What is Steam: Definition and 534 Discussions

Steam is water in the gas phase. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Steam that is saturated or superheated is invisible; however, "steam" often refers to wet steam, the visible mist or aerosol of water droplets formed as water vapour condenses.
Water increases in volume by 1,700 times at standard temperature and pressure; this change in volume can be converted into mechanical work by steam engines such as reciprocating piston type engines and steam turbines, which are a sub-group of steam engines. Piston type steam engines played a central role in the Industrial Revolution and modern steam turbines are used to generate more than 80% of the world's electricity. If liquid water comes in contact with a very hot surface or depressurizes quickly below its vapor pressure, it can create a steam explosion.

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  1. wolram

    Is a Cheap, Eco-Friendly, and Tax-Free Steam Car Possible?

    I have in mind to build a super light steam car, my aims are 40/50 mph, no creature comforts, runs off cheap farm fuel or even waste chip shop oil, steam powered cars are not taxable, start with a modest range of 60 miles or so, other advantages are, no gear box, a go and a stop peddal, light...
  2. J

    Steam Turbine generator work done

    I will start my junior year as a ME major in the fall, I currently am working for a power company on a co-op. I work with the Predictive Maintance department corporate so I am not at the plant all the time but have a question about the turbine that might be more of a generator question. If...
  3. P

    Is a Vertical Increase in Pressure Possible in the Pump Stage of a Steam Engine?

    My textbook shows a PV diagram for a steam engine with the pump stage having no change in volume and with only a vertical increase in pressure. How can that be done. I can only imagine pumping a substance by pushing it inwards hence increasing its pressure but also reducing its volume. How can...
  4. P

    Water vs Steam Burns: Which is More Severe?

    Which gives the more sever burn, water or steam both at 100°C? I think it is the steam because it has more kinetic energy in it, as the water molecules have broken the bonds of the liquid and has a lower specific heat capacity, but I would like some confirmation, or if incorrect the right answer...
  5. R

    Is This Calculation of Steam Expansion and Superheater Efficiency Correct?

    Need some help here please, Steam at 2000 Kpa and 250 degree centigrade is expanded isentropically to a pressure of 550 Kpa. Determine the a) dryness fraction of steam b) change in specific enthalpy of steam
  6. K

    Exploring Advantages & Disadvantages of Superheated Steam Cycle

    does anyone knows what are the advantages and disadvantages of using a superheated steam cycle (i.e. effect of turbine blade)?
  7. M

    Carnot and renkine steam cycle

    Hello to all, this is my first post on this forum. I'm electrical engineer (technical informatics) but in my spare time I'm interested in thermodynamics especially about steam cycle in power plant. I know that condenser is meant to convert steam to water and here we have pure losses of...
  8. J

    Calculating Steam Turbine Work & Power from 2 Unknowns

    A steam turbine has an inlet of 2kg/s water at 1000kPa and 350C and velocity of 15m/s. The exit is at 100kPa, 100% quality and very low velocity. Find specific work and power produced. I have done a lot of these problems but it usually says adiabatic or the inlet and exit temp is the same...
  9. D

    Exploring Energy Transfers between Ice and Steam

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  10. wolram

    Novel Steam Engine: Amazing Power for Airplanes

    What do you think of this crazy looking engine. http://www.greensteamengine.com/ And a steam engine that powered an aeroplane. http://www.tinypower.com/airplane.htm
  11. J

    Changes of State ice to steam problem

    Ok, I am having some trouble with this problem: How much energy does it take to convert .500 kg ice at -20C to steam at 250 C? Specific heat capacities: ice: 2.1 j/g C, liquid: 4.2 j/g C, steam: 2.0 j/g C. Hvap = 40.7 kj/mol, and Hfus = 6.02 Kj/mol. What I have done so far is use q=mst...
  12. H

    Mass of Steam Needed for 1kg of Ice to Yield 20°C Water

    what mass of steam at 100 c must be added to 1.ookg of ice to yeild liquid water 20c ? this is what I have so for c*m* displacement of temperature =m *L
  13. D

    Checking Work on Condensing Steam: A Challenge!

    I'm not sure if I'm approaching these problems correctly. Could someone check my work? Steam at 100°C is condensed in 500g of water at 20°C. a. What is the maximum amount of steam that can be condensed in this amount of water? Q[steam] = m[steam] * L[c steam] * (T[f] – T[i]) Q[steam]...
  14. M

    Calculate Specific Entropy of Steam: 2MPa, 0.63 Dryness Fraction

    Ok, using steam tables, calculate the specific entropy of steam with dryness fraction 0.63 and pressure of 2MPa. Can someone suggest how Id go about this? Thanks.
  15. M

    Calculate the specific entropy of steam

    Ok, using steam tables, calculate the specific entropy of steam with dryness fraction 0.63 and pressure of 2MPa. Can someone suggest how Id go about this? Thanks.
  16. D

    How many grams of water at 20 degrees Celsius can be converted into steam

    can someone give me a hand on this one? How many grams of water at 20 degrees Celsius can be converted into steam at 500 degrees Celsius with 10 kJ of energy? wat i know is that this question is 2 parts: Water being heated to 100 C (80 C change)using the specific heat of water n then...
  17. P

    Freezing Water with a Reversed Steam Engine

    The steam engine which operates between 500°C and 200°C is run in reverse. How long would it take to freeze a tray of a dozen 37 g compartments of liquid water at room temperature (20°C) into a dozen ice cubes at the freezing point, assuming that it takes 300 W of input electric power to run it...
  18. P

    Calculating Coal Usage for a 1000 MW Steam Power Plant

    At a steam power plant, steam engines work in pairs; the rejected heat from the first is the heat input to the second. The operating temperatures of the first are 670 C and 440 C. The operating temperatures of the second are 440 C and 290 C. Assume both engines work at 60% of their Carnot...
  19. Astronuc

    Conference on Water, Steam, and Aqueous Solutions for Electric Power

    – Advances in Science and Technology – Proceeings of the 14th International Conference on the Properties of Water and Steam Editors: Masaru Nakahara, Nobuyuki Matubayasi, Masakatsu Ueno, Kenji Yasuoka and Koichi Watanabe http://www.iapws.jp/proceedings.html Some very useful and...
  20. PeteGt

    Creating Super Heated Steam: Igniting Paper at 300°C

    I searched for this and get conflicting results. I have setup a demonstration that has a erlymeyer flask with a one hole stopped and water on top of a heating mantle. I then have a copper tube comming out of the hole in the stopper going into about 5-1"diameter coils and then finally comming...
  21. R

    Question about steam pressure and velocity

    I am trying to figure out a problem we are having with a steam boiler. First, it is a natural gas fueled boiler rated at 2,000,000 BTU. In the summer time, the boiler supplies heat to the indoor pool through a heat exchanger. There is approximately 10 ft of 1 inch black iron pipe feeding into...
  22. R

    Question about steam pressure and velocity

    I am trying to figure out a problem we are having with a steam boiler. First, it is a natural gas fueled boiler rated at 2,000,000 BTU. In the summer time, the boiler supplies heat to the indoor pool through a heat exchanger. There is approximately 10 ft of 1 inch black iron pipe feeding into...
  23. H

    Searching for Steam Tables: What Programs are Worth Getting?

    I've been looking for steam tables on the internet, but all that I can find are those steam table computer programs. So... Does anyone know a site which has the old fashioned steam tables? And which of those steam table computer programs would be worth getting?
  24. P

    Steam Engine/Rotation Problem

    Hi, I came across this problem when browsing through a AP Physics B book (the answer was not in there). Can anyone help me? Heron of Alexandria invented the steam jet engine in the first century A.D. One of his many inventions, the one shown below was invented for amusement but employs...
  25. C

    How Much Steam is Needed to Raise Water Temperature from 20°C to 50°C?

    hi guys, i have the following question to answer: a 40g copper calorimeter contains 200g of water at 20 degrees celsius, it asks how much stam must be condensed in order to achieve a final temperature of 50 degrees celsius. I was just wondering what formula to use?, and do i need to know the...
  26. Pengwuino

    Creating Steam in the Shower: Exploring the Science

    So why exactly do you get steam in the shower when you put hot water on? I assume the water isn't 100 C because I am not jumping out of hte shower and yelling for my life so why is there steam?
  27. L

    Heat Absorption by a Person's Hand from Steam to Liquid

    O.K. HOw much heat is absorbed by a person's hand if steam at 100degree C is first converted to liquid water at 100 degree C and then cooled to normal body temperture? I'm not sure of the formula for this one.
  28. wolram

    Modern Steam Car: Costs, Efficiency, & Everyday Use

    modern steam car If found this website on steam cars http://www.geocities.com/MotorCity/Shop/3589/ The author seems very down to earth, and his project worthwhile. I wondered as he mentions, about the production costs of such vehicles, the engines would surly be cheap to produce en mass...
  29. D

    Steam vs water at the same temperature

    if steam and water are both at 100 degrees celsius, why would the steam scald you more, even if they both have the same kinetic energy?
  30. M

    Ethel Alcohol vs Steam: Power Plant Turbines

    I have been told steam is used to turn turbines in a power plant. Why wouldn't they use ethel alcohol? It has a lower heat of vaporization. So if I am not mistaken you would produce roughly twice as much ethel vapor to turn a turbine quicker generating more energy.Any help would be appriciated.
  31. J

    Is Steam Really Invisible? Exploring the Truth Behind This Common Misconception

    When I was at school, some 15 years ago, I was taught that steam was not a gas. This always seemed a very odd thing to say. I think it was based on the idea that it contains suspended water droplets, but wouldn't any gas have suspended droplets near it's boiling point? I'd like to settle this in...
  32. M

    What is the significance of pursuing reversibility in power plant processes?

    Carnot Cycle is the ideal heat engine cycle with maximum efficiency. We use Rankine Cycle as the working cycle for steam power plant which has significantly lower efficiency that Carnot Cycle. My question is why we don't adopt Carnot Cycle as ideal Steam Power Plant cycle? Thanks in advance!
  33. N

    Analysis of Pressurized Cylinder: Flashing to Steam or Hot Water?

    I have a question for you all, say you have a pressurized cylinder with water in it, it is at 200*F and at a pressure of 300psig. Now you open a drain valve on the bottom to the atomosphere. Will it flash to stream or just come out as hot water or a combo of the two? What equations and...
  34. ceptimus

    Crossing the desert (in a steam powered car)

    By one of those inexplicable quirks of puzzle land, it is necessary that you cross a desert in a steam-engine powered car. Your steam car is very reliable, but it can't carry enough coal to cross the whole desert without refuelling. Fully loaded with coal, it can travel just half way across...
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