A fuel cell system is disclosed that includes a heat exchanger having first and second heat exchanger portions arranged in a fluid flow passage. The second heat exchanger portion is arranged downstream from the first heat exchanger portion. The first and second heat exchanger portions include a coolant flow passage and are configured to transfer heat between the fluid flow and coolant flow passages. The first heat exchanger portion includes a first corrosion-resistant material and the second heat exchanger portion includes a second corrosion-resistant material that is less corrosion-resistant than the first corrosion-resistant material. A collector, which includes a tray and/or a mist trap, is configured to collect acid in the first heat exchanger portion from a gas stream in the fluid flow passage. Collected acid can be sprayed into a gas stream upstream from a flow field of the fuel cell.