The present invention provides heat transfer apparatus and method for enhancing the heat transfer of fluid passing along a tubular heat exchange surface including positioning a heat exchange insert of planar or, sheet-like shape to form an unobstructed area of about 20%-80% of the tubular cross section. The heat exchange insert is constructed of a material having an absorptance and emittance to provide high radiative heat transfer over a substantially unobstructed line of sight between the insert surface and the tubular surface. Heat exchange inserts are further positioned in the tube or pipe to increase the mass of fluid contacting the insert by alternating the position of insert in the tube.