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. tobitronics

    Calculating velocity of steam through orifice

    Hi all, First time poster here and I'm stuck with what for me seems to be a simple problem. The situation is this: I have a 100mm diameter pipe connected to a steam kettle, which produces steam at a constant 0.3barG. This pipe is split up into 4 50mm pipes, each pipe has a valve at the end...
  2. M

    Calculating Minimum Hole Size for Steam Pressure Relief in a Sealed Container

    Hi, Consider I have a sealed container with some water in it, put it on a normal stove. Obviously after some time it will explode due to the steam pressure. To avoid this, I drill a hole so the steam can escape. Is there a minimum diameter for this hole? How should I calculate it? Assuming 1...
  3. P

    Compressing steam and water together

    I want to describe here an imaginary experiment. First. take a thick walled cylinder with an open end and pour boiling water into it. The steam coming out will replace the air and then put a piston over the open end and fix it in an airtight way. But, the piston can move up and down. Now, as the...
  4. P

    How to calculate the power consumption during steam compression

    Being a man who learned physics in college, I have tried to calculate that in the simplest way. As for example, if we need to know the power consumption to compress steam from 50C saturated pressure level to 1 bar i.e. 100C saturated pressure level, the best way is to know the gross enthalpy of...
  5. P

    What are the efficiencies of steam compressors that are available?

    For some purpose, I need a steam compressor that can compress sub atmospheric level steam to atmospheric and above. I want to know what's the efficiency of an average steam compressor available in market. I have got some replies from a few steam compressor manufacturers, but the system they are...
  6. P

    Need help to find a steam compressor

    At present, I am looking for a steam compressor or steam compressor system that can compress very low pressure steam (2.56 kPa) to 1 bar and above. I know well that such high compression ratio will be impossible for a single set to achieve, therefore it more than one sets have to set in series...
  7. I

    Steam Calcs: Turbine Intake Pressure & 90% Steam Content

    Homework Statement The maximum steam pressure by the turbineintake is 550 C. Based on available cooling water the pressure in the condensor will be 0,06bar the isentropic efficency is 80 %. Decide the steam pressure at the turbine intake if the steam content is at least 90 % We have struggled...
  8. Nemo's

    What is the exit steam velocity?

    Homework Statement Steam, at 15 bar and 280oC, enters a nozzle with an initial velocity of 125 m/s. The steam enthalpy at the exit section is 2800 kJ/kg and the heat loss is 25 kJ/kg. What is the exit steam velocity?. Homework Equations 1)Qin - Qout = m [h2-h1+((c22-c12))/2] 2)h = Pv + u...
  9. C

    Exploring the Potential for Water Gas Formation from Steam and Coke Reactions

    Once upon a time I managed (unintentionally) to use a primitive centrifuge to spin a jet of steam. The spinning steam jet separated (or more likely partially separated) into hydrogen and oxygen components. A blue flame appeared at the confluence of gasses. I do believe that steam had partial...
  10. Elena14

    1 kg of ice at -20°C is mixed with 1kg steam at 200°C......

    1 kg of ice at -20°C is mixed with 1kg steam at 200°C. Then find equilibrium temperature and mixture content. Please DON'T use Joules as unit while answering the question. Converting 1 kg steam at 200°C to 1 kg water at 0°C requires : (1* 0.5*100) + ( 1*540) + (1* 1 * 100 ) k cal heat = 690...
  11. R

    Understanding how to use steam tables

    Homework Statement I have a table for 5 sets of data. Each set includes data from one ore more of the following properties - temperature, pressure, energy, and steam quality. I have to look at steam tables for water to find the missing values. For the data set in question I'm given T = 75 C...
  12. Gary K

    Steam Condensation: Calculating Area for Experiment

    Greetings, I'm preparing for an experiment on a modified Tesla Turbine design and will need to condense the exhaust steam rapidly in order to measure the pounds per hour of saturated steam that goes through the system. Incoming steam could be as high as 90 PSI through a 1" pipe. As the turbine...
  13. E

    Can boiling water inside steel cube make it explode?

    Hello Lets say we have a steel cube, then fill it with water and close all the gaps very strong with welding. If we leave the cube on a stove for a lot of time, is the produced steam of the boiling water, enough to destroy and smash the steel cube?
  14. A

    Fluids:What happens to steam after a heat exchanger/condenser & Pump....

    I need some basic help as someone who has never done this before and have little understanding of what's going on: Suppose I have steam with mass flow rate of W [kg/s] at 100C and 1 bar going to a heat exchanger (secondary side at 30C, 5 bar, 5 kg/s). First Question) This steam should condense...
  15. M

    Steam generation for an experiment

    What would be the best, cheapest way to generate steam intended for introduction to a device for testing? I would use a standard American 110v three-prong outlet as a power source for the steam generator. All I really need is a steam source with an absolute pressure of 2 atm/202650 Pa/29.39...
  16. P

    Throttling Strategy for Steam Process

    ohk, let me make it more clear for you, the situation is we have a boiler generating steam at 23.5 barg, which is throtlled down to 12 barg for import/ export, this 23.5 barg steam is throttled down to 3 barg by another valve to use in heat exchanger, and then this 23.5 barg steam is throttled...
  17. evan-e-cent

    At what pressure does steam exiting a nozzle reach mach 1

    I am planning to build a Hero's steam engine or Aeolipile. This is the steam engine invented by the Greeks about 2000 years ago. It is attributed to Hero or Heron (10-70 AD) but was also referred to in 15 BC. My grandfather build one for a show. I have inherited it but rather than try to repair...
  18. Lagraaaange

    Change in Internal Energy of 1kg Water to Steam?

    Homework Statement Hvap = 22.6E5 J/Kg. R=8.315E3 Jkmol^-1K^-1. 1kmol water = 18kg Keeping in mind that latent heats are enthalpies, what is the change in internal energy when 1kg water is converted to steam at pressure of 1atm and temperature of 100C. Homework Equations dU = dQ - PdV. The...
  19. Absentee

    Exergy of combustion products, steam and the loss of exergy

    Homework Statement Biomass with a heating value of 15 MJ/kg burns in steam generator at a temperature of 1200K and all of the heat is given to the steam at a temperature of 600K. The ambient temperature is 300K. Calculate exergy of combustion products, steam and the loss of exergy.Homework...
  20. Ariel Jo

    Supercooled Steam Homework: Solving for Tf, Condensation Fraction & ΔS

    Homework Statement You have 0.50 mol of steam which has been supercooled to 95˚C at 1 atm. Since the steam is below the boiling/condensation point, it proceeds to partially condense into liquid water. This happens in a thermally-insulated vessel at constant pressure. (a) When the system...
  21. J

    Calculating Heat Loss for Improved Efficiency in a Steam Generator Design

    At current I am trying to redesign a steam generator as seen in the picture attached, the requirements for this are as follows: · The water contain must have a minimum capacity of 2.25 litres · The heat loss as boiling point shall not exceed 75W in ambient of -3 C +/- 1 C · The fan shall have...
  22. J

    Reading Steam Tables for Saturated Liquid Not Vapor

    Hello, I have an assignment that centers around the Rankine cycle and requires me to find the enthalpy of water entering the boiler. My professor has told me to take the enthalpy value at boiler conditions for a saturated liquid. I'm not really sure why I should make this assumption as I was...
  23. R

    Thermodynamic Steam Trap; Pressure needed to Drive

    How much of a differential pressure does a typical thermodynamic steam trap need to discharge condensate? i.e. Say one needs to drain condensate from a shell under vacuum 310 mmHg abs, would a thermodynamic steam trap work correctly if I connected the discharge pipe to a vessel maintained at...
  24. JasonHathaway

    What are the thermodynamic properties and efficiency of a steam plant?

    Homework Statement The steam enter the turbine (3) of the steam plant at 8 MPa and 500°C. The steam extends in an isentropic process and leaves the turbine (4) at 200 kPa, then enters and leaves the condenser at constant pressure (You may treat the steam as a saturated liquid when it leaves the...
  25. Brakwa

    Is my air ejector condenser causing vacuum issues?

    Having trouble at a plant where the vacuum has increased to the point where a pump has been put on the end of the air ejector condenser to maintain vacuum, without it the limits would be too high and trip the Steam Turbine. The question is, does the air ejector condenser continuously drain...
  26. 0

    How to calculate pressure from steam

    So let's say we have a cylindrical pressure vessel of volume 2.4 x 10^-3 m^3 carrying 2 liters of water heated to 130 degrees Celsius, how would I calculate the circumferential pressure inside the container? radius = 56x10^-3 m height = 0.24 m I know the equation would be stress=pressure x...
  27. R

    What controls the Steam Pressure inside a boiler?

    I've seen various types of boilers in industries e.g. 7 bar, 10 bar, 30 bar etc. What exactly in the operations / design of these boilers sets the steam pressure that will be produced? For simplicity let us restrict ourselves to fire tube coal fired boilers that produce saturated steam...
  28. K

    What is the specific heat of boiling water converting into steam?

    What is the specific heat of boiling water converting into steam?
  29. P

    Thermodynamics -- Calculate the pressure and temperature

    Homework Statement A rigid vessel of volume 5m^3 contains 1.0 kg of water and steam at 19 degree C.Find the pressure and the mass of liquid and vapour in the vessel. The vessel is now heated unit the water is just evaporated. Calculate the the pressure and temperature of this process. The...
  30. B

    Effect of air on condensing steam heat tranfer coefficient

    I am working on a model for predicting cooling in a system that evacuates a vessel and cools by evaporation of water and the water vapor is condensed in a tube and shell heat exchanger. My concern is the prediction of the steam side heat transfer coefficient as the air is removed from the...
  31. joanlluch

    Can a Computerized System Improve Performance of Miniature Steam Locomotives?

    Hi, I wonder if someone has experience on steam engines or locomotives, even miniature ones. Some time ago I had the thought of applying a computerised system to miniature steam locomotive. The idea is to remove the traditional mechanism that drives the steam distribution valves (that's known...
  32. D

    Steam Generation Rate of a Heat Exchanger

    Let's say I have a shell and tube heat exchanger that is producing steam. I have a known volume of water entering the shell of the heat exchanger. Would the rate of steam generation be something like... rate of steam generation = (volume of water)*(density of steam)/(time it takes to deplete...
  33. L

    Pressure Vessels: Internal & External Pressure Effects

    When a pressure vessel is subjected to internal pressure of 3 bar and external pressure of 4 bar..Is it right to say resultant pressure is 1 bar external? Does both cases (3 bar int& 4 bar ext,only 1 bar ext) produce the same result considering all other factors like thickness,material etc constant?
  34. P

    Creating oxygen free environment

    Hello, Say I have air circulating in a low pressure loop at 200C, and there are two openings; one for introducing steam and another that allows excess gases to exit. Through experimentation, I know that purging this loop with steam will bring down the oxygen content of this loop to 0% (unless...
  35. Blane E. Chism

    Steam, are there additives or solutions that work

    HI; How do you keep the water from freezing when the steam engine is not in use, other than obviously draining and refilling.
  36. M

    Determining Liters of ethane burned to convert H20 to steam

    Homework Statement The Heat of combustion of Ethane is 373 kcal/mole. Assuming that 60% of the heat is useful , how many liters of ethane,, measured at standard temperature and pressure, must be burned to convert 50.0kg of water ar 10.0C to steam at 100.0C? One mole of a gas occupies 22.4...
  37. S

    Mixing water with steam, find equilibrim

    Homework Statement 100 g of steam at 100 °C is mixed with 500 g of water at 25 °C. What is the final temperature of the mixture? Homework Equations Q= mL Q= mcΔT The Attempt at a Solution Heat given by to water = heat loss at condensation = mLv...
  38. K

    I with steam boiler + generator theory

    Hi. My group and I did a practical the other day and we have to write a lab report on it using our data and the data of another group. The steam boiler creates steam which is fed through a nozzle to a turbogenerator. The generator creates electricity, and this is fed into a loop with a...
  39. B

    Oil Fired Boiler Steam exam revision question

    Homework Statement See image attached, have completed the parts a and b using steam tables and interpolation and got the answers a) Wet steam h at 10.5 bar: h = 2378 kj/kg b) Superheated steam at 10.5 bar @ 285 Degrees Celsius: h = 3018.12 kj/kg Which I believe to be correct now, parts c,d...
  40. B

    Steam Tables: Oil fired boiler questions

    Homework Statement This is from a practice mechanical science exam for HNC engineering. See attachment for the question sheet off a practice exam. I have no idea how to do this after the a and b parts and my answers for which are below the question (underlined), any suggestions or solutions...
  41. smoothie king

    Finding the internal energy using a steam table

    Homework Statement What is entropy of water at 5 Bar and an internal energy of 2724 kJkg-1? The Attempt at a Solution I have looked at the steam tables, i found where the pressure is 500kpa, then i do not know where to go from there. Thank You
  42. A

    Evacuated Tube with Steam

    Hey everyone, I'm building my first evacuated tube solar oven and I seem to run into a problem I can't get around. First of all, I am going to use half inch type K copper pipes with water as a heat transfer fluid. I am putting a vacuum (100 mbar or so) on the tubes to lower the boiling point...
  43. S

    Steam consumption calculation on a steam exchanger

    We are having a steam heat exchanger. Its made up of finned tubes. Tube id 22.7mm Tube od 26.7 mm Tube length 1310.0mm Tube material ss304 Fin od 66.0 mm Fin thk 1.5mm No of fins on one tube 260 Fin material ss304 Total no of tubes 10 Supplied steam pressure 3.5 kg/sqcm A inverted bucket...
  44. M

    Is there a difference between water vapor and wet steam?

    Both water vapor and wet steam contain both contain tiny droplets of water particles(correct me if I'm wrong).Does it mean both water vapor and wet steam are same and one ?
  45. C

    Superheated Steam Turbine - on a question please

    1. Superheated Steam enters a turbine with a pressure of 10 bar and a temp of 300 degrees celcius, and exits with a pressure of 0.046 bar. As the steam flows through the turbine it undergoes adiabatic expansion according to the law pv to the power 1.131 = constant From Steam tables I have to...
  46. y2j

    Control Flow Rate & Pressure of Boiler Steam Engine

    How can one control the flow rate and the pressure of the outlet steam from the Boiler of steam engine
  47. R

    Energy Content of Steam: Variation with Pressure

    I was playing with an online steam calculator provided by TLV, one of the bigger steam equipment vendors & the steam cost it calculates ($/ton) seems lower at high P than low Pressure. http://www.tlv.com/global/TI/calculator/steam-unit-cost.html e.g. The $/ton of 200 bar steam seems 6.09 vs...
  48. S

    Mix steam with colder water, what is final temp?

    Homework Statement 100 g of steam at 100C is mixed with 1 kg of water at 10C. What is the final temperature of the mixture? (in C) heat capacity of water: cw = 4.186 kJ kg-1 K−1 latent heat of vapourisation for water: Lv = 2256 kJ kg−1 latent heat of fusion for water: Lf = 334 kJ kg−1 Homework...
  49. R

    Automotive As a mechanical project we have been asked to design a micro steam car

    [ mod note: moved from homework ] as a mechanical project we have been asked to design a micro steam car. we have chosen to use a wobbler engine for this. The aim of the project to see how far this car can travel based on a given amount of fuel. We are making a boiler which will provide the...
  50. L

    Writing fiction, steam power, hydrogen internal combustion engine

    Question: is it possible to have any of the following - 1. Steam engine in a car 2. A steam internal combustion engine 3. A hydrogen internal combustion engine Background info Hi all, I am working on a fiction short story for fun. It is set in a parallel universe so history and a few...
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