A heat exchanger includes a plurality of tubes wherein at least some of the tubes are elliptical or oval in cross section and each tube includes a longitudinal axis. Each elliptical tube includes a major axis and a minor axis. The plurality of tubes is arranged in a radial pattern such that the major axes of the elliptical tubes intersect a centerline of the heat exchanger. The plurality of tubes is connected to a heater mount and a heater is also connected to the heater mount. A securing element holds the plurality of tubes, the heater and the heater mount together. A tube liner can extend along the longitudinal axis of at least one of the elliptical or oval tubes of the plurality of tubes. If a tube liner is employed, a purge fluid flow channel is defined between an outer periphery of the tube liner and an inner periphery of at least one of the elliptical or oval tubes of the plurality of tubes.