Numerical predictions of the effective thermal conductivity of the rigid polyurethane foam

Fang, Wenzhen; Tang, Yuqing; Hu, Zhang; Tao, Wen‐Quan

doi:10.1007/s11595-017-1655-1

Cited by 6 publications

(3 citation statements)

References 18 publications

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“…Two cylinder specimens, with diameters about 50 mm and in the 30-50 mm height range for each type of geomaterial, were used to conduct the thermal conductivity tests under five different conditions via Hot Disk-TPS500 ( Figure 4). The related detailed principle and method of TPS were introduced in Fang et al (2017) and Liu et al (2014). The cylinder specimens must have a perfectly flat cylindrical surface to achieve sufficient contact between two separated specimens on the sensor of the thermal conductivity testing device.…”

Section: Experimental Materials Methods and Procedures Water Absorbmentioning

confidence: 99%

Meso-characterization of the effective thermal conductivity of selected typical geomaterials in an underground coal mine

Chu

Zhou

Shike³

2017

Energy Exploration & Exploitation

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To comprehensively understand the bulk macro conduction characteristics of typical geomaterials existing in deep underground coal mines, i.e. coal, rock, and concrete (shotcrete), meso-scale composition (solid mineral and fluids such as water and air) and structure (particle and pore size, shape, and contact form) analyses were conducted via water absorbability and thermal conductivity measurements, scanning electron microscope, and X-ray diffraction technologies. The results indicate that coal, rock, and concrete's respective meso-scale composition and structures have different degrees of influence on their macro bulk effective thermal conductivity at various conditions. First, the fluid (water and air) composition significantly impacts thermal conductivity at a certain bulk effective porosity: coal < rock < concrete. The ranking of thermal conductivity shows two different forms: concrete < coal < rock in a dry state and coal < concrete < rock in a watersaturated state. Second, the surface morphology and face porosity obtained by scanning electron microscope imaging can explain thermal conductivity fluctuations at various moisture contents and magnification times. The face porosity as well as its quadrant anisotropy degree can also be achieved via scanning electron microscope digital image processing technology, and both of them have a certain relationship with magnification times (scale effect) and effective volumetric porosity, as obtained by water absorbability experiments. In addition, apart from the fluid composition, the mineral composition (species and content of mineral) of the solid skeleton or matrix also significantly influences the macro-scale thermal conductivity of geomaterials. Furthermore, a quantitative comparison analysis can be performed by X-ray diffraction, but further research is needed to improve its accuracy. This study's detailed meso-characterization of the macro effective thermal conductivity for typical geomaterials in an underground coal mine may be of reference value to establish the relationship between different properties of differing scales.

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Section: Experimental Materials Methods and Procedures Water Absorbmentioning

confidence: 99%

Meso-characterization of the effective thermal conductivity of selected typical geomaterials in an underground coal mine

Chu

Zhou

Shike³

2017

Energy Exploration & Exploitation

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“…Theoretical and practical works have shown that the impact of the radiative constituent on the overall thermal conductivity strongly depends on cell sizes. The reduction in cell sizes yields smaller radiative contributions in thermal conductivity [25,[58][59][60][61][62].…”

Section: Conductivity Versus Foam Density and Cell Sizementioning

confidence: 99%

Methods to Increase or Decrease Resistance to Photodegradation and Biodegradation of Polyurethane/Polyisocyanurate (PU/PIR) Foams

Liszkowska,

Gozdecka,

Sitarz

2023

Materials

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Two series of rigid polyurethane–polyisocyanurate (PU/PIR) foams were obtained. They were modified using powder fillers, such as industrial food cocoa (K5–K15 foam) and instant freeze-dried coffee (KR-KR15) added in amounts of 5, 10 and 15 wt.%. W foam (reference) was obtained without filler. The foams were degraded in a climate chamber for 1 week, 2 weeks or 3 weeks. Appropriate temperature, humidity and UV radiation were set in the chamber, which did not change throughout the degradation process. The foams were also degraded in an oven for two days at 120 °C. The foam tests carried out indicated, among others, on the decrease in compressive strength along with the increase in the residence time of the samples in the chamber. Degraded foams also changed color. Foams containing 5% and 10% of industrial cocoa or freeze-dried coffee were more susceptible to degradation. The addition of 15% coffee or cocoa slows down the degradation process. In the present study, industrial food cocoa and instant freeze-dried coffee were used as modifiers of rigid PU/PIR foam. These fillers have two functions: they accelerate the biodegradation of foams and have antioxidant properties.

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“…The popular polymeric foams in worldwide are the polyurethane foams (PUFs) followed by the polystyrene and polyvinyl chloride [33][34][35][36]. Closed-cells PUFs are commonly used in building constructions as an integrated insulation layer or as insulation filler in the wall cavities as they are considered the lower thermal conductivity that offers the best thermal resistance compared to the other insulation materials such as PS, PE, PVC, mineral wool and cellulose materials [37][38][39][40][41][42]. In the last two decades, studies focused on producing of PUFs from renewable feedstocks that increase the positive properties of the PUFs, especially when related to the environment [7,35].…”

Section: Materials and Mathematical Model Insulation Polyurethane Foamsmentioning

confidence: 99%

Multiscale Approach of the Equivalent Thermal Conductivity of Modified Foam-Filled and Non-Filled Hollow Brick and a Brick Wall

Hashim

Almensoury

Ali

et al. 2021

Journal of Thermal Engineering

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The energy loss through building components resulting in higher energy consumption, thus energy saving has become an essential aspect in design and comfort. This study aims to optimize the thermal insulation of red clay bricks used in the walls of buildings by using a multiscale method. The finite element approach in ABAQUS software has been used to simulate the bricks under different configurations and conditions. Due to cost and time challenges and difficulties in simulation and complex calculations, simplified and applicable equations have been derived to calculate thermal insulation properties. The results show that the paper's brick design has a significant thermal conductivity reduction that could reach more than one-third of the other corresponding studies. The study goes to fill the hollow bricks by the insulation polyurethane foam (PUF) and comparing the results with air hollow bricks. Besides its other advantages, the outcomes reveal that using the PUF has a noticeable desired-influence in thermal insulation when considering the heat transfer by convection and radiation inside the air cavity of bricks.

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Numerical predictions of the effective thermal conductivity of the rigid polyurethane foam

Cited by 6 publications

References 18 publications

Meso-characterization of the effective thermal conductivity of selected typical geomaterials in an underground coal mine

Meso-characterization of the effective thermal conductivity of selected typical geomaterials in an underground coal mine

Methods to Increase or Decrease Resistance to Photodegradation and Biodegradation of Polyurethane/Polyisocyanurate (PU/PIR) Foams

Multiscale Approach of the Equivalent Thermal Conductivity of Modified Foam-Filled and Non-Filled Hollow Brick and a Brick Wall

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