Combine harvester working conditions are harsh, not only the ambient temperature is high, dust is large, but the full load operation time is long, so the supporting diesel engine often suffers from poor heat dissipation due to poor heat dissipation and poor heat dissipation occurs, radiator tank boiling, cylinder pull cylinder and Other heat malfunction. This issue has plagued the overheating problems of harvesters and diesel engines. 1. With regard to combuster combine harvester operation, the combustion chamber is the starting source of heat for the diesel engine. The temperature of the working gas in the combustion chamber is very high, up to 1500-2000 degrees Celsius. In order to ensure the normal operation of the relevant parts of the combustion chamber, the periphery of the combustion chamber must have a certain amount of cooling medium as water. For a diesel engine with a divided combustion chamber such as a pre-chamber and a vortex chamber, the ratio of the cooling area to the working volume is larger than that of a direct injection diesel engine. Moreover, since the cooling area increased in the vortex chamber in the pre-chamber is the most intense in heat exchange, the strong vortex in the main combustion chamber of the separate combustion chamber further promotes the heat transfer during combustion and expansion. Therefore, the diesel engine is prone to overheating under the same conditions. Taking into account the high operating temperature of the combine harvester, large dust, and poor cooling conditions of the diesel engine, we recommend that when the combine harvester plant selects power, the direct injection diesel engine is preferentially used to reduce the load of the cooling system from the source. 2. The intake conditions (pressure and temperature) with different intake conditions directly affect the combustion performance of the diesel engine. Therefore, in the overall design of the combine, any arrangement that deteriorates the intake air pressure and intake air temperature conditions of the diesel engine should be avoided as much as possible. For example, the inlet of a diesel engine should not be too close to the duct behind the radiator and other components on the harvester, so as to avoid the fresh air entering the olefin chamber from increasing the heat load of the whole machine because the flow resistance is too high or the temperature is too high. 3. Regarding the cooling water flow on the premise of determining the structure and working conditions of the diesel engine combustion chamber, in order to increase the flow of cooling water, on the one hand, the average temperature of the cooling water outside the combustion chamber is reduced; on the other hand, the water flow disturbance is enhanced and the heat exchange can be improved. The coefficient reduces the thermal resistance and ensures the normal heat transfer. The amount of water flow depends on the pump characteristics and system resistance, and increasing the speed of the water pump is an effective way to increase water flow. However, there is a limit to the increase in the speed, that is, when the cooling water overflows the system resistance in the diesel water chamber and the radiator, the pressure in the water pump is higher than the evaporation pressure of the water pump. Otherwise, the diesel engine just starts to work and the cooling water will immediately steam (the thermal conductivity of water vapor is less than 1/25 of the water). Therefore, when designing, manufacturing, installing, and maintaining the diesel engine cooling system, factors that can affect the flow of water (such as the casting accuracy of the inlet of the cooling water channel on the diesel engine body, the distortion of the inlet and outlet hoses of the diesel engine, and the blockage of the radiator heat pipe, etc.) ), should arouse our attention. 4. Regarding the quality of cooling water and water quality directly affects the thermal conductivity of cooling water and the formation of scale. Since the thermal conductivity of scale is only about 1/3000 of that of water, a thin scale will seriously increase the hot shade, and the increase of scale will also affect the flow resistance and flow of the cooling water. Therefore, when actually using the harvester, the cooling water of the diesel engine must not use hard water such as river water or well water. 5. About Fan Speed â€‹â€‹The higher the fan speed, the greater the cooling air flow rate. Since the fan and the water pump are coaxial, the flow rate of the water pump increases at the time of increasing the fan speed, further reducing the overall thermal resistance of the radiator. Therefore, the use of a smaller diameter water pump pulley is advantageous for substantially improving the heat dissipation effect. Of course, the increase in the fan speed will inevitably lead to an increase in the extra power consumption of the diesel engine. The strength of the fan and the water pump also imposes higher requirements. 6. With regard to the inside and outside of the cooling system, when the combine is put into use, if the user does not pay attention to the cleaning of the outside of the radiator and the softening of the added cooling water, the dirt inside and outside the radiator will build up and thicken, which will greatly increase the heat dissipation. The overall thermal resistance of the device, together with the flow and velocity of the fluid flowing through the heat pipe, is affected at the same time, thereby seriously reducing the heat dissipation efficiency of the heat sink. 7. Another way to increase the heat dissipation of the total heat dissipation area of â€‹â€‹the heat sink is to increase the total heat dissipation area of â€‹â€‹the heat sink. However, the effect of the heat sink of the heat sink on the air flow must be considered. Under certain spatial conditions, excessively increasing the number of fins or the length of the fins will inevitably increase the flow resistance of the cooling air, thereby affecting the static pressure of the front end of the fan (that is, the inner side of the radiator) and reducing the effective flow of air. Therefore, when designing or selecting a radiator, it is advisable to blindly increase its total heat dissipation area and radiator thickness, and to adopt a radiator structure and form that conforms to national standards as far as possible so as to avoid excessive air flow resistance during work and reduce the flow of cooling air. It has hindered the improvement of heat dissipation efficiency.
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