Abstract: A heat exchange device utilizing variable tube materials is provided. In one particular embodiment, the heat exchange device is an evaporative condenser with a multi-pass tube bundle. The first few tube passes (typically 1-3 tube passes) of the tube bundle, which in operation are typically exposed to superheated refrigerant gas, are comprised of a material that is highly resistant to corrosion (e.g., 316/316L stainless steel). The remaining tube passes, which in operation are typically exposed to a lower-temperature refrigerant (i.e., saturated two-phase or subcooled liquid), are comprised of one or more lower-cost, less corrosion-resistant material (e.g., 304/304L stainless steel).

Abstract: A hot gas defrost condensate pan for collecting condensation from a refrigerator evaporator system is disclosed and claimed. In an embodiment, the condensate pan includes a heat exchanger with a header forming a closed loop and a tube bank disposed within the closed loop. The upper plane of the tube bank sits below the upper plane of the header, forming a recess in which an inner pan section sits. The header and tube bank collectively define a frame for the condensate pan. Further, the header surrounds the perimeter of the inner pan section, providing defrost heat in ice-prone areas. An outer pan section is provided on the underside of the heat exchanger. The inner pan section and the outer pan section are preferably seam welded to the heat exchanger, to protect the internal components of the condensate pan, and to prevent the ingress of dirt and bacteria.