Using POD to Characterise Panel Backside Heat Losses

2014 ◽  
Author(s):  
A. F. Emery
Keyword(s):  
Composite Structures ◽  
Heat Losses ◽  
Short Paper ◽  
Alternative Analysis ◽  
Temperature Variations ◽  
Metal Structures ◽  
Repair Site ◽  
Heating And Cooling ◽  
High Thermal Resistance ◽  
Proper Orthogonal

Repairing composite structures requires heating the repair site to a specific temperature and holding it at this temperature for a length of time. This is usually accomplished by placing a heating blanket over the repair site or by thermally radiating it. In either case, significant heat conduction occurs through the composite repair zone resulting in spatial variations in temperature. In general, one has access only to one side of the structure and is not aware of the specific nature of conditions on the backside. It is not uncommon for the backside structure in the neighborhood of the repair site to be such that the heat transfer is inhibited by pockets of trapped air or increased by metal structures. If the applied heat can be spatially controlled it is possible to eliminate temperature variations in the repair zone. This short paper describes attempts to estimate backside heat losses, or at a minimum to detect the presence/magnitude of these losses. Early attempts to estimate these losses by parameter estimation proved not to be adequate. The test was modified to include a backside heat sink, but thermocouple measurements suggested that there was negligible effect. The use of proper orthogonal decomposition of thermographic images taken during heating and cooling was considered as an alternative analysis. The POD indicated that there was no substantial heat loss to the sink because of the high thermal resistance of the panel. Given this finding, it appears that eliminating spatial temperature variations can only be done by active control of the heat source.

scholarly journals Investigation of Bath/Freeze Lining Interface Temperature Based on the Rheology of the Slag

JOM ◽  
2021 ◽  
Author(s):  
Samant Nagraj ◽  
Mathias Chintinne ◽  
Muxing Guo ◽  
Bart Blanpain
Keyword(s):  
Thermal Degradation ◽  
Thermal Resistance ◽  
Conceptual Framework ◽  
Batch Process ◽  
Heat Losses ◽  
Interface Temperature ◽  
Freeze Lining ◽  
High Thermal Resistance ◽  
Critical Viscosity ◽  
Physical And Chemical

AbstractFreeze lining is a solidified layer of slag formed on the inner side of a water-cooled pyrometallurgical reactor, which protects the reactor walls from thermal, physical, and chemical attacks. Because of the freeze lining's high thermal resistance, the reactor heat losses strongly depend on the freeze lining thickness. In a batch process such as slag fuming, the conditions change with time, affecting the freeze lining thickness. Determining the freeze lining thickness is challenging as it cannot be measured directly. In this study, a conceptual framework based on the morphology and microstructure of freeze lining and the rheology of the slag is discussed and experimentally evaluated to determine the freeze lining thickness. It was found that the bath/freeze lining interface lies just below critical viscosity temperature. The growth of the freeze lining is primarily controlled by the mechanical and thermal degradation of the crystals forming at the interface. The bath/freeze lining interface temperature for the measured slag lies in the range of 1035–1070°C.

scholarly journals The use of slotted – displacement ceiling diffuser in rooms with stationary workplaces with computer equipment

2019 ◽  
Vol 100 ◽  
pp. 00090
Author(s):  
Agnieszka Zając
Keyword(s):  
Vertical Plane ◽  
Heat Losses ◽  
Public Utility ◽  
Air Distribution ◽  
Transverse Axis ◽  
Heating And Cooling ◽  
Computer Equipment ◽  
Air Stream ◽  
Plane Passing ◽  
Winter Time

This paper presents a specification of premises with a stationary workstations. An analysis of thermal loads occurring in a public utility rooms equipped with a computer, electronic and multimedia equipment was carried out. Attention was drawn to an annual occurrence of a positive heat balances in an occupied workstations and heat losses in winter time in unoccupied premises. For an air distribution a slotted displacement ceiling diffuser was proposed, used for mixing ventilation (MV) in up-up type of air exchange in room. The results of measurements in the form of air flows in the area of its operation are provided. The graphs show the graphical distribution of air velocities and temperatures in the vertical plane passing through the transverse axis of the air diffuser. The study focused on one of the representative airflow of supply air and the behaviour of the air stream during heating and cooling was presented.

scholarly journals Investigation on Relative Heat Losses and Gains of Heating and Cooling Networks

2021 ◽  
Vol 25 (1) ◽  
pp. 479-490
Author(s):  
Violeta Madan ◽  
Ingo Weidlich
Keyword(s):  
District Heating ◽  
Energy System ◽  
Heat Losses ◽  
Heat Sources ◽  
Temperature Level ◽  
Near Surface ◽  
Heating And Cooling ◽  
Surface Soil Temperature ◽  
Steady State Heat ◽  
Sustainable Energy System

Abstract The integration of district heating (DH) and cooling (DC) in the sustainable energy system of the future requires a significant reduction in operating temperatures. Supply temperatures below 70 °C are required for new 4th Generation DH. Main benefits are the use of low exergy heat sources and the reduction of heat losses. The reduction of heat losses is achieved by reducing the driving temperature difference between the medium pipe and the ground. The decrease of the return temperature level is limited by the consumer behaviour and the ground temperature level. As a consequence, the reduction of the supply temperature is accompanied by a reduction of the maximum transmittable heat flow. For energy efficiency and economic reasons, the relative heat losses are therefore an important design value for DH networks. The study proposes an approach to estimate the relative heat losses by using steady-state heat loss models and analyses the values for different DH generations. In particular, due to the rising of the near-surface soil temperature, the relative cold losses are also studied.

scholarly journals The Right Amount of Technology in School Buildings

2020 ◽  
Vol 12 (3) ◽  
pp. 1134 ◽  
Author(s):  
Thomas Auer ◽  
Philipp Vohlidka ◽  
Christine Zettelmeier
Keyword(s):  
Energy Demand ◽  
Age Groups ◽  
Heat Losses ◽  
School Buildings ◽  
School Construction ◽  
Passive House ◽  
Technical Aspects ◽  
Heating And Cooling ◽  
The Right ◽  
Indoor Comfort

What is an adequate school building nowadays and which amount of technology does it need? How high is the indoor comfort in terms of thermal, visual, hygienic, and acoustical comfort? Are there technical aspects that stand out to other solutions? How do users feel and act in the buildings? For this purpose, the Chair compared, in total, twelve selected modern, older, and renovated school buildings from different building age groups. For the comparison, it was essential to intensively analyze each of the twelve schools. This included visiting the schools, talking with the participating architects, specialist planners, builders, and school managers, procuring and analyzing planning documents and, where available, publications and reports, performing simulations and measurements in the classrooms, and surveying the buildings’ users. The predominant energy demand in schools is the energy expenditure for heating and cooling the air, especially for heating the air in the winter. Nevertheless, it turns out that from a purely energy-focused perspective, mechanical ventilation cannot be justified. It is also evident that transmission heat losses play a negligible role in school construction, which is why the “passive house” as a goal for renovations must be called into question.

Interaction of Heat Transfer by Conduction, Convection, and Radiation in a Radiating Fluid

1963 ◽  
Vol 85 (4) ◽  
pp. 318-328 ◽  
Author(s):  
R. Viskanta
Keyword(s):  
Heat Transfer ◽  
Energy Transport ◽  
Relative Role ◽  
Heat Transfer Characteristics ◽  
Temperature Variations ◽  
System Parameters ◽  
Heating And Cooling ◽  
Finite Distance ◽  
Parallel Surfaces

Consideration is given to the interaction of conduction, convection, and radiation in a fully developed laminar flow. The flat duct consists of two diffuse, nonblack, isothermal parallel surfaces a finite distance apart; the fluid between them emits and absorbs thermal radiation. The problem is formulated in terms of a nonlinear integro-differential equation, and the solution is obtained by a method employed by Barbier. Numerical examples show the influence of the system parameters such as the optical thicknesses, the ratio which determines the relative role of energy transport by conduction to that by radiation, the emissivity of the duct walls as well as the differences between heating and cooling on the temperature variations across the duct and on the heat-transfer characteristics. Two methods for obtaining approximate temperature distributions for optically transparent and opaque radiating media are outlined and the results discussed.

Experimental Validation of a Shape Memory Alloy Constitutive Model by Heterogeneous Thermal Loading Using Infrared Thermography and Digital Image Correlation

2013 ◽  
Author(s):  
Stephen R. Cornell ◽  
Darren J. Hartl ◽  
Dimitris C. Lagoudas
Keyword(s):  
Digital Image Correlation ◽  
Constitutive Model ◽  
Infrared Thermography ◽  
Digital Image ◽  
Thermal Loading ◽  
Mechanical Response ◽  
Image Correlation ◽  
Short Paper ◽  
Heating And Cooling ◽  
Localized Heating

This work introduces the use of digital image correlation together with infrared thermography to study non-uniform deformations due localized heating of equiatomic NiTi. While this short paper focuses on demonstrating the mechanical response of the material to localized heating, future work will also demonstrate calibration and validation of a 3-D constitutive model of the material using the concepts presented here. A comparison is made between the behavior of the material due to localized heating and the behavior due to uniform heating and cooling. The relevant parameters used for calibration of the constitutive model are quantified using the results of an ambient heating and cooling experiment.

scholarly journals Trombe Wall Application with Heat Storage Tank

2019 ◽  
Vol 5 (7) ◽  
pp. 1477-1489 ◽  
Author(s):  
Kıvanç Topçuoğlu
Keyword(s):  
Reinforced Concrete ◽  
Heat Storage ◽  
Heat Losses ◽  
Paraffin Wax ◽  
Concrete Wall ◽  
Heating And Cooling ◽  
Reinforced Concrete Wall ◽  
Trombe Wall ◽  
Wall System ◽  
Heat Store

In this study, an investigation was made of the performance of a Trombe wall of classical structure used together with a heat store. Most Trombe walls are able to supply the heating needs of a space to which they are connected without the need for extra heating at times when the sun is shining. However, the heat obtained from the Trombe wall can be in excess of needs at such times, and measures must be taken to provide ventilation to the heated space. It is thought that the heat energy can be used more efficiently and productively by storing the excess heat outside the building and using it inside the building when there is no sunlight. To this purpose, a tank full of water and marble was built as a heat store as an alternative to the general Trombe wall design, and an attempt was made to minimise heat losses by burying it in the ground. It was concluded that in place of a traditional Trombe wall system using a massive wall heat store, a heat store could be constructed in a different position and with different materials. The Trombe wall system which was developed and tested met up to 30% of the energy needed for heating and cooling the building, and reduced the architectural and static disadvantages of Trombe wall systems. As a result of the study, it was seen that where a standard reinforced concrete wall could supply heat to the inside for 7 hours and 12 minutes, the figure for a wall made of paraffin wax was 8 hours and 55 minutes. In the same study, the heat storage thickness of a reinforced concrete wall was calculated as 20 cm, while that of a paraffin wax wall was calculated as 5 cm.

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