Thickness Of Insulation Material Research Articles

Silica Aerogel-Modified Polyacrylonitrile Nanofibers to Reduce Heat Flux in Heat Storage Tanks of Greenhouse Buildings.

Polyacrylonitrile (PAN) nanofibers have specific characteristics such as thermal insulation, weatherproofing, and sunlight resistance and therefore are appropriate to be applied as insulation materials for various industries, especially in greenhouse construction. The heat source in greenhouse buildings that operate independently in the heating network comes from heat storage tanks. In the present study, employing thermal field numerical simulations, we investigate the heat flux of a cylindrical heat storage tank with silica aerogel-modified PAN nanofibers as thermal insulation materials. The geometric scale of the tank body, thermal insulation material thickness, and outdoor temperature are optimized to improve thermal insulation. The significant discrepancy in heat flux at different parts of the heat storage tank leads to the extreme heat flux arising at the water-gas interface on the inner and outer walls. It is indicated that the heat flux distribution can be effectively ameliorated by modifying the scale of the tank body to retain the overall water temperature. In particular, effective insulation can merely be acquired when the thermal conductivity of the insulation material is below 3.3 W·m-1·K-1. Eventually, the heat storage tank is optimized to store 1400 L water at 100 °C with a radius of 0.6 m and a thermal insulation thickness of 50 mm at an outdoor temperature of -10 °C, which can maintain excellent thermal insulation for 8 and 24 h at 87.7 and 69.9 °C, respectively.

Optimizing wall structure for enhanced thermal performance: A layer-specific dimensionless parameter analysis in multi-layer walls

Enhancing building energy efficiency and thermal comfort crucially involves optimizing the phase shift (PS) and decrement factor (DF) of exterior walls. Using the auxiliary function method, this paper presents analytical solutions for the DF and PS in double-layer walls, subsequently extending these to multi-layer walls. Insulation and structural material properties (density, thermal conductivity, specific heat capacity), thickness, internal and external convective heat transfer coefficients, outdoor temperature fluctuations, and insulation layering in multi-layered walls were taken into consideration in acquiring analytical solutions. Our findings in double-layer walls and analogous structures show that the DF and PS are largely governed by two dimensionless parameters per layer: thermal diffusivity index and Biot number. Regardless of Biot numbers (ε1 and ε2), an increase in thermal diffusivity indexes (δ1 and δ2) consistently reduces the DF and enhances the PS. Moreover, a larger ε1 with a smaller ε2 generally associates with a lower DF, but their impact on PS is less significant compared to thermal diffusivity index. In multi-layer walls, especially with mirror symmetry, we observe a dual extremum phenomenon, marked by prolonged PS and reduced DF. This underlines the importance of structural configuration in wall thermal performance. Thus, in double-layer structures, while the DF decreases and PS increases with increasing thermal diffusivity index, the influence of Biot numbers is comparatively minimal, highlighting the paramount role of thermal diffusivity index in optimizing thermal behavior. This discovery provides valuable guidance for identifying wall structures with minimal DF and maximal PS during the architectural design phase.

Heat of Hydration Analysis and Temperature Field Distribution Study for Super-Long Mass Concrete

In this study, the combination of ordinary cement concrete (OCC) and shrinkage-compensating concrete (SCC) was utilized to pour super-long mass concrete. The temperature and strain of the concrete were continuously monitored and managed actively after pouring. The investigation focused on the temporal and spatial distribution patterns of the temperature field, the temperature difference between the core and surface, and the strain evolution. Based on the constructed hydration exothermic model of layered poured concrete, the effects of the SCC, molding temperature, and surface heat transfer coefficient on the temperature field were analyzed. The results show that the temperature of super-long mass concrete rises quickly but falls slowly. SCC exhibits higher total hydration heat than OCC. The temperature field is symmetric along the length but asymmetric along the thickness due to varying efficiency of heat dissipation between the upper and lower parts of the concrete. After final setting of the concrete, the strain varies opposite to the temperature and peaks at −278 με. A few short cracks are observed on the end of the upper surface. Moreover, the numerical simulation results are in good agreement with the measured results. Increasing the molding temperature and surface wind speed increases the temperature difference between the core and surface. Conversely, increasing the thickness of the insulation layer is an effective way to curtail this difference. Thermal stress analysis is carried out and shows that lowering the molding temperature of SCC and increasing the thickness of insulation material can effectively reduce thermal stress.

Research on energy-saving renovation of solar greenhouses based on multiple factors and multiple objectives

The applicability of the traditional energy-saving renovation method for greenhouses is limited and influenced by the subjective decisions of researchers. Therefore, in this paper, a multifactor and multiobjective unbiased evaluation method is proposed based on the orthogonal test and entropy methods to study energy-saving transformation of solar greenhouses. The results show that the thickness of the gas layer, type of front roof glass and thermal insulation material of the rear roof greatly influence energy consumption, accounting for 45.5 %, 34.4 % and 15.3 %, respectively, of the total energy consumption, followed by the type of gas, thickness of glass and thermal insulation material of the heat storage wall, accounting for 3.2 %, 1.1 % and 0.5 %, respectively, of the total energy consumption. Based on energy savings, carbon emission reduction, investment cost and payback period, all renovation cases are comprehensively analyzed by the entropy weight method. The results show that Case m is the best renovation case, i.e., the front roof comprises three-layer glass, the glass thickness is 3 mm, the width of the cavity is 6 mm, which is filled with krypton gas, the rear roof insulation material is 100-mm thick extruded polystyrene (XPS), and the heat storage wall insulation material is 100-mm thick expandable polystyrene (EPS). This renovation method provides a systematic and objective theoretical basis for energy-saving renovation of solar greenhouses in cold regions.

Optimization of air-conditioning load for a residential building using Taguchi method

Economic growth has been raised in many countries in recent years, prompting people to seek out human comforts. For human comfort, residential buildings consume a significant amount of energy for air-conditioning systems. Building materials are the most significant factor in deciding the air-conditioning load. In this research work, a typical residential flat model is prepared using AutoCAD software and the building energy simulation is done for this model using hourly analysis program software. The results obtained from the building simulation are optimized using the Taguchi method. For optimizing the air-conditioning load, five influencing factors such as the overall heat transfer coefficient of wall (A), thickness of roof insulation material (B), heat transfer coefficient of window glass (C), bypass factor (D) and cooling coil supply temperature (E) of air-conditioning equipment at three levels are selected. For the experimental tests, an orthogonal L27 arrangement is chosen for experimental trials and in every trial, air-conditioning load of the typical residential flat has been calculated. After that, using Minitab 17 statistical software, the signal-to-noise ratios are obtained for different factors by selecting smaller-is-better option. After studying the response table for Taguchi tests, the optimum levels for all five factors are obtained. The analysis of variance method was also used to identify the main factors affecting the results significantly by finding out the contribution of all five factors in percentage. The results indicated that the most efficient set of all five factors is A1B3C1D2E3 and the most affecting factor is the wall material of the residential flat having a contribution of 91.91%.

Optimizing the Heat Loss from an Insulation Material and Boundary Layer Thickness of Airflow through a Hot Plate Using Nonlinear Least-Squares Error and Linear Programming Algorithms.

Heat loss is a major challenge in heat transfer problems. Several researchers have minimized heat loss for different heat transfer cases, focusing on one optimization technique; however, not all optimization techniques are suitable for a given problem. A limited number of studies have compared different techniques for a given problem under boundary conditions and constraints. This review revisits basic heat transfer problems and identifies a promising technique for each problem to minimize heat loss. The paper considers three techniques: nonlinear least-squares error (LSE), interior point linear programming (IPLP), and genetic algorithm. Two cases are studied: 1. heat loss optimization from cylindrical insulating surfaces and 2. laminar airflow on a heated plate. The results are compared for each technique, and a suitable technique is recommended for each considered case. Nonlinear LSE is found to be most suitable for case 1. IPLP and GA are recommended for the Case 2 problem. The average thermal conductivity is found to be 0.081 W/mK. The average insulation thickness is found to be 213.25 mm. This research will act as a basis for future research to justify and implement suitable techniques for different heat transfer problems.

Dynamic Simulation Analysis of Influencing Factors of Energy Consumption of Public Building Envelope in Central China

It difficult for buildings in cold regions to reasonably meet ultra-low energy consumption requirements. To explore the influencing factors of building energy consumption in this type of climatic region, this paper takes a typical public building in Zhengzhou, China as a case study to dynamically simulate an entire building. The influence of the window glass, window-to-wall ratio (WWR), thermal insulation material thickness and other factors on building energy consumption is considered. The sensitivity of envelope design factors to energy consumption is analyzed by the orthogonal test. The results indicate that the effect of changing the technical parameters of the external envelope structure on building energy efficiency is significant. Moreover, range analysis is used to determine the primary and secondary factors with regard to their influence on the energy consumption of the building. The WWR, the type of external window glass and the thickness of the external wall insulation layer should be considered first in energy-saving design; the energy-saving potential of the roof insulation thickness is not as significant as these factors. The results of the study can provide a reference for the energy-saving design of public buildings in Central China.

Evaluating carbon payback time by optimizing insulation materials for different orientations: A cradle-to-gate life cycle assessment

The European Union aims to reduce greenhouse gases emissions by 80–95% compared to 1990 levels by 2050. Therefore the life cycle concept has gained widespread acceptance as a model for evaluating the environmental impact of goods and services. In this study, the optimal thickness of various insulation materials for external walls, roofs, and floors using a Mediterranean climate zone's hot summers and mild winters for a hypothetical residential building for four cardinal orientations was determined. The criteria for determining the optimum thickness represent a turning point in terms of cooling energy consumption (electricity). The optimum thickness of nine different types of insulation materials was defined using the aforementioned approach. These materials included aerogel, polyisocyanurate, polyurethane, extruded polystyrene, expanded polystyrene, phenolic foam, cellulose fiber (cellulose), mineral wool, and glass wool (GW). The purpose of this paper is to calculate the carbon payback time (CPBT) using the cradle-to-gate life cycle assessment method by considering the global warming potential (GWP) of insulation materials at their optimum thickness. The CPBT is calculated as the ratio of the total building's GWP to the GWP of savings from cooling and heating (electricity and natural gas). The results indicated that when evaluating the average CPBT for four cardinal orientations (FCO), aerogel has the longest CPBT of 2.34 years, and GW has the shortest CPBT of just 0.09 years. Aside from cost payback time, the findings of this study provide a new perspective on selecting appropriate thermal insulation.

Influence of Insulation Material Thickness on Spread of Thermal Runaway in Battery Packs

Thermal runaway occasionally happens in batteries. A single battery, after thermal runaway, will release heat and transfer it to neighboring batteries, leading to thermal runaway of battery packs. Thus, it is necessary to explore the diffusion law of thermal runaway in battery modules. Heating is by far the most common way to trigger thermal runaway propagation of battery modules. In this paper, experiments and simulations were conducted to explore the influence of different heat insulation thicknesses on the thermal propagation of lithium iron phosphate batteries, and the result shows that the best thickness between adjacent batteries is 2 mm. For complex modules, the simulation analysis shows that when the spacing between adjacent modules in the battery pack was 10 mm and thermal runaway occurred on one side of the battery pack, it did not occur on the other side for a certain period of time. Therefore, the recommended spacing between modules in the battery pack is 10 mm. This lays a foundation for the safe design of battery modules.

An Analysis of The Use of Insulation Systems on OTTV Values of Residential Building in Hot Humid Climate

In tropical climates, the main problems are high solar radiation and humidity. The aim of this study is to find the right insulation material to provide thermal comfort of BSPS houses in Pamekasan Regency. The method use in this study is experimental with quantitative data analysis. Experiments were conducted on aspects that affect the value of thermal transmittance (U-value) and type of materials (glass wool, VIPs, and aerogel). The result shows that the best insulation material for thermal comfort is Vacuum Insulation Panels (VIPs). It could provide a significant reduction in OTTV value. The final results of the research by applying the insulation system to the BSPS house of Pamekasan Regency, Proppo Subdistrict, Panaguan Village show that the OTTV value of the alternative model in a house type 24 m2 is 29.505-23.462 W/m2 with a decrease of 22.86%-38.66% while in a house type 33.12 m2 it is 30.205-24.217 W/m2 with a decrease of 22.74% -38.06% and in a house type 84.46 m2 it is 27.223-21.084 W/m2 with a decrease of 26.19%-42.84%. Furthermore, the best type and thickness of insulation material used in this study is Vacuum Insulation Panels (VIPs).

Technical Suitability of Energy Saving Scheme for Optimizing the Thermal Insulation Layer Thickness of Residential Building Exterior Wall

From the perspective of technical suitability, this paper comparatively analyzed the economical thickness and suitable thickness of exterior wall thermal insulation material with the highest energy saving rate of building envelop, and attained the relationship, curves, and model of the economical thickness and suitable thickness of the insulation material. The purpose of this paper is to provide useful evidences for the energy saving of residential buildings and the optimization of the design of exterior wall, so that architectural designers could be inspired to consider the energy-saving issue of buildings from multiple angles such as economy and environment, and the optimal design scheme that is most beneficial to the environment could be created. This paper lays a theoretical basis for making investment decisions of energy saving buildings and avoiding unwise investment.

Analysis of Thermal Insulation Thickness for a Container House in the Yanqing Zone of the Beijing 2022 Olympic and Paralympic Winter Games

A large number of temporary housings (THs) were used in the Yanqing zone of the Beijing 2022 Olympic and Paralympic Winter Games. Taking a kind of container house (CH) used in Yanqing zone as a model, the objective of this paper is to analyze the effect of insulation thickness on heating energy consumption and corresponding carbon emission. The effect of service life of THs on economic thickness was also discussed. The simulation model was developed using EnergyPlus and the heating energy consumption with different insulation materials was simulated based on the meteorological parameters of the top of Xiaohaituo Mountain (2177.5 m) and the Olympic/Paralympic Village (950 m) in Yanqing zone. In the simulation process, the thermal insulation performance of the CH was enhanced with reference to the requirements of GB/T 51350-2019 Technical Standard for Nearly Zero Energy Buildings (NZEB) on one hand. Additionally, the insulation performance was evaluated in terms of payback period and carbon emission. On the other hand, the economic thickness of different insulation materials (rock wool (RW), extruded polystyrene (XPS), polyurethane (PU)) and the high performance vacuum insulation panel (HVIP)) for different service lives of CH was studied. Results show that the U-values of the envelope meeting the NZEB standard can decrease approximately 21.4-32.8% of the heating energy consumption, compared with the original envelope. When the service life of CH is extended to 20 years, the carbon emission is reduced by 18.5% and 29.5%. The payback period of HVIP is longest, up to 31.4 a, and the results of economic thickness show that when the service life of the CH ranges from 1 year to 20 years, the economic thickness range of RW is 47-235 mm, XPS is 41-197 mm, PU is 33-149 mm and HVIP is 4-18 mm at the altitude of 2177.5 m. At the altitude of 950 m, the economic thickness range of RW is 28-158 mm, XPS is 26-131 mm, PU is 25-118 mm, and HVIP is 2-12 mm. From an economic point of view, the service life of a CH has a significant impact on the choice of insulation thickness.

Determination of optimum thickness of nano and traditional insulation materials for building external walls by using degree-day approach for different climatic regions in Egypt

Determination of optimum thickness of nano and traditional insulation materials for building external walls by using degree-day approach for different climatic regions in Egypt

Economic strategies for low-temperature transportation of asphalt pavement: a comparative analysis of temperature variations

ABSTRACT Highway construction strategies impact the early damage of asphalt pavement and its sustainability. The pavement quality is directly influenced by the temperature segregation of the mixture during transportation, which has rarely been investigated. Low-temperature transportation strategies for highway pavement are proposed by assessing the temperature variations in the mixture through field tests. The extreme condition of winter construction is considered, and the effects of insulation materials are considered in laboratory and field tests. A 3D Multiphysics Coupling Finite Element model is developed in COMSOL to analyse the heat transfer mechanism. The vehicle speed, thermal conductivity and ambient temperatures are considered in this parametric study. The economic efficiency of intelligent transportation is improved by optimising the effective area and the thickness of insulation materials. This study aims to propose economic strategies to avoid the temperature segregation of pavement materials and to explore more environmentally friendly insulation measures for low-temperature highway constructions.

Energy Improvement in the Building Sector: An Economic Analysis Relating to the most Common Italian Masonry

The construction sector is a major contributor to total energy consumption, therefore, it is crucial to adopt energy efficiency strategies capable of reducing energy impact in buildings. Among these strategies, exterior wall insulation is one of the most cost-effective options to achieve energy savings for both newly constructed and renovated buildings. In this paper, based on an economic analysis, we aim to determine the economically optimal thickness of insulation material to be used for retrofit interventions of masonry structures. The study analyzes 10 different insulating materials and 5 masonry structures widespread in Italy. The results show that each masonry structure requires a careful evaluation of the thickness of the insulating material to be applied in retrofit operations. Moreover, varying the type of insulating material used, even if applied to the same wall structure, there are different levels of thickness to be applied in order to optimize the performance of the structure.

Experimental Investigation and Numerical Simulation on the Thermal Insulation Materials Using Recycled Thermoplastic Polymers

In construction building, the optimum insulation material thickness determines the efficiency of energy consumption. In this paper, heat transfer and the temperature distribution of recycled polymers between construction building components are investigated using theoretical and simulation methods. It has been shown that when the thickness of all recycled polymers being studied is increased, insulation improves and energy consumption decreases, indicating that XPS is the best recycled plastic and the optimum thickness is 7 cm. In this work, experimental and numerical approaches have been used, to conduct a qualitative and quantitative analysis of the thermal performance of an external wall outfitted with new insulation materials, based on the most commercialized recycled thermoplastic polymers (Polyethylene RPE, Polyethylene terephthalate RPET, and Expanded Polystyrene RXPS) waste.

Experimental and Numerical Study on the Insulation Performance of a Photo-Thermal Roof in Hot Summer and Cold Winter Areas

The use of a solar architecture system is a feasible way to reduce the energy consumption of a building. The system also has important significance to the “Dual-carbon” plan. In this study, the heat transfer characteristics of a photo-thermal roof were analyzed in hot summer and cold winter zones; a model to calculate insulation performance was established. In the summer climate, the thermal performances of the photo-thermal roof and an ordinary roof were explored through experiments and simulations. The results showed that the heat transfer and temperature of the photo-thermal roof were lower than those of the ordinary roof. Heat transfer through a photo-thermal roof can be changed by adjusting the water flow of collectors. The water saturation of insulation materials is an important factor that affects the insulation performance of a roof. Compared with the ordinary roof, the change in water saturation was shown to have less impact on the insulation performance of the photo-thermal roof. The water saturation increased from 0 to 30%, while the heat transfer per unit area of the photo-thermal roof only increased by 0.9 W/m2; 97.3% lower than that of the ordinary roof. The effect of reducing the insulation material thickness was less for the photo-thermal roof than for the ordinary roof. When the insulation material thickness was reduced from 100 mm to 0 mm, the average temperature in the indoor non-working area reached 38.5 °C and 27.1 °C in the ordinary roof and the photo-thermal roof, respectively. The insulation thickness of the photo-thermal roof had little effect on the indoor air temperature. The research results provide a reference for the roof energy-saving design of new buildings and the roof energy-saving transformation of existing buildings.

A study on influencing factors of optimum insulation thickness of exterior walls for rural traditional dwellings in northeast of Sichuan hills, China

Thermal performance of exterior walls can be improved with increasing insulation thickness, but the corresponding material cost will also rise. Therefore, the optimum thickness of insulation material necessarily exists when the economy is considered. Adding insulation materials with the optimum thickness for exterior walls of rural traditional dwellings in northeast of Sichuan hills can effectively enhance their thermal performance and lighten the economic burden of residents while decreasing energy consumption. Hence, the optimum thickness of five insulation materials was calculated by using the degree-days method and P1-P2 economic model as well as the energy-saving and economic benefits were evaluated based on EnergyPlus and dynamic investment payback period model. Then the influence law and the impact degree of influencing factors on the optimum thickness were analyzed via orthogonal test and analysis of variance. Eventually, the remarkable energy-saving and economic benefits of modifying the most crucial factor (heating-degree day) were assessed. Results show that the optimum insulation thickness ranges from 0.081 m to 0.144 m under the local climate and economic context. Besides, rationally lowering the heating-degree day can increase the energy-saving rate and economic benefits by 29.5% and 78.2%, respectively. The results can provide some new insights into the energy-saving retrofit of local traditional dwellings.

Numerical investigation on cooling effect in the circuit cabin of active cooling system of measurement-while-drilling instrument based on split-Stirling refrigerator

The thermal protection technology for high-temperature environment has made great progress in recent years. Restricted by the harsh environment of oil drilling, the design and development of measurement-while-drilling instrument (MWD) for high-temperature wells are still a worldwide issue. Although quite a few scholars have proposed a variety of thermal protection schemes, the feasibility or practical using effect has not been fully verified. Through comparative analysis of various cooling methods, it is considered that the active cooling scheme based on split-Stirling refrigerator is feasible, and a set of active cooling system is designed. The temperature distributions on the circuit cabin are presented. The influences of the structure parameters of circuit cabin, circuit board and refrigerator, the thermal conductivity of insulation material, the cooling power of refrigerator, the circuit board power, the annulus and water eye temperature on the cooling effect are discussed. The results show that the circuit board structure parameters, the insulation material thickness and thermal conductivity, the ratio between circuit board power and cooling power of split-Stirling refrigerator, the temperature difference between water eye and annulus are the key parameters affecting the cooling effect.

Comparative Study on Thermodynamic Characteristics of Composite Thermal Insulation Systems With Liquid Methane, Oxygen, and Hydrogen

Abstract Composite passive insulation technology has been proved to be an effective method to reduce heat leakage into the cryogenic storage tank. However, the current related research mainly focused on liquid hydrogen (LH2). The thermophysical properties of different cryogenic liquids and the thermal insulation materials at different temperatures are significantly different, so whether the results related to LH2 are applicable to other cryogenic liquids remains to be further determined. In fact, the insulation technology of LH2 itself also needs further study. In this paper, a thermodynamic calculation model of a composite insulation system including hollow glass microspheres (HGMs), multilayer insulation (MLI), and self-evaporating vapor cold shield (VCS) has been established. The accuracy of the calculation model was verified by the experimental results, and a comparative study on thermodynamic characteristics of the composite thermal insulation system with liquid methane, liquid oxygen (LO2), and LH2 was carried out. The results show that the heat leakage reduction of the proposed system for liquid methane, LO2, and LH2 is 25.6%, 29.7%, and 64.9%, respectively, compared with the traditional SOFI + MLI system (1 × 10−3 Pa). The type of liquid and the insulation system structure has a relatively large influence on the VCS optimal position. While for a specific insulation system structure, the insulation material thickness, storage pressure, and hot boundary temperature have a weak influence on the VCS optimal position.