Steam pressure and temperature relationship

thermodynamics - Pressure Temperature relation of saturated steam - Engineering Stack Exchange

steam pressure and temperature relationship

Or, absolute pressure minus equals gauge pressure. Pressure/Temperature Relationship. (Columns 1, 2 and 3). For every pressure of pure steam there is a. Online calculator with Saturated Steam Table by Pressure. Includes 53 different calculations. Equations displayed for easy reference. To use the well-known “Marcet Boiler” experiment to find the relationship between temperature and pressure of the steam. To be familiar with the tables in the.

Pressure - temperature relation for saturated steam - Tubes International

Property Rapid, even heating through latent heat transfer Improved product quality and productivity Pressure can control temperature Temperature can be quickly and precisely established High heat transfer coefficient Smaller required heat transfer surface area, enabling reduced initial equipment outlay Originates from water Safe, clean, and low-cost Tips Having said this, it is necessary to be mindful of the following when heating with saturated steam: Heating efficiency may be diminished if steam other than dry steam is used for process heating.

Contrary to common perception, virtually all of the steam generated from a boiler is not dry saturated steam, but wet steam, which contains some non-vaporized water molecules. Radiant heat loss causes some of the steam to condense. The generated wet steam thus becomes even more wet, and condensate also forms, which must be removed by installing steam traps at appropriate locations. Heavy condensate that falls out of the steam flow can be removed through drip leg steam traps.

However, the entrained wet steam will reduce heating efficiency, and should be removed through point-of-use or distribution separation stations Steam that incurs pressure losses due to piping friction, etc.

steam pressure and temperature relationship

When steam is generated using a boiler, it usually contains wetness from non-vaporized water molecules that are carried over into the distributed steam.

As the water approaches the saturation state and begins to vaporize, some water, usually in the form of mist or droplets, is entrained in the rising steam and distributed downstream. This is one of the key reasons why separation is used to dis-entrain condensate from distributed steam. Superheated Steam Superheated steam is created by further heating wet or saturated steam beyond the saturated steam point.


This yields steam that has a higher temperature and lower density than saturated steam at the same pressure. Advantages of using superheated steam to drive turbines: To maintain the dryness of the steam for steam-driven equipment, whose performance is impaired by the presence of condensate To improve thermal efficiency and work capability, e.

Steam Theory Fundamentals

Ice In ice, the molecules are locked together in an orderly lattice type structure and can only vibrate. In the solid phase, the movement of molecules in the lattice is a vibration about a mean bonded position where the molecules are less than one molecular diameter apart. The continued addition of heat causes the vibration to increase to such an extent that some molecules will eventually break away from their neighbours, and the solid starts to melt to a liquid state.

However, it has been shown that the melting point of ice falls by 0. Heat that breaks the lattice bonds to produce the phase change while not increasing the temperature of the ice, is referred to as enthalpy of melting or heat of fusion.

This phase change phenomenon is reversible when freezing occurs with the same amount of heat being released back to the surroundings.

steam pressure and temperature relationship

For most substances, the density decreases as it changes from the solid to the liquid phase. However, H2O is an exception to this rule as its density increases upon melting, which is why ice floats on water.

Water In the liquid phase, the molecules are free to move, but are still less than one molecular diameter apart due to mutual attraction, and collisions occur frequently. More heat increases molecular agitation and collision, raising the temperature of the liquid up to its boiling temperature. The enthalpy of all other states can then be identified, relative to this easily accessible reference state. Sensible heat was the term once used, because the heat added to the water produced a change in temperature.

However, the accepted terms these days are liquid enthalpy or enthalpy of water. It is from these figures that the value for the specific heat capacity of water Cp of 4.

steam pressure and temperature relationship

Steam As the temperature increases and the water approaches its boiling condition, some molecules attain enough kinetic energy to reach velocities that allow them to momentarily escape from the liquid into the space above the surface, before falling back into the liquid.

Further heating causes greater excitation and the number of molecules with enough energy to leave the liquid increases. As the water is heated to its boiling point, bubbles of steam form within it and rise to break through the surface.

Types of Steam | TLV - A Steam Specialist Company (UK)

Considering the molecular arrangement of liquids and vapours, it is logical that the density of steam is much less than that of water, because the steam molecules are further apart from one another. The space immediately above the water surface thus becomes filled with less dense steam molecules.

When the number of molecules leaving the liquid surface is more than those re-entering, the water freely evaporates. At this point it has reached boiling point or its saturation temperature, as it is saturated with heat energy. If the pressure remains constant, adding more heat does not cause the temperature to rise any further but causes the water to form saturated steam. The temperature of the boiling water and saturated steam within the same system is the same, but the heat energy per unit mass is much greater in the steam.

However, if the pressure is increased, this will allow the addition of more heat and an increase in temperature without a change of phase. Therefore, increasing the pressure effectively increases both the enthalpy of water, and the saturation temperature. The relationship between the saturation temperature and the pressure is known as the steam saturation curve see image below.

Water and steam can coexist at any pressure on this curve, both being at the saturation temperature. Steam at a condition above the saturation curve is known as superheated steam: Temperature above saturation temperature is called the degree of superheat of the steam.