| 摘要 |
A heat exchanger 11 comprises a heat exchanger matrix 12, header tanks 13, 14 and a side plate 16 arranged at the upper of a pair of opposite side edges 17 of the matrix. The matrix comprises tubes 18 which extend in a parallel array between the header tanks and cooling fins (19, fig.2). In use, air flows not only between adjacent pairs of tubes but also between the side plate and its adjacent tube. A heat transfer restrictor, such as a restrictor plate 21, is arranged on the side plate 16 to restrict the flow of air between the side plate and the adjacent, uppermost, tube 18A. Preferably, the restrictor plate is in the form of a rectangular blanking plate which blocks the flow of air between the side plate and the uppermost tube over part of its length and allows air to flow through cut-out gaps or castellations 22 over the remainder. This reduces heat transfer through the fins above the uppermost tube by blocking the air flow over part of their length. The restrictor plate may alternatively comprise a perforated blanking plate or a strip of constant width extending the length of the side plate. The restrictor plate is preferably attached to, or forms part of, a cooling fan cowl. In use, the heat exchanger is designed to prevent the tubes which are adjacent to the side plates from being overcooled. The reduced heat transfer allows for an even temperature distribution in the uppermost tube 18A and the tube 18B below and thus reduces the stress from thermal expansion; this reduces the risk of coolant loss due to stress cracking of the tubes or tube to header tank joint. The heat exchanger may be arranged as a cross-flow radiator for an engine cooling system. |
