PURPOSE:To improve the heat transfer efficiency of a heat exchanger without making the heat exchanger large-sized by a mthod wherein in the heat exchanger for a clothing drier, plastic pipes each formed by winding a plastic film about a mandrel with the side edges of the turns of the pipe overlapped partially are used as heat transfer pipes. CONSTITUTION:The plastic film in the form of a tape made of polyester is wound aslant about the small cylindrical mandrel 2 with the side edges of the turns of the film partially and the overlapped parts are bonded with a thermohardening acrylic bond to thereby produce the plastic pipe. Then a plurality of such plastic pipes are held between plastic support plates 3. Thus, when the plastic pipes are used as the heat transfer pipes, it is possible to increase the strength of the heat exchanger, to make the heat exchanger small-sized and to increase the number of the pipes so that the heat transfer efficiency of the heat exchanger is improved.
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