Incorporation Of Phase Change Materials Research Articles

Developing Heat Mitigation Wall by Integrating PCM into Building Material

Population growth and industrial demand are related in construction of buildings and houses which contribute to increment of energy consumption. The invention of phase change materials (PCMs) with high latent heat capacity were explored to be integrated into building materials. PCMs are substances that are capable of storing large amounts of thermal energy as latent heat during their phase transition. Development of this product can ensure a comfortable indoor temperature in buildings without depending on air conditioning system which consumes more energy and damage the environment not to mention contributing towards global climate change. This research concentrated on proposing the method of PCM incorporation and its heat resistance performance. Calcium Chloride Hexahydrate (CaCl<sub>2</sub>.6H<sub>2</sub>O) was used in this research while the incorporation method is direct mixing into gloss paint and added into zip-lock plastic then covered by conventional cement plaster. From the data obtained, we can see the PCM incorporated wall is better in heat resistance than wall without PCM resulting difference in temperature between internal and external wall 3 ˚C rather than 1 ˚C. For the conclusion , PCM incorporated wall can decrease the internal temperature of building slightly contributing to conserving nature by reducing air conditioner system consumption.

Experimental study on the heat transfer characteristics of different walls with phase change materials in summer

The incorporation of phase change materials (PCMs) into building walls is a novel strategy for reducing heating and cooling energy consumption. The location of the PCM layer has an important influence on the non-stationary heat transfer characteristics and insulation performance of the wall. In this study, a novel experimental device was designed to test PCM and normal walls simultaneously in a two-sided artificial environment. This aimed to avoid the errors that occur when such walls are tested separately. Brick walls were constructed with a PCM layer on the outside, middle (sandwiched), or inside of the wall. One side of the wall was subject to a fluctuating air temperature to simulate summer outdoor conditions, while the other side was subjected to a constant temperature to simulate indoor air-conditioned conditions. Using sensors placed at various locations on the walls and test apparatus, characteristics such as temperature distribution and surface heat flow density were tested. The wall with the PCM layer on the outside surface exhibited the best insulation performance. Compared with ordinary wall, the maximum temperature of its inner surface was 0.2 °C lower, its surface heat flow density was 19.6% lower, its average heat transfer coefficient was 19.94% lower, and its temperature delay time was 1.33 h longer. The conclusions of this study provide a basis for determining the optimal location for PCM layers on building walls.

Design and control of radiant ceiling panels incorporating phase change materials for cooling applications

Experimental and numerical studies have demonstrated that thermally activated building systems (TABS) may lead to significant energy savings. However, TABS are generally incorporated into the building during the construction phase, limiting their adoption to new buildings. To encourage the application of TABS during building refurbishments, the authors have developed a radiant ceiling panel (RCP) with macroencapsulated phase change materials (PCM). This study aims to provide the criteria to design, size, and control the newly proposed RCP-PCM system. A simplified method to size and design the RCP-PCM system for cooling applications is developed from a set of parametric dynamic simulations. At first, the thermal storage properties of the macro-encapsulated PCM were determined using the standard ASTM C1784-20. The obtained properties were then used in a whole-building simulation model validated using measurements in a small test chamber that replicates the conditions of an actual test room. The PCM panel thickness of 0.015 m and a supply water temperature of 15 ℃ showed the best results in terms of thermal comfort and effective thermal energy storage capacity. The implementation of the simplified method in a case study showed that the RCP-PCM system maintained room conditions within the specified thermal comfort range (−0.5 < PMV < 0.5) for more than 90% of the occupied periods in all of the evaluated cooling-dominated climates. Moreover, yearly-round, the PMV values never reached values higher than 0.8 or lower than −0.6, confirming the effectiveness of the proposed method for designing a RCP-PCM system. The results show that energy savings of 22% could be obtained in a very hot and humid climate using an RCP-PCM system instead of a conventional all-air system. In conclusions, this paper offers a new system to promote energy flexibility and Demand-Side Management (DSM) strategies to modulate the energy demands in retrofitted buildings.

Numerical simulation of a phase change material in a spherical capsule with a hollow fin

The global objective of this paper is to study the incorporation of phase change materials (PCM) into passive solar construction and other applications for the storage and stability of thermal energy. The PCM used is the n-octadecane and Gallium confined in a spherical capsule with normal and hollow fins. CFD numerical simulations have been carried out to increase the heat exchange area and to compare the effect of the regular fin with hollow one at different angles. The temperature changes inside the spherical capsule on the horizontal and vertical lines for a deep understanding of the PCM behavior are also realized. The results show that the melting time is reduced 14 times in the case of PCM with hollow fin compared to a configuration without fins.

Understanding the compressive strength degradation mechanism of cement-paste incorporating phase change material

This study aims to elucidate the effect of different mixing speeds on microencapsulated phase change material (mPCM) and examine the associated degradation mechanism of compressive strength of cement-paste. Experimental results showed that moderate to high mixing speed led to the damage of mPCM particles and consequently the PCM leakage. The PCM leakage was evidenced by changes in the rheological properties of the mPCM-pastes. The early age compressive strength seemed to be more sensitive to the PCM leakage than the 28-day compressive strength. The XRD results showed no evidence of any chemical change in the mPCM-paste associated with this leakage. Therefore, the lowered compressive strength in mPCM-paste was mainly ascribed to the decrease in the heat of hydration along with a significant increase in porosity and coarsening of pore structure.

PCM-containing bi-layered alkali-activated materials: A novel and sustainable route to regulate the temperature and humidity fluctuations inside buildings

Energy demand in the construction sector has continued to grow over the past years, despite the European commitment to promote energy efficiency. The development of multifunctional materials to tackle the energy consumption and improve the thermal performance of buildings is in huge demand. Herein, we report for the first time the synthesis of a bi-layered alkali-activated composite having a highly porous top-layer and a dense bottom-layer containing varying amounts of phase change material (PCM). This novel material can regulate the temperature swings inside buildings and simultaneously buffer the humidity levels to improve the comfort for inhabitants. Results show that the PCM content controls the specimens’ mechanical and thermal performance, while the thin porous layer regulates their moisture buffer ability. A PCM incorporation of 30 wt% strongly reduces the indoor thermal fluctuation (up to 5 °C) compared to the reference cell. Additionally, this novel material showed high potential to control indoor humidity, as demonstrated by the very high practical MBV (2.71 g/m2 Δ%HR). These are promising results suggesting that these waste-derived materials can be an interesting tool towards the develop of sustainable and energy efficient buildings.

Potential of integrating PCMs in residential building envelope to reduce cooling energy consumption

Increasing energy consumption during summer periods is becoming an increasing problem worldwide, particularly in Iraq. Air-conditioning applications account for approximately half of the energy used in residential buildings. Thus, this study mainly aims to investigate the potential of using phase change material (PCM) numerically to reduce cooling energy consumption in residential buildings. Ansys Fluent software was used to study the heat transfer in the proposed geometrical model. Thermal performance, such as wall surface temperature, has been investigated. Different types of PCMs were examined to test their suitability for a selected weather data. Results show that the PCM with higher melting temperature was more efficient for locations with hot weather, such as the cities of Basra and Baghdad. The incorporation of PCM in the exterior layer of the external wall could reduce the peak interior wall surface temperature in summer and this will reduce the heat gain. As a result, the cooling energy consumption used to cool the building is reduced. The numerical results were validated with the experimental and numerical data available in the literature.

Energetic and exergetic analysis of a sloped solar still integrated with a separated heat storage system incorporating phase change material

A single slope solar still coupled with a separated heat storage system consisting of a double glazing solar collector provided with latent heat storage material(PCM) is investigated in this paper. This system is moulded for working autonomously and continuously throughout the day. A transient model is developed for assessing the performances of this device under summer climatic conditions of the Algerian Sahara. In this model, the fraction of molten PCM was assessed at each time step, which allowed inspecting the evolution of PCM material during all the time of computations.The results indicate that the additional heat storage system supplied heat to the still for 20 h continuously during the daytime. Accordingly, it is found that the increase rates of daily and nocturnal yields were respectively 63% and 635% (an increase of more than six times) compared to the conventional system. Furthermore, it is exhibited that the useful energy is strongly influenced by the increase of PCM mass, so this parameter must be lowered as possible. Also, it is shown that in the summer season; there is an optimum tilt angle of 15° Meanwhile, it is demonstrated that a great part of the irreversibility generated in the system is caused by the solar radiation and the PCM irreversibility represents only 7% of the total irreversibility. It is also revealed that the daily irreversibility decreases slightly with increasing the water mass and collector slope angle, but possesses an optimum at a PCM thickness of 6 cm.

A novel porous metal hydride tank for hydrogen energy storage and consumption assisted by PCM jackets and spiral tubes

Hydrogen energy storage through Metal Hydride (MH) reactors has various applications in concentrated solar powers and fuel cells for stationary applications in renewable energy systems. Hydrogen storage performance and consumption of these systems are strongly dependent on heat and mass transfer characteristics. Incorporating Phase Change Materials (PCMs) and spiral tube heat exchangers into metal hydride reactors improves storage performance significantly. The present paper includes a numerical investigation on the storage performance of a novel Porous Metal Hydride Tank (PMHT) integrated with PCM as a passive heat transfer system. Moreover, a heat exchanger with newly-offered Flat Spiral Tube Planes (FSTPs) is mounted into a reactor for heat transfer enhancement. The air as Heat Transfer Fluid (HTF) flows into the metal reactor through a spiral tube to enhance the heat and mass transfer. The effects of various spiral configurations, different shapes, and thicknesses of PCM jackets on the absorption/desorption process of hydrogen are investigated in detail. Also, various inlet temperatures are applied to the system to examine its impact on the absorption/desorption process. According to the results, increasing the number of FSTPs along the PMHT reduces the absorption duration by 8%. Moreover, compared with PMHT without PCM, the absorption and desorption performance of PCM-based PMHT is improved by 44% and 20%, respectively. Furthermore, increasing and decreasing the air inlet temperature leads to a 43% and 47% reduction in total desorption and absorption duration, respectively. Finally, conical-shaped PCM-jackets are found to be capable of demonstrating better absorption and desorption performances. They offer the advantage of less PCM usage to provide even a higher performance than annulus PCM-jackets. In this regard, the conical-shaped PCM provides the means for the PMHT to reach its maximum hydrogen absorption by only 85% usage of its PCM volume. In comparison, annulus-shaped PCM uses 98% of its PCM volume to help the PMHT reach its maximum hydrogen absorption capability.

Thermal efficiency analysis of buildings with phase change materials.

Increasing global temperature is alarming the need for construction industry to have thermally efficient building materials. Incorporating Phase Change Materials (PCM) in buildings is widely accepted method for reduction in temperature, thereby achieving better thermal efficiency. This paper focuses on the assessment of thermal performance of PCM-incorporated building under tropical climatic condition. The simulation process was carried out using Design Builder Software and the developed building model is validated with the results available in the literature. A parametric study is also performed in order to identify the effect of different parameters like building orientation, window to wall ratio, ceiling height and construction material on the indoor air temperature. The results showed that the maximum reduction was up to 2.76°C.&#x0D; Keywords- Thermal Efficiency, Tropical climate, PCM

Performance characterization of novel caisson-based thermal storage for ground source heat pumps

To avoid the catastrophic results of climate change, a major shift towards clean, sustainable and renewable energy technologies is inevitable. Since buildings are capable of on-site thermal energy generation and exhibiting predictive patterns of heating and cooling, many attempts are currently underway to incorporate more renewable energy (e.g., geothermal heating and cooling) systems in buildings. Subsurface geothermal resources represent a great potential for direct use of energy; put another way, the planet is a six sextillion (1021) metric ton battery that is continually being replenished by solar radiation, lightning, and heat from its deep-down molten core. Despite the enormous energy potential, geothermal systems are not adopted widely due to three main reasons: high drilling costs, energy imbalance in the ground, and lack of drilling space. To address these challenges, a novel foundation-based geothermal heat exchanger system incorporating phase change material (PCM) has been designed. The proposed technology, utilizing a foundation caisson, reduces the construction and installation costs by integrating energy and structural systems together into a single ground installation. The present study aims to characterize the thermal performance of the proposed system through a numerical model that is validated and calibrated using the experimental data generated from a demonstration site that hosts a foundation caisson. Efficacy of the use of PCM on improving the thermal performance of the system is characterized in terms of energy savings and greenhouse gas (GHG) emission reduction. Sensitivity studies demonstrate improvement in the performance of the caisson with the use of PCM with increased thermal conductivity. Also, as the seasonal heat injection to extraction ratio deviates further away from unity, the PCM helps improve the thermal performance as evidenced through reduced primary energy consumption.

Implementation of phase change materials for thermal regulation of photovoltaic thermal systems: Comprehensive analysis of design approaches

This work was focused on the investigation of various photovoltaic thermal (PVT) solar collector designs incorporating phase change materials (PVT-PCM systems) as suitable material for thermal management. In general, the PCM materials utilized in such systems were analyzed along with a discussion regarding the main thermal properties. The experimental works were covered from existing literature and related to PVT-PCM systems in various climates. The results revealed the importance of a PVT-PCM collector design concerning the overall efficiency improvement of systems. Depending on the specific design, as well as on the specific working fluid (water, air, or nanofluids), the electrical efficiency improvement was usually less than 20%, while the improvement in thermal efficiency was usually up to 70%. The electrical efficiency improvement is especially sensitive to the specific PVT-PCM collector design. The economy of the PVT-PCM system was not addressed well in the existing literature as well as its environmental evaluation. The usual payback time of the PTV-PCM systems ranged from 4 to 15 years. The conducted review indicated the necessity for more intense research investigations related to improvements in collector designs (tube geometry and layout, novel absorbers, optimization of the PCM layer) and for an integral assessment of PVT-PCM collector designs, considering performance, economic and environmental evaluations.

A Critical Review on the Control Strategies Applied to PCM-Enhanced Buildings

The incorporation of phase change materials (PCM) in buildings has the potential to enhance the thermal efficiency of buildings, reduce energy cost, shift peak load, and eventually reduce air pollution and mitigate global warming. However, the initial capital cost of PCM is still high, and thus the establishment of a control strategy has become essential to optimize its use in buildings in an effort to lower investment costs. In this paper, an extensive review has been made with regard to various control strategies applied to PCM-enhanced buildings, such as ON/OFF control, conventional control methods (classical control, optimal, adaptive, and predictive control) and intelligent controls. The advantages and disadvantages of each control strategy are evaluated. The paper further discusses the opportunities and challenges associated with the design of PCM-enhanced buildings in combination with control strategies.

Impact of phase change materials on lightened earth hygroscopic, thermal and mechanical properties

Climate change is leading construction engineers and building stakeholders to improve materials thermal insulation and heat storage capacity. The development of energy efficient building materials with a low environmental impact is a real challenge. In this sense, earth-based materials are known worldwide and have been used since thousands of years. These materials present many advantages but their deployment on a large scale, while respecting the operative standards, is still limited.Considering lightened earth, present work aims to improve their thermal properties by using phase change materials (PCM). The incorporation of PCM in construction materials has aroused great interest due to their capacity to store thermal energy.In present study, mechanical, hygrometric and thermal experimental studies were carried out on soil-fiber-PCM mixtures. The PCM incorporation showed an interesting improvement of the lightened earth thermal properties and a deterioration of the hygrometric properties while keeping their mechanical properties relatively unchanged.

Enabling high-strength cement-based materials for thermal energy storage via fly-ash cenosphere encapsulated phase change materials

The incorporation of phase change materials (PCMs) in cement-based materials opens pathways for large-scale thermal energy storage with tremendous opportunities for energy saving. However, traditional use of polymer micro-encapsulated PCMs (MEPCM) in cement-based materials lead to several well-known drawbacks (e.g., detrimental to mechanical performance, lower thermal conductivity, and high costs). In this research, a novel micro-encapsulation pathway is pursued, using fly-ash cenosphere to encapsulate PCMs for high volume use in cement-based materials. A comparative study was conducted to elucidate the effects of the cenosphere encapsulated PCMs (namely CenoPCM) and its polymer micro-encapsulated counterparts on the mechanical and thermal properties of functionalized cement-based materials. In addition, a micro-mechanics-based model was developed to predict properties of cementitious materials containing MEPCM. Property trade-off analysis shows that CenoPCM has substantial potential in the development of heat-storing cement-based materials, due to its significantly improved mechanical properties, good thermal conductivity, and much lower cost than other MEPCMs.

Mitigation of thermal curling of concrete slab using phase change material: A feasibility study

In this study, the effects of phase change material (PCM) on the thermo-mechanical behaviors of concrete pavement slabs are investigated so as to test the feasibility of utilizing PCM for mitigation of thermal curling of pavement. The PCM is elaborately stabilized in porous lightweight aggregate then loaded into concrete, without compromising strength associated with PCM incorporation. Thermal analysis indicates that the PCM introduces a latent heat capacity of about 21 J/g to the pavement slab. Two emerging fiber-optic monitoring techniques, i.e., truly distributed strain/temperature sensors and a high-resolution inclinometer, are employed to continuously monitor distributions of the temperature, strain, and tilting angle of the slabs subjected to heating and cooling, respectively. Validated by the obtained experimental results, a finite element simulation framework is established to further investigate the temperature gradient distributions, slab deformations/curvatures, and thermal strain and stress inside the slabs. The results suggest that the PCM-incorporated slab has a higher top surface temperature, a larger top-vs-bottom surface temperature difference, and thereof a larger curvature. However, the temeprature gradient reveals that heat accumulates at the upper layer before PCM melts completely, thus accounting for most of the temerpature difference. Moreover, regardless of the larger top-vs-bottom strain difference and stress nonlinearity, the linear strain of the PCM slab is smaller due to its lower coefficient of thermal expansion, and the later stage stress at the middle of the PCM slab center is smaller. Based on the findings, strategies of using PCM to control thermal curling of pavement slabs are proposed.

Thermal performance of concrete sandwich panels incorporating phase change materials: An experimental study

The employment of phase change materials (PCMs) in the construction of concrete building components has engaged many researchers’ interest. In this study, a novel reduced-scale experiment is employed to perform a parametric investigation of the thermal performance of PCM-integrated wall specimens considering two types of concrete, two types of PCM, and different thicknesses of the concrete and PCM layers. Moreover, three different ambient temperature profiles of a summer day in three different cities were considered as the outside ambient temperature to evaluate the performance of each PCM under different temperature conditions. The test procedure is capable of evaluating the thermal performance of different wall configurations under various temperature conditions. The inside temperature variations of the wall specimens were monitored as the thermal performance criteria. In consequence, integrating the PCM layer with normal concrete or with slimmer concrete layers resulted in better thermal performance of PCM in absorbing heat in comparison to lightweight concrete or thicker specimens due to the considerable effect of density and specific heat capacity of different types of concrete. Moreover, the compatibility of the melting temperature of PCMs with the ambient temperature of the considered cities in summer is assessed and discussed.

Effect of scale-up on the properties of PCM-impregnated tiles containing glass scraps

In the latest years, the interest about Phase Change Materials (PCM) in building applications grew in force of their capability to adsorb heat and limit in-out building heat exchanges. The main problem is how to introduce PCM into the building envelope, also in case of ventilated façades. For this purpose, a ceramic foam was studied. Two different batches based on porcelain stoneware and soda-lime glass scraps were prepared to understand the involved bloating phenomena. Suitable bulk density and porous microstructure were achieved by adding a foaming agent and batch optimization. Specimen size was scaled up (from ∅ 3 cm to 15 × 15 cm) and its effect on bloating, PCM incorporation, and thermal properties was studied. Furthermore, different firing temperatures and heating rates were evaluated. The whole study was focused to disclose possible drawbacks in the industrial transfer of the PCM-bearing composite production.

Novel composite phase change materials based on hollow carbon nanospheres supporting fatty amines with high light-to-thermal transition efficiency

The construction of high-performance materials with superior light-to-thermal conversion efficiency is of great importance for harvesting and utilization of solar energy. Hence, we report the creation of novel composite phase change materials (CPCMs) CPCMs by incorporating three kinds of organic phase change materials (PCMs), i.e. 1-Tetradecylamine (TDA), 1-hexadecanamine (HDA) and Octadecylamine (ODA), into hollow carbon nanospheres (HCNS) via a simple impregnation treatment for efficient light-to-thermal transition. Owing to their carbon in nature, the HCNS show better light absorption of higher than 90%. After incorporation of organic PCMs, their light absorption could still attain 62–70%, which can compete with the existing CPCMs. Beneficial from their abundant porosity and high specific surface areas, organic PCMs can be spontaneously diffused and immersed into the porous architecture of HCNS. In this way, the as-resulted CPCMs containing with TDA, HDA and ODA show high phase change enthalpy of 61.23J/g, 119.5J/g and 101.8J/g, respectively. The CPCMs also exhibit better thermal conductivity and excellent thermal stability, e.g., the enthalpy of HAD based CPCMs remains nearly unchanged even after 100 times of melting/freezing cycles. Under 1 sun irradiation, the light-to-thermal conversion efficiency of CPCMs containing with TDA, HDA and ODA were measured to be 73.04%, 74.46% and 71.74%, respectively, Thus showing great potential as a kind of promising photothermal conversion devices for solar or thermal energy storage applications.

Thermoeconomic analysis of a wall incorporating phase change material in a rural residence located in northeast China

In this work, the influence of PCM wall utilization on the heating energy consumption of a typical northeastern Chinese rural house is numerically investigated by EnergyPlus, together with its economic and environmental impacts on carbon emissions. Simulations are conducted considering three different configurations of the PCM layer and other building materials inside the wall by taking the wall without PCM as the reference case. Furthermore, three wall directions, namely north, south and west, for the installation of PCM and eight different phase transition temperatures (Tm) are considered in order to evaluate the situation in different aspects. In the second part of the study, the cost-saving, payback period and reduction of carbon emissions by PCM utilization are discussed. The computed results revealed that the orientation of PCM close to the inner surface inside the wall saves 12.9% of energy during the heating period, while improper configuration slightly increases energy consumption. Besides, the PCM with Tm = 16 °C for the indoor temperature set to 18 °C results in the highest energy saving, while the PCM with Tm = 26 °C has the lowest payback period (1.8 year). Carbon emissions are reduced by 52.7 kg/m2 by using the most suitable PCM wall, throughout its lifetime.