Integration Of Phase Change Materials Research Articles

Energy analysis of evacuated tube solar collector integrating phase change material in northeast China

Evacuated tube solar collectors (ETSCs) are one of the most popular collector types with regard to solar energy utilization. However, the poor energy performance of ETSCs results in equal timeliness with solar energy. Incorporating phase change material (PCM) into ETSCs is regarded as a novel strategy to alleviate the challenge by means of enhancing their thermal energy storage capacity and improving energy performance. Since thermophysical parameters of PCM have a vital influence on energy performance of ETSCs, the present work aims to identify the effects of density, specific heat capacity, latent heat, thermal conductivity, and melting temperature of PCM on energy performance of ETSCs. The findings exhibit that increasing the density, specific heat capacity and melting temperature of PCM, the peak outlet temperature of heat transfer fluid and effective heat collection of ETSCs containing PCM decreases, while temperature time lag and effective heat collection time increases. Compared with ETSCs containing PCM with density of 425 kg/m3, the effective heat collection time is prolonged up to 44.41 % for the scheme with PCM density of 1700 kg/m3. Utilization of PCM with higher melting temperature is beneficial to enhance energy performance of ETSCs, which the maximum effective heat collection is increased by 4.31 % for ETSCs containing PCM with melting temperature of 333–335 K. However, increasing the values beyond 1700 kg/m3, 1 W/(m·K), 4000 J/(kg·K) and 247,500 J/kg in cold regions of northeast China are not beneficial.

Thermal energy storage enhancement of a forced circulation solar water heater’s vertical tank unit using phase change material

This work aims to investigate the thermodynamic effect of phase change material integration within vertical storage tanks that are connected to forced circulation solar water heaters, on their thermal energy storage capability. The phase change material is encapsulated in cylindrical and elliptical capsules, which are integrated at the bottom, middle and top sections of the tank. Hence, three parametric studies were carried out depending on the geometry of the encapsulation, besides to their integration position inside the tank, through computational fluid dynamic calculations. The numerical model was established under “OpenFOAM” and the enthalpy-porosity method for the phase change phenomena modeling was validated against the experimental data of the literature. For this purpose, the following thermal performance indicators were used: temperature, liquid fraction contours and the tank’s energy storage efficiency. It was found that the time required for a complete melting of the phase change material inside the cylindrical capsules is higher than that of the elliptical ones (beyond 17.50 s), for a fixed integrating location. Otherwise, 21, 23 and 17.50 s were necessary for the melting of the phase change material filling the vertical ellipse (top configuration), horizontal ellipse (bottom configuration) and cylindrical cavity (middle configuration) respectively. In addition, results showed that the shapes of phase change materials affect the thermal storage efficiency. For example, 25, 28 and more than 40 s were sufficient to reach 100% of the vertical tank’s storage efficiency for the following top configurations: vertical ellipse, horizontal ellipse and cylindrical cavity, respectively. Finally yet importantly, integrating the phase change materials at the middle section of the tank can be considered as the optimal configuration, because it allows a gain of 2 °C compared to the bottom and top zones.

Performance Optimization of a Simulation Study on Phase Change Material for Photovoltaic Thermal

The integration of Phase Change Material (PCM) with the Solar Photovoltaic Thermal (PVT) serves as heat storage to enhance the system's performance. Temperature rises have an undesirable effect on efficiency results in a diminishment in the amount of energy produced by the solar panel. Parametric analysis and temperature investigation are involved in improving the performance of the system. The variation of performance will assist in developing an optimized PVT-PCM system. The model is validated by comparison from published journals on the studies related to phase change material implemented in solar PVT. For the variation of mass flow rate, the overall efficiencies achieved by 10 kg/h, 30 kg/h, 50 kg/h and 70 kg/h are 90.82%, 90.54%, 90.48% and 90.46%, respectively. In addition, solar irradiance of 200 W/m2, 450 W/m2 and 800 W/m2 produced 91.17%, 90.82% and 90.33% of overall efficiencies. Increased in flow rate requires stronger pumps which increase the total cost of the system. Therefore, identifying the optimal flow rate might help to achieve an appropriate thermal efficiency while sustaining in low costs. Finally, this paper presented a numerical investigation of PCM acts as promising elements incorporated in the PVT system that has the capability to reduce the temperature of the PVT-PCM system.

Passive control and stability of the indoor temperature of a closed cavity based on the process of integrating phase change materials

Passive control and stability of the indoor temperature of a closed cavity based on the process of integrating phase change materials

A hybrid photovoltaic and water/air based thermal(PVT) solar energy collector with integrated PCM for building application

Based on the different requirements of solar energy integrated with buildings, a hybrid photovoltaic and thermal solar energy collector with integrated phase change material (PVT-PCM) have been developed. The thermal system combines air-based and water-based conditions to meet the building heat demand in different seasons. In addition, PCM is used to absorb the heat that was not taken away by the thermal system. And the vessel is optimized to enhance its thermal conductivity. The results of cross-season test show that the overall efficiency of the system is 39.4%, and the energy-saving efficiency is 64.2%. The system controls the temperature and utilizes the heat through the thermal system. The economic analysis and energy saving potential of the system in low latitude areas are analyzed. The results show that the additional payback period of the system is 13.1 years. And based on the local energy structure, the maximum CO2 emission can be reduced by 156.1 kg/year. The optimization systems BPVT and CPVT are proposed, and simulation and analysis results show that BPVT is more valuable for further exploration. Compared with the traditional PV system, PVT-PCM system improved the comprehensive utilization rate of solar energy and has a broader research and development prospect.

An innovative thermal protective clothing system for firefighters

Nowadays, despite the evolution of personal protective equipment (PPE), the number of firefighters injured and burned during fire extinguishing operations is still very high, leading in some cases to loss of life. Therefore, the research and development of new solutions to minimize firefighters’ heat load and skin burns, with consecutive improvements of commercial firefighters’ suits, is of extreme importance. The integration of phase change materials (PCMs) in a protective clothing system has been used to significantly reduce the incoming heat flux from the fire environment. This study consists in the development of a protective clothing system composed by a vest, specially designed to protect the torso (back, chest and abdomen) with a layer of PCM pouches, to be worn over a fire-resistant jacket – selection and design based on numerical models’ predictions. Therefore, several mockups were made, varying the number of PCM pouches and their distribution in the vest, allowing the creation of air ducts to increase the breathability of the vest. The most promising solutions are being evaluated in a real controlled environment, at a Portuguese National School of Firefighters (ENB) simulation site, using a fire manikin and thermocouples to monitor vest temperature during heat and flame exposure, and consequently to verify PCMs influence in heat protection. Results regarding the development of a PCM vest will be presented, focusing on the integration of PCM pouches and the thermal performance of the most promising solutions.

Phase change material based thermal energy storage applications for air conditioning: Review

• Application of PCM TES for indoor environment control is presented. • From assessments made, 5% energy savings can be achieved by using PCM TES. • PCMs integration in AC unit enhance its coefficient of performance by ∼ 1.8% least. • Optimized PCM TES units can reduce CO 2 emissions by 30%. Phase change material thermal energy storage is a potent solution for energy savings in air conditioning applications. Wherefore thermal comfort is an essential aspect of the human life, air conditioning energy usages have soared significantly due to extreme climates, population growth and rising of living standards. Resultantly research efforts have shown increasing innovation towards the integration of phase change material based thermal energy storage technology with space heating/cooling systems to achieve significant savings. The review therefore focuses on the previous published experimental and theoretical works to organize these important milestones, analyze energy saving avenues as well as giving highlights on best practices and widely accepted techniques and recommendations for all reviewed studies to achieve cost cutting but accurate results. It also discusses the useful enhancements that can be implemented for optimum performance of the PCMs. The reviewed potential benefits of PCMs integration in air conditioning units include enhancements in the coefficient of performance by ∼1.8% at minimum, at least 5% energy savings and estimated reduction of CO 2 emissions by about 30%.

Phase-change materials for thermal management of electronic devices

The increase in power density of electronic devices, driven by the higher performance and miniaturization demands, has led researchers seek new and alternative thermal management techniques. Since most of the electronic devices often experience high frequency power cycles, cooling systems must also be capable of managing transient thermal profiles to delay the temperature response and reduce the temperature gradients within the device, which can cause thermal stresses and, in the long run, the failure of the electronic device. The integration of Phase-Change Materials (PCM) into heat sinks for electronic devices represents an interesting technique to increase the thermal inertia of the cooling system, while also ensuring more stable operating temperatures within the electronic components. However, several technical challenges still limit their commercial viability in electronic applications. The present paper critically discusses the latest research trends in this field, with a special focus on electric batteries, power electronic and portable device applications. Methods to enhance PCM-based heat sinks for electronic devices are also discussed. Generally, integrating PCMs into the thermal management system of electronic devices is an effective technique to reduce hot spots (between 6%–10%) and have a more uniform temperature distribution inside the component. However, more experimental research is needed to test their suitability over extended usage period and to establish practical design procedures. • Integration of PCMs in electronic devices can reduce temperature hot spots by 6%–10%. • PCMs are effective for the thermal management of EV batteries. • Microencapsulated PCM thin-film layers can be integrated in portable devices. • The use of porous media and metal foams can enhance the performance. • More experiments are needed to fully characterize PCMs in electronic applications.

Measuring the maximum capacity and thermal resistances in phase-change thermal storage devices

Thermal energy storage can increase the efficiency of the electric grid by adding flexibility to thermal systems. The value of thermal storage is a function of its energy and power density, which are driven by the capacity and thermal resistances in the storage device. Measuring these properties in-situ at the device level is an important step to understanding the performance and improving the design of thermal storage systems. In this paper, we present methods to measure the total capacity and thermal resistances in heat exchangers with integrated phase change materials. These methods are demonstrated on two thermal storage devices—a 570-kWh ice-based storage tank and a 0.35-kWh graphite-tetradecane composite device. The results show how thermal resistances evolve with the state of charge and discharge rate in these devices and quantify the impact of applied pressure on the contact resistance in composite phase change material heat exchangers. The proposed method allows for easy comparison between different systems and provides information on the thermal bottlenecks limiting performance. Ultimately, these measurements will allow designers to make robust, high-performance thermal storage devices for next-generation thermal systems.

Three-dimensional and high-resolution building energy simulation applied to phase change materials in a passive solar room

Phase change materials (PCMs) reduce energy consumption and improve indoor thermal comfort in buildings. Various numerical models have been developed to evaluate the thermal performance of the PCMs integrated into building enclosures. To remain computationally efficient, these models typically adopt a trade-off between the ability to investigate complex and realistic configurations and the prediction accuracy of the heat transfer associated with the phase change. This study developed a model to simulate a room with three-dimensional heat conduction in PCM-integrated walls and to analyze the surface heat balances with high resolution. The model was validated using experimental data of a passive solar test cell with a non-uniform and dynamic thermal environment. The model was then applied to investigate the PCMs integrated into the test cell during the summer. The PCM with a narrow phase change temperature range and a thickness of approximately 10mm was highly effective in reducing the indoor temperature fluctuations; the peak surface temperature was reduced by up to 6°C in the sun patch, and the operative temperature fluctuations decreased by up to 2.6°C. The PCM integration could be limited to the sun patch trajectory on the wall surfaces to optimize its utilization and limit the installation cost.

Integration of PCM as an external wall layer in reducing excessive heat of building walls

Innovative building approaches, which take advantage of heat energy in buildings, have recently appeared as part of a global effort to save energy. Incorporating phase change material (PCM) into the building envelope helps in reducing energy consumption and regulating energy demand by managing the thermal inertia of designed PCM thermal characteristics. A study was conducted to assess the performance benefits provided by the latent heat of the concrete wall combined with PCM. This study focuses on developing and testing heat barrier performance by incorporating PCM into wall external finishing, i.e. cement plaster and gloss paint. The effect of PCM inclusion in building wall were investigated by experimental work. The results indicate that incorporating PCM into the building wall reduced the surface temperature by up to 9 °C. Furthermore, the application of the PCM in the plaster layer is more reliable in reducing the internal wall surface temperature by a value of 8.1 °C when compared to the PCM in a painted coating. Painted wall panels experienced more significant temperature reduction differences than other wall panels, i.e. 9.2 °C and 9.5 °C, respectively. However, painted wall panels experienced higher internal surface temperatures than external surface temperatures compared to plastered wall panel at night. This could be due to the paint reactions, which are ineffective at releasing internal heat from the building at night. The yearly energy demand is decreased by 64.3% by incorporating PCM to the building wall, with a total annual electricity bill savings of 42.3% (8695.8 kWh yr−1). Therefore, it was concluded that wrapped PCM integrated into plaster layers on external surface building walls could decrease the indoor building temperature and thus contribute to conserving the energy required for an air conditioning system.

Impact of building integrated photovoltaic-phase change material panels on building energy efficiency improvement: a case study

ABSTRACT Integrating phase change material with building envelopes is recently considered one of the most reliable passive solutions to mitigate indoor temperature fluctuations, improving therefore indoor comfort. In addition, the integration of photovoltaics to combat the gradual increase in energy consumption is highly increasing to meet the growing demand for energy. Using phase change material to improve thermal and electrical performances of building integrated photovoltaic systems and to reduce incoming heat energy indoors, simultaneously, were performed. Interestingly, it is highly recommended to integrate the building integrated photovoltaic phase change material systems on inclined roofs in order to perform the phase change material as preferred through a cyclic process. The peak temperature of the inclined and vertical building integrated photovoltaic systems decreased from 70.5°C and 41°C to 41.4°C and 31°C, respectively. Hence, a drop in average indoor daytime temperature where the peak indoor temperature has been reduced to about 4.5°C. The inclined and vertical building integrated photovoltaic systems’ DC power output, at midday, has been increased from 74.5 W to 108.5 W and 37.5 W to 38.5 W. Eventually, the use of phase change material decreased the thermal load leveling by 7%, 2% and 1.5% during the first three days, respectively, After the third day, the decrease of the thermal load leveling remained constant at 3%. Consequently, findings reveal that using phase change material could be an excellent solution to decrease indoor air temperature fluctuation and can bring higher temperature drops.

Energy, economic and environmental impact analysis of phase change materials for cold chain transportation in Malaysia

The tropical climate of Malaysia presents higher environmental temperatures ranging from 27 to 31 °C and refrigerated semi-trailer trucks are utilized in cold chain transportation which is subjected to high thermal stresses and leads to elevated refrigeration load requirements. This subsequently causes a surge in diesel fuel consumption by the auxiliary refrigeration unit and greenhouse gas emissions into the atmosphere. To address the issue, this research evaluates the integration of phase change material (PCM) in refrigerated vehicle walls for latent heat storage purposes, which consequently reduces refrigeration load. Reference cases without PCM and 10 different PCM cases of commercially available organic-based paraffin PCM are investigated, whereby the conventional insulation method of a refrigerated semi-trailer is modified by adding a layer of PCM within its envelope, to simulate refrigeration loads during an 8-hour vehicle operational period. The PCMs are assessed based on their physicochemical properties, and performance in energy savings, economic, and environmental benefits. Results show that daily refrigeration loads can be reduced up to 34.4 % upon PCM integration in refrigerated vehicle walls, and besides, economically, the solution is highly profitable with a benefit-cost ratio above 1. The highest performing PCMs in terms of energy savings yield short payback periods of <3 years, which are at least 2.6 times lesser than the vehicle's lifetime, whilst providing greenhouse gas emission savings of above 2700 kgCO2/year. This research indeed serves as a starting point to explore the large-scale usage of PCMs in cold chain transportation in Malaysia.

Design of MoS2/MMT bi-layered aerogels integrated with phase change materials for sustained and efficient solar desalination

Solar desalination is a promising technology which can produce drinkable water from seawater or wastewater driven by solar energy. However, the intermittency of the sun restricts the evaporation rate and freshwater output yield. Here, in order to promote solar energy utilization efficiency and freshwater yield, phase change materials used as solar thermal energy storing materials are introduced into the solar evaporators. The designed solar evaporator has a double layer aerogel structure, in which the bottom layer is constructed by montmorillonite (MMT) aerogel with a function of water supply and thermal insulation. At the same time, the upper layer aerogel, which are constructed by MoS2 and paraffin@SiO2 phase change microcapsules, plays the role of solar energy harvesting, storage and solar steam generation. In this strategy, the phase change microcapsules with a latent heat of 177.85 J/g enables the solar evaporator to store solar thermal energy during illumination, and to release heat for continuous seawater desalination when there is no sunlight. Results show that MoS2/MMT solar evaporator achieves a water evaporation rate of 1.32 kg·m−2·h−1 and an evaporation efficiency of 86.22 % at a light intensity of 1 kW·m−2. When there is no sunlight, the evaporation rate and evaporation efficiency are still as high as 0.71 kg·m−2·h−1 and 44.36 % even after 20 min running, which greatly promotes the solar energy utilization efficiency and freshwater yield. In addition, the solar evaporator can produce high-quality fresh water with 99.9 % salt ions removal. Through the integration of phase change materials, the solar evaporator enables sustained and efficient solar desalination regardless of solar intermittency, resulting to great promising future in the large-scale freshwater production.

Short recent summary review on evolving phase change material encapsulation techniques for building applications

As the world deviates towards sustainability in buildings due to massive increase in energy demand, the effective integration of Phase Change Material (PCM) in buildings gained substantial attention. The capability of PCM in enhancing the thermal performance of buildings relies heavily on the encapsulation technique used as it is in direct link with enhancement techniques required for upgrading thermo-physical, chemical and environmental PCM properties. The current study reviews shortly recent literature involving PCM integration in buildings and highlights different encapsulation techniques used for their proper active and passive incorporation. It also summarizes recent methodologies of properties enhancements prior to encapsulation. Preliminary results reflect the importance of proper encapsulation using the five distinct techniques: direct mixing, imbibing, shape-stabilization, macro-encapsulation and micro-encapsulation. Commercialization of macro-encapsulated PCMs is dominant over other techniques, where micro/nano-encapsulation technique is still limited and requires further study being the most promising.

Energy, environmental, and economic analysis of different buildings envelope integrated with phase change materials in different climates

Several technologies were been developed to store the solar energy for different applications especially in the construction sector. Integrating phase change materials (PCM) into building is one of the effective solutions for energy efficiency.This paper aims to evaluate the optimal envelope type and climatic zone able to improve the performance of buildings using PCM. A numerical simulation was conducted using the difference finite method by Energy plus, in three climates of North Africa; Mediterranean, arid and sub-arid climate, concerning four different building envelopes (brick, concrete block, reinforced concrete and earth) to analyze the energy, economic and environmental impact.The maximum values of energy saving rate is found in the arid and sub-arid climate, with the highest value of 10.5 % for earth envelope, and the lowest value of 2.57 % for concrete block envelope in Mediterranean climate. The use of PCM is more efficient for cooling in arid climate for the different considered envelopes with a maximum of cooling energy reduction of 7.3%, and its use in the sub-arid climate and the Mediterranean one is more efficient for heating with a maximum value of 10.7% in the earth envelope.The environmental and economic analysis shows that the use of PCM in optimal conditions can reduce 10 % of energy cost and 707 kg/year of CO2 emissions. Furthermore the payback period obtained varied between 7 and 43 years with an average of 23 years.Conclusively, the use of PCM for thermal energy storage in buildings still a good solution for energy performance.

Energy performance enhancement of residential buildings in Pakistan by integrating phase change materials in building envelopes

The residential sector of Pakistan is a prime consumer of energy. With the fossil fuel-dependent energy generation setup and an increasing energy supply–demand gap, Pakistan is headed towards an energy fiasco. Therefore, drastic measures are required to enhance the energy efficiency of residential buildings in Pakistan. The current study is aimed to numerically investigate the energy performance enhancement of residential buildings by integrating Phase Change Materials (PCM) in the building envelopes of five major cities of Pakistan having different climates. The numerical computations are carried out in open-source building-simulation software, EnergyPlus. Initially, fifteen suitable PCMs are evaluated for a single-room base case house. CrodaTherm24 having a melting temperature of 24 °C with a thickness of 40 mm is found to be the optimum PCM choice when it is placed on the inner sides of building envelopes. It is then integrated into typical single-Storey and two-Storey multi-zone residential buildings. For a single-Storey building, the average monthly energy saving of 44.9% is achieved in Islamabad, 35% in Karachi, 32% in Lahore, 35% in Peshawar, and 49.6% in Quetta while for two-Storey buildings the average monthly energy saving of 12%, 21.4%, 15.5%, 12.9%, and 13.5% are achieved, respectively. The economic feasibility of implementing PCM in building envelopes is evaluated through static and dynamic payback period calculations. The usage of PCM for energy efficiency enhancements of residential buildings is found to be economically feasible for Lahore, Karachi, and Peshawar whereas, it is unsuitable for Islamabad and Quetta.

Effectiveness of phase change material in improving the summer thermal performance of an office building under future climate conditions: An investigation study for the Moroccan Mediterranean climate zone

The rise in global temperature due to the climate change phenomenon would increase the severity of summer season in the future. The integration of phase change materials (PCM) into the building envelope has been considered as one of the most promising measures to improve the thermal performance of buildings. This paper aims at investigating the effectiveness of the PCM in improving summer thermal performance of buildings under the climate conditions of the next three decades. The moderate scenario RCP4.5 of the Intergovernmental Panel on Climate Change was used to simulate future climate conditions. The present study was conducted for two building case studies: free-running and air-conditioned office buildings located in the north of Morocco (Mediterranean climate with hot summer). The findings have disclosed that an appropriate selection of the PCM melting temperature could enhance the thermal performance by 9.87 % for the free-running building and by 20.5 % for the air-conditioned building case over the whole building lifespan (30 years). A decade-by-decade analysis showed that the effectiveness of the optimum selected PCM would slightly decline over time. The research involved an economic analysis of the air-conditioned building case study. The latter led to calculating the maximum allowable cost of the PCM installation to achieve a payback period within the lifespan of the building. The findings of the present work can be used as guidelines to design office buildings integrated with PCM in the Mediterranean region.

Design and Performance Evaluation of Thermoelectric Cooling System Integrated with PCM (Phase Change Material)

A thermoelectric system integrated with PCM (Phase Change material) for cooling vaccines has been introduced, thermal management techniques (i) using high performance heat sink on sides(hot, cold) of module (ii) integration of PCM (ice) on cold side were analysed. Experimental results infers that, by adopting water cooled heat sinks at hot side and air cooling at cold side of module, a COP of 0.124 with minimum cooling temperature (Tc) of 6°C (at 130 minutes) is attained by the system. Performance simulations were carried with CFD (computational fluid dynamics) model of system for different heat sink configurations (with or without integration of PCM). Simulation results shows that, (i) in the absence of PCM, a COP of 0.261 and 0.245 is achieved by the system for heat sink configuration of fin and fan on both sides, fin and fan on hot side and fan on cold side respectively, (ii) COP is improved to 0.406 with integration of PCM and is 55.55% higher, considering the same heat sink configuration (fin and fan on both sides), with cooling temperature of 4°C.

Hierarchically nanostructured Co(OH)2/MXene/SiO2/n-docosane phase-change composites for enhancement of supercapacitor performance under in-situ thermal management

Electrochemical energy-storage devices usually suffer from performance deterioration at high operating temperatures due to exothermic redox reactions during the cyclic charge–discharge process. Aiming at addressing this crucial issue, we have developed a novel type of thermoregulatory electrode material based on the hierarchically nanostructured Co(OH)2/MXene/SiO2/n-docosane phase-change composite for enhancing electrochemical energy-storage performance of supercapacitors through in-situ thermal management. The resultant composite shows a regular spherical morphology and a layer-by-layer core-shell microstructure for the phase-change microcapsules anchored on MXene nanosheets, together with a well-defined nanostructured Co(OH)2 layer deposited on the surfaces of the microcapsules and nanosheets. Through a multilevel integration of phase change material (PCM) and electroactive materials in an electrode material, the microenvironmental temperature surrounding the working electrode can be regulated effectively, buffering the heat impact to supercapacitors at high temperature. The phase-change composite achieved a satisfactory latent heat capacity of over 130 J/g together with good thermal cycling stability for long-term use in thermal management of supercapacitors. Compared to conventional electrode material without a PCM, the thermoregulatory electrode material developed in the current work exhibits an increase in specific capacitance by 6.6% at 45 °C and in capacitance retention by 10.8% after 3000 charge-discharge cycles at 45 °C, suggesting better electrochemical energy storage performance and higher charge-discharge cycling stability at high operating temperature thanks to its in-situ thermal management effectiveness. This study provides a promising approach to developing high-performance electrode materials for supercapacitor application over a broad temperature range.