A heat and mass exchanger system comprising: a first array of tubes, each of said tubes having an coating of a desiccant about a peripheral surface; an interstitial space between said tubes, said interstitial space arranged to receive a fluid, such that at least a portion of the peripheral surface is a wetted area of said fluid; said tubes arranged to transport a heat transfer liquid within an internal bore, said fluid and heat transfer liquid in heat transfer communication; wherein the cross sectional shape of each of said tubes is convex.