| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a heat exchanger for a heat pump type water heater of high pressure tightness and corrosion resistance while keeping high heat exchanging performance. <P>SOLUTION: This heat exchanger for a heat pump type water heater comprises a plurality of primary-side heat transfer tubes 20 composed of fine tubes of a circular cross-section, in which a refrigerant of high temperature and high pressure flows, and secondary-side heat transfer tubes 21 of the flat hollow shape, which have flat portions 21A, 21B on outer peripheries and in which hot water of low pressure flows, the plurality of primary-side heat transfer tubes 20 are respectively held between the flat portions 21A, 21B of the secondary-side heat transfer tubes, and spirally wound as a whole, and the primary-side heat transfer tubes 20 and the secondary-side heat transfer tubes 21 are joined and integrated by brazing processing. In the flat hollow-shaped secondary side heat transfer tubes 21, an inner end-side dimension HA between the flat portions 21A, 21B before winding is determined to be smaller than an outer end-side dimension HB. Voids Y not filled with the brazing material are formed among the plurality of primary-side heat transfer tubes 20, and the voids are opened to the atmospheric air at end portions of the primary-side heat transfer tubes 20. <P>COPYRIGHT: (C)2008,JPO&INPIT |
