Experimental Research On Enhancement Heat Transfer Of Lubricating-oil Cooler And Its Optimization Design

Currently, oil cooler is used in marine commonly with plain tubes as heat transfer components, which lead to the low efficiency of heat transfer and the large volume of heat exchanger. To resolve these problems, base on consulting a great deal of literatures and the conclusion of the predecessor's experience, a new type of longitudinal-flow oil cooler is designed, which use integral pin-fin tube and plain tube as heat transfer components, which are mixed and arranged in the oil cooler. For there is no baffle in the heat exchanger bundle, the volume of the oil cooler is greatly decreased, the heat transfer efficiency of the oil cooler is greatly improved, and the fabrication and installation of the oil cooler are more convenient.A lot of experimental research has been done to the new oil cooler. The experimental oil is the 68# turbine oil. At first, it is determined by experiment that the effect of cooling water inlet temperature, cooling water flow rate and the layout of the intake and the outlet of the oil on the heat transfer and resistance characteristics of the new oil cooler. Second, for embodying the characteristics of the new oil cooler, a concept of heat transfer per unit volume is introduced as the important parameter of heat exchange capability. And, compared with the plain tubes baffled oil cooler, in the experimental range and the same mass flow conditions, its heat transfer per unit volume is 1.6～2 times of latter, shell-side pressure drop is only the 30～39% of the latter and its integrated performance k/ΔP is 2.2～3.7 times of latter; In the same mass velocity, its heat transfer per unit volume is 3.4～3.8 times of latter, shell-side pressure drop is 1.3～1.5 times of the latter, heat transfer coefficient is 1.8～2.0 times of the latter and its integrated performance k/ΔP is 1.1～1.4 times of latter. Compared with he experimental data of other oil coolers with integral pin-fin tube as heat transfer components, its heat capacity in unit volume is the highest, and pressure is lower, integrated performance is superiority .Through analyzing and regressing to experimental data, the empirical correlations of the heat transfer coefficient and the friction coefficient of the new oil cooler are proposed respectively, and the calculative value agreed well with experimental data. And, based on experiments research, aiming at the problems to the new oil cooler in experiment, some suggestions are given for structure optimization of the new oil cooler and further developing.