A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
The influence of natural convection on thermal properties of building enclosure with polystyrene boards/Putų polistireno plokštėmis izoliuotų pastatų sienų šiluminių savybių priklausomybė nuo natūralios konvekcijos
Building insulating materials with good insulation properties usually are porous, because they contain large amounts of air or other gas inside. The pore system can be closed, as in many cellular plastics, or open as in fibre materials. The mechanisms of heat transfer in porous material are: conduction in solid phase, radiation within material and conduction due to the gas confined in the insulation. In an open-pore material, like lightweight mineral wool, the transportation of heat can be further increased by air movement (convection) through the permeable material. Convection is impossible in a closed porous materials like polystyrene (EPS, XPS) boards. But heat losses can be increased by air movement if there are cracks between boards and other building envelope structures. The airflow velocity and direction may vary strongly due to the changing boundary condition. However, at the present time in Lithuania convection in insulating materials is considered as non-existent, when calculating heat transmission and designing building structures. Because of the lack of knowledge concerning air movement in external building structures, and how it is affecting the heat transfer, this investigation has been carried out. For research an equipment (Fig 2) was made, assigned for exploring both vertical and horizontal structures (height 2100 mm, width 1100 mm and thickness up to 300 mm). For reducing heat losses through the sides up to minimum, an equipment was built from slabs (thickness 150 mm). As the hot side of equipment gypsum board was applied to the surface of which 8 heat flow sensors and 9 thermocouples were attached. For maintaining constant and isothermal temperature of the surface of this partition (Θi, =+20°C), heating elements and ventilators were mounted inside the equipment. The cold surface of the equipment was of the same construction as the warm one only with the regulated slide valve with an area of 0,02 m2. It allows exploring the so-called not-ventilated structures. During the test, temperature was ...
The influence of natural convection on thermal properties of building enclosure with polystyrene boards/Putų polistireno plokštėmis izoliuotų pastatų sienų šiluminių savybių priklausomybė nuo natūralios konvekcijos
Building insulating materials with good insulation properties usually are porous, because they contain large amounts of air or other gas inside. The pore system can be closed, as in many cellular plastics, or open as in fibre materials. The mechanisms of heat transfer in porous material are: conduction in solid phase, radiation within material and conduction due to the gas confined in the insulation. In an open-pore material, like lightweight mineral wool, the transportation of heat can be further increased by air movement (convection) through the permeable material. Convection is impossible in a closed porous materials like polystyrene (EPS, XPS) boards. But heat losses can be increased by air movement if there are cracks between boards and other building envelope structures. The airflow velocity and direction may vary strongly due to the changing boundary condition. However, at the present time in Lithuania convection in insulating materials is considered as non-existent, when calculating heat transmission and designing building structures. Because of the lack of knowledge concerning air movement in external building structures, and how it is affecting the heat transfer, this investigation has been carried out. For research an equipment (Fig 2) was made, assigned for exploring both vertical and horizontal structures (height 2100 mm, width 1100 mm and thickness up to 300 mm). For reducing heat losses through the sides up to minimum, an equipment was built from slabs (thickness 150 mm). As the hot side of equipment gypsum board was applied to the surface of which 8 heat flow sensors and 9 thermocouples were attached. For maintaining constant and isothermal temperature of the surface of this partition (Θi, =+20°C), heating elements and ventilators were mounted inside the equipment. The cold surface of the equipment was of the same construction as the warm one only with the regulated slide valve with an area of 0,02 m2. It allows exploring the so-called not-ventilated structures. During the test, temperature was ...
The influence of natural convection on thermal properties of building enclosure with polystyrene boards/Putų polistireno plokštėmis izoliuotų pastatų sienų šiluminių savybių priklausomybė nuo natūralios konvekcijos
Samajauskas, Rolandas (author) / Stankevičius, Vytautas (author)
2000-08-31
doi:10.3846/13921525.2000.10531600
Journal of Civil Engineering and Management; Vol 6 No 4 (2000); 272-277 ; 1822-3605 ; 1392-3730
Article (Journal)
Electronic Resource
English
DDC:
690