Thermo Flashcards
γ = ?/?
Cp / Cv
Cp = _ + _
Cp = Cv +R
Diatomic Cp
Cp, dia = 7/2 R
Diatomic Cv
Cv, dia = 5/2 R
γ, Dia
1.4
Cp, mono
5/2R
Cv, mono
3/2 R
γ, mono
1.67
A closed rigid container has a volume of 1 m3 and holds air at 345 kPa and 20 °C. Heat is added until temperature is 327 °C. Determine
the change in internal energy using an average value of the specific heat.
932 KJ
A closed rigid container has a volume of 1 m3 and holds air at 345 kPa and 20 °C. Heat is added until temperature is 327 °C. Determine
the variation of the specific heat.
1018
reciprocating compressor
is always a closed system
But a “compressor” is an open system
A burner heats air from 20 to 40oC at constant pressure. Determine the change in entropy for a unit
mass of air going through the heater, assuming that for air
Cp= 1 kJ/kgK
S = 0.03356 KJ/ kgK
A solid metallic block weighing 5 kg has an initial
temperature of 500C. 40 kg of water initially at 25C is contained
in a perfectly insulated tank. The metallic block is brought into
contact with water. Both come to equilibrium. Specific heat of
block material is 0.4 kJ/kg-K. Ignoring the effect of expansion and
contraction and also the heat capacity to tank, the total entropy
change in kJ/kg-K.
1.25 answer BUT 0 in indiabix
The cylinder of an engine has a stroke of 300mm and a bore of 250mm. The volume ratio of compression is 14:1. Air in the cylinder at
the beginning of compression has a pressure of 96 kN/m2 and a temperature of 93 ºC. The air is compressed for the full stroke according
to the law PV1.3 = C. Determine the work transfer per unit mass of air. Assume air R = 287 J/kg-K.
424 kJ
Latent heat of fusion at 0C of water (Lambda f)
80 cal/g
Latent heat of vaporization at 100C of water (Lambda v)
540 cal/g
Phase change is called
latent heat
Constant phase, but temperature changes
sensible heat
Specific heat of water in english units
specific heat of water in SI units
A nuclear reactor generates 3000 MW of heat. The heat is transferred in a heat exchanger of
energy transfer efficiency 75% into steam which is expanded in a turbine in order to produce a
power output. The steam is condensed in a condenser, releasing 1800 MW of heat, and pumped
back through the heat exchanger by a feed pump which requires 3% of the power output from the
turbine. Determine:
a) The net power output from the plant.
b) The power output from the turbine.
c) The overall thermal efficiency of the plant.
A 450 MW
B 464 MW
C 15%
