Simulation of Ventilation Flow at Different Conditions Through a Two-Dimensional Room Incorporated With Phase Change Materials

2020 ◽  
Author(s):  
Angel Reyes-Cubas ◽  
Peter Abdo
Keyword(s):  
Energy Consumption ◽  
Phase Change ◽  
Natural Ventilation ◽  
Phase Change Materials ◽  
Liquid Fraction ◽  
Air Flow ◽  
Building Energy Efficiency ◽  
Two Dimensional ◽  
Latent Heat Storage ◽  
Flow Through

Abstract Climate change and global warming have raised many concerns, highlighting the necessity to reduce energy consumption associated with the building sector. HVAC systems account to almost 40% of the building’s energy consumption. Natural ventilation is the process of supplying and removing air through an indoor space by natural means. Windcatchers have been used over centuries for providing natural ventilation using wind power. Moreover, it is an effective passive method to provide healthy and comfortable indoor environment by decreasing moisture content in the air and reducing pollutants concentration significantly. Materials that change phase at certain temperature are frequently referred to as Phase Change Materials (PCMs). Phase Change Materials, also known as Thermal Energy Storage (TES), are substances with high latent heat storage capacity which absorb or release the heat from or to the surrounding environment. PCMs could be used in passive cooling systems and they are directly related to building energy efficiency. This study investigates air flow through a windcatcher into a two-dimensional room incorporated with phase change materials (PCMs). The temperature change in the room implementing PCM is analyzed to monitor the PCMs’ performance. To achieve this, Computational Fluid Dynamics (CFD) tool is used to simulate the air flow through a two-dimensional standard room (3 m × 5 m) fitted with a windcatcher at its roof. Ansys Fluent is utilized to simulate and display the contours of temperature, liquid fraction, and velocity of both PCM and air. The energy model as well as the solidification and melting model are employed, and the K-Epsilon turbulence model is implemented. PCM is placed at the right and left walls of the room, as well as at its bottom. The inlet velocity ranges between 1 m/s and 7 m/s, simulating the average wind speeds in Sydney-Australia during summer [1]. Different inlet temperatures are used, specifically at 302 K and 310 K. The effect of the phase change material presence on the air flow pattern is also investigated.

Simulation of Ventilation Flow Through a Room Fitted With a Windcatcher Incorporating Phase Change Materials

2020 ◽  
Author(s):  
Peter Abdo ◽  
Angel Reyes-Cubas
Keyword(s):  
Phase Change ◽  
Natural Ventilation ◽  
Phase Change Materials ◽  
Melting Process ◽  
Inlet Temperature ◽  
Building Energy Efficiency ◽  
Ansys Fluent ◽  
Indoor Space ◽  
Flow Through ◽  
The Right

Abstract Natural ventilation is the process of supplying and removing air through an indoor space by natural means. Windcatcher has been used over centuries for providing natural ventilation using wind power, it is an effective passive method to provide healthy and comfortable indoor environment by decreasing moisture content in the air and reducing pollutants concentration effectively. The windcatcher’s function is based on the wind and on the stack effect resulting from temperature differences. Materials that change phase at certain temperature are frequently referred to as Phase Change Materials (PCMs). PCMs change from solid to liquid and vice versa. PCMs could be used in passive cooling systems and they are directly related to building energy efficiency. In this study air flow through a two-dimensional room fitted with a windcatcher and incorporated with phase change materials (PCMs) is simulated. The temperature change in the room implementing PCM is analyzed to monitor the PCMs’ performance. To achieve this, Ansys Fluent is used to simulate the temperature changes inside the room as well as the melting process of PCM. PCM is placed at the right and left walls of the room and at its bottom. Two cases have been considered (with and without PCM) and the average temperatures at three locations have been compared for an inlet velocity of 1 m/s and an inlet temperature of 302 K. The average temperature at 1.2 m high inside the room with PCM dropped by about 1–2 °C compared to that without PCM.

Effect of Wind Speed on Ventilation Flow Through a Two Dimensional Room Fitted With a Windcatcher

2018 ◽  
Author(s):  
Rahil Taghipour ◽  
Peter Abdo ◽  
B. P. Huynh
Keyword(s):  
Indoor Environment ◽  
Natural Ventilation ◽  
Air Flow ◽  
Two Dimensional ◽  
Cross Sectional ◽  
Indoor Space ◽  
Wind Speeds ◽  
Flow Through ◽  
Convergent Inlet ◽  
Natural Means

Natural ventilation is the process of supplying and removing air through an indoor space by natural means. Windcatcher has been used over centuries for providing natural ventilation using wind power, it is an effective passive method to provide healthy and comfortable indoor environment by decreasing moisture content in the air and reducing pollutants concentration. The windcatcher’s function is based on the wind and on the stack effect resulting from temperature differences. Generally, it is difficult for wind to change its direction, and enter a room through usual openings, the windcatcher is designed to overcome such problems since they have vertical columns aimed at helping wind to channel down to the inside of a building. The efficiency of a windcatcher is maximized by applying special forms of opening and exit. The openings depend on the windcatcher’s location and on its cross sectional area and shape such as square, rectangular, hexagonal or circular. In this study the effect of different wind speeds on the total air flow captured by different inlet designs is investigated. To achieve this, CFD (computational fluid dynamics) tool is used to simulate the air flow in a two dimensional room fitted with a windcatcher applying wind speeds from 1 m/s up to 14 m/s and based on different inlet designs such as a uniform inlet, a divergent inlet and a bulging-convergent inlet.

Modeling and Simulation of Phase Change Materials: Application to Building with Low Energy Consumption

2019 ◽  
Vol 297 ◽  
pp. 187-194
Author(s):  
Izzeddine Saouane ◽  
Abla Chaker ◽  
Tarek Messai ◽  
Hichem Farh
Keyword(s):  
Energy Consumption ◽  
Phase Change ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Liquid Interface ◽  
Latent Heat Storage ◽  
Change Behavior ◽  
The One ◽  
Solid Liquid Interface ◽  
Solid Liquid

The use of phase change materials must allow storage / destocking of energy from solar or internal gains. The applications in the case of light constructions will lead to an improvement in the thermal comfort of users and a reduction in energy consumption. The use of phase change materials (PCMs) in the energy-saving walls themselves makes it possible to substitute sensible heat storage for latent heat storage which requires a much lower volume and mass for the same amount of thermal energy. The objective of this work is the study of heat transfer by conduction during a phase change, and aims on the one hand to model and simulate the phase change behavior and on the other hand to approach the mechanism of heat exchange at the solid-liquid interface. The results obtained in 2D show the temporal evolution of the temperature, the position and the speed of the solid-liquid interface.

scholarly journals Effect of Phase Change Material on Temperature in a Room Fitted With a Windcatcher

2019 ◽  
Author(s):  
Peter Abdo ◽  
B. Phuoc Huynh ◽  
Ali Braytee ◽  
Rahil Taghipour
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Natural Ventilation ◽  
Phase Change Materials ◽  
Renewable Energy Sources ◽  
Rapid Development ◽  
Inlet Channel ◽  
Latent Heat Storage ◽  
Channel Temperature ◽  
Change Material

Abstract Global warming and climate change have been considered as major challenges over the past few decades. Sustainable and renewable energy sources are nowadays needed to overcome the undesirable consequences of rapid development in the world. Phase change materials (PCM) are substances with high latent heat storage capacity which absorb or release the heat from or to the surrounding environment. They change from solid to liquid and vice versa. PCMs could be used as a passive cooling method which enhances energy efficiency in buildings. Integrating PCM with natural ventilation is investigated in this study by exploring the effect of phase change material on the temperature in a room fitted with a windcatcher. A chamber made of acrylic sheets fitted with a windcatcher is used to monitor the temperature variations. The dimensions of the chamber are 1250 × 1000 × 750 mm3. Phase change material is integrated respectively at the walls of the room, its floor and ceiling and within the windcatchers inlet channel. Temperature is measured at different locations inside the chamber. Wind is blown through the room using a fan with heating elements.

Effect of Windcatcher’s Inlet Shape on Ventilation Flow Through a Two Dimensional Room

2018 ◽  
Author(s):  
Peter Abdo ◽  
Rahil Taghipour ◽  
B. P. Huynh
Keyword(s):  
Indoor Environment ◽  
Natural Ventilation ◽  
Air Flow ◽  
Two Dimensional ◽  
Sectional Area ◽  
Cross Sectional ◽  
Indoor Space ◽  
Flow Through ◽  
Convergent Inlet ◽  
Natural Means

Natural ventilation is the process of supplying and removing air through an indoor space by natural means. Windcatcher has been used over centuries for providing natural ventilation using wind power, it is an effective passive method to provide healthy and comfortable indoor environment by decreasing moisture content in the air and reducing pollutants concentration. The windcatcher’s function is based on the wind and on the stack effect resulting from temperature differences. Generally, it is difficult for wind to change its direction, and enter a room through usual openings, the windcatcher is designed to overcome such problems since they have vertical columns aimed at helping wind to channel down to the inside of a building. The efficiency of a windcatcher is maximized by applying special forms of opening and exit. The openings depend on the windcatcher’s location and on its cross sectional area and shape such as square, rectangular, hexagonal or circular. In this study the effect of the inlet design is investigated to achieve better air flow and increase the efficiency of windcatchers. To achieve this, CFD (computational fluid dynamics) tool is used to simulate the air flow in a two dimensional room fitted with a windcatcher based on different inlet designs such as a uniform inlet, a divergent inlet and a bulging-convergent inlet.

Selection of Phase Change Materials for Latent Heat Storage

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
J. Martínez-Gómez ◽  
E. Urresta ◽  
D. Gaona ◽  
G. Guerrón
Keyword(s):  
Phase Change ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Latent Heat Storage ◽  
Toma De Decisiones ◽  
Selection Of

Esta investigación tiene como objetivo seleccionar un material de cambio de fase (PCM) que cumplen mejor la solución del almacenamiento de energía térmica entre 200-400 ° C y reducir el costo de producción. El uso de métodos multicriterios de toma de decisiones (MCMD) para la evaluación fueron proporcionales implementados como COPRAS-G, TOPSIS y VIKOR. La ponderación de los criterios se realizó por el método AHP (proceso analítico jerárquico) y los métodos de entropía. La correlación de los resultados entre los tres métodos de clasificación ha sido desarrollada por el coeficiente de correlación de Spearman. Los resultados ilustran el mejor y la segundo mejor opción para los tres MCDM fueron NaOH y KNO3. Además, tenía valores de correlación de Spearman entre los métodos excede de 0.714.

scholarly journals Encapsulation of Phase Change Materials Using Layer-by-Layer Assembled Polyelectrolytes

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Qiangying Yi ◽  
Gleb B. Sukhorokov ◽  
Jin Ma ◽  
Xiaobo Yang ◽  
Zhongwei Gu
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Low Cost ◽  
Sodium Dodecyl ◽  
Layer By Layer ◽  
Latent Heat Storage ◽  
Good Thermal Stability ◽  
Lbl Assembly ◽  
Acid Sodium Salt ◽  
Assembly Technique

Phase change materials absorb the thermal energy when changing their phases (e.g., solid-to-liquid) at constant temperatures to achieve the latent heat storage. The major drawbacks such as limited thermal conductivity and leakage prevent the PCMs from wide application in desired areas. In this work, an environmentally friendly and low cost approach, layer-by-layer (LbL) assembly technique, was applied to build up ultrathin shells to encapsulate the PCMs and therefore to regulate their changes in volume when the phase change occurs. Generally, the oppositely charged strong polyelectrolytes Poly(diallyldimethylammonium chloride) (PDADMAC) and Poly(4-styrenesulfonic acid) sodium salt (PSS) were employed to fabricate multilayer shells on emulsified octadecane droplets using either bovine serum albumin (BSA) or sodium dodecyl sulfate (SDS) as surfactant. Specifically, using BSA as the surfactant, polyelectrolyte encapsulated octadecane spheres in size of ∼500 nm were obtained, with good shell integrity, high octadecane content (91.3% by mass), and good thermal stability after cycles of thermal treatments.

scholarly journals Experimental Characterization of Phase Change Materials for Refrigeration Processes

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3033
Author(s):  
Anastasia Stamatiou ◽  
Lukas Müller ◽  
Roger Zimmermann ◽  
Jamie Hillis ◽  
David Oliver ◽  
...  
Keyword(s):  
Energy Density ◽  
Phase Change ◽  
Thermophysical Properties ◽  
Phase Change Materials ◽  
Cost Effective ◽  
Latent Heat Storage ◽  
Lower Energy Density ◽  
Change Material ◽  
Storage Units

Latent heat storage units for refrigeration processes are promising as alternatives to water/glycol-based storage due to their significantly higher energy densities, which would lead to more compact and potentially more cost-effective storages. In this study, important thermophysical properties of five phase change material (PCM) candidates are determined in the temperature range between −22 and −35 °C and their compatibility with relevant metals and polymers is investigated. The goal is to complement existing scattered information in literature and to apply a consistent testing methodology to all PCMs, to enable a more reliable comparison between them. More specifically, the enthalpy of fusion, melting point, density, compatibility with aluminum, copper, polyethylene (PE), polypropylene (PP), neoprene and butyl rubber, are experimentally determined for 1-heptanol, n-decane, propionic acid, NaCl/water mixtures, and Al(NO3)3/water mixtures. The results of the investigations reveal individual strengths and weaknesses of the five candidates. Further, 23.3 wt.% NaCl in water stands out for its very high volumetric energy density and n-decane follows with a lower energy density but better compatibility with surrounding materials and supercooling performance. The importance of using consistent methodologies to determine thermophysical properties when the goal is to compare PCM performance is highlighted.

scholarly journals Performance Improvement of a Household Refrigerator using Phase Change Material

2021 ◽  
Vol 16 (1) ◽  
pp. 032-041
Author(s):  
Pradeep N ◽  
Somesh Subramanian S
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Energy Savings ◽  
Storage System ◽  
Thermal Storage ◽  
Latent Heat Storage ◽  
Peak Loads ◽  
Change Material

Thermal energy storage through phase change material has been used for wide applications in the field of air conditioning and refrigeration. The specific use of this thermal storage has been for energy storage during low demand and release of this energy during peak loads with potential to provide energy savings due to this. The principle of latent heat storage using phase change materials (PCMs) can be incorporated into a thermal storage system suitable for using deep freezers. The evaporator is covered with another box which has storage capacity or passage through phase change material. The results revealed that the performance is increased from 3.2 to 3.5 by using PCM.

scholarly journals Enhancement of the Thermal Energy Storage Using Heat-Pipe-Assisted Phase Change Material

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6176 ◽  
Author(s):  
Hamidreza Behi ◽  
Mohammadreza Behi ◽  
Ali Ghanbarpour ◽  
Danial Karimi ◽  
Aryan Azad ◽  
...  
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Heat Pipe ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Liquid Fraction ◽  
Energy Storage Applications ◽  
Change Material

Usage of phase change materials’ (PCMs) latent heat has been investigated as a promising method for thermal energy storage applications. However, one of the most common disadvantages of using latent heat thermal energy storage (LHTES) is the low thermal conductivity of PCMs. This issue affects the rate of energy storage (charging/discharging) in PCMs. Many researchers have proposed different methods to cope with this problem in thermal energy storage. In this paper, a tubular heat pipe as a super heat conductor to increase the charging/discharging rate was investigated. The temperature of PCM, liquid fraction observations, and charging and discharging rates are reported. Heat pipe effectiveness was defined and used to quantify the relative performance of heat pipe-assisted PCM storage systems. Both experimental and numerical investigations were performed to determine the efficiency of the system in thermal storage enhancement. The proposed system in the charging/discharging process significantly improved the energy transfer between a water bath and the PCM in the working temperature range of 50 °C to 70 °C.

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