Performance comparison of heat exchangers with different circuitry arrangements for active chilled beam applications

•This paper gives the first reported research about heat exchanger issues for ACB.•Four different circuitry arrangements are investigated.•The effectiveness of circuitry adjustment to ACB terminal unit is confirmed.•The unexpected conclusion indicates much potential improvement of ACB system.

This paper presents a performance comparison study of heat exchangers with different circuitry arrangements for active chilled beam (ACB) applications. Supported by a two-way discharge ACB terminal unit and a performance test pilot plant, four 2-rows plain fin and tube heat exchangers, namely, 1-circuit, 2-circuits, 4-circuits, and 8-circuits, are investigated under a wide range of chilled water volume flow rates. The chilled water side thermal and hydraulic characteristics are evaluated. The heat transfer rates are compared under three sets of criteria: identical water volume flow rate, identical pressure drop, and identical pumping energy consumption. Meanwhile, the comparisons are also performed in terms of two non-dimensional parameters: heat exchanger effectiveness and performance index. The study shows that different circuitry arrangements should be preferred in different operation conditions and under different evaluation criteria, while the 2-circuits arrangement is the most comprehensive and reasonable option rather than the 1-circuit one that is widely used in all available ACB products.