Experimental And Numerical Investigation Of Steam-water Mixing Heater

Steam-water mixing heater is a kind of heat exchange device,which can mix steam and water with heat water directly,and it has developed in recent years.This kind of heater has the advantages of high heat transfer efficiency,simple structure and low-cost of operation.It is widely used in heating,electric power,oil and chemical industry fields.This research was based on the background of actual project application.A series of research and analysis about the structure designs of the steam water mixing heater were carried out by the methods of experiment and numerical simulation.Comparing with the conventional jet pipe steam-water mixing heater,the radial deviation of the steam inlet pipes from the central line of the heater was carried out,which results in a steam vortex in the chamber.Four steam inlet pipes are provided to further enhance the uniform injection of steam.This paper studied the influence factors of temperature increment characteristics i.e.including volume fraction of the vapor phase,water phase and condensed water phase.And the quadrupole noise sources and local dipole noise sources by the internal structures of steam-water mixing heater were also analyzed.The tests of temperature increment of water and noise sound pressure levels were carried out under different conditions.Experimental data shows that with the increase of the steam inlet pipes,the temperature increment of water outlet gradually increases with the same amount of steam.When using the mode of steam swirling into chamber from four steam pipes,the temperature increment of water can reach 14.7 degree centigrade.The theoretical calculation value of temperature increment of water was 15 degree centigrade.And the error value between the data of experiment and theoretical calculation was about 2%.The rationality experimental design was proved.Numerical simulation of steam-water mixing heater was simulated by the CFD software,the results shown that the difference of temperature increment between the experiment and simulation was within 0.5K.The data were consistent with the experimental and theoretical results.Through using broadband noise model in the numerical simulation,the field distribution of heater was obtained.And the strong location of noise source was found in the mixing heater.In this paper,the average value of the sound pressure level in the numerical simulation results was 72.6dB,and the noise source of the sound pressure level error remains within 2.1% when comparing with the average noise pressure level value of 74.1dB in experiment.The broadband noise source model has high-precision in simulation of noise sound pressure level in the steam-water mixing heater.The influences of different internal structures on the mixing heating effects and the noise distribution were analyzed,i.e.the influence of different angles by the steam injection holes,the radial deviation of the steam pipes,the number of steam pipes and the arrangement of the four steam pipes.In the four groups of different structure contrast conditions,factors i.e.the axial radial deviation and the number of steam pipes have significant influence on the design of noise reduction.The values of the maximum difference of sound pressure level caused by the two different internal structures change were 4.8% and 4.4%.This has the reference value for efficient heating and noise reduction design of steam-water mixing heater.