Abstract
In the rooms with dominant sensible heat load, volume airflow depends on many factors incl. pre-established temperature difference between exhaust and supply airflow. As the temperature difference is getting higher, airflow volume drops down, consequently, the cost of AHU is reduced. In high industrial halls with air exhaust grids located under the ceiling additional temperature gradient above working zone should be taken into consideration. In this regard, experimental research of the vertical air temperature gradient in high industrial halls were carried out for the case of mixing ventilation system The paper presents the results of air temperature distribution measurements in high technological hall (mechanically ventilated) under significant sensible heat load conditions. The supply airflow was delivered to the hall with the help of the swirl diffusers while exhaust grids were located under the hall ceiling. Basing on the air temperature distribution measurements performed on the seven pre-established levels, air temperature gradient in the area between 2.0 and 7.0 m above the floor was calculated and analysed.
Highlights
To calculate of volume airflow in mechanical ventilation systems, it’s necessary to establish maximum allowed air temperature increase between air supply and exhaust zone
Fig.4. and Fig.5. present air temperature changes and average air temperature gradient observed in April 2014 (Fig. 4) and in July and August (Fig. 5) 2014
Temperature in the operating zone was at the level of 26°C and temperature of exhaust air was at the level of 29°C
Summary
To calculate of volume airflow in mechanical ventilation systems, it’s necessary to establish maximum allowed air temperature increase between air supply and exhaust zone This issue is quite easy for the rooms with relatively low height (h ≤ 4 m) and for the rooms where exhaust element is located in users’ operating zone. On the other hand, when temperature increase over operating zone (without impairing conditions in this zone) will be taken into account, lower air flow rates will be necessary for ventilation (resulting in air treatment costs reduction) This problem is crucial in rooms where due to constructional or technological requirements, air must be blown from the top of the room and exhaust grids are high above occupied zone. Discussed issue was not described satisfactory for higher rooms (h>4m) with significant heat load
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