How to Use Steam Tables

This screencast demonstrates how to use steam
tables, and steam tables list certain properties of steam, and the ones in particular that we’re interested in are specific enthalpy, specific internal energy, and specific volume. They can also list specific
entropy, but in this screencast we will focus on the 3 I mentioned. So what do we mean by
specific? This means per unit mass or unit moles, and in the steam tables that we are
going to look at. It will be per mass and in particular the enthalpy and the internal
energy will be in kJ per kg, and the specific volume will be in meters cubed per kg. So
there are three parts of the steam tables that are usually used. The first ones have to do
with saturated steam. What that means is that you have steam and water in equilibrium. So
once you have a pressure or you know the pressure the temperature is automatically fixed. Vice
versa if you know the temperature the pressure is automatically fixed. The third one we are going
to look at is superheated steam, and superheated steam you are going to need both the pressure
and the temperature to find your properties, because you are beyond the vapor liquid equilibrium
line. So let’s start with saturated steam. We can look at 2 different tables, but let’s
look at the first one, which lists the properties by pressure. Note we have in this column the
different pressures in bar, and in this column we have temperatures that correspond to these pressures
again because this is saturated once you have the pressure you know the temperature. So let’s
see how we use this. We are told that we have saturated steam at 30 bar, and we are looking
for the specific enthalpy. So we go to our table and we find 30 bar. So at 30 bar you
see that the temperature is 233.85 degrees Celsius, and we have our specific volume of
both the water and the steam. We have our specific internal energy, and now we have
our specific enthalpy. So we are asked for the steam. So our specific enthalpy is therefore 2803.2 kJ/kg. If we had wanted instead the enthalpy of the saturated water, then we would look at this one right
here. So let’s try another one. Let’s say we want the saturated water and it is at 45 bar,
and we are looking for the specific volume. So let’s go to our chart again. Here we are at
45 bar, and here would be all the properties that we would need for saturated water or steam
at 45 bar. Here we want saturated water and we want the specific volume. So we would look
at this value right here. 0.0012696 meters cubed per kg. So that is the first way that
you can use a steam table. Again for saturated steam. Now we are going to look for our properties
under temperature. So let’s use this to find another value. Let’s say that we have a pressure
that is equal 60 bar and our temperature is equal to 500 degrees C. Now we are looking at this particular
part of the table, and the properties we therefore have are the specific enthalpy, which is 3423.1
kJ/kg. The specific internal energy, which is 3083.1 kJ/kg and finally our specific volume,
which is 0.056671 meters cubed per kg. Again note that you need both the pressure and temperature
to find superheated steam properties. So once you are comfortable with steam tables you can
use their properties to solve mass and and energy balances that use steam.

19 thoughts on “How to Use Steam Tables

  1. can you please make a video explaining how to construct the steam tables from scratch. how did they do it? if i wanted to verify a data point how do i recreate the experiment? how can you calculate the entropy, enthalpy, etc. what equipment do you use. they have to come from somewhere right? someone had to perform the measurements and experiments, right? how did they do it?? if civilization ended and you had to recreate the steam tables, how do you do it??

  2. At 1:30 where she says that saturated steam is water and steam in equilibrium, I thought steam was water but just at a higher temperature?

  3. i think its so basic, what we want now is how what is the meaning of the underline numbers, italic numbers, the numbers above the tables and the table to know where the saturation will start, this is too basic i swear i bought a steam table last week i just dunno how to use it, i aldy read books and still during interpolation i always fail in first attempt if u can do tutorial for that please we beg u 🙁

  4. Can someone explain how I would read a table like this if I were given °F (instead of °C) and pound force/in^2 (instead of bar)

Leave a Reply

Your email address will not be published. Required fields are marked *