Phase Change Material Wallboard Research Articles

Experimental investigation on heating performance of long- and short-term PCM storage in Chinese solar greenhouse

Phase change material (PCM) board on north wall of the greenhouses can absorb and store solar heat during the daytime, then releases it at night to provide the thermal environment for crop growth. However, its capability to regulate the greenhouse temperatures in severe winter is limited, necessitating an additional heat source. The heat gap within the greenhouse can be replenished flexibly and promptly by controllable triggering of supercooled salt hydrate for long-term heat storage. This study proposed a synergetic energy storage and release system, combining the short-term storage and passive release of the PCM wallboard with the long-term storage and active triggering solidification of the supercooled salt hydrate in separate storage unit. The temperature regulation effect of this synergetic system was experimentally investigated in a test Chinese greenhouse. The results showed that the combination of the PCM north wallboard with the supercooled salt hydrate storage unit reduced the daytime average temperature by 2.0 °C ~ 3.8 °C compared with the control greenhouse. In sunny days, the PCM north wallboard could meet the nighttime heat demand of the greenhouse with the average temperature rise of 5.2 °C ~ 6.7 °C. In severe weather, by triggering supercooled sodium acetate trihydrate (SAT, CH3COONa·3H2O, Tm = 58.0 °C) at late night, the temperature rose by 5.3 °C in 1 h, effectively heating for 5 h. While supercooled sodium thiosulfate pentahydrate (STP, Na2S2O3·5H2O, Tm = 48.5 °C) was triggered, the temperature rose by 3.3 °C in 1 h, effectively heating for 4 h. Furthermore, the synergetic system was still effective for greenhouses under ventilation and irrigation conditions during the day. This study provides guidance for the development of synergetic PCM systems with long- and short-term solar thermal storage and release for greenhouse heating.

Novel modular PCM wall board for building heating energy efficiency: Material preparation, manufacture and dynamic thermal testing

With the comprehensive implementation of China’s “dual carbon” goals, the building heating sector, characterized by high energy consumption and emissions, urgently requires low-carbon transformation. However, energy-saving measures for plateau regions are scarce and face challenges due to harsh climates. This study proposes an innovative heating method utilizing composite phase change materials. A new modular phase change thermal storage electric heating terminal integrated with a photovoltaic thermal system has been designed to address issues of high building energy consumption and problems related to heating system freezing and leakage in the Tibetan Plateau (Qinghai-Xizang Plateau). Laboratory tests were conducted on six groups of samples with different structures and placements to examine their heat storage and release characteristics. Results indicate: The system’s temperature stabilization time totals 14.6 h; Horizontally placing the terminal reduces melting time by up to 2.7 h, enhancing heat storage performance; Structure three shortens solidification time by up to 2.2 h compared to structure one, improving heat release performance; Vertically placed terminals have better heat release performance than horizontally placed ones, resulting in more effective indoor heating. This study proposes a modular design for phase change heat storage electric heating walls, simplifying installation and maintenance while maintaining aesthetic appeal. Detailed temperature measurements of different wall surfaces revealed excellent cyclic heat storage and release performance. The developed phase change heat storage electric heating terminal is expected to significantly reduce heating energy consumption in the Tibetan Plateau (Qinghai-Xizang Plateau), enhancing building energy efficiency and providing valuable insights for further applications of phase change materials in building design.

A numerical study on summer operation performance of PCM wallboard cooling tower coupling system in hot-summer and cold-winter regions of China

The use of phase change materials in building envelopes shows promise in reducing overall building energy consumption. Researchers are focusing on designing optimal wall structures based on varying climate characteristics to enhance building energy efficiency. This study presents a novel system that couples phase change material wallboard with cooling tower. In the summer months, the system efficiently utilizes cooling water to dissipate heat stored in the phase change material during the day, thereby maximizing the utilization of the phase change material. The research includes the design and optimization of a southward prefabricated phase change material wallboard and evaluates the long-term performance of the phase change material wallboard cooling tower coupling system through a validated numerical model. The optimization findings indicate that the system achieves maximum energy savings with a cooling water flow velocity of 0.0125 m/s. Moreover, double-level control shows a substantial improvement in system performance compared to single-level control. Long-term operation results demonstrate that the phase change material wallboard cooling tower coupling system effectively reduces indoor heat gain during summer, with a cumulative indoor heat gain of −16.29 kWh/m2, representing a 343.5 % reduction compared to the common wallboard. The system has the potential to significantly decrease power consumption in air-conditioning systems, particularly in regions with hot summers and cold winters.

Performance analysis of a novel phase-change wall of wood structure coupled with sky-radiation cooling

The integration of phase-change materials (PCM) into building enclosures can effectively improve the thermal performance of buildings. In this study, a novel phase-change wall of a wood structure with embedded capillaries that can utilize sky-radiation cooling is proposed to reduce energy consumption. The performance of the proposed wall was experimentally investigated and compared to that of an ordinary wood-structured wall under summer conditions. The results show that the proposed wall can significantly reduce the internal temperature of the wallboard and indoor air temperature. Compared with a traditional room with ordinary wood structure walls, the room using the PCM wallboard results in a more stable temperature fluctuation. Furthermore, the load from the east-oriented wall was reduced by 15.63%, the optimum decrement factor was 0.44, and the intensity of thermal discomfort was reduced in all directions. Therefore, the proposed wall has great application potential for reducing energy consumption and improving thermal comfort.

Numerical investigation on thermal performance of a solar greenhouse with synergetic energy release of short- and long-term PCM storage

To address the problem of low greenhouse temperature at late night in north China, a new strategy of synergetic release of short- and long-term PCM heat storage is proposed in this paper, i.e. supercooled salt hydrate units are activated to release seasonally stored latent heat after the organic PCM north wallboard with daily storage cannot provide the required indoor temperature. To achieve this strategy, a microclimate model considering multiple greenhouse elements, including solar radiation, crops, indoor air, water vapor, soil and PCMs, is developed and 3D computational fluid dynamic (CFD) simulations are employed to examine the thermal performances of this strategy under Beijing climate conditions. The results demonstrated that the new strategy promotes the greenhouse temperature suitable for tomato growth (15 °C) throughout the whole night in winter. The organic PCM (Tm = 25 °C) wallboard can reduce the daytime indoor temperature by 0.5–1.5 °C and increase the nighttime indoor temperature by 4–5.5 °C than without PCM wallboard on January 1st. But the greenhouse temperature with this single daily storage is still lower than the required 15 °C after 4:00 a.m. With consideration of the unit numbers and heating effects, triggering two supercooled sodium thiosulfate pentahydrate (STP) units at one time (rather than sodium acetate trihydrate (SAT) and calcium chloride hexahydrate (CCH)) is the reasonable choice for greenhouse heating under present conditions. The system can achieve synergetic energy release across seasons, days and nights, regulate the thermal environment in the greenhouse, and promote the quantity and quality of crop output.

Impact of Positioning Phase Change Materials on Thermal Performance of Buildings in Cold Climates

The building envelope, an essential component of any building, plays a critical role in meeting energy efficiency and thermal comfort requirements. Incorporating phase change materials (PCM) into the building envelope can offer an opportunity to minimize energy usage and enhance thermal comfort by offsetting daily temperature fluctuations. However, the optimal performance of PCM is contingent on the material’s placement and thickness within the building envelope. Therefore, this study investigated the effects of positioning and thickness of PCM on thermal comfort and heating loads in a lightweight timber building in Trondheim, Norway. Four scenarios were considered based on the positioning of the PCM layer in the exterior wall and roof. Using IDA ICE, parametric simulations were conducted for various PCM wallboard positions and thicknesses in the exterior wall and roof. In Nordic climates, adding PCM reduces the risk of annual overheating. The findings of this study showed that installing 75mm of PCM wallboard in the exterior wall’s inner layer reduced the annual heating load by 2.3%. Compared to the base case scenario, increasing PCM thickness reduced zonal maximum indoor air temperatures by up to 6.2°C. This study underscored the importance of carefully considering the placement and thickness of PCM in building envelopes for optimal performance.

Preferred method and performance evaluation of heterogeneous composite phase change material (CPCM) wallboard in different seasons

The application of phase change materials (PCMs) in building envelopes has been developed in past decades and many strategies have been adopted to improve the heat resistance and capacity performance. However, rare studies focused on optimizing these characteristics of PCM wallboard in different seasons and providing preferred method for selecting the optimal PCMs. This study constructed a heterogeneous wall acting in different seasons and developed a pre-screening method of PCMs based on the analytic hierarchy process. CA-HD/EG with higher thermal conductivity (2.16 W/(m·K)) and lower melting point (25.4 °C) acted as the inner layer, and paraffin/porous silica with lower thermal conductivity (0.37 W/(m·K)) and higher melting point (29.3 °C) acted as the outer layer. Two experimental boxes were built to compare the thermal performance of CPCM and gypsum wallboard. The decrement factor in winter increased by 6.7 %, and the heat storage coefficient in summer increased by 0.97. The thermal comfort duration in winter was extended by 17.9 %, and the thermal load leveling in summer was reduced by 11.5 %. The heating/cooling water supply duration was shortened by 2.5 h, resulting in an energy-saving rate of 13.3 %. Consequently, the CPCM wallboard maintained a better indoor thermal environment with a lower energy consumption.

Thermal performance improvement of PCM layers

Thermal shielding through phase change material wallboards exposed to oscillating temperature conditions has been previously studied by several authors. PCM layers provide thermal comfort by releasing(absorbing) latent heat energy, constituting a sort of active cooling(heating) system produced by the dynamics of liquid-solid interfaces. In this work, the effect of volume displacements in the thermal performance of PCM wallboards is analyzed. The thermal energy released(absorbed) at the inner wall is greatly affected by the dynamics of volume displacements and the formation of one or more interfaces, when exposed to temperature oscillations around the melting point of the material. Equations of motion for the thickness of the PCM layer and interfaces, are derived. Volumetric effects produced by the sharp density change of liquid-solid transitions as well as the thermal expansion of each phase are considered in the analysis. We found that the term proportional to the expansion coefficient that appears in the equations of motion is negligible. The effect is hidden by volume displacements produced through the density difference between phases. Semi-analytical methods were used to solve the equations of motion described in this work. We found that the thermal energy released(absorbed) is deeply affected by the initial configuration of phases and the time instant of exposure to ambient conditions. Thermal shielding can be improved through PCM preparation and time of installation, according to the results found in this work. Finally, examples with two alkanes are provided when the external wall is exposed to different weather conditions.

Coupling PCM wallboard utilization with night Ventilation: Energy efficiency and overheating risk in office buildings under climate change impact

The rising population and increasing thermal comfort expectations are expected to exacerbate the already high HVAC use in offices, which unavoidably places a strain on energy supply systems. Storing thermal energy by incorporating phase change materials (PCMs) is an effective method for improving the buildings’ energy efficiency. Understanding how a PCM wallboard responds to climate change (CC) is crucial to maintaining its viability and effectiveness in achieving energy efficiency and sustainability goals during a building’s lifetime. This study presents a methodological framework to assess the performance of a building utilizing PCM wallboards in terms of cooling/heating energy demand (and corresponding GWP and operation cost) and occupant thermal comfort considering the changing climate. As a case study, a hypothetical office building located in a cold semi-arid climate with high diurnal fluctuations was selected, and the performance of offices orienting in different directions was evaluated when PCM wallboards with different melting ranges were utilized. PCM19 with a melting range close to heating set point reduced the heating demand by 5.0–7.4% for 2020 and 7.8–9.2% for 2050; while PCM25 with a melting range close to cooling set point yielded cooling reductions of 1.9–4.3% for 2020 and 0.7–2.4% 2050. However, PCM19 and PCM25 were ineffective in cooling and heating, respectively, as they were not compatible with the chosen set points. Coupling PCM25 with night-ventilation (NV) significantly enhanced the cooling savings (NV: 23.2–25.7% for 2020; 13.9–15.7% for 2050; NV + PCM25: 29.4–30.6% for 2020; 16.6–17.5% for 2050); though, the effectiveness of NV was impaired with rising night temperatures due to CC. Hourly energy analysis demonstrated varying performance of wallboards based on the time of day, suggesting potential benefits in supply–demand dynamics and time-of-use energy pricing. In naturally-ventilated scenarios, PCM utilization was ineffective in reducing indoor overheating risk, even when night-ventilation was introduced. Results highlight that to effectively mitigate indoor overheating risk in office buildings, PCM wallboards should be coupled with air-conditioning and night-ventilation. Furthermore, for a comprehensive evaluation of the energy/GWP/cost saving potential of a PCM wallboard during a building's lifetime, not only the current but also the projected local climate should be considered given the shifting energy demand towards cooling due to climate change. Overall, this study provides valuable insights into effective PCM wallboard utilization and lays the groundwork for enhancing the resilience of built environments in the face of climate change challenges.

Energy analysis of the building integrated with a double PCM wallboard system in various climate regions of Iran

Energy analysis of the building integrated with a double PCM wallboard system in various climate regions of Iran

EXPERIMENTAL INVESTIGATION AND LIFE-CYCLE COST ANALYSIS OF A MULTI-PIPE ARRAY HEAT STORAGE SYSTEM USING PHASE-CHANGE MATERIALS FOR SOLAR GREENHOUSE HEATING

To simplify the structure of accumulator and enhance the utilization of phase-change materials (PCM), this paper presents the development, experimental investigation, and life-cycle cost of a novel phase-change heat storage system with multi-pipe array type for greenhouse heating. The platforms of single accumulator performance evaluation and multi-pipe array storage system performance evaluation were established in the paper, and the life-cycle cost analysis was also studied in contrast to the PCM wallboard storage system and coal-fired heating system. It was found from the experimental investigation that the blackened coating treatment of PVC pipe could improve the thermal storage capacity by 66.7% compared to the original surface after 6 h of sun exposure. The preferred package size in multi-pipe array system was 75 mm in diameter under an illumination time of 6 h and long-lasting heat release (> 10 h), which not only guaranteed higher thermal storage capacity and transformation ratio but also maintained long-term heat discharge. The PCM loading capacity of 1560 kg can raise the night temperature by 1.6°C in the multi-pipe array storage system performance evaluation experiments under ambient temperature range of -18°C-+5&#176C. Due to its cost-effectiveness in terms of both system operation and initial investment, the life-cycle costs of the multi-pipe array system were USD1606, which was only 63.2 and 31.3% that of the wallboard system and coal-fired heater, respectively.

Model predictive control in phase-change-material-wallboard-enhanced building energy management considering electricity price dynamics

Incorporating phase-change material (PCM) wallboards into building envelopes can help reduce electricity costs associated with heating and enhance demand flexibility in dynamic building energy management in response to electricity price volatility. The conventional control strategies adopted in current building energy management systems are ‘reactive’ in nature, hence, they are not ready to exploit the full potential of PCM wallboards for price-based, demand-responsive building control applications. This study proposes a model predictive control (MPC) framework for price-based, demand-responsive control of PCM-wallboard-enhanced space heating systems to minimize electricity costs and maximize demand flexibility by fully exploiting PCM wallboards. A high-fidelity, linear PCM wallboard and building thermodynamics model are developed for computationally efficient building control. The model is then incorporated into an MPC framework considering the PCM wallboard dynamics and dynamic electricity prices. A simulation case study is conducted for a single-family house employing the proposed MPC approach to control its space heating system. Compared to conventional control, the MPC approach reduces space heating electricity costs by more than 60 %. The MPC approach also shifts more than 80 % of peak heating loads to off-peak periods, much higher than conventional control achieves (less than40 %). The simulation results also show good synergistic benefits of MPC in fully exploiting PCM wallboards in optimizing building space heating operation: achieving additional 31.1 % electricity cost savings and 38.7 % peak load shifting than without leveraging PCM wallboards. In contrast, conventional control cannot achieve such synergistic benefits. The proposed MPC framework is also proven computationally viable for real-time building control.

Future performance evaluation of PCM integrated buildings under changing climate

The high energy consumption and associated carbon emissions due to the heating and cooling of buildings create a heavy environmental burden. One of the cost-efficient solutions to reduce the heating and cooling demands is to incorporate phase change materials (PCMs) in the building components, increasing the thermal mass of the building and providing latent heat thermal storage. However, the rising temperatures over the years will alter the effectiveness of PCM in building envelopes. In this study, four cities in Turkey with different climatic characteristics were selected. For each city, future weather files representing the climatic conditions of 2050 and 2080 were generated from the current weather data using CCWorldWeatherGen. A typical office building that utilizes gypsum wallboards was modeled with EnergyPlus as a reference case. Alternative energy models were generated by modifying the wallboard compositions (PCM melting temperature: 19-27°C). The building’s annual heating and cooling energy demands were calculated for each city, year, and wallboard alternative. Generated data were analyzed to evaluate the future efficiency of the wallboards with the changing climate over the years in order to maximize the long-term performance gains from PCM incorporating wallboards. The results showed that the selection of the optimum PCM melting temperature of a location should not only depend on thermo-physical and layer properties of the PCM wallboard as the optimum melting temperature of the PCM is subject to change with rising temperatures. The impact of climate change should be considered to fully evaluate the long-term performance of the PCM wallboard in terms of energy use and CO2 emissions.

Energy performance of buildings with composite phase-change material wallboards in different climatic zones of China

The incorporation of phase-change material (PCM) into construction materials has been proposed to indirectly accomplish indoor thermal comfort and energy saving. To adapt to seasonal changes (e.g., hot summer and cold winter), a novel type of hybrid PCM-containing wallboard (including three different PCMs) was proposed with a wide phase-change temperature range and that can work in various climates. In this study, a small building equipped with a hybrid PCM wallboard was established to evaluate energy-saving performance using EnergyPlus. To compare different hybrid PCM wallboards, four building models were considered, including Mode 1, Mode 2, Mode 3, and gypsum wallboard (BASE). The building performance in terms of heating and cooling energy consumption over one year was investigated at seven locations in China to represent different climate zones. The results show that less heating and cooling energy was required for Mode 2 than for the other models. Further investigation of the Mode 2 PCM wallboard revealed that the location of the PCM layer also influenced the energy savings. The total energy requirements for Mode 2 were lower than those for BASE by 2.15%, 4.33 %, 1.77 %, 5.56 %, 7.65 %, 5.84 %, and 0.2% for Shanghai, Beijing, Kunming, Lanzhou, Xining, Harbin, and Hong Kong, respectively. We conclude that the hybrid PCM wallboard can effectively reduce the heat gain through the building envelope throughout the year, presenting a considerable advantage of using it in buildings located in Shanghai, which experiences a hot summer and cold winter.

Modeling of the effect of nano-enhanced phase change material on the performance of a large-scale wallboard

The main goal of this present study is to investigate the effects of the application of PCM and Nano-enhanced PCM as wallboard on the thermal behavior of a room. For this purpose, a room was modeled in two dimensions under Tehran's summer weather conditions through computational fluid dynamics (CFD). The effect of using the PCM as a wallboard in the southern wall in both pure and enhanced with nanoparticles was investigated. The indoor temperature, the wall surface temperature, and the interior wall heat flux, in both cases, were reported and compared. At the end of this study, the acquired results were compared with the pre-modified room, and thermal improvement was reported. The results indicate that the use of solid nanoparticles in PCM reduces the energy consumption of air-conditioning system by 7.4% compared to the conventional room. In the case of the Nano-enhanced PCM wallboard, the room has better thermal performance than the pure PCM, with 4.37% more energy storage, about 0.273 reductions in temperature decrement factor, and a 21.6 min increase in the time delay to peak temperature. Compared to the conventional room and room with pure PCM, the room’s temperature fluctuation, modified by Nano-enhanced PCM, reduces by 52% and 31%, respectively. This study's obtained results could help the researchers and designers have a more appropriate PCM selection for building ventilation system applications.

Experimental study on the performance of an active novel vertical partition thermal storage wallboard based on composite phase change material with porous silica and microencapsulation

In this study, a microencapsulated phase change material (MPCM) was mixed with a composite phase change material (CPCM) made of porous silica/paraffin to produce hybrid PCMs (C-MPCM), and then prepared two types of gypsum-based PCM wallboards (model A, which is M-A for short henceforth: Split; and model B, which is M − B for short henceforth: Hybrid). After that the physical properties and microstructure of the samples were evaluated. The results showed that paraffin wax was well immersed in porous silica with an optimal adsorption rate of 70% with no leakage. Meanwhile, the CPCM maintained good chemical compatibility and thermal stability. In addition, the thermal properties of PCM wallboards and gypsum wallboard were studied through an automatically controlled test system. Thermal performance showed that, both the M-A/B wallboards were able to keep the temperatures of room A/B within the thermal comfort range throughout the year. M-A wallboard was more energy efficient than M − B wallboard in summer working conditions; M − B wallboard was more energy efficient in winter working conditions. The total water supply duration consumed by M − B wallboard was far less than that of M-A wallboard. Considering comprehensively, M − B wallboard is more suitable for practical application in building energy saving.

Investigating the performance of the PCM-integrated building envelope on a seasonal basis

BackgroundThe PCM-integrated building envelope has shown significant potential in energy management and heating/cooling loads reduction. However, PCM layer performance highly depends on environmental conditions, configuration and its thermo-physical properties. The right choice of these characteristic features is great of importance since it may cause inverse effects. MethodsSo, in this comprehensive study, the performance of PCM wallboard under realistic sessional weather and solar radiation by considering different values of melting points (22, 24 and 26 °C) is investigated. To capture the solid/liquid interface and liquid fraction, the precise enthalpy-porous model, as well as the actual heat transfer chain consisting of radiation, convection and conduction from the environment to the room ambient, are implemented. Significant findingsThe results showed that the PCM layer is not always advantageous and more than 5% negative impact on energy loss is observed. So, the performance is highly dependent on other key factors including the environmental conditions and its volumetric amount. Also, the existence of optimum values for PCM layer thickness regarding the costs and wall density is observed for different types of PCM. The effect of the melting point on energy-saving is another significant parameter that has shown a considerable impact on appropriate PCM selection for specific regional conditions.

Complex Fourier series expansion for the liquid-solid phase transition in PCM layers: transient and steady state periodic regimes

Semi-analytical solutions to the classical two phase Stefan problem are proposed. Time dependent solutions to the one-dimensional liquid-solid phase transition in a PCM wallboard subjected to isothermal and periodic Dirichlet boundary conditions are obtained. Transient and steady state solutions are found in finite size systems, and the semi-analytical solutions are validated through the asymptotic time limit behaviour of the phase transition. In this work, complex Fourier methods are proposed to find the solutions in the transient and steady state periodic regimes. Semi-analytical solutions based on the heat balance integral method (HBIM) are used to verify the consistency of the proposed method. The Fourier method can be pictured as a generalization of the phasors based method recently introduced by other authors. The proposed method incorporates a complete set of complex functions, which allows finding the transient and steady state response of the system. Finally, solutions for the time dependent interface position, liquid and solid temperature distributions and the thermal energy penetrating through the PCM wallboard, are shown. The solutions from the proposed method are found to be consistent when compared to the semi-analytical solutions estimated through the HBIM.

Modeling and Simulation of Phase Change Material Wallboards to Improve Indoor Thermal Comfort: A Case Study of Residential Buildings of urban village in Guangzhou

Phase change materials can not only save thermal storage, but also improve residential thermal comfort. In this paper, the finite element software COMSOL is used to simulate the effect of phase change material wallboards on the improvement of residential comfort in the urban village of Guangzhou, China. The results clearly show that the use of phase change material wallboards has a positive influence on the indoor thermal comfort of the urban village.

Dynamic state-space model and performance analysis for solar active walls embedded phase change material

Abstract Building-based active envelopes play an important role to reduce active heating supplies. Several techniques are developed to enhance the energy performances of active building envelopes; meanwhile, numerous numerical and mathematical models are also developed to conduct the performance analysis of these techniques. In this paper, we propose a state-space model for solar active wall-based Phase Change Materials (PCM). The advantage of this method remains in its simplicity to provide details of internal nodes and input/output parameters. The low-cost calculation is a supplementary advantage versus a heavy numerical method. The proposed numerical model is applied for a multi-layer wall with PCM Wallboards (PCMW) embedded between indoor and outdoor environments. The results show the ability of the state-space model to estimate the thermal behavior of the system, as well as the thermal characteristics of embedding PCM in the internal face of the wall. It significantly contributes to stabilize the indoor temperature and to ensure the thermal comfort.