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The general definition of the heat transfer coefficient is: where: : heat flux (W/m²); i.e., thermal power per unit area, : difference in temperature between the solid surface and surrounding fluid area (K) The heat transfer coefficient is the reciprocal of thermal insulance. This is used for building materials (R-value) and for clothing ...
Thermal transmittance. Thermal transmittance is the rate of transfer of heat through matter. The thermal transmittance of a material (such as insulation or concrete) or an assembly (such as a wall or window) is expressed as a U-value. The thermal insulance of a structure is the reciprocal of its thermal transmittance.
An example of lateral earth pressure overturning a retaining wall. The lateral earth pressure is the pressure that soil exerts in the horizontal direction. It is important because it affects the consolidation behavior and strength of the soil and because it is considered in the design of geotechnical engineering structures such as retaining walls, basements, tunnels, deep foundations and ...
The effectiveness of bulk insulation is commonly evaluated by its R-value, of which there are two – metric (SI) (with unit K⋅W −1 ⋅m 2) and US customary (with unit °F⋅ft 2 ⋅h/BTU), the former being 0.176 times the latter numerically, or the reciprocal quantity the thermal conductivity or U-value W⋅K −1 ⋅m −2.
Ground-coupled heat exchanger. A qanat and windcatcher used as an earth duct, for both earth coupling and evaporative cooling. No fan is needed; the suction in the lee of the windtower draws the air up and out. A ground-coupled heat exchanger is an underground heat exchanger that can capture heat from and/or dissipate heat to the ground.
A basement wall is thus one kind of retaining wall; however, the term usually refers to a cantilever retaining wall, which is a freestanding structure without lateral support at its top. [2] These are cantilevered from a footing and rise above the grade on one side to retain a higher level grade on the opposite side.
law of the wall, horizontal velocity near the wall with mixing length model. In fluid dynamics, the law of the wall (also known as the logarithmic law of the wall) states that the average velocity of a turbulent flow at a certain point is proportional to the logarithm of the distance from that point to the "wall", or the boundary of the fluid region.
The insulation in the windward and leeward walls is behaving dynamically in the contra-flux mode with U-values of 0.0008 W/(m 2 K) and 0.1 W/(m 2 K) respectively. Since the building has a square footprint the average U-value for the walls is 0.1252 W/m 2 K. For other wind speeds and directions, the U-values will be different.