Thermal performance of PCM-glazing unit under moderate climatic conditions

Considering physical properties, transparent or translucent building components like windows or glazing facades are the weakest elements of building envelope. The heat transfer coefficient of such elements is approximately four times higher than for opaque partitions, which causes considerable increase of heat loss during winter. In summer relatively high solar transmittance is a source of heat gains which results in undesirable overheating. Application of phase change materials in glazing components affects its thermal performance by the increase of its heat capacity and decrease of solar heat gains, with regard to the current physical state of the PCM. The aim of this paper is investigation and determination of the thermal performance of PCMglazing unit, under real, moderate climatic conditions in summer season. Analysis conducted by the authors aims to find the proper arrangement of PCM-glazing unit and proper material properties design, allowing effective overheating control. To meet the stated goals, dynamic simulations of thermal performance of triple-glazing unit were carried out, using ESP-r software. It was assumed that one chamber, filled with PCM will adjust the solar heat gains flux while the second one will assure required thermal resistance of the partition. Original model of heat transfer through transparent partition, taking into account latent heat storage by effective heat capacity method was applied. Different phase change materials, characterized by various phase transition temperatures were considered in the analysis. Based on the obtained results it can be concluded that application of a PCM in the external cavity of the triple glazing window effectively affects the thermal performance of the component, stabilizing the diurnal temperature fluctuations. Simulation results revealed that transition temperature should be close to the assumed cooling set point

Dynamics of melting process in phase change material windows determined based on direct light transmission

Detailed analyses of melting processes in phase change material (PCM) glazing units, changes of direct transmittance as well as investigation of refraction index were provided based on laboratory measurements. The main goal of the study was to determine the direct light transmittance versus time under constant solar radiation intensity and stable temperature of the surrounding air. The experiment was conducted on a triple glazed unit with one cavity filled with a paraffin RT21HC as a PCM. The unit was installed in a special holder and exposed to the radiation from an artificial sun. The vertical illuminance was measured by luxmeters and compared with a reference case to determine the direct light transmittance. The transmittance was determined for the whole period of measurements when some specific artefacts were identified and theoretically explained based on values of refractive indexes for paraffins in the solid and liquid state, and for a glass. The melting process of a PCM in a glass unit was identified as a complex one, with interreflections and refraction of light on semi layers characterized by a different physical states (solid, liquid or mushy). These optical phenomena caused nonuniformity in light transmittance, especially when the PCM is in a mushy state. It was revealed that light transmittance versus temperature cannot be treated as a linear function.Fil: Heim, Dariusz. Lodz University of Technology; PoloniaFil: Krempski Smejda, Michael. Lodz University of Technology; PoloniaFil: Dellicompagni, Pablo Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; ArgentinaFil: Knera, Dominika. Lodz University of Technology; PoloniaFil: Wieprzkowicz, Anna. Lodz University of Technology; PoloniaFil: Franco, Ada Judith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; Argentin

Caracterización energética de materiales de cambio de fase para uso en acondicionamiento edilicio

En el presente trabajo se muestra el estudio sobre el potencial energético de un material de cambio de fase (PCM) como la parafina de estado puro para su uso en aplicaciones destinadas al acondicionamiento edilicio. El estudio de las propiedades físicas, como ser capacidad específica y temperatura de cambio de fase se realiza mediante calorimetría diferencial de barrido (Differential Scanning Calorimetry, DSC) sobre una muestra de volumen y masa especificados. Las propiedades ópticas, como ser transmitancia espectral, se determinaron mediante un espectroradiómetro Li – 1800 para los casos en que la parafina se encuentra en estado sólido y líquido. Por último, se realiza la simulación de las condiciones térmicas para un recinto cerrado y aislado térmicamente del exterior y con una ventana doble vidriada, orientada hacia al norte, en la cual se coloca la parafina entre dichos vidrios. Se toma el caso de estudio para la ciudad de Santiago de Chile, considerando los días característicos de cada mes.The present work studies the energetic potential of a certain phase-change materials (PCM): pure state paraffin, for being used in building climatization applications. The physical properties studied have been carried out through differential scanning calorimetry (DSC) over a specified volume and mass sample. Concerning the optical properties, the spectral transmittance was determined by a Licor LI-1800 spectro-radiometer, for the paraffin in both solid and liquid state. Finally a simulation of the thermal conditions for an enclosure and thermal isolated room were done in Simusol. The room had double-glazed window, orientated towards the North, with paraffin between both glasses. The case study was located for the climatic conditions of the city of Santiago de Chile, considering the characteristic days of each month.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Caracterización energética de materiales de cambio de fase para uso en acondicionamiento edilicio

En el presente trabajo se muestra el estudio sobre el potencial energético de un material de cambio de fase (PCM) como la parafina de estado puro para su uso en aplicaciones destinadas al acondicionamiento edilicio. El estudio de las propiedades físicas, como ser capacidad específica y temperatura de cambio de fase se realiza mediante calorimetría diferencial de barrido (Differential Scanning Calorimetry, DSC) sobre una muestra de volumen y masa especificados. Las propiedades ópticas, como ser transmitancia espectral, se determinaron mediante un espectroradiómetro Li – 1800 para los casos en que la parafina se encuentra en estado sólido y líquido. Por último, se realiza la simulación de las condiciones térmicas para un recinto cerrado y aislado térmicamente del exterior y con una ventana doble vidriada, orientada hacia al norte, en la cual se coloca la parafina entre dichos vidrios. Se toma el caso de estudio para la ciudad de Santiago de Chile, considerando los días característicos de cada mes.The present work studies the energetic potential of a certain phase-change materials (PCM): pure state paraffin, for being used in building climatization applications. The physical properties studied have been carried out through differential scanning calorimetry (DSC) over a specified volume and mass sample. Concerning the optical properties, the spectral transmittance was determined by a Licor LI-1800 spectro-radiometer, for the paraffin in both solid and liquid state. Finally a simulation of the thermal conditions for an enclosure and thermal isolated room were done in Simusol. The room had double-glazed window, orientated towards the North, with paraffin between both glasses. The case study was located for the climatic conditions of the city of Santiago de Chile, considering the characteristic days of each month.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Attenuation of Temperature Fluctuations on an External Surface of the Wall by a Phase Change Material-Activated Layer

Periodical changes of temperature on an external surface of building envelope, e.g., thermal stress or excessive heat gains, is often an undesirable phenomenon. The idea proposed and described in the following paper is to stabilize the external surface temperature in a period of significant heat gains by the originally developed, novel composite modified by phase change material (PCM) and applied as an external, thin finishing plaster layer. The PCM composite is made from porous, granulated perlite soaked with paraffin wax (Tm = 25 °C) and macro-encapsulated by synthetic resin. The effect of temperature attenuation was estimated for two designated periods of time—the heat gains season (HGS) and the heat losses season (HLS). The attenuation coefficient (AC) was proposed as evaluation parameter of isothermal storage of heat gains determining the reduction of temperature fluctuations. The maximum registered temperature of an external surface for a standard insulation layer was around 20 K higher than for the case modified by PCM. The calculated values of AC were relatively constant during HGS and around two times lower for PCM case. The obtained results confirmed that the proposed modification of an external partition by equipped with additional PCM layer can be effectively used to minimize temperature variations and heat flux in the heat gains season

Greenery in the urban environment as a nature based solution for thermal stress mitigation

The problem of thermal environment in the city and small urban settlement is described and discussed in the paper. The study was performed for two areas differed in the intensity of development, buildings height and greenery in the nearest surrounding. The results of measurements compared and discussed come from two, local meteorological stations located in both environments. The summer temperature history was compared and analysed using daily maximum, minimum and averaged values. For 85% of analysed days the minimum air temperature in the rural zone was lower than in the regular city area

Greenery in the urban environment as a nature based solution for thermal stress mitigation

The problem of thermal environment in the city and small urban settlement is described and discussed in the paper. The study was performed for two areas differed in the intensity of development, buildings height and greenery in the nearest surrounding. The results of measurements compared and discussed come from two, local meteorological stations located in both environments. The summer temperature history was compared and analysed using daily maximum, minimum and averaged values. For 85% of analysed days the minimum air temperature in the rural zone was lower than in the regular city area