HEAT EXCHANGER

PROBLEM TO BE SOLVED: To prevent the deterioration in heat exchange performance as a whole, while restraining functional stopping of a heat exchanger by deposit of a mineral component such as calcium of tap water only on the high temperature side, and realizing high heat exchange efficiency with a simple structure. SOLUTION: Water flows inside an inner pipe 2, and carbon dioxide oppositely flows in an annular part 6 between the inner pipe 2 and an outer pipe 4, and the high heat exchange efficiency is provided by securing the sufficient contact area with a safe double wall 3. The flow passage cross-sectional area on the outflow side 2b of the inner pipe 2 for flowing the water, is expanded more than the flow passage cross-sectional area on the inflow side 2a, and heat exchange stopping can be restrained without sealing a flow of the water even if the calcium included in the water deposits and sticks to a pipe wall 2b1 of the inner pipe 2 on the outflow side 2b. Since the water becomes the low temperature on the inflow side 2a, even if a spiral wire rod 7 is contained, sticking of a scale is eliminated, and a heat transfer rate is improved by disturbing the water while minimizing flowing resistance of the water, and reduction in the heat exchange performance as a whole of the heat exchanger 1 can be prevented. COPYRIGHT: (C)2006,JPO&NCIPI