Good Example OF Aim : To Determine The Relationship Between Particle Size And Settling Velocity Report

(Laboratory Records Book ) : Fluid Mechanics

Industry uses water in many different ways and in different amounts. However, water saving technology exists that could be employed in many applications. Highly efficient water saving techniques have been shown to not only reduce an organization’s carbon footprint but to also make huge savings in energy bills.
Nevertheless, in many operations within the manufacturing, industrial and commercial sectors, the use of water is often an accepted process cost. There is often scant attention paid to reducing such a significant service cost. With water, unlike with electricity or gas, the consumer pays for both the supply of water to the plant and once used pays again for its disposal. The cost of treating water effluent is based on many factors, including solids, heat, pH and volume, and under the policy of ‘the polluter pays’ this cost of effluent treatment. Effluent treatment is a prime area where the terminal settling velocity becomes important.
Industry uses water in many different ways and in different amounts. However, water saving technology exists that could be employed in many applications. Highly efficient water saving techniques have been shown to not only reduce an organization’s carbon footprint but to also make huge savings in energy bills. Nevertheless, in many operations within the manufacturing, industrial and commercial sectors, the use of water is often an accepted process cost. There is often scant attention paid to reducing such a significant service cost.

With water, unlike with electricity or gas, the consumer pays for both the supply of

for its disposal. The cost of treating water effluent is based on many factors, including solids, heat, pH and volume, and under the policy of ‘the polluter pays’ this cost of effluent treatment
The energy input of the boiler or the chiller is significant whether using gas, oil or electricity to achieve the required heating/cooling. The color of the water in this system will range from pale straw (usually found in a newsystem) to black (found in a typical system).

This discoloration has a major negative effect on the system. From our experience, it is not

uncommon to see large commercial buildings lose between 15-20% of its total heating energy
input, just because the water is dirty. The discoloration is a product of the corrosion
that takes place naturally within the system, and this corrosion reduces the heat transfer from
the heat source to the water, and then from the water to the heating/cooling outlet. This contamination in the water is a combination of bio-mass and mineral scale, both of which will attach to the inner heat transfer surfaces of the system, including the pipework, chiller/heater
surfaces and all water contact controls. The biofilm now acts as an adhesive for all the
other contamination present, allowing the layers to build up. This build-up can often get out of control leading to severely restricted pipework or, in extreme but not unknown cases, blockages. bIn addition, if chemicals are used to treat this dirty water, then the effectiveness of the chemical treatment will be reduced because of the high solid load within the water. Past e examinations of this process have shown that filtration to remove particulates down to 10 microns can improve heat transfer significantly. However, further tests on many systems have shown that the majority of this contamination is between 1.0 micron and 10 micron. Savings of 15-20% in total energy costs in this process can be readily achieved by cleaning up the heating/ cooling water using reliable filtration to less than 1.0 micron connected to both the hot and
cold water system. If the water in the system is anything but clear, then energy is being wasted.
CrossFlowMF1.0 is new technology that can filter reliably below 1.0 micron – even
achieving filtration down to 0.45 micron to ensure cleaner process water which in
turn can reduce a business’ carbon footprint. Operationally, this technology utilizes a unique patented vortex bed stabilizer which maintains flatbed filtration with high surface turbulence. This ensures that no bio-fouling can be seeded whilst holding filtered contamination in suspension above the media bed. This gives lower pressure drops, longer filtration and shorter backwash cycles, making direct savings on operational costs.

THEORY

Let us hypothetically assume that a particle is falling down through a viscous fluid than under the action of g. Since it starts, it is acted upon constantly and therefore wants to plunge faster the deeper it goes. However what happens is that the inertial force brought about

Weight of the Particle

Particle of mass m
Viscous Drag force Viscous Fluid
works up and increases and at a particular depth, both the forces balance each other. From this point onwards the fall is at a constant velocity. In other words, acceleration becomes zero