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2586138 
Journal Article 
Energy Efficiency Analysis of Mixing Ventilation in a Ventilated Chamber -Comparison among Four Types of Diffusers 
Wang, Y; Lian, Z; Liu, J; Qi, D 
2009 
1348-1354 
WOS:000276109800183 
Previous papers have shown that physical parameters have great influence on thermal comfort and dispersion of contaminant concentration in mixing ventilation. However, the influence on energy efficiency was not shown. The purpose of the present work is to research air inlet type effect on energy efficiency of air distribution, and to determine more efficient air diffuser configurations.



Here, eight experiments of air distribution with four different kinds of diffusers (Line type down flow diffuser (LDD), round type horizontal flow diffuser (RHD), round type down flow diffuser (RDD) and square type horizontal flow diffuser (SHD)) are carried out in a full scale chamber under both cooling and heating conditions. In all of the tests, diffusers and return air vent were installed on the ceiling. Two flow rates (35 and 19m(3)/min) were employed individually in cooling and heating condition.



Based on the test data, comparisons of energy efficiency were conducted with energy utilization coefficient (EUC). In cooling condition, energy utilization coefficients of the four kinds of air distribution systems are similar, and close to 1. EUC of air distribution with RDD, wich is the highest, is a little higher (no more than 5%) than others. In heating condition, air distribution system with RDD is the most energy conservation. EUC of RDD is 25% higher than that of RHD, of which EUC is the lowest.



It was shown that air inlet type is an important physical determinant to energy efficiency because they generate different airflow patterns and thus different spatial temperature distribution. RDD was suggested to be employed in mixing ventilation system. Air distribution with RHD and SHD, discharge angle of which are horizontal flow, should be avoided, especially in heating condition. 
Mixing ventilation; Ceiling diffuser; Air distribution; Energy efficiency