Wyniki wyszukiwania - BazTech

1

Numerical Investigation of Heat Transfer in Garment Air Gap

Zhang Yijie, Jia Juhong

Autex Research Journal

|

2022

|

Vol. 22, no. 1

89--95

EN

This article aimed to study the characteristics and mechanisms of 3D heat transfer through clothing involving the air gap. A three-dimensional finite volume method is used to obtain the coupled conductive, convective, and radiative heat transfer in a body-air-cloth microclimate system. The flow contours and characteristics of temperature, heat flux, and velocity have been obtained. The reason for the high flux and temperature regions was analyzed. Computational results show that the coupled effect of the air gap and the airflow between the skin and garment strongly influences the temperature and heat flux distribution. There are several high-temperature regions on the clothing and high heat flux regions on the body skin because the conductive heat flux can cross through the narrow air gap and reach the cloth surface easily. The high-speed cooling airflow brings about high forced convective heat flux, which will result in the temperature increase on the upper cloth surface. The radiative heat flux has a strong correlation with the temperature gradient between the body and clothing. But its proportion in the total heat flux is relatively small.

2

Study on the Solar Radiation and Heat Transfer of Cabin Fabric Using the Finite Volume Method

Zhang Yijie, Jia Juhong

Fibres & Textiles in Eastern Europe

|

2021

|

Vol. 29, no. 2 (146)

41--47

EN

The heat transfer of different fabrics was investigated numerically in the cabin of an aircraft. The discrete ordinate (DO) radiation model was adopted to describe the solar radiation through the cabin window and the fabric’s reflection. The conjugate heat transfer between the air flow and the seat fabric was included to study the influence of the textile type and fabric thickness. Some important parameters such as the temperature, radiative heat flux, and heat transfer coefficient on the fabric surface were evaluated. The results showed that both altering of the textile type and thickness will bring about the variation of temperature on the cushion surface. The carbon fibre yarn seat and thinner padding fabric provide a much more enjoyable environment than others. The air circulation in the cabin can improves the thermal environment to some degree.

PL

W pracy zbadano przenikanie ciepła różnych tkanin stosowanych w kabinie samolotu. Do opisu promieniowania słonecznego wpadającego przez okno kabiny i odbicia tkaniny został przyjęty model promieniowania na osi rzędnych dyskretnych (DO). Zbadano wpływ rodzaju tkaniny i grubości tkaniny uwzględniając przenoszenie ciepła koniugatu między przepływem powietrza a tkaniną siedziska. Oceniono niektóre ważne parametry, takie jak: temperatura, strumień ciepła promieniowania i współczynnik przenikania ciepła na powierzchni tkaniny. Wyniki pokazały, że zarówno zmiana rodzaju, jak i grubości tkaniny powoduje zmianę temperatury na powierzchni poduszki. Stwierdzono, że siedzisko z włókna węglowego i cieńsza tkanina wyściełająca zapewniają znacznie przyjemniejsze środowisko, a cyrkulacja powietrza w kabinie może w pewnym stopniu poprawić warunki termiczne.

3

Numerical Simulation of Solar Radiation and Conjugate Heat Transfer through Cabin Seat Textile

Zhang Yijie, Jia Juhong

Autex Research Journal

|

2021

|

Vol. 21, no. 4

501--507

EN

The solar radiation and the conjugate heat transfer through the cabin seat fabric were investigated numerically with a focus on a comparative analysis of various fabric solar reflectance or reflectivity (SR) and inlet cooling air velocity. For this purpose, 3D compressible Reynolds-averaged Navier–Stokes equations with the low Reynolds number turbulence model were utilized to simulate the airflow in the cabin. The discrete ordinate radiation model was adopted to describe the solar radiation. The conjugate heat transfer between the airflow and the fabric seats was included. The airflow temperature, radiative heat flux, and radiative heat transfer through the fabrics in a fixed cross section were studied. The results demonstrate that the increase in fabric SR leads to the increase in energy reflected to the atmosphere, which will bring about a lower temperature on the seat fabric. The decrease in emissivity and the energy absorbed results in the lower heat transfer and heat radiation and leads to the improvement of the cabin thermal environment. The high-temperature gradient near the seat causes the forced air circulation and is beneficial for the improvement of the thermal comfort. However, the cooling effect is not so obvious near the cabin seats when the inflow speed is increased.