have been involved in this field in order to accomplish the targets of environmentally friendly solutions and higher efficiency. For domestic use, materials with melting temperature between 40 and 80 °C are commonly studied, with paraffins, fatty acids, salt hydrates and alcohols being the most popular. For harvesting the solar radiation, usually flat plate or evacuated tubes solar collectors are used, either commercial ones or modified. The storage unit may include only phase change material or it can have a hybrid form combined with water. The outcome of the most studies, is that the addition of phase change materials in comparison to systems without latent storage, increases the duration of heat release towards the domestic water at the end of the day and also increases the solar collector's efficiency because it does not experience large temperature fluctuations. However, difficulties emerge during the selection of the appropriate storage material as this must have a high melting temperature in order to provide hot enough domestic water, but not higher than the temperature that the solar collector can produce, in order to fully melt the material. Moreover, investigation is necessary for the selection of the optimum water flow rate that minimizes the charging duration and maximizes the system efficiency and hot water amount. Another challenge that researchers face is the low thermal conductivity of many phase change materials. For this purpose, methods for improving the performance of the systems have been examined and they are also reported.

Phase change materials in solar domestic hot water systems: A review

Experimental investigation of downdraft gasifier at various conditions

Performance of laboratory scale packed-bed thermal energy storage using new demolition waste based sensible heat materials for industrial solar applications

Mathematical Model of Packed Bed Solar Thermal Energy Storage Simulation

Determination of thermophysical properties of phase change materials using T-History method

Design of Experimental Investigations on the Effect of Equivalence Ratio, Fuel Moisture Content and Fuel Consumption on Gasification Process☆

Abstract One of the main pollution types is air pollution, which has a significant impact on the surrounding environment and on living beings. Major source of air pollution is combustion processes. There are many flue gas treatment technologies around the world. In this paper a new, innovative flue gas treatment technology – fog unit – is introduced. The goal of the fog unit is to treat flue gases that are emitted from households. In the European Union, including Latvia, at the beginning of 2020, a directive will come into effect that will set limits for emissions and the effectiveness for incinerators in households. The main focus of this study was to determine the most optimal operating mode for the fog unit by changing different operating parameters: sprayed water temperature, sprayed water flowrate and types of nozzles (drop diameters). Results show that the most optimal operating mode in terms of flue gas treatment efficiency and recovered energy is at water temperature: 20 °C, sprayed water flowrate: 250 l/h and nozzle: MPL1.12 M. However, electrical consumption of water circulation pump leaves negative effect on this operating mode.

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Mikelis Dzikevics

Papers

Mathematical Model of Packed Bed Solar Thermal Energy Storage Simulation

Determination of thermophysical properties of phase change materials using T-History method

Design of Experimental Investigations on the Effect of Equivalence Ratio, Fuel Moisture Content and Fuel Consumption on Gasification Process☆

Sprayed Water Flowrate, Temperature and Drop Size Effects on Small Capacity Flue Gas Condenser's Performance

Energy Accumulation Using Encapsulated Phase Change Materials with Recycled Material Components