# Convergent nozzle and preesure of steam

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 March 6, 2011, 05:28 Convergent nozzle and preesure of steam #1 New Member   Pranab Jyoti Ghosh Join Date: Mar 2011 Posts: 4 Rep Power: 6 I want to know about a fact first. In conventional thermal power plants, highly-pressurized water is heated and evaporated inside Boiler. But, instead of highly pressurized fluid like water, low-pressure fluid like steam at pressure around 10-12 bars were heated, does the whole process will remain isobaric? If yes, then I want to know whether a convergent nozzle can be used to inject the steam into comparatively higher pressure of about 45 bars without using much energy or not. Probably some explanation will clear it to the readers. A convergent nozzle can convert internal heat i.e. random motion in velocity in a particular direction. While, we all know that pressure is an expression of velocity of molecules of fluid, whatever kind that may be. So, if a convergent nozzle can convert internal heat into velocity in a particular direction, then the velocity i.e. pressure of steam in the particular direction can be highered at the expense of pressure on other direction. In short, by using a convergent nozzle, we can inject steam at higher pressure without using much energy at the compressor. I want to know how much right I am in this regard.

 March 6, 2011, 18:17 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 10,949 Rep Power: 85 Looks to me like you are trying to prove the laws of thermodynamics are wrong. Good luck. In other words, have you considered the basic thermodynamics of what you are proposing?

 March 6, 2011, 23:17 #3 New Member   Pranab Jyoti Ghosh Join Date: Mar 2011 Posts: 4 Rep Power: 6 Which laws of thermodynamics? First law or 2nd law? For your information: http://www.globalwarmingsolutions.co...sion_cycle.htm Some excerpts from this paper: "When a gas flowing down a pipe of cross-sectional area A1 (as in Figure 1) encounters a change in the cross-sectional area to A2 there is a change in the gas velocity such that V2=(A1/A2)V1 As the gas flows through the narrowing neck of the nozzle, enthalpy is converted into kinetic energy such that H1 − H2 = ½V2 ² − ½V1 ² Where H1 is the original enthalpy and H2 is the enthalpy in the throat of the nozzle." Now, what is the source of this change in enthalpy? The internal energy of the gas molecules are changing into velocity in a particular direction. I hope you have some idea of physics and know that pressure is nothing but a result of motion of gas molecules. Now, when the nozzle have changed random motion into a particular direction, therefore why we can't say that pressure in the direction of that flowing gas has increased. Now, I just want to know whether we can use this change in enthalpy to inject low pressure steam into higher pressure or not. If there any example? But just unable to understand why the matter of violation of laws of thermodynamics arise. Why do you guys just throw remarks without properly understanding the matter?

 March 7, 2011, 20:04 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 10,949 Rep Power: 85 Now I am even more confused. I have no idea what you are talking about. So what is your question?

 March 7, 2011, 22:11 #5 New Member   Pranab Jyoti Ghosh Join Date: Mar 2011 Posts: 4 Rep Power: 6 My proposition is clear. Whether a convergent nozzle can be used with a compressor to inject low pressure gas/steam in higher pressure to reduce power consumption.

 March 8, 2011, 17:57 #6 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 10,949 Rep Power: 85 No. Obviously the high pressure gas will reverse the flow in the nozzle.

 March 10, 2011, 12:02 #7 New Member   Pranab Jyoti Ghosh Join Date: Mar 2011 Posts: 4 Rep Power: 6 I am requesting you to go the webpage I mentioned in my first post and read it carefully. Convergent nozzles can convert enthalpy of hot gas into velocity in a specific direction and those with little idea of physics should know well that pressure is nothing but expression of motion of molecules. If convergent nozzles can turn enthalpy into motion, then pressure of the fluid must be increased in that specific direction (while decreased in other directions) and that means it can penetrate into vessels with higher pressure.

March 10, 2011, 20:23
#8
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Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
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Quote:
 I am requesting you to go the webpage I mentioned in my first post and read it carefully.
I am a busy man and post stuff on the forum because I like helping people. I don't have time to research your particular case in detail.