scholarly journals Thermographic Analysis of Joints of Supporting Structures

2021 ◽  
Vol 51 (1) ◽  
pp. 94-103
Author(s):  
Laima Skridailaitė ◽  
Loreta Kelpšienė ◽  
Edita Mockienė

The external partitions of a building (walls, roof, etc.) in addition to their supporting functions must also ensure an internal microclimate suitable for comfortable human work, recreation and other activities. This article analyzes the thermal characteristics of the external walls of a residential house and thermographically examines the joints of the different structures of the building. Thermographical examination may be performed either passively or actively. In the former case, the object of the examination ir heated up to a given temperature, after which thermographical images of the object are taken and analyzed. In the latter case, thermographical analysis is made of the object in its naturally established thermal conditions. This article examines the thermal characteristics of the partition structures of a residential building. The values of the thermal properties of the materials are taken from the documentation provided by their manufacturers, and in their absence, the data of the technical building regulations is used. Calculated analytically: the wall of the western annex only meets the C energy class requirements, the insulation of the old part of the building raised the heat transfer coefficient of the partition to class A, the thermal characteristic of the eastern annex wall corresponds to the A + energy class. This thermographic examination showed that the facade covered by the fibrous cement siding absorbed less heat compared to the masonry facades. Based on theoretical calculations and the thermographic analysis, it is recommended to additionally insulate the western annex from the inside. If possible, it is also recommended to additionally insulate both facade joints with polyurethane foam and to seal them with waterproofing mastic to prevent the sunrays from reaching the foam.

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110208
Author(s):  
Yuan Zhang ◽  
Lifeng Wang ◽  
Yaodong Zhang ◽  
Yongde Zhang

The thermal deformation of high-speed motorized spindle will affect its reliability, so fully considering its thermal characteristics is the premise of optimal design. In order to study the thermal characteristics of high-speed motorized spindles, a coupled model of thermal-flow-structure was established. Through experiment and simulation, the thermal characteristics of spiral cooling motorized spindle are studied, and the U-shaped cooled motorized spindle is designed and optimized. The simulation results show that when the diameter of the cooling channel is 7 mm, the temperature of the spiral cooling system is lower than that of the U-shaped cooling system, but the radial thermal deformation is greater than that of the U-shaped cooling system. As the increase of the channel diameter of U-shaped cooling system, the temperature and radial thermal deformation decrease. When the diameter is 10 mm, the temperature and radial thermal deformation are lower than the spiral cooling system. And as the flow rate increases, the temperature and radial thermal deformation gradually decrease, which provides a basis for a reasonable choice of water flow rate. The maximum error between experiment and simulation is 2°C, and the error is small, which verifies the accuracy and lays the foundation for future research.


2021 ◽  
pp. 111030
Author(s):  
Jianming Yang ◽  
Huijun Wu ◽  
Xinhua Xu ◽  
Gongsheng Huang ◽  
Jian Cen ◽  
...  

2007 ◽  
Vol 74 (3) ◽  
pp. 774-782 ◽  
Author(s):  
Charles K. Lee ◽  
S. Craig Cary ◽  
Alison E. Murray ◽  
Roy M. Daniel

ABSTRACT The equilibrium model, which describes the influence of temperature on enzyme activity, has been established as a valid and useful tool for characterizing enzyme eurythermalism and thermophily. By introducing K eq, a temperature-dependent equilibrium constant for the interconversion between Eact, the active form of enzyme, and Einact, a reversibly inactive form of enzyme, the equilibrium model currently provides the most complete description of the enzyme-temperature relationship; its derived parameters are intrinsic and apparently universal and, being derived under reaction conditions, potentially have physiological significance. One of these parameters, T eq, correlates with host growth temperature better than enzyme stability does. The vent-dwelling annelid Alvinella pompejana has been reported as an extremely eurythermal organism, and the symbiotic complex microbial community associated with its dorsal surface is likely to experience similar environmental thermal conditions. The A. pompejana episymbiont community, predominantly composed of epsilonproteobacteria, has been analyzed metagenomically, enabling direct retrieval of genes coding for enzymes suitable for equilibrium model applications. Two such genes, coding for isopropylmalate dehydrogenase and glutamate dehydrogenase, have been isolated from the A. pompejana episymbionts, heterologously expressed, and shown by reverse transcription-quantitative PCR to be actively expressed. The equilibrium model parameters of characterized expression products suggested that enzyme eurythermalism constitutes part of the thermal adaptation strategy employed by the episymbionts. Moreover, the enzymes' thermal characteristics correspond to their predicted physiological roles and the abundance and expression of the corresponding genes. This paper demonstrates the use of the equilibrium model as part of a top-down metagenomic approach to studying temperature adaptation of uncultured organisms.


2020 ◽  
Vol 10 (2) ◽  
pp. 71-77
Author(s):  
Svetlana G. GOLOVINA

The paper presents a review of architectural and design techniques which were characteristic for residential development in the second half of the XVIII century in St. Petersburg. During that period, there was formed the urban planning, volumetric spatial and constructional structure of residential buildings, which later, in the XIX - early XX century, became a typical solution for residential development in St. Petersburg. The fi rewalled residential house was usually built along the perimeter of the possessory plot of land with an inner courtyard formed inside. The residential house consisted of a two-span front building and one-span side buildings located along the perimeter of the site. The constructional system of a residential building in the second half of the XVIII century was a vaulted-beam scheme along the longitudinal walls. The main construction structures are described, such as brick walls with subsequent fi nishing, strip stone footings based on wooden joists, roofs built on wooden batt er rafters in a cold att ic with no heating.


Author(s):  
Manish Sakhlecha ◽  
Samir Bajpai ◽  
Rajesh Kumar Singh

India is a rapidly growing economy witnessing continuous growth in the housing sector and living standards. The main focus of construction practices still remains on the architectural aspects of the buildings, largely unconcerned with their environmental impacts. The current thrust of concern for building sector, especially in developing countries, is to assess the environmental impact of buildings in a quantifiable way for implementing sustainable measures and achieving sustainability. Lifecycle assessment (LCA) is a comprehensive tool that is used worldwide to assess the environmental performance of any product or a process. This paper assesses the environmental impact of a residential house at planning stage on the basis of lifecycle assessment (LCA) considering various stages of building like construction, operation (for service life) and demolition, and identifies the hot-spots in the form of building components, materials, and stages.


Buildings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 217 ◽  
Author(s):  
Joanna Krasoń ◽  
Przemysław Miąsik ◽  
Lech Lichołai ◽  
Bernardeta Dębska ◽  
Aleksander Starakiewicz

The article presents a comparative analysis carried out using three methods, determining the heat transfer coefficient U for a ceramic product modified with a phase change material (PCM). The purpose of the article is to determine the convergence of the resulting thermal characteristics, obtained using the experimental method, numerical simulation, and standard calculation method according to the requirements of PN-EN ISO 6946. The heat transfer coefficient is one of the basic parameters characterizing the thermal insulation of a building partition. Most often, for the thermal characteristics of the partition, we obtain from the manufacturer the value of the thermal conductivity coefficient λ for individual homogeneous materials or the heat transfer coefficient U for the finished (prefabricated) partition. In the case of a designed composite element modified with a phase change material or other material, it is not possible to obtain direct information on the above parameter. In such a case, one of the methods presented in this article should be used to determine the U factor. The U factor in all analyses was determined in stationary conditions. Research has shown a significant convergence of the resulting value of the heat transfer coefficient obtained by the assumed methods. Thanks to obtaining similar values, it is possible to continue tests of thermal characteristics of partitions by means of numerical simulation, limiting the number of experimental tests (due to the longer test time required) in assumed different partition configurations, in stationary and dynamic conditions.


Author(s):  
Eric M. Burger ◽  
Scott J. Moura

Model predictive control (MPC) strategies hold great potential for improving the performance and energy efficiency of building heating, ventilation, and air-conditioning (HVAC) systems. A challenge in the deployment of such predictive thermo-static control systems is the need to learn accurate models for the thermal characteristics of individual buildings. This necessitates the development of online and data-driven methods for system identification. In this paper, we propose an autoregressive with exogenous terms (ARX) model of a thermal zone within a building. To learn the model, we present a backpropagation approach for recursively estimating the parameters. Finally, we fit the linear model to data collected from a residential building with a forced-air heating and ventilation system and validate the accuracy of the trained model.


2019 ◽  
Vol 111 ◽  
pp. 06014
Author(s):  
Andrew Lyden ◽  
Paul Tuohy

Decentralised energy systems provide the potential for adding energy system flexibility by separating demand/supply dynamics with demand side management and storage technologies. They also offer an opportunity for implementing technologies which enable sector coupling benefits, for example, heat pumps with controls set to use excess wind power generation. Gaps in this field relating to planning-level modelling tools have previously been identified: thermal characteristic modelling for thermal storage and advanced options for control. This paper sets out a methodology for modelling decentralised energy systems including heat pumps and thermal storage with the aim of assisting planning-level design. The methodology steps consist of: 1) thermal and electrical demand and local resource assessment methods, 2) energy production models for wind turbines, PV panels, fuel generators, heat pumps, and fuel boilers, 3) bi-directional energy flow models for simple electrical storage, hot water tank thermal storage with thermal characteristics, and a grid-connection, 4) predictive control strategy minimising electricity cost using a 24-hour lookahead, and 5) modelling outputs. Contributions to the identified gaps are examined by analysing the sensible thermal storage model with thermal characteristics and the use of the predictive control. Future extensions and applications of the methodology are discussed.


Batteries ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 3 ◽  
Author(s):  
Gerd Liebig ◽  
Ulf Kirstein ◽  
Stefan Geißendörfer ◽  
Frank Schuldt ◽  
Carsten Agert

To draw reliable conclusions about the thermal characteristic of or a preferential cooling strategy for a lithium–ion battery, the correct set of thermal input parameters and a detailed battery layout is crucial. In our previous work, an electrochemical model for a commercially-available, 40 Ah prismatic lithium–ion battery was validated under heuristic temperature dependence. In this work the validated electrochemical model is coupled to a spatially resolved, three dimensional (3D), thermal model of the same battery to evaluate the thermal characteristics, i.e., thermal barriers and preferential heat rejection patterns, within common environment layouts. We discuss to which extent the knowledge of the batteries’ interior layout can be constructively used for the design of an exterior battery thermal management. It is found from the study results that: (1) Increasing the current rate without considering an increased heat removal flux at natural convection at higher temperatures will lead to increased model deviations; (2) Centralized fan air-cooling within a climate chamber in a multi cell test arrangement can lead to significantly different thermal characteristics at each battery cell; (3) Increasing the interfacial surface area, at which preferential battery interior and exterior heat rejection match, can significantly lower the temperature rise and inhomogeneity within the electrode stack and increase the batteries’ lifespan.


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