Thermal Insulation Techniques Research Articles

Numerical simulation research on thermal insulation performance of composite heat-insulation zone structure in hydrothermal high-temperature mine

In hydrothermal high-temperature abnormal mines, the composite heat-insulation zone structure, formed through a combination of guniting and grouting, serves to mitigate heat dissipation from the surrounding rock into the airflow. To comprehensively understand the thermal insulation performance of the composite heat-insulation zone structure, this study employs numerical simulation to analyze the following aspects: the variation in the temperature field within the surrounding rock of the roadway without insulation, the influence of structural parameters of the composite heat-insulation zone on temperature distribution in the surrounding rock of the roadway, and the thermal insulation effectiveness of the composite heat-insulation zone with varying structures. The findings indicate that the temperature distribution within the surrounding rock of the roadway lacking a heat-insulation zone is relatively uniform. However, as ventilation time extends, the heat regulation zone within the surrounding rock gradually extends deeper, ultimately forming an elliptical cooling area. The composite heat-insulation zone structure effectively mitigates heat transfer from deeper surrounding rock to the roadway wall, consequently altering the scope of the roadway's heat regulation zone. Enhancing the thermal insulation performance of the composite heat-insulation zone structure can be achieved by increasing the thickness of the thermal insulation layer, adjusting grouting rate and depth, and reducing the thermal conductivity of insulation materials. The thermal insulation effectiveness of the thermal insulation layer surpasses that of the grouting layer, with its performance primarily influenced by the thermal conductivity of the materials used. Simulation results demonstrate that the composite heat-insulation zone structure reduces the maximum heat flux on the roadway wall from 47.4 to 37.7 W/m2, resulting in a 20% reduction in heat transfer from deeper surrounding rock. These findings offer valuable insights for implementing thermal insulation techniques in hydrothermal high-temperature anomaly mines.

Development of the Al2O3-B2O3-SiO2 glass for thermal barrier coating

Glass coating is an important thermal insulation technique used in the aerospace industry that serves as a thermal protection system (TPS) to protect the inner layer at elevated temperatures. This work highlights the superb mechanical and thermal properties of the B2O3-SiO2 glass systems as a surface coating for space shuttle. In the B2O3-SiO2 system, the glass transition temperature raises from 650 °C to 750 °C with increasing SiO2 content and devitrification of the α-cristobalite phase. The Al2O3 addition in B2O3-SiO2 glass can increase the glass transition temperature from 750 °C to 1000 °C and inhibit the α-cristobalite phase. The phase transition from an unstable α-cristobalite phase to an amorphous phase was achieved at 10 wt% Al2O3-added specimens. This study demonstrates that the Al2O3-B2O3-SiO2 glass (ABS glass) exhibits thermally stable behavior, making it an effective thermal barrier coating at elevated temperatures.

The Effectiveness of a Simulation Model of Thermal Insulation in Building Materials Using Cellulose Extracted from Agricultural Waste in Baghdad

This study found that one of the constructive, necessary, beneficial, most effective, and cost-effective ways to meet the great challenge of rising energy prices is to develop and improve energy quality and efficiency. The process of improving the quality of energy and its means has been carried out in many buildings and around the world. It was found that the thermal insulation process in buildings and educational facilities has become the primary tool for improving energy efficiency, enabling us to improve and develop the internal thermal environment quality processes recommended for users (student - teacher). An excellent and essential empirical study has been conducted to calculate the fundamental values ​​of thermal conductivity coefficient for different types of cement mortar, including the different concentrations of cellulosic fibers. And in our study, those cellulosic fibers obtained from sugarcane and sugarcane residues (agricultural waste materials) were used. The percentage is 10%; 20% and 30% of cellulose fibers were added to the cement mixtures. Then the differences are measured, specifically in the physical properties (heat capacity, density, and thermal conductivity coefficient) for 28 days. The Design-Builder program also implemented a precise simulation of the thermal loads of the external envelope of the educational building that is exposed to direct sunlight before and after the insulation process. It was found that with the use of thermal insulation material (meaning the cellulosic fiber technology) mixed with the cement mortar layer of the educational building, the given value of the heat transfer coefficient W/m2 Kelvin decreased by 47.2%. Accordingly, this contributed significantly to a significant and very significant saving in the values ​​of electrical energy consumption by 11.9% for cooling and heating operations and to reducing dangerous carbon dioxide emissions by 52.2%. The simulation has shown that applying thermal insulation techniques to all buildings and educational facilities is highly recommended to save a large consumption in the value of electrical energy and the costs of waste materials and to ensure integrated protection for the ecosystem.

Experimental study on the thermal performances of a non-pump-driven thermo-activated building system based on flat-plate heat pipe array

• A non-pump-driven thermo-activated building system based on FPHPs is proposed. • Effects of tilt angles and heat loads on FPHP are experimentally investigated. • Preliminary performances of the FPHP-embedded wall are experimentally investigated. • The optimal tilt angle of FPHP is not a fixed value for building integration. • The measured U d is 0.19 and −0.08 W/m 2 °C when Ths is 25 and 35 °C, respectively. As a burgeoning active thermal insulation technique, the pipe-embedded building system has attracted particular attention from architects and engineers. A novel pipe-embedded building system based on flat-plate heat pipe (FPHP) is proposed to solve the inherent issues like operation energy consumption and façade integration. The experimental investigation is firstly conducted on an FPHP prototype to explore its thermal response characteristics at different tilt angles and heat loads and then performed on an FPHP-embedded composite wall to explore the preliminary thermal performances. Results showed that the length of the condensation section with uniform temperature distribution accounted for at least 88.9% when the heat load was smaller than 3000 W/m 2 , which verified the feasibility of using FPHP to complete the heat charging process. The tilt angle had a significant influence on the thermal resistances, startup behavior, and effective thermal conductivity of FPHP, and the optimal tilt angle could be reduced for load reduction mode, while this value could be increased for supplementary heating mode. When the heat source temperature is 25 and 35 °C, the equivalent heat transfer coefficient value of the FPHP-embedded wall under test conditions is 0.19 and −0.08 W/m 2 ·°C, respectively. Meanwhile, the corresponding heat loss reduction rate could reach 62.7% and 116.4%, respectively. Overall, the results evidenced the effectiveness of FPHP-embedded building systems, which could also contribute to its system design, operation control, and further investigation.

The impact of efficient insulation on thermal performance of building elements in hot arid region

The application of thermal insulation technique for buildings in hot arid region still under development and requires investigation for many aspects, especially those related to the individual elements of the construction. The present study investigates the impact of efficient insulation on the thermal performance of the following construction elements: wall, roof and foundation. The techniques used for the insulation have followed the Passive House criteria. The study introduces many benefits for passive design of the building in extreme hot climate. The work has done experimentally in Kirkuk, Iraq for two building models; one is efficiently insulated and the other is traditional. The data, which are collected in summer time, show reduction in indoor temperature of the efficient model by 8 °C in average comparing to that of traditional one. Measurements show stability in the internal wall temperatures for efficient model with an average temperature of 33 °C comparing to 42 °C for traditional one. Similarly, the insulated roof radiates less heat into the indoor than that of traditional model. Furthermore, the effect of both efficient insulated roof and canopy shading reduces the temperature of internal surface temperature of the roof by 12 °C comparing to the traditional model. A local simulation program based on ASHRAE relations has shown an energy saving in the cooling load up to 70%.

Old Buildings’ Façades: Fieldwork and Discussion of Thermal Retrofitting Strategies in a Mediterranean Climate

This work is within the scope of thermal retrofitting, applied to old buildings’ façades (built between 1700 and 1960) located in Mediterranean climates, such as Portugal. The aim is to increase the sustainability of existing buildings, by reducing their energy consumption needs, for heating and cooling, and the corresponding gaseous emissions, while increasing their users’ comfort. Firstly, an analysis of the advantages and disadvantages of several thermal insulation solutions for façades was carried out, supported in current literature. Then, a survey of real retrofitting scenarios and interviews with experts was completed, to allow the selection of the most adequate thermal insulation techniques. Finally, as a result of this study, the discussion of retrofitting strategies was carried out to support the designer’s decision process, based on a flowchart with complementary tables, discussing the best thermal retrofitting technique to be implemented on old buildings’ façades, case-by-case.

Analysis of Heat Reduction through Technique Roof Using Innovative Insulation Technique

Buildings have a significant and continuously increasing impact on the environment. The powerconsumption for comfortable housing is ever increasing, which is adding additional burden to the powercrisis of the world. The main objective of this project is to reduce the heat transfer through the buildingroof by providing thermal insulation, thereby reducing the heat load on the building. Moreover, if thebuilding is to be air-conditioned then effective thermal insulation will reduce the power consumptiondrastically and saves lot of energy consumption. New innovative type of insulation is proposed in this workto reduce the heat transfer through roof structure by using seashells and coconut shells. The coconut shellsand seashells layer along with normal tiles will provide very good thermal insulation and it will maintainlow roof bottom surface temperature when compared with the normal conventional concrete roof withoutinsulation. Two identical experimental rooms were constructed on the top of the college mechanicalengineering department block and were instrumented with thermocouple and RTD along with data loggerfor obtaining continuous experimental results. The amount of heat reduction provided by the insulated roofstructure was calculated using the analytical method. Then the cooling load requirement for airconditioningand the corresponding energy cost per year was calculated for the new CAD lab of themechanical engineering department. The result showed the huge energy savings potential for thisinnovative thermal insulation technique. The electricity savings obtained is around 39.7%. when comparedwith the conventional concrete roof. This innovative technique for providing thermal insulation to thebuilding is more affordable and comfortable for living.

Nanocalorimeters for biomolecular analysis and cell metabolism monitoring.

Nanocalorimeters, or microfabricated calorimeters, provide a promising way to characterize the thermal process of biological processes, such as biomolecule interactions and cellular metabolic activities. They enabled miniaturized heat measurement onto a chip device with potential benefits including low sample consumption, low cost, portability, and high throughput. Over the past few decades, researchers have tried to improve nanocalorimeters' performance, in terms of sensitivity, accuracy, and detection resolution, by exploring different sensing methods, thermal insulation techniques, and liquid handling methods. The enhanced devices resulted in new applications in recent years, and here we have summarized the performance parameters and applications based on categories. Finally, we have listed the current technical difficulties in nanocalorimeter research and hope for future solutions to overcome them.

Application of Thermal Insulation Gunite Material to the High Geo‐Temperature Roadway

Thermal insulation gunite (TIG) in roadways is an effective method for regional thermal hazard control in mines. The development of mine TIG materials is the foundation of thermal insulation technique. However, some conventional and advanced insulation materials are inapplicable to deep mines which are rather humid with high in situ stress and high geo‐temperature. In this study, a kind of fly ash‐inorganic mineral TIG material was developed and applied to the modelling of a high geo‐temperature roadway. Moreover, the thermal insulation effect of the TIG layer was analyzed, and the temperature field characteristics of the TIG surrounding rock were discussed. Results reveal that (1) the TIG layer has a significant impact on the heat release of the wall and stability of the surrounding rock temperature field; (2) the initial temperature disturbance times, temperature disturbance ranges, and temperature drop rates differ with whether a TIG layer exists or not; (3) after the TIG roadway starts to be ventilated, the thermal flux densities tend to be consistent, which indicates the end of temperature disturbance; besides, the dimensionless temperature shares an exponential relation with the dimensionless radius; and (4) the characteristics of temperature drops vary with the radial positions of the surrounding rock. The research results provide a certain reference for thermal hazard control, temperature prediction, and ventilation network adjustment.

A passive thermal control method by radiative shield with multi-parameter adjustment capacity

To ensure the stability and reliability of the orbit transfer vehicle and its equipments, a multi-parameter adjustable radiative shield is adopted in the passive thermal control method. The principle of the radiative shield by radiation heat transfer is first expounded and the multi-parameter adjustment strategy is then thoroughly analyzed. Taking a typical power system which is used in orbital transfer vehicle as an example, temperature evolutions of the storage tank, pipelines and electrical equipments are obtained by numerical simulations. The thermal control results of the radiative shield method, in which the multi-parameter adjustable characteristic is dominated, is compared with those of thermal insulation technique. Comparison results indicated that the proposed passive thermal control method completely takes advantage of the thermal inertia and radiative properties of the radiative shield, which extends the high thermal flux at both time and spatial domains.

New Concept for Indoor Fire Fighting Robot

In this paper, a new concept of indoor firefighting robot is proposed and developed. It has the capability to climb stairs and negotiate several types of floor materials inside buildings. It can withstand high temperatures up to 700° C for about 60minutes using multiple thermal insulation technique. It can communicate with trapped and injured victims inside the fire seen and can send video and audio information to the control unit describing the fire environment inside the building. Several of those firefighting robots can be launched to work together collaboratively with the assistance of a remote control unit.

ＩＶ‐３‐１． クライオスタットの真空断熱

In the structure of any cryogenic system, thermal isolation of the low temperature environment must be achieved effectively. Fundamental thermal insulation techniques and heat transfer mechanisms are shown in the framework of cryostat design described below. Heat leaks onto a low temperature environment through the thermal insulation of the cryostat can be devided into three different mechanisms. (1) Gas conduction in void spaces contained between the insulation materials. (2) Radiation across these void spaces and through the components of the insulation. (3) Solids conduction through the insulation materials and contact heat transfer between individual components of the insulation. The type of vacuum insulation, such as evacuated powder insulation, plain vacuum insulation, and multilayer insulation (MLI), must be chosen suitably for a given cryogenic application. The selection must be aided by a study of the heat transfer in the particular vacuum insulation.