Figure 5 - uploaded by Arthur M James Rivas
Content may be subject to copyright.
Source publication
![Figure 2. Hot water temperature vs. time and the number of families [13].](profile/Arthur-James-Rivas/publication/358191409/figure/fig1/AS:1117355337887744@1643409680287/Hot-water-temperature-vs-time-and-the-number-of-families-13_Q320.jpg)
In recent years, phase change materials (PCMs) have been presented as a suitable alternative for thermal energy storage (TES) systems for solar water heater (SWH) applications. However, PCMs' low thermal conductivity and the high dependence on external conditions are the main challenges during the design of TES systems with PCMs. Design actions to...
Contexts in source publication
Context 1
... proposed four-step methodology can be finally summarized in the flow chart illustrated in Figure 5. ...
Context 2
... results are attributed to the reduction in the PCM and the increase in water, which implies an increment of material with higher thermal conductivity and sensible heat storage capacity. Based on these results, the configuration of thermal energy storage with reduced lauric acid prisms (LA_Rr) was selected as the proposed geometry and amount of lauric acid as shown in Figure 15. Finally, the all-day simulation of the selected configuration was performed to analyze the effect of PCM amount and geometry changes. ...
Similar publications
In recent years, latent heat thermal energy storage systems have emerged as a significant technique for addressing the variable nature of renewable energy sources, balancing energy demand, and enhancing energy efficiency. Additionally, phase change materials (PCMs) with high latent energy storage capabilities have become increasingly popular as the...
The thermal conductivity of PCM is one of the essential variables for the fast heat transfer process for latent heat energy storage (LHES) units. The thermal characteristics of a novel LHES rectangular enclosure based on multiple chambers separated by insulating and rigid walls are numerically investigated. The enthalpy porosity strategy supported...
The problem of heat dissipation has become a key to maintain the operation state and extending the service time of electronic components. Developing effective thermal management materials and technologies is of great significance to solve this problem. Previously, passive cooling using phase change materials (PCMs) has been proposed as a thermal ma...
Thermal energy storage systems using PCM offer promising solutions for efficient thermal applications. This study aims to provide valuable insights into the PCM melting process and compare the thermal performance of different heat exchanger models. The experimental rig is carefully designed to simulate a shell and tube heat exchanger with five long...
Investigating the thermophysical properties of substances is crucial for using them as phase change materials (PCMs) and heat transfer fluids (HTFs) in thermal energy applications. In this study, the thermophysical properties of three medium-temperature PCMs (around 338 K) and one ionic liquid, tetrabutylammonium chloride ([N4444⁺][Cl⁻]), were eval...
Citations
... Thermal storage systems based on phase change materials (PCM) allow for high energy storage density with very small temperature variations. A thermal energy storage system with PCM [1] in the configuration of a heat exchanger has been redesigned, concluding that the type, encapsulation shape, and amount of PCM slightly impacted the system's performance; however, selecting a suitable sensible heat storage material had the highest impact on meeting the system's targets. A PCM storage system, which therefore utilizes the latent heat of fusion energy, can store from 5 to up to 14 times more heat per unit of volume than a system based only on sensible energy [2]. ...
In this paper, a thermal storage system based on a phase change material is proposed and investigated. The system is composed of several tubes that cross a phase change material mass. A fluid flowing in the tubes charges and discharges the heat storage system. A mathematical model of the system has been developed, which provides the time and space distribution of velocity, temperature, and liquid phase-changing material concentration in a non-stationary regime. A hybrid solution method based on finite volumes and finite differences techniques has been employed for the model equations in the MATLAB environment. To the tubes, a rectangular cross section has been assigned. The performance of the system in terms of accumulated energy density and accumulated power density has been investigated by varying some geometric parameters. The considered geometric parameters influence the number of tubes per unit of system width, the tube hydraulic resistance, the amount of phase change material around each tube, the heat transfer surface of the tube, and the heat storage velocity. In the parametric analysis, peaks have been evidenced in the investigated performance parameters at different instants after the beginning of the heat storage.
... Another technology that is also frequently encountered is the PCM encapsulation [34] which ensures chemical and mechanical stability of the material and reduced superheating [27]. Harris Bernal et al. [35] investigated the operation of an existing TES of 400 l with PCM encapsulation. In their study, the efficiency of the TES reached 76.1 %. ...
... The integration of artificial intelligence is also beginning to spread in this field [38]. In many cases, the research of a system or device starts with analytical or numerical methods [35]. Therefore, there are more theoretical studies on TES with PCM than on full-scale PCM TES prototypes, which are more practically relevant. ...
The paper presents an experimental analysis of the full-scale phase change material (PCM) thermal energy storage (TES) prototype that is designed for use in domestic hot water preparation systems. The PCM-TES prototype is based on the external arrangement of organic PCM and a custom-made compact fin-and-tube type of heat exchanger. The prototype has been designed, constructed, and tested according to the Ecodesign Directive requirements for water heaters and hot water storage tanks. Several parameters have been analysed, including the heat transfer fluid (HTF) temperature and mass flow rate, heat transfer rate, accumulated and released energy, and quantity of domestic hot water (DHW) delivered. Additional attention was paid to the reliability and repeatability of the results. Experimental research allowed to determine the quantity and temperature of DHW at a constant mass flow rate of 0.1 kg/s. The prototype unit showed that it can deliver 99.1 l of hot water at 40 °C for up to 15 min and 39 s, while the use of lower temperature DHW (up to 37 °C) allows to increase the quantity of hot water delivered up to 156.2 l. Experimental results showed the viability of the prototype, areas for improvement and further possibilities for its optimization. Overall, the study results are relevant for developing latent heat thermal energy storage systems using fin-and-tube heat exchangers in tanks and the feasibility of integrating such systems into DHW systems.
... Technical requirements have also been considered in their design process by other authors. For example, Harris et al. [118] developed a redesign methodology based on numerical simulations in COMSOL Multiphysics 5.6 to enhance the performance of an SWH with PCM for 24-hour operation, with a technical requirement of a minimum hot water temperature of 43 • C. The application of a four-step redesign methodology based on numerical simulations modified the PCM (lauric acid instead of n-eicosane), shape (half cylinder instead of a complete cylinder), size (50% less PCM), and the sensible heat storage substance (steatite instead of water), resulting in an efficiency increase from 43.06% to 76.08%. In addition, the hot water at the desired temperature was available for 15 h after 9 h of charging time, enabling the system to operate autonomously for 24 h. ...
... The possible sanitary risks associated with PCM use in SWH systems, such as a contaminant mixture of PCM with the water supply and the growth of Legionella bacteria, should be considered [124]. Legionella bacteria growth can be avoided with minimum hot water temperatures of 60 • C. Some have considered it by designing tankless SWHs with PCMs that eliminate any risk of contact between the water and the PCM [36,118,125]. ...
... melting time was reduced by 16% and the effectiveness was improved by 13.06%. Harris et al.[118] B (tankless) Numerical Thermal design (based on technical requirements)-The definition and application of a four-step redesign methodology improved performance and met technical requirements.-The efficiency increased from 43.06% to 76.08% Luu et al.[35] B (tankless) Numerical Thermal design (based on technical requirements) -The redesigned system resulted in higher water temperatures which meet the goal, and an increased exergy efficiency from 26% to 42.7%. ...
... The majority of this research asserted that it showed the beneficial effects of adding PCMs in terms of various methods and criteria, including system efficiency, energy storage capacity, shifting hours, and energy savings. In order to present the practicality of the proposed system and its efficiency in comparison with other proposed systems, the maximum outlet water temperature and the highest thermal efficiency obtained from the proposed system were compared to that obtained by the previous studies [27,36,37] and presented in Table 3. Table 3. Comparison of key performance indicators related to the present SSWH-PCM system and that for the previous studies. ...
... The majority of this research asserted that it showed the beneficial effects of adding PCMs in terms of various methods and criteria, including system efficiency, energy storage capacity, shifting hours, and energy savings. In order to present the practicality of the proposed system and its efficiency in comparison with other proposed systems, the maximum outlet water temperature and the highest thermal efficiency obtained from the proposed system were compared to that obtained by the previous studies [27,36,37] and presented in Table 3. ...
... In their research, it was found that the SWH-PCM tank has an efficiency of 58%. Harris B. et al. [37] implemented a redesign methodology to enhance an existing TES with PCM system for a SWH tank. Their results show that the redesigned TES reached a minimum outlet water temperature of 45.30 • C and a thermal efficiency of 76.08%. ...
Integrating a solar water heater (SWH) with a phase change material (PCM)-based latent heat storage is an attractive method for transferring load from peak to off-peak hours. This transferring load varies as the physical parameters of the PCM change. Thus, the aim of this study is to perform a parametric analysis of the SWH on the basis of the PCM’s thermophysical properties. A mathematical model was established, and a computation code was developed to describe the physical phenomenon of heat storage/release in/from the SWH system. The thermal energy stored and the energy efficiency are used as key performance indicators of the new SWH–PCM system. The obtained numerical results demonstrate that the used key performance indicators were significantly impacted by the PCM thermo-physical properties (melting temperature, density, and latent heat). Using this model, various numerical simulations are performed, and the results indicate that, SWH with PCM, 20.2% of thermal energy on-peak periods load is shifted to the off-peak period. In addition, by increasing the PCM’s density and enthalpy, higher load shifting is observed. In addition, the PCM, which has a lower melting point, can help the SWH retain water temperature for a longer period of time. There are optimal PCM thermo-physical properties that give the best specific energy recovery and thermal efficiency of the SWH–PCM system. For the proposed SWH–PCM system, the optimal PCM thermo-physical properties, i.e., the melting temperature is 313 K, the density is 3200 kg/m3, and the latent heat is 520 kg/kg.
... Both methods include data from experimental measurements of the PCM thermal properties. Both methods are employed in commercial CFD software, e.g., the enthalpy method in Ansys Fluent (finite volume solver); effective capacity method in COMSOL Multiphysics (finite element solver) [48,50]. ...
... An encapsulated design of LHS is considered in Ref. [50] (Figure 7). A methodology based on CFD simulations by COMSOL in a 3D domain is suggested for design improvement. ...
... After investigating different approaches to enhance heat trans- Figure 9. Comparison between performance parameters evaluated in step 1 (R) and step 4 (Final TES) in the redesign method [50]. ...
The current interest in thermal energy storage is connected with increasing the efficiency of conventional fuel-dependent systems by storing the waste heat in low consumption periods, as well as with harvesting renewable energy sources with intermittent character. Many of the studies are directed towards compact solutions requiring less space than the commonly used hot water tanks. This is especially important for small capacity thermal systems in buildings, in family houses or small communities. There are many examples of thermal energy storage (TES) in the literature using the latent heat of phase change, but only a few are commercially available. There are no distinct generally accepted requirements for such TES systems. The present work fills that gap on the basis of the state of the art in the field. It reviews the most prospective designs among the available compact latent heat storage (LHS) systems in residential applications for hot water, heating and cooling and the methods for their investigation and optimization. It indicates the important characteristics of the most cost- and energy-efficient compact design of an LHS for waste heat utilization. The proper design provides the chosen targets at a reasonable cost, with a high heat transfer rate and effective insulation. It allows connection to multiple heat sources, coupling with a heat pump and integration into existing technologies and expected future scenarios for residential heating and cooling. Compact shell-tube type is distinguished for its advantages and commercial application.
The utilization of phase change materials (PCMs) in solar water heating systems (SWHS) has undergone notable advancements, driven by a rising demand for systems delivering superior performance and efficiency. Extensive research suggests that enhancing heat transfer (HTE) in storage systems is crucial for achieving these improvements. This review employs a bibliometric analysis to track the evolution of HTE methods within this field. While current literature underscores the necessity for further exploration into hot water generation applications, several methodologies exhibit significant promise. Particularly, strategies such as fins, encapsulation, and porous media emerge as prominent HTE techniques, alongside nanofluids, which hold the potential for augmenting solar water heating systems. This review also identifies numerous unexplored techniques awaiting investigation, aiming to pave new paths in research and application within the field of hot water generation. It highlights methods that could be used independently or alongside predominantly used techniques.
A flexible paraffin/hollow fiber phase change composite was prepared using a simple impregnation method, and the thermal release performance of a piece of woven paraffin/hollow fiber rectangular blocks was systematically investigated using experimental and numerical methods. The experimental results of the thermal release performance were highly consistent with the numerical results. Consequently, the thermal release performance, including the available energy and solidification time, of the paraffin/hollow fiber with different melting temperatures, mass fractions (corresponding to the enthalpy), specific heat and thermal conductivity were numerically investigated. The available energy of the paraffin/hollow fiber completely depends on the mass fraction of the paraffin. The solidification time mainly depends on the mass fraction of the paraffin and secondarily on the thermal conductivity, while the specific heat has little effect on the solidification time. Therefore, the thermal release performance of the paraffin/hollow fiber could be optimized through numerical simulation by altering the solidification temperature, mass fraction, thermal conductivity, and specific heat.
