| With the rapid growth of the number of retained motor vehicles, the problem of environmental pollution and shortage of oil resources is becoming increasingly serious. In view of this, countries around the world are committed to the work of new-energy vehicles. Therefore, natural gas vehicles are popular and promoted in the world because of its low-emission, inhibition of the greenhouse effect and independence of oil. In many cities of China, lots of fuel busses and taxies have switched or are switching to compressed natural gas (CNG) or liquefied petroleum gas (LPG). As a kind of independent heating device, fuel heaters have been widely used by automobiles, ships and other transport machinery in the cold condition for heating, defrost, cold start and so on. It is inevitable to develop gas heaters to match the gas vehicles, with the number of gas car in China increasing rapidly. Performance tests were carried out on the domestic YJT-Q30 liquid natural gas heater. According to the rules obtained from the test, corresponding improvements were made out to the heater, and the experimental results are obvious.First, some experimental researches were carried out on the gas-jets used in natural gas heater with high-pressure air. There are many factors influencing the performance of gas jet used in gas heater, such as, different pore size and pore number of the nozzle, size of metering jet and flow channel, diameter and length of gas-supply pipe and so on. The above aspects were all changed and combined with the research in many ways in our research. And then, the laws were found out which showed natural gas flow changed with the gas-supply pressure through related modified formula, which will meet the power requirements of natural gas heater.Next, experimental researches were carried out on the YJT-Q30 natural gas heater. Since gaseous fuel mixed with air is easy to burn, little of carbon distribution is produced in the interior of heater exchanger, and the thermal efficiency of gas heater can be improved by more than 10% compared with fuel heater. In order to reduce the thermal losses because of hot gas flowing in a short way, a gas current-sharing hoop was added on the exit of heater exchanger rib. In addition, a heat-protection tube was installed out of the combustion chamber so that the thermal lost during the process of heat radiation and heat exchange was diminished obviously.Moreover, the performance researches about different assembling clearance between the rotor blade and fan cover of domestic YJT-Q and Germany heater fans are carried out on the self-made experiment device including the tests of the discharge characteristic of rated voltage and rated speed, and the speed characteristic.And then it analyzed the rotor blade structure and wind pressure characteristics of combustion-improving fan on vehicle heater theoretically.Since the water circulating pump is an important part of the heat transfer system in vehicle heater, to ensure normal heating for liquid type heater. At last, the operation characteristic test and the comparative analysis on the circulating pumps of domestic YJT-Q30 heater and the same type heater of German were carried out on the self-made experiment device. |
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