The present paper is the first comprehensive review of the integration of phase change materials in building walls. Many considerations are discussed in this paper including physical considerations about building envelope and phase change material, phase change material integration and thermophysical property measurements and various experimental and numerical studies concerning the integration. Even if the integrated phase change material have a good potential for reducing energy demand, further investigations are needed to really assess their use.

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A review on phase change materials integrated in building walls

Recent developments in phase change materials for energy storage applications: A review

Thermal energy storage (TES) systems using phase change material (PCM) have been recognized as one of the most advanced energy technologies in enhancing the energy efficiency and sustainability of buildings. Now the research is focus on suitable method to incorporate PCMs with building. There are several methods to use phase change materials (PCMs) in thermal energy storage (TES) for different applications. Microencapsulation is one of the well known and advanced technologies for better utilization of PCMs with building parts, such as, wall, roof and floor besides, within the building materials. Phase change materials based microencapsulation for latent heat thermal storage (LHTS) systems for building application offers a challenging option to be employed as effective thermal energy storage and a retrieval device. Since the particular interest in using microencapsulation PCMs for concrete and wall/wallboards, the specific research efforts on both subjects are reviewed separately. This paper presents an overview of the previous research work on microencapsulation technology for thermal energy storage incorporating the phase change materials (PCMs) in the building applications, along with few useful conclusive remarks concluded from the available literature.

Development of phase change materials based microencapsulated technology for buildings: a review

In recent years, energy conservation and environmental protection have become most important issues for humanity. Phase change materials (PCMs) for thermal energy storage can solve the issues of energy and environment to a certain extent, as PCMs can increase the efficiency and sustainability of energy. PCMs possess large latent heat, and they store and release energy at a constant temperature during the phase change process. Thereby PCMs have gained a wide range of applications in various fields, such as buildings, solar energy systems, power systems and military industry. However, low thermal conductivity of PCMs leads to low heat transfer rate, thus, numerous studies have been carried out to improve thermal conductivity of PCMs. The main purpose of this paper is to review the methods for enhancing thermal conductivity of PCMs, which include adding additives with high thermal conductivity and encapsulating phase change materials. It is found that addition of thermal conductivity enhancement fillers is a more effective method to improve thermal conductivity of PCMs, where carbon-based material additives possess a more promising application prospect. Finally, the applications of PCMs in solar energy system, buildings, cooling system, textiles and heat recovery system are also analyzed.

Review on thermal conductivity enhancement, thermal properties and applications of phase change materials in thermal energy storage

Phase change materials (PCM) for cooling applications in buildings: A review

The phase change of a material is accompanied by a release or absorption of a considerable amount of heat. That makes a phase change a phenomenon effectively usable in various thermal storage applications. There are many materials with a melting temperature lying within the thermal comfort range for indoor environments. These materials can be utilized in building-integrated thermal storage. The performance of such latent-heat thermal storage integrated with the room structures was investigated through numerical simulations and experiments. The studied case involved two adjacent rooms of the same dimensions. The hydrated-salt-based phase-change material (PCM) was used as a thermal storage medium. A comparative approach was adopted in which the internal structures of one of the rooms contained the PCM, while the structures in the other room did not. The simulation model of the rooms was created in the numerical simulation tool TRNSYS 17, and this model was coupled with a PCM model created in MATLAB. The enthalpy method was used for the simulation of the phase change. This approach allowed for different time steps in the room model and the PCM model (the time step in the PCM model needed to be much shorter). The data from the real-scale experiments (ventilation rates, temperature of supply air, outdoor temperature, solar radiation intensity, etc.) as well as the physical properties of the PCM acquired in the laboratory testing were used as inputs to the simulation models. The analysis of the results was carried out, in which the simulation results were compared with the experimentally obtained data.

Simulation of latent-heat thermal storage integrated with room structures simulacija hranjenja latentne toplote, integrirane v sobnih strukturah

Phase-change materials (PCMs) are a well-established category of materials with many possible applications, ranging from the stabilization of temperature to heat or cold storage The main principle of PCMs is the utilization of the latent heat of a phase change for energy storage Though many pure chemical elements can be used as PCMs, a PCM very often consists of a number of substances The main reason for creating a PCM as a mixture of various substances is to achieve a desirable melting temperature for a particular application However, these mixed PCMs require accurate and reliable methods for determining their physical properties, since for numerical modeling the thermal properties of materials and their proper determination represent a significant issue that considerably affects the accuracy and credibility of numerical simulations and their outcomes The thermal properties of PCMs are usually obtained by differential scanning calorimetry (DSC), based on temperature and heat measurements of the investigated and reference materials There are several approaches to modeling materials with phase changes In this paper, the focus is on the enthalpy approach and the effective heat capacity method Both techniques, which utilize the results from a particular DSC measurement, allow a treatment with the latent heat, and as a result the desired heat or cold storage may be effectively simulated The presented methods were implemented using the results from DSC measurements in order to simulate a solar air collector with a PCM The obtained results are presented and discussed The paper also concerns the problems associated with the uncertainty of material properties and their influence on numerical simulations

Challenges in the computer modeling of phase change materials izzivi v ra^unalni(kem modeliranju materialov s fazno spremembo

Experiments have been carried out in order to investigate the stabilization of water temperature with a water-PCM heat exchanger. The water-PCM heat exchanger was of a rather simple design. It was a round tube, through which the water flowed, surrounded with an annular layer of PCM. The heat exchanger was divided into one meter long segments (modules) and the water temperature was monitored at the outlet of each of the segments. A paraffin-based PCM with the melting temperature of 42 °C was used in the experiments. The experimental set-up consisted of two water reservoirs kept at different temperatures, the water-PCM heat exchanger, PC controlled valves and a data acquisition system. As the first step a response to a step change in the water temperature at the inlet of the heat exchanger was investigated. Subsequently, a series of experiments with a square wave change of temperature at the inlet of the exchanger were carried out. The square wave temperature profile was achieved by periodic switching between the two water reservoirs. Several amplitudes and periods of temperature square wave were used. The results of experiments show that a water-PCM heat exchanger can effectively be used to stabilize the flowing water temperature when the inlet temperature changes are around the melting range of the PCM.

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Experimental investigation of stabilization of flowing water temperature with a water-PCM heat exchanger

Simulations of building performance or HVAC systems performance usually cover a time period of several weeks, months or even a year. Therefore, the computational demand of simulation models of buildings or HVAC systems can be quite constraining for their practical application. A substantial simplification of the simulated problem is usually necessary to reduce the computational demand. The paper reports the development of a quasi 1D model of a thermally activated layer with phase change material. The model was developed in MATLAB and subsequently implemented as a TRNSYS type. The model was validated with data obtained from experiments with thermally activated panels. The experimental panels contained a 15 mm thick layer of gypsum plaster comprising 30 wt.% of microencapsulated phase change material. Plastic tubes for liquid heat carrier (water in the presented study) were embedded at the bottom of the plaster layer. Thermal imaging was used to acquire the average surface temperatures of the panels in the experimental investigations. The experimental and numerical results were in a good agreement.Copyright © 2015 by ASME

A Validated TRNSYS Model of Thermally Activated Layer With Phase Change Material

Latent heat storage represents technology with significantly higher energy storage density. The thermal energy storage capacity of building structures and storage units integrated into building services contribute to the energy flexibility of buildings. This paper presents results from laboratory experiments focused on the compatibility of heat storage media represented by phase change materials (PCMs) with materials of container. Material compatibility of selected PCMs with the plastics and metals were tested by a long-term experiment. Two organic-based and two inorganic-based phase change materials were selected for tests of compatibility with selected metals (aluminium, copper and brass) and plastics (PP-H, PE-HD, and PVC-U). Plastic-PCM compatibility was determined by gravimetric method. For evaluation of metal-PCM compatibility, calculation of corrosion rate was applied. The less mass changes and lower penetration of PCMs to the matrix was observed for inorganic-based PCMs compared to organic-based PCMs. In case of compatibility between metals and PCMs, the highest values of corrosion rate were calculated for copper immersed in inorganic-based PCMs Rubitherm SP25.

Milan Ostry

Papers

Simulation of latent-heat thermal storage integrated with room structures simulacija hranjenja latentne toplote, integrirane v sobnih strukturah

Challenges in the computer modeling of phase change materials izzivi v ra^unalni(kem modeliranju materialov s fazno spremembo

Experimental investigation of stabilization of flowing water temperature with a water-PCM heat exchanger

A Validated TRNSYS Model of Thermally Activated Layer With Phase Change Material

Durability of latent heat storage systems