A Review of Recent Improvements, Developments, Effects, and Challenges on Using Phase-Change Materials in Concrete for Thermal Energy Storage and Release

Most concrete employs organic phase change materials (PCMs), although there are different types available for more specialised use. Organic PCMs are the material of choice for concrete due to their greater heat of fusion and lower cost in comparison to other PCMs. Phase transition materials are an example of latent heat storage materials (LHSMs) that may store or release thermal energy at certain temperatures. A phase transition occurs when a solid material changes from a solid state to a liquid state and back again when heat is added or removed. It is common knowledge that adding anything to concrete, including PCMs, will affect its performance. The goal of this review is to detail the ways in which PCMs affect certain concrete features. This overview also looks into the current challenges connected with employing PCMs in concrete. The review demonstrates a number of important findings along with the possible benefits that may pave the way for more research and broader applications of PCMs in construction. More importantly, it has been elucidated that the optimum PCM integrated percentage of 40% has doubled the quantity of thermal energy stored and released in concrete. Compared to conventional concrete, the macro-encapsulated PCMs showed thermal dependability, chemical compatibility, and thermal stability due to delaying temperature peaks. Furthermore, the maximum indoor temperature decreases by 1.85 °C and 3.76 °C in the test room due to the addition of 15% and 30% PCM composite, respectively. Last but not least, incorporating microencapsulated PCM has shown a positive effect on preventing freeze-thaw damage to concrete roads

Recent Advances on The Applications of Phase Change Materials in Cold Thermal Energy Storage: A Critical Review

Cold thermal energy storage (CTES) based on phase change materials (PCMs) has shown great promise in numerous energy-related applications. Due to its high energy storage density, CTES is able to balance the existing energy supply and demand imbalance. Given the rapidly growing demand for cold energy, the storage of hot and cold energy is emerging as a particularly attractive option. The main purpose of this study is to provide a comprehensive overview of the current research progress on the utilisation of PCMs in CTES. The greatest difficulties associated with using PCMs for CTES are also examined in this overview. In this regard, a critical evaluation of experimental and numerical studies of the heat transfer properties of various fundamental fluids using PCMs is conducted. Specifically, several aspects that affect the thermal conductivity of PCMs are investigated. These factors include nanoparticle-rich PCM, a form of encapsulated PCM, solids volume percentage, and particle size. Discussions focus on observations and conclusions are drawn from conducted studies on PCMs used in CTES. Based on the findings of this study, a set of plausible recommendations are made for future research initiatives

Evaluation of draw solution effectiveness in a forward osmosis process

© 2015 Balaban Desalination Publications. All rights reserved. This work investigates the effectiveness of sodium chloride and sucrose binary draw solutions in a forward osmosis pilot plant unit with either deionised or salt water feeds. Specifically, the effects of draw solution concentration on water flux through the membrane, the overall water recovery and the specific energy consumption of the unit are considered. For both feed types, sodium chloride draw solution exhibited a relatively high effectiveness in terms of all the measured performance indicators. Further, improvements in flux and recovery were also achievable with an increase in the sodium chloride (draw solution) concentration. In contrast, a sucrose-based draw solution led to a severe deterioration of the membrane performance that could not be effectively overcome by an increase in the draw solution concentration. This observation was attributed to the relatively large increase in the viscosity of the draw solution with increase in sucrose concentration. Interestingly, in the case of a salt water feed, an increase in the sucrose draw solution concentration led to a relatively small increase in flux and recovery, suggesting some complex but favourable interaction between the salt and sucrose due to the reverse diffusion of the salt into the draw solution

Regeneration of dimethyl ether as a draw solute in forward osmosis by utilising thermal energy from a solar pond

Utilisation of solar thermal energy in forward osmosis (FO) can provide an attractive method for seawater desalination. This study presents a novel process for the regeneration of dimethyl ether (DME) as a draw solute in FO using thermal energy from a solar pond. The location considered for this process is Chabahar (Iran) which benefits from a very high solar irradiance and access to an abundance of seawater from the Sea of Oman making it an ideal location for the proposed process. The average daily volume of desalinated water produced using this process coupled to a solar pond of 10,000 m2 was determined. It is indicated that a solar pond of such moderate size can drive a forward osmosis plant to provide 5,210 m3 of freshwater in the first two years of operation in Chabahar. The proposed process provides freshwater at varying rates throughout the year and benefits from a very low electricity consumption rate of 0.46 kWh per cubic metre of desalinated water offering a viable option for solar desalination. Considering that there are vast uninhabited coastal areas particularly in the Middle East and North Africa (MENA) region, the proposed method can contribute towards addressing the growing potable water scarcity

Regeneration of dimethyl ether as a draw solute in forward osmosis by utilising thermal energy from a solar pond

Utilisation of solar thermal energy in forward osmosis (FO) can provide an attractive method for seawater desalination. This study presents a novel process for the regeneration of dimethyl ether (DME) as a draw solute in FO using thermal energy from a solar pond. The location considered for this process is Chabahar (Iran) which benefits from a very high solar irradiance and access to an abundance of seawater from the Sea of Oman making it an ideal location for the proposed process. The average daily volume of desalinated water produced using this process coupled to a solar pond of 10,000 m2 was determined. It is indicated that a solar pond of such moderate size can drive a forward osmosis plant to provide 5,210 m3 of freshwater in the first two years of operation in Chabahar. The proposed process provides freshwater at varying rates throughout the year and benefits from a very low electricity consumption rate of 0.46 kWh per cubic metre of desalinated water offering a viable option for solar desalination. Considering that there are vast uninhabited coastal areas particularly in the Middle East and North Africa (MENA) region, the proposed method can contribute towards addressing the growing potable water scarcity

Heat Transfer Measurements in a Three-Phase Direct Contact Condenser for Energy Production and Water Desalination

An experimental investigation of heat exchange in a three-phase direct contact condenser was carried out using a 70-cm-high Perspex tube with a 4-cm inner diameter. The active direct contact condenser comprised 48 cm. Pentane vapour at three initial temperatures (40℃,43.5℃, and 47.5℃) and water at a constant temperature (19℃) were used as the dispersed and continuous phases, respectively, with different mass flow rate ratios. The results showed that the continuous phase outlet temperature increased with increasing mass flow rate ratio. On the contrary, the continuous phase temperature decreased with increases in the continuous mass flow rate. The initial temperature of the dispersed phase slightly affected the direct contact condenser output, which confirms a latent phase effect in this type of heat exchanger