Structure Design And Combustion Experimental Study Of 5kW Air Heater

Winter is cold and long in northern China,and it's not enough to just turn on the car's air conditioning.Long-distance truck drivers need to turn on the auxiliary heater to ensure a comfortable temperature in the cab.But existing domestic auxiliary heater combustion chamber's design is simple,whose service life is only a year.Usually after a winter,carbon deposition can lead to many problems,like black smoke,low hot air temperature.While the price of imported air heater is high,which is not acceptable to consumers in our country.Therefore,the design of a new auxiliary heater has obvious practical significance.This paper analyzes the research status of the existing air heater.From the basic principle and design method of micro gas turbine combustor,with countercurrent air intake layout,I design the swirl atomizing head,flame tube,casing head,seal head,heat exchanger,shell and a series of supporting structure,set up air heater machine experiment system and the system for flame observation.After the preliminary design was completed,the following three aspects of in-depth research were mainly carried out:(a)Based on the overall design structure,the contrast of different structural parameters of cyclone numerical simulation of cold conditions,analysis of cyclone swirl hole number,swirl hole eccentricity,cyclone diffuser height for flow field velocity nonuniform coefficient,air quantity distribution of each section,axis speed,the influence of the reflux area location.In order to make the smooth circulation of gas,avoid the flame tube is ablation,avoid and atomization nozzle are ablation,finally selected cyclone eccentricity between 3.5-5.5 mm,cyclone height is 45 mm,with eight swirl holes.(b)The ignition and combustion experiments were carried out for different metal networks with different layers and orders under 384 m L/h diesel volume flow.The influence of metal mesh structure on the concentration of CO,NO and O2 in flue gas and flue gas temperature was comprehensively analyzed.To carry out ignition combustion experiment in high,medium and low three gears to oil with different cyclone eccentricity,flue gas characteristics with different cyclone eccentricity and combustion-supporting air supply are transversely compare,and combustion characteristic of different oil amount are longitudinally compare,and combustion performance under different heat load demand have been analyzed.In the highlands,cold area we carry out the auxiliary heater machine,by running the auxiliary heater in actual driving on the way,and the flue gas composition content,hot air temperature and the relationship between oil,air volume have been analyzed.(c)The flame burning in the combustion chamber at different oil feeding frequencies is observed by the fire observation system.The flame video was photographed with a high-speed camera.In the experiment,5.2s video was photographed and 88328 512×512 pixel color images were extracted frame by frame.Experimental images are processed by matlab: cutting target area,color threshold segmentation,binary image conversion,the flame area computation,the center of mass calculation,polar coordinates conversion.The flame area is transformed by fast Fourier transform to obtain the main frequency of flame oscillation.It was found that the variation law of flame area was consistent with the period function,and the flame oscillation frequency was consistent with the oil delivery frequency.Each combustion cycle in flame can be divided into four stages: initial flame,developing flame,mature flame and attenuating flame.In the initial stage of flame,it can be found that the flame has a phenomenon of obvious clockwise rotation with the combustion air.