The water in a 40-L tank is to be heated from 15°C to 45°C by a
25-cm-diameter spherical heater whose surface temperature is
maintained at 85°C. Determine how long the heater should be kept
on.
Given: The properties of air at 1 atm and the film temperature
of 57.5°C.
Fluid temperature = Average temperature for water
(15+45)/2=30°C
k = 0.6515 W/m.°C, v = 0.493 x 10-6 m2/s,
Pr = 3.12, and ? = 0.501 x 10-3 K-1
The properties of...
A rigid, insulated, empty vessel is to be filled with steam from
a steam line at 7 bar and 320°C. Steam flows into the vessel until
the pressure in the vessel is 7 bar. At this instant the valve on
the charging line is closed.
(a) What is the temperature of the
steam in the vessel at the instant the valve is closed?
(b) What is the final pressure of
the steam in the vessel after it has reached mutual stable
equilibrium...
A heater is used to heat 100 SCM of nitrogen
in a rigid vessel from 26.85oC to
126.85oC. Do energy balance and calculate heat duty Q
(kJ) using data from Table A-2a,b,c and A18. State your assumption
and explain your results.
Water at a mean velocity of 0.2 m/s is heated from 20
to 40°C by passing it through a 0.5-cm-ID tube. The 2
surface is heated with a uniform heat flux of 6000 W/m . Find the
following: a) The length required to heat the water to a given
temperature.,b) the surface temperature at the inlet of the tube.
Given that the following information: The physical properties of
liquid at 30 °C:
??
=4182?⁄??.°?,?=0.6405?⁄?.°?,??=3.57,?=0.5537×10−6?2⁄?,?=988??⁄?3
One kilogram of Refrigerant 134a vapor initially at 2 bar and
20°C fills a rigid vessel. The vapor is cooled until the
temperature becomes -24°C. There is no work during the
process.
Let To = 20°C, po = 0.1 MPa and ignore the
effects of motion and gravity.
2. For the refrigerant, determine the change in exergy, in
kJ.
Note: for part 1: q=-98.086kj please find part two- the change
in exergy in kj
A monoatomic, ideal gas in a sealed, rigid container is heated
until its temperature rises from 50oC t0
100oC. If the initial pressure is 1 atm., find the final
pressure.
A rigid, sealed container of R134a initially at -30°C and 40%
quality is placed inside a room so that it heats up at 5°C/hr. If
there is 3 kg of R134a in the container, determine:
a) The volume of the container
answer must be 0.2723 m3
b) The specific volume of the vapour when the R134a finishes
converting into a gas
answer must be 0.09075 m3/kg
c) The pressure when all the R134a has finished converting into
a gas
answer...
2. A 1.00 m3 rigid vessel is filled with steam with a quality of
98.0% at 180◦C. Energy is added to the vessel until the pressure
reaches 3,000 kPa. Determine the following:
a) The initial pressure in the vessel
b) The mass of water in the vessel
c) The final temperature in the vessel
d) The change in enthalpy