Water in all its forms, solid, liquid and gaseous is one of the most abundant compunds on earth. Water covers 71% of the Earth's surface and is vital for all known forms of life. Steam is the technical term for water vapour, the gaseous phase of water.
Steam power was the engine that drove the industrial revolution. In 1698, British inventor Thomas Savery patented a simple steam-powered pump, which he described as an "engine to raise water by fire." In 1712, Englishman Thomas Newcomen developed the first practical steam engine complete with pistons and cylinders, which was used primarily to pump water out of mines. By the 1770s, Scottish inventor James Watt had further improved on Newcomen’s work. Steam power had overcome the limitations of physical labour and sped factories along at a pace never before seen.
Model of James Watt's steam engine.
With the power of steam harnessed, factories no longer had to rely on wind or water power to drive their machines. By the early 1800s, high-pressure steam engines had become compact enough to move beyond the factory, prompting the first steam-powered locomotive to hit the rails in Britain in 1804. For the first time in history, goods were transported over land by something other than the muscle of man or animal. In the early 1800s, American Robert Fulton built the first commercially successful steamboat, and by the mid-19th century, steamships were carrying freight across the Atlantic. Charles Parsons' invention of the steam turbine in 1884 had direct application to marine propulsion and electrical generation.
Parsons Steam turbine circa 1887.
Steam is still used today to produce electrical energy in power plants fueled by nuclear and fossil fuels. These are collectively known as "thermal" power plants because they derive their energy from the heat released from their fuels. They transfer that heat to the water and steam in their boilers (or steam generators) and then use that steam to drive large turbine-generators that produce the electricity we use every day.
Thermodynamics is a branch of natural science concerned with heat and its relation to energy and work and the thermal properties of the 'working fluids' such as steam. Under pressure, steam has the ability to carry, and then give up, large amounts of heat energy, making it a good working fluid.
Saturated Steam. Steam is traditionally created by heating water in a boiler. The water vapour produced includes water droplets and is described as wet steam. As the wet steam is heated further, no change in temperature occurs but all of the water droplets evaporate and the steam is considered dry saturated steam. For every pressure of saturated steam there is a corresponding temperature.
Superheated Steam. When additional heat is added to dry saturated steam, its temperature is raised above the saturation temperature. This is called superheated steam.
Steam Tables contain thermodynamic data for water, saturated steam and superheated steam and are used by engineers and scientists in the design and operation of equipment where thermodynamic cycles involving steam are used. The following properties of steam at various temperatures and pressures will be found in steam tables.
- Absolute pressure: is the pressure in kPa above a perfect vaccuum.
- Atmospheric pressure is 101.325 kPa absolute
- Guage pressure: is the pressure in kPa above atmospheric pressure. Atmospheric pressure = zero guage pressure. Guage pressure plus 101.325 kPa = absolute pressure
- Saturation Temperature: The boiling point, the temperature of ebullient water and saturated vapour under the same pressure.
- Specific volume: Volume in m3 occupied by 1 kg of saturated liquid vf or saturated vapour vg.
- Density of the steam: Specific mass of the steam in a volume of 1 m3.
- Enthalpy of the saturated liquid or fluid hf: sensible heat, the quantity of heat contained in 1 kg of ebullient water at the selected pressure & temperature. Units are kJ/kg
- Enthalpy of Evaporation hfg: the latent heat of vaporization: Heat necessary to completely transform 1 kg of water at the saturation temperature into steam vapour without change of temperature (the thermal energy necessary for the change of state from liquid to vapour). Units are kJ/kg
- Enthalpy of the steam hg: the total heat contained in 1 kg of saturated steam. It is the sum of the enthalpy of the saturated liquid plus the enthalpy of evaporation. Units are kJ/kg
- Specific heat of steam: the quantity of heat necessary to increase the temperature of 1 kg of steam by one Celsius degree at constant pressure. Units are kJ/kg
The cache is a small camo'd lock'n'lock container. To find it, you will need to calculate the North and West offsets and add them to the following coordinates:
N 42° 46.465 W 080° 02.162
North Offset = (A + B) / 1000
A = the saturation temperature of water at a pressure of 10 MPa
B = the heat of evaporation for saturated water at 14.0 Mpa
West Offset = C/1000 - D
C = the enthalpy of the saturated liquid at 310 Deg C and 9.865 MPa
D = the specific volume of the saturated vapour (steam) at 205 Deg C and 1.7243 MPa
