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DETERMINATION OF HEAT TRANSFER COEFFICIENTs UNDER CLIMATIC CONDITIONS OF ISTANBUL. Mustafa Kemal Kaymak and Ahmet Duran Şahin İstanbul Technical University, Aerospace and Aeronautics Faculty, Meteorology Department, Energy Group, 80626 Maslak/İstanbul
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Mustafa Kemal Kaymak and Ahmet Duran Şahin
İstanbul Technical University, Aerospace and Aeronautics Faculty,
Meteorology Department, Energy Group, 80626 Maslak/İstanbul
Airflow around buildings affects weather and pollution protection at inlets, and the ability to control environmental factors of temperature, humidity, air motion, and contaminants.
As known that topographical conditions are very important for calculation of wind profile at different heights. Roughness length represents sea, shore, land/complex topography and urban areas effects to the wind profile. For urban area roughness length is suggested to consider as 1.5 m or over this value.
In here,V1 represents measured wind speed values at 10 m that is reference level for this paper and V2represents wind speed at desired building height.
In addition to this, as mentioned before roughness length changes from sea level to complex urban topographical conditions.
In order to satisfy the minimisation of supplementary mechanical energy demand, the optimum value of the overall heat transfer coefficient for opaque components should be determined in terms of the climatic conditions of the predominant period for the region.
Figure Wind profile changes during day for different heights in Sarıyer-İstanbul
Calculation of external surface heat coefficient, hw at different heights of buildings depends on wind velocity is the main approach of this study.
for leeward as
hw = 7.4 + 4.0 V
hw = 4.2 + 3.5 V
Figure Heat loss coefficient variation during day for different heights in Sarıyer-İstanbul on windward side.
For leeward side of the building approximately 25% less than windward heat losses occur. Atmospheric boundary layer conditions also effect low level urban conditions on the leeward side.
Figure . Heat loss coefficient variation during day for different heights in Sarıyer-İstanbul at leeward side.
Summation of WCB gives heating or cooling degree of the building.