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冷却塔实验室模型英文文献和中文翻译(4)

时间:2017-05-12 21:13来源:毕业论文
transmitted through lines 9 to personal electronic computer 10 for subsequent recording and processing. Experiments were conducted with water with an initial temperature of 40-80~ In addition to tempe


transmitted  through  lines  9  to  personal  electronic computer  10  for subsequent  recording and  processing.
Experiments were conducted with water with an  initial temperature of 40-80~  In addition to temperature
measurements,  standard  instruments  controlled  the humidity of the  air  surrounding  the  facility,  the  speed  of the
external wind flow, and  the vertical velocity of  the vapor-air mixture flow ascending above  the model.
For  each  fixed temperature of the water supplied  for cooling, we changed  the  conditions of the  flow of the
external wind stream around  the model. At a  temperature of the  supplied water of 60~  experiments were carded
out additionally with  periodic  supply of warm water  to  the water distributor.
For the most part,  experiments were conducted for two positions of the lower rotating plates:  the angle 90  ~
corresponds  to completely open windows  (the conditions of operation of an actual cooling tower)  and  the angle 45  ~
corresponds  to  the mode with  flow swirling.  Some of  the  experiments were  carried  out with  two-sided  symmetric
swirling of the  flow with  respect  to  the  external wind.
Each  set of experiments was performed in  the following way. Heated water of prescribed  temperature was
pumped  through  the water distributor. After the attainment of quasisteady conditions with respect  to  the  principal
controlled parameters  (temperature and  volumetric flow rate  of the  entering water),  the  surrounding air humidity
and  the  ascending  flow velocity were  recorded,  the measuring  system was  actuated,  and  data was  collected with
subsequent  statistical processing.
Results of the Investigations. From the results of visual observations we can draw the following conclusions.
Under conventional conditions  (when S << 1)  unstable vortices with a  characteristic dimension  on  the order of 0.1D
are  formed  spontaneously  in  the  conelike  portion  of  the  tower.  The  process  of  the  formation  and  existence  of
separate  vortices  terminates near  the mouth of the  tower. Against  the background of the  general circulation of the
vapor-air mixture the above effect was not observed in the mode of swirling of the incoming flow. As  the wind speed
increases  (the  parameter  S >>  1),  a  large-scale vortical flow originates  in  the  conventional mode  in  the  lower part
of the  tower model above  the water distributor  (stagnant zone)  with a  characteristic dimension of about  2/3  of the
height  of  the  tower.  Flow  swirling  (even  at  a  strong wind  S  =  2)  eliminates  the  formation of stagnant  zones  that
affect the  thermal operating efficiency of the  tower negatively.
In what follows, we present  quantitative results obtained on  the  laboratory setup at one  temperature mode
of the  entering water  (T  O  = 60~  This mode makes  it possible to create a  rather  intense ascending vapor-air  flow
in  the  laboratory model with  a  large  concentration of droplets, which  improves  the  visualization of  the  structures 冷却塔实验室模型英文文献和中文翻译(4):http://www.youerw.com/fanyi/lunwen_6883.html
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