THERMODYNAMICS (MECHANICAL
ENGINEERING) QUESTIONS AND
VERIFIED ANSWERS|100%
CORRECT|GRADE A+
one-dimensional flow - ANSWER flow is normal to the boundary at locations where mass enters/exits the
control volume, all intensive properties are uniform with position over each inlet/exit area 'A' through
which matter flows rate of mass flow=(area)(velocity)/(specific volume)
Steady state - ANSWER no properties change with time, for a control volume, mass in=mass out
Energy Rate Balance (most comprehensive form) - ANSWER dKE/dt+dPE/dt+dU/dt=Q*cv-W*cv+(sum of
all)m*i(ui-pivi+Vi^2/2+gzi)-(sum of all)m*e(ue-peve+Ve^2/2+gze) where W*cv is the rate of work
associated with shafts, boundary displacement, and electricity
Nozzle - ANSWER A flow passage of varying cross-sectional area in which the velocity of a gas or liquid
increase in the direction of flow, 0=(h1-h2)+(v1^2-v2^2)/2
Diffuser - ANSWER A flow passage of varying cross-sectional area in which the velocity of a gas or liquid
decreases in the direction of flow, 0=(h1-h2)+(v1^2-v2^2)/2
Turbine - ANSWER A device in which power is developed as a result of a gas or liquid passing through a
set of blades attached to a shaft free to rotate, W*cv=m*(h1-h2)
Pump/Compressor - ANSWER Devices in which work is done on the system flowing through them to
change the state of the substance, typically to increase the pressure and/or elevation, pump-substance is
liquid, compressor-substance is gas, W*cv=m*(h1-h2)
Heat Exchangers - ANSWER direct contact: a mixing chamber in which hot and cold streams are mixed
directly
tub-within-a-tube-counterflow: a gas or liquid stream is separated from another gas or stream by a wall
through which energy is conducted. Heat transfer occurs from the hot stream to the cold stream as the
streams flow in the opposite direction.
ENGINEERING) QUESTIONS AND
VERIFIED ANSWERS|100%
CORRECT|GRADE A+
one-dimensional flow - ANSWER flow is normal to the boundary at locations where mass enters/exits the
control volume, all intensive properties are uniform with position over each inlet/exit area 'A' through
which matter flows rate of mass flow=(area)(velocity)/(specific volume)
Steady state - ANSWER no properties change with time, for a control volume, mass in=mass out
Energy Rate Balance (most comprehensive form) - ANSWER dKE/dt+dPE/dt+dU/dt=Q*cv-W*cv+(sum of
all)m*i(ui-pivi+Vi^2/2+gzi)-(sum of all)m*e(ue-peve+Ve^2/2+gze) where W*cv is the rate of work
associated with shafts, boundary displacement, and electricity
Nozzle - ANSWER A flow passage of varying cross-sectional area in which the velocity of a gas or liquid
increase in the direction of flow, 0=(h1-h2)+(v1^2-v2^2)/2
Diffuser - ANSWER A flow passage of varying cross-sectional area in which the velocity of a gas or liquid
decreases in the direction of flow, 0=(h1-h2)+(v1^2-v2^2)/2
Turbine - ANSWER A device in which power is developed as a result of a gas or liquid passing through a
set of blades attached to a shaft free to rotate, W*cv=m*(h1-h2)
Pump/Compressor - ANSWER Devices in which work is done on the system flowing through them to
change the state of the substance, typically to increase the pressure and/or elevation, pump-substance is
liquid, compressor-substance is gas, W*cv=m*(h1-h2)
Heat Exchangers - ANSWER direct contact: a mixing chamber in which hot and cold streams are mixed
directly
tub-within-a-tube-counterflow: a gas or liquid stream is separated from another gas or stream by a wall
through which energy is conducted. Heat transfer occurs from the hot stream to the cold stream as the
streams flow in the opposite direction.
