Condensate drainage performance of a plain fin-and-tube heat exchanger constructed from anisotropic micro-grooved fins

In this research, the feasibility of using non-homogeneous, chemically-modified aluminum surfaces to more effectively manage condensate formation on a round-tube, plain-fin heat exchanger is explored. Surfaces having an anisotropic, patterned wettability may be preferred in HVAC&R applications since droplet motion can be restricted to one direction (i.e. downward with gravity) thereby mitigating condensate carryover into the occupied space. In this work, micro-grooved aluminum surfaces were created and then used to construct two prototype heat exchangers for testing. The results have shown that the micro-grooved structure of the fin surface in combination with an alkyl silane coating can reduce water retention by more than 27 percent. The new fin surface design was also shown to decrease the air-side core pressure drop of the prototype heat exchangers during wet operation by an average of 30–36 percent over the baseline heat exchanger, with the actual percentage strongly dependent on the flow rate.