Done by:
Ng Zi Yao
Edmond Chen
Kelvin Lim
A fluid is a substance that continuously
undergoes deformation when a force is exerted
onto it
All gases are fluids, but not all liquids are fluids
Fluids does not resist deformation, or only
resisting it very lightly
Fluids has the ability to take the shape of its
container
Density is defined as an object’s mass per unit
volume
The S.I. unit for density is kg/m3
It can also be expressed as: ρ = m/V = 1/vg
p = density
m = mass
V = volume
Vg = specific volume (volume occupied by a unit
of mass)
A common laboratory device is the pycnometer
(also known as the specific gravity bottle)
It measures the density of a fluid
by reference to a common fluid,
e.g. water or mercury, using an
analytical balance
http://www.museumboerhaave.nl/AA
collection/AAJPEGS/M20/11203.jpg
The density of a fluid changes with temperature
and pressure
Formula when temperature is changed:
ρ1 = ρ0 / [1 + β (t1 - t0)]
ρ1 = final density
ρ0 = initial density
β = volumetric temperature expansion coefficient
t1 = final temperature (Co)
t0 = initial temperature
Formula when pressure is changed:
ρ1 = ρ0 / (1 - (p1 - p0) / E)
p1 = final pressure (N/m2)
p0 = initial pressure
E = Bulk modulus elasticity (compressibility of a
fluid)
The density of water versus temperature and pressure
- http://www.engineeringtoolbox.com/fluid-density-temperature-pressure-d_309.html
In a denser object, the intermolecular distance
is shorter
Hence, heat energy is able to be transferred
from one molecule to another faster
Therefore, a denser substance will increase the
efficiency of the heat exchanger, while a less
dense substance will decrease the efficiency
Defined as the measure of the ability of a
material to conduct heat
Watts per metre Kelvin
SI Unit: W/(m·K)
English Unit: Btu/(hr·ft·°F)
British Thermal Unit per
hour foot Fahrenheit
Important in designing heat exchangers
Heat transfer coefficients in these components
are usually computed using correlations which
require thermal conductivity data
quantity of heat
thermal conductivity
thickness of conducting
surface separating the 2
temperatures
Temperature Gradient
temperature difference
rate of heat flow
total cross sectional area
of conducting surface
defined as the quantity of heat, ΔQ, transmitted during time Δt through a thickness x, in a
direction normal to a surface of area A, due to a temperature difference ΔT, under steady
state conditions and when the heat transfer is dependent only on the temperature gradient.
Hot-wire apparatus can accurately measure and
mixtures at temperatures from 30 K to 750 K with
pressures to 70 Mpa
How different materials interact when mixed
To show difference or degree of density in materials
Density allows you to solve for mass and
volume, if given the other quantity.
v * rho = m
Case Study
Crude Oil
790 - 973 kg/cu.m
Water
1000 kg/cu.m
Crude Oil does not mix with sea water
(1025.18 kg/cu.m).
http://en.wikipedia.org/wiki/Conductivity
http://en.wikipedia.org/wiki/Fluids
http://fluidproperties.nist.gov/thermal.html
http://www.engineeringtoolbox.com/fluid-density-temperaturepressure-d_309.html
http://www.engineeringtoolbox.com/density-specific-weight-gravityd_290.html
http://en.wikipedia.org/wiki/Density
http://en.wikipedia.org/wiki/Pycnometer
http://images0.redbubble.com/img/art/border:whitewithdetail/product:laminatedprint/size:small/view:preview/363431-4-floating-wood.jpg
http://www.simetric.co.uk/si_liquids.htm