| 摘要 |
PURPOSE:To reduce the thermal strain of an upper tube plate by a structure wherein the flow passage openings of straightening plates arranged around an outer shround are changed along the peripheral direction of the straightening plates so as to uniformize the flow rate of coolant passing through the straightening plates in the peripheral direction of the straightening plates. CONSTITUTION:A straightening plate 50 is divided into 6 parts, each of which is nearly fan-shaped and in each of which a large number of flow passage opening 52 are formed as same in number along the parts. The size of the opening 52 is made larger in the opening ratio (or opening area) at the primary fluid inlet nozzle side (or 0 deg. side) and smaller in the opening ratio at the side opposite to the primary fluid inlet nozzle (or 180 deg. side). Consequently, because the primary fluid passing through the openings at 180 deg. part is subjected to larger resistance than the primary fluid passing through the openings at 0 deg. part, the rate of the flow passing through the straightening plates 50 is uniformized peripherally. Accordingly, the primary fluid flowing through inlet windows 32 into the outer shroud 30 is uniform peripherally, resulting in uniformly heating a heat tube bundle 24. As a result, the heat transfer characteristics of the heat exchanger can be improved and the stress of the upper tube plate 14 due to the thermal strain can be reduced. |
