Wyniki wyszukiwania - BazTech

1

The Flow and Heat Transfer Behavior of Liquid COMP-B3 in Slow Cook-off

Zhou Jie, Wang Shuai, Liu Zide, Zhang Haiyan, Pi Aiguo

Central European Journal of Energetic Materials

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2023

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Vol. 20, no. 3

340--363

EN

In order to investigate the flow and heat transfer characteristics of COMP-B3 under thermal stimulation, a series of slow cook-off experiments were designed and conducted, encompassing different sample sizes and heating conditions. The internal temperature profiles were captured using a high-speed data acquisition system. Subsequently, the internal flow and heat transfer conditions of the liquid COMP-B3 were analyzed through numerical simulations employing a non-Newtonian flow model. The results demonstrated the presence of heat convection within the liquid COMP-B3, regardless of sample sizes or heating conditions. However, it should be noted that the occurrence of heat convection is not necessarily observed at the onset of melting. The overall cook-off process can be categorized into three phases: solid (with melting), thermal conduction, and thermal convection. If convection occurs prior to the self-heating reaction, the direction of the flow field within the liquid COMP-B3 experiences a reversal near ignition. Additionally, a predictive method for the flow behaviour inside the liquid COMP-B3 during slow cook-off is proposed. Rough estimates of the flow conditions can be made based on the charge temperature, the internal temperature difference, and the characteristic length. Importantly, these phenomena are theoretically applicable to a wide range of mixed melt-cast explosives, extending beyond COMP-B3. The results provide additional reference value for further investigations into the ignition characteristics of mixed melt-cast explosives under thermal stimulation.

2

Practical aspects of heat conduction simulation in household heating optimization tasks

Duda Jan Tadeusz

Science, Technology and Innovation

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2019

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Vol. 5, no. 2

9--22

EN

Mathematical model selection for simulation heat conduction processes in household heating optimization task is considered. The essence of the matter is that the heat transfer dynamics properties are very diversified, so simulation procedure formulae and parameters should be properly selected to avoid excessive modeling errors with reasonable calculation time being held. The typical state-space model and analytical formulae for step response of the heat conduction across a homogeneous wall are presented and compared in terms of modeling errors. Formal and numerical problems of heat losses simulation are discussed. Semi-analytical step-response formulae for multilayer walls are derived and their accuracy is compared with effects of simulation based on the state-space model. Some recommendations for time and space discetization parameters are given.

3

Zastosowanie konwekcji cieplnej do określania kierunku przepływu dwuwymiarowego

Jamróz P.

Prace Instytutu Mechaniki Górotworu PAN

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2017

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T. 19, nr 1

35--43

PL

W artykule przedstawiono badania nad możliwością wykorzystania zjawiska konwekcji cieplnej do określania kierunku przepływów. Rozwiązanie takie mogłoby znaleźć zastosowanie w warunkach pomiarów przepływów cechujących się niskimi wartościami prędkości i fluktuacjami kierunku. W oparciu o przedstawioną ideę pomiaru opracowano prototypowy czujnik wyposażony w cienkie włókna termorezystancyjne pozwalające na określanie chwilowych wartości temperatury i wykonano badania laboratoryjne na stanowisku do pomiarów charakterystyk kątowych czujników termoanemometrycznych.

EN

The article presents studies on the use convective heat for determination the air fl ow direction. This solution could be applied in case of two-dimensional fl ows measurements, characterized by low velocity range and fl ow direction fl uctuations. Based on described idea of measurement, a prototype sensor was developed. The sensor was equipped with eight temperature probes made of the very thin (5 μm diameter) wires. The laboratory tests were performed using the modernised measurement stand dedicated to determine of anemometers sensors characteristic.

4

3D Numerical Simulation of Laminar Flow and Conjugate Heat Transfer through Fabric

Zhu G., Kremenakova D., Wang Y., Militky J., Mishra R., Wiener J.

Autex Research Journal

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2017

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Vol. 17, no. 1

53--60

EN

The air flow and conjugate heat transfer through the fabric was investigated numerically. The objective of this paper is to study the thermal insulation of fabrics under heat convection or the heat loss of human body under different conditions (fabric structure and contact conditions between the human skin and the fabric). The numerical simulations were performed in laminar flow regime at constant skin temperature (310 K) and constant air flow temperature (273 K) at a speed of 5 m/s. Some important parameters such as heat flux through the fabrics, heat transfer coefficient, and Nusselt number were evaluated. The results showed that the heat loss from human body (the heat transfer coefficient) was smallest or the thermal insulation of fabric was highest when the fabric had no pores and no contact with the human skin, the heat loss from human body (the heat transfer coefficient) was highest when the fabric had pores and the air flow penetrated through the fabric.

5

Application of pigfarms radiation heating systems

Makarukha O., Spodyniuk N., Zhelykh V.

Zeszyty Naukowe Politechniki Rzeszowskiej. Budownictwo i Inżynieria Środowiska

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2009

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z. 54 [266]

53-55

EN

The folIowing results of the investigation are shown: infrared heater's work with outlet in changing it's heating power and the quantity of exhaust air. The results of investigations can be used for projection of heating systems of pigfarms.