Principles of Steam Engineering Flashcards
the term energy is defined as?
the capacity for producing effect
what is the definition of mechanical energy?
energy associated with large bodies or objects
what is the definition of thermal energy?
energy associated with very small particles called molecules
what is the definition of chemical energy?
energy that arises from the forces that bind the atoms together in a molecule
what is potential energy?
energy at rest; stored energy
kinetic energy is defined as?
energy in motion, producing work
combustion is an example of what type of energy?
chemical energy
thermal energy in transition is termed?
work
what are the two forms of mechanical energy?
mechanical potential and mechanical kinetic energy
what is mechanical potential energy measured in?
foot-pounds
what is the potential energy of an object that weighs 5 pounds and is held 20 feet off earth?
100 foot-pounds
potential energy equals what?
work times distance ( W X D) = PE
force times distance (F X D) equals?
Work
what is the definition of power?
the rate at which work is done
power is measured in what common unit?
horsepower
one horsepower is equivalent to what?
33,000 foot pounds of work per minute or 350 foot pounds of work per second
A 3 horsepower engine generates how many foot pounds per second?
1650
what is the horsepower generated, if an engine is producing 5, 500 foot pounds of work per second?
10 horsepower
what are two forms of stored thermal energy?
internal potential energy and internal kinetic energy
what unit is heat measured in?
British thermal unit (BTU)
what is defined as the quantity of heat required to raise the temperature of 1 pound of water through 1 degree on the Fahrenheit scale?
1 British thermal unit (BTU)
how many calories equal 1 BTU?
approximately 252
what is defined as the quantity of heat required to raise the temperature of 1 gram of water through 1 degree on the Celsius scale?
calorie (cal)
what are the three types of heat transfer?
conduction; radiation; convention
what is the mode of heat transfer by which heat flows form a hotter to a colder substance when there is physical contact between the two substances?
conduction
what is the mode of heat transfer that does not require any physical contact between the warmer substance and the cooler substance?
radiation
what type of heat transfer is generated by the sun as it heats the earth without heating space?
radiation
what is the mode of heat transfer that occurs by transmission of heat by the circulation of a liquid or a gas such as air?
convection
what are the three basic physical states of all matter?
solid, liquid and gases
what are the two effects that the flow of heat has on a substance?
sensible and latent
sensible heat is defined as?
when the flow of heat is reflected in temperature change and not in a change in physical state
latent heat is defined as?
when the flow of heat is not reflected in a temperature change but is reflected in the changing physical state of a substance
to change a pound of ice at 32 degrees F. to a pound of water at 32 degrees F., we must add how many BTU?
144
what is the term associated with a substance that changes from a gas or vapor to a liquid?
latent heat of condensation
what is the definition of specific heat?
a thermal property of matter that must be determined experimentally for each substance
how is the principle of the conversation of energy most simply stated?
energy in = energy out
what is the formula for converting heat to work?
1 BTU = 778 foot-pounds
thermal energy of main steam is transformed to mechanical energy at what point in the basic steam cycle?
high and low pressure turbines
fuel oil used in the boiler is considered what type of energy?
chemical
when a vapor is in contact with the liquid from which it was generated, it remains the same temperature as the boiling liquid. in this condition the liquid and the vapor are said to be in?
equilibrium contact
the temperature at which a liquid boils under pressure is called the saturation temperature, and the corresponding pressure is called what?
saturation pressure
atmospheric pressure is expressed as?
14 psi at sea level and lesser at higher altitudes
what term is used when the water and steam reach a point that they are no longer indistinguishable from each other, and no further changes in state can occur with the addition of heat or pressure?
critical point
steam which has been heated above its saturation temperature for any give pressure is called what?
superheated steam
the amount by which the temperature of the superheated steam exceeds the temperature of the saturated steam at the same pressure is know as what?
degree of superheat
if saturated steam at a pressure of 1200 psig and the corresponding saturation temperature of 567 degrees F. is superheated to 900 degrees F., what is the degree of superheat?
333 degrees F
what is the saturation pressure for water at a saturation temperature of 212 degrees F.?
14.7 psi
the changing of steam to condensate in the main condenser is an example of what heat effect?
latent heat of condensation
the circulation in a natural circulation boiler is an example of what heat effect?
natural convection
when the main feed pump discharges feed water toward the boiler, the feed water is transported by what kind of heat transfer?
forced convention
