Research on low temperature fuel heating system for heavy vehicles
One of the conventional solutions is to use diesel oil with a suitable temperature for the ambient temperature, or to add antifreeze to improve the fluidity of diesel. However, high-grade diesel has low combustion efficiency, high price and poor economy. Another common method is to use The method of burning the fuel tank and hot watering the fuel pipe to solve the problem of starting the engine is not only inconvenient to operate, but also brings a safety hazard.
Low temperature fuel heating supply system
At present, domestic and international low-pressure fuel supply oil heating products, it is more common to use electric heating diesel filter technology in the low-pressure oil circuit. The electric heating diesel filter is provided with an electric heating plate, which can effectively dissolve the diesel wax or fine ice particles in the filter cup. However, if the diesel wax is present in the tubing, fittings and fuel tank, the viscosity of the diesel fuel increases, the engine starting is still difficult. There is also a method of using full oil circuit heating, but due to unreasonable temperature control or improper selection of the structure and materials of the heater, the reliability of the performance of the heating system is poor, the heating effect is not satisfactory, and there are still safety hazards. For example, some manufacturers use titanium-chromium alloy heating wire, although the price is low, but it is easy to be oxidized during use, the oxide layer will fall off and pollute the fuel, and the nozzle of the high-pressure common rail pump of the National III engine is very thin. It has high requirements on the cleanliness of the fuel. Therefore, the use of the heating wire of this material will cause greater damage to the engine and affect the service life of the engine.
Design of automatic temperature control low pressure oil passage heating system
In order to solve the problem of engine starting in low temperature environment, we designed a heating system for low-pressure fuel supply system, which can still use low-grade diesel in low temperature environment (such as ambient temperature at -10 °C, using 0# diesel) , smoothly start the engine.
The automatic temperature control low pressure oil circuit heating system is composed of electric heating oil quantity sensor, heating type fuel pipe, integrated oil pump type fuel filter, fine filter heating jacket, etc. The working principle is shown in Fig. 1.
Figure 1 Working principle of low pressure oil heating system
The electric heating oil quantity sensor can not only collect the signal of the fuel liquid level height, but also observe the fuel quantity in the fuel tank on the fuel gauge of the cab instrument panel. At the same time, it is also the fuel outlet pipe of the fuel tank, and the heater can be installed in the oil discharge pipe. The fuel in the fuel tank and the fuel in the oil pipe are heated to dissolve the diesel wax and improve the fluidity of the diesel. The heater material can be PTC (ie, positive temperature coefficient thermistor), featuring no open flame, automatic constant temperature, no oxygen consumption and corrosion resistance.
A heating wire is designed inside the fuel pipe. The electric heating wire is made of nickel-chromium alloy material, which has strong oxidation resistance and good heat generation. It maintains high strength and does not undergo brittleness under repeated temperature shock cycles. The heating power per meter length is set to about 20W. According to the different lengths of the fuel pipe, different heating wires are selected, and the heating power should be increased with the increase of the length to ensure the same heating power for the same length. 2 is a schematic view showing the structure of a fuel pipe with electric heating.
Figure 2 Fuel-heated fuel pipe structure
1. wire 2. heating wire 3. fuel pipe
The integrated oil pump fuel filter has the functions of oil-water separation, impurity filtration, air in the electric oil removal circuit, fuel heating, etc. The structure is shown in Figure 3. The filter base is embedded with a microcomputer processing unit CPU and a temperature sensor. When the fuel temperature is lower than 0 to 2 ° C, the heating function is activated; when the temperature is higher than 20 ° C, the heating element will automatically stop working. The microcomputer controls the heating of the entire low pressure oil circuit system (including heating of components such as oil water separators, fuel pipes and oil quantity sensors). For safety reasons, the system will automatically stop heating when the load is running for more than 15 minutes. The oil-water separator adopts a filter element that meets the requirements of the National III engine supply system. The filtration precision is 30 μm, the water separation efficiency is 99%, the rated flow rate is 454 L/h, and the original resistance is not more than 8 kPa at the rated flow rate. The filter paper of the filter element is easy to adhere to the fuel wax and block the oil passage. Therefore, a heater is added to the bottom of the filter to decompose the diesel wax in the oil filter cup, and the power of the heater is set to 160W. Usually, the heating plate of the oil-water separator with electric heating is located at the upper part of the filter element, and the fuel in the bottom oil cup is not easily heated. To solve this contradiction, the heating wire is passed into the oil cup, so that the fuel in the oil cup can also be heated. Increases heating efficiency.
When the diesel engine is restarted after a long shutdown, or there are more bubbles in the fuel pipe, the engine is difficult to start, and even the engine cannot be started after multiple ignitions. The usual solution is to manually press the hand pump to discharge the air bubbles in the fuel pipe. However, it is more laborious and time-consuming. Therefore, it is designed as an Electromagnetic pump. It is easy to operate. Pressing the button can automatically complete the exhaust task within 1 to 3 minutes. At the same time, it can reduce the pressure drop caused by the flow resistance, and the engine starts quickly.
Figure 3 Fuel filter structure
1. drain valve 2. oil water separator 3. oil inlet interface 4. electromagnetic pump 5. hand oil pump 6. connection terminal 7. vent valve 8. oil outlet
In the cold environment, the fine filter element of the engine is also easy to adhere to the diesel wax, which is also a non-negligible link that affects the engine start. In order not to damage the structure of the engine's original fuel supply system, we designed a heating jacket wrapped around the fine filter of the engine to dissolve the diesel wax, and the heating power was set to 60W.
Economic Benefit Analysis of Automatic Temperature Controlled Low Pressure Oil Circuit Heating System
According to the current market price, 0# diesel is about 0.37 yuan/L lower than -10# diesel, and the combustion value is about 1% to 2% higher. The fuel is heated and burned more fully, and the fuel consumption is reduced by about 1% to 3%. According to the general cargo vehicle 100km fuel consumption is about 40L, 500km per day calculation, can save 150 yuan per day.
Conclusion
The use of automatic temperature control and low pressure oil circuit heating system not only improves the adaptability of heavy vehicles in low temperature environment, but also uses low grade diesel in low temperature environment, which improves the fuel burning rate and reduces the carbon deposit of engine combustion cylinders. Users will bring higher economic benefits, which will become a major technological innovation for heavy-duty vehicles.
Trimethylsilyl Chloride,Insulating Agent,Cas 75-77-4,Min Trimethylsilyl Chloride
Quzhou CanWin New Material Co., Ltd. , http://www.canwinnm.com