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Long-stay parking in the fire load, the temperature of the power take off fast rise in the temperature of the output shaft bearing easily exceed the upper limit of the temperature of the national standard, and the impact of the fire engines and fire jobs. This article is for the power take existing fire engines to design a power take off an additional cooling device aims to solve the power take off to stop working because of the high temperature condition. First create a 3D geometric model of the power take off, its necessary simplified grid model to calculate the heat flux value of the gear surface and the bearing inner and outer rings, power take-in cabinets and outer surfaces, respectively calculate the corresponding convective heat transfer coefficient, finite element steady-state thermal power take cabinet, the cabinet steady-state temperature field distribution, the results show that the fire engines at full load for four hours work, taking force the temperature range of 345K to 382K, the surface temperature of the power take box is little change in the output shaft temperature reached 108.7 ° C beyond the state regulations PTO output shaft bearing temperature does not exceed 100 ° C standards. Spatial parameters on the basis of comprehensive consideration of fire engines, to ensure that the effect of heat transfer, low investment and operating costs, this choice of ordinary single-arched as power take oil heat exchanger shell and tube heat exchanger device. To establish 3D geometric model of the heat exchanger and the grid model, the use of standard K-ε model, standard wall function method using the FLUENT software to simulate the first six ordinary baffle heat exchanger shell side fluid convection heat transfer process . Paper comparing four different baffle spacing and four different baffles resection height four kinds baffle spacing respectively 250mm, 200mm, 85.6mm and 68.2mm, and four kinds of baffles resection height are 75% D, 65% D, 50% D and 25% D, through a comparative analysis of the temperature field, pressure field and velocity field, compared to the impact on the flow of the shell, studies have shown that when the baffle spacing decreases increase in the turbulence intensity of the shell-side fluid, the heat exchanger of the heat exchanger performance enhancement, the shell side fluid reflow phenomenon is also a corresponding reduction, but gradually increases shell side pressure drop, and decreasing the pitch showed increasing trend; when baffles resection height decreases, the increase in the turbulence intensity of the shell-side fluid, and the heat transfer performance of the heat exchanger to enhance the shell side fluid reflux phenomenon is also a corresponding reduction, but gradually increases shell side pressure drop, and with the resection height. decreases showed increasing trend; contrast found that when the heat exchanger baffle plate spacing smaller baffles resection height may be suitably increased baffle spacing is large the baffle plate can be reduced to the removal of height values, so that both can guarantee that the heat transfer performance of the heat exchanger can also be appropriate to reduce the pressure drop of the shell. Finally, the whole of the cooling device of the power take simulation study results show that equipped with a cooling device, power take off work after high-speed stage gear and bearing temperature dropped about 20K, the temperature value falls within the scope of the relevant provisions of the State.
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