PERMEABILITY

Mercado, Mary Joy Pangilinan, Alyssa Pamela Silva, Lourdes

Ventilacion, Isiah Bernard

• Pre - Lab Report

• Post – Lab Report

THEORY ON PERMEABILITY

Permeability is a separation process where in the semi-permeable membrane acts as a barrier that controls the rate and movement of various molecules between two liquid phases, two gas phases, or a liquid and a gas phase.

DARCY’S LAW

Va = kdh dL

Volumetric flow rate per unit cross-sectional area

Hydraulic gradient

K = PERMEABILITY

POROSITY

also called the void fraction is the measure of the empty space in

a material It is a ratio of the void volume to the

total volume of the material. It is usually ranges from 0-1, or in

percentage 0-100% Є = Vv

VT

Objectives

To determine the permeability and the filtration grain diameter of the porous granular media (sand)

Equipments/Materials

Permeability and Fluidization Apparatus

Pre-sieve sand (ds > 0.5mm and approximately 0.54kg)

Electronic balance 50-mL beaker (2pcs) Thermometer (0.1 °C calibration)

Operating Procedures and Conditions

Preliminary Operation Experimental Procedure Shutdown

Treatment of Results

Flow rateHead Loss (mm

H2O)Velocity, Va

(mm/s)

dh/dLManometer Difference(mm H2O)

0 0.095 4.0584 0.5278 95 .5278

100 0.097 4.1437 0.05389 97 .5389

200 0.114 4.8696 0.06333 114 .6333

300 0.122 5.2117 0.06778 122 .6778

400 0.169 7.2194 0.09389 169 .9389

500 0.233 9.9529 0.12944 233 1.2944

600 0.323 13.7975 0.04944 323 1.7944

700 0.420 17.9412 0.03333 420 2.3333

600 0.390 15.9662 0.07166 390 2.1667

500 0.346 14.1645 0.01922 346 1.9222

400 0.321 13.1410 0.10783 321 1.7833

300 0.275 11.2582 0.03527 275 1.5278

200 0.226 9.2524 0.02255 226 1.2556

100 0.191 7.8192 0.01061 191 1.0611

0 0.125 4.1170 0.00694 125 .694

Computations

Determine the porosity, ε, of the bed.

100

100

ε = volume of void space total volume occupied

ε = 100 = 0.67 150

Computations

Determine the permeability, k, of the filter media ( such as sand)

KOZENY-CARMAN

K = ρg ε³ (d/6)² 5μ (1-ε)²

Determining the Head Loss, h, of mm H2O.

Headloss = ∆P/ ρ

∆P = difference in manometer reading

ρ = density of the water, 1000kg/m³

Computations

Determining the Velocity, Va in mm/s

Va = Kdh dL

Computations

K = ρg ε³ (d/6)² 5μ (1-ε)²

Headloss = ∆P/ ρ

Length (height of the media inside the perspex column) =constantVa = _________________

Determine the filtration grain diameter, d, using the Kozeny-Carman Equation

Computations

Va = K dh dLdh = 5μVa (1 - ε)²

(6/d)²dL ρg ε³

K = ρg ε³ (d/6)² 5μ (1-ε)²

K = ρg ε³ (d/6)² 5μ (1-ε)²

Va = ρg ε³ (d/6)² dh 5μ (1-ε)² dL

d = ___________

Analysis / Interpretation of the Results

Figure 1. The relationship between Head Loss (h) and Flow Velocity (Va).

0 2 4 6 8 10 12 14 16 18 200

0.5

1

1.5

2

2.5 head loss (h) vs flow velocity (Va)

increasing flowrate

decreasing flowrate

Va

h

Analysis / Interpretation of the Results

0 2 4 6 8 10 12 14 16 18 200

0.1

0.2

0.3

0.4

0.5

0.6

hydraulic gradient (dh/dL) vs flow velocity (Va)

Va

dh/d

L

Figure 2. The relationship between Hydraulic Gradient (dh/dL) and Flow Velocity (Va)

Answers to Guide Questions :

What are the importance of knowing the permeability of a given porous medium ?

Porosity and permeability are two of the primary factors that control the movement and storage of fluids in rocks and sediments. They are intrinsic characteristics of these geological materials. The exploitation of natural resources, such as groundwater and petroleum, is partly dependent on the properties of porosity and permeability. Oil mining is the most relevant field in chemical engineering that applies the concept of permeability. It is important to know the permeability of the rock, or the reservoir, to calculate how easily the hydrocarbons will flow out of them. This is the simplest level in analysis of reservoir in oil mining.

What operating parameters must be considered in determining the permeability of a given porous media ? Does the choice of liquid affect the result of the experiment ?

The operating parameters are the grain size diameter and the porosity of the granular media.

Yes. A viscous fluid will have a hard time passing a low porosity media.

Answers to Guide Questions :

What is the importance of having a high or low permeability of certain material ?

Permeability is the capacity of a rock or sediment to move water or other fluids through it's pore space. Things with high permeability would be things like beach sand or a loosely packed sandstone, and things will low permeability would be things like granites and other igneous porphyries.

Answers to Guide Questions :

Conclusions, Findings, Recommendation

Based on the data gathered in the experiment, it shows that the flowrate is directly proportional to its pressure drop. As you increase the flow rate, the pressure inside the column is also increasing causing the granular material to move. However, there are some discrepancies in the experimental data. The liner relationship between Hydraulic Gradient and flow velocity cannot be observed. This may be because of technical errors involved.

  It is highly recommended that before starting the

experiment, the apparatus is in good condition. Leaks and other important factors must be check before doing the experiment. More importantly, the apparatus should be calibrated well to become more accurate and less to errors.

Recommendation

Always look for the bubble cap to prevent the over pressuring or open the bubble cap when calibrating to prevent bubble from building up.

Valve 1 & 4 MUST be closed at the start of zero flowrate reading. Only valve 5 & 6 must be open.

When increasing flowrates always open the Valve 5 to releave pressure on the rotameter and allow a good passage of air.

When the water on the sides of water manometer reaches the extreme points close Valves 5 & 6 and open Valve 4.

Do not open Valve 5 & 6 in the same manner when calibrating, because air will penetrate the whole system, therefore water will not move.

Always open the faucet during the experiment to maintain the proper amount of water in the head tank. Loss of water would give an error on your reading.

Recommendation

References

Unit Operation of Chemical Engineering 6th Ed by McCabe, Smith, Harroitt Transport Phenomena and Separation Process by Geankoplis Physical Chemistry 6th Ed by Levine Physical Science by Keith Instrumentation and Design of Chemical Eng’g

Equipments Perry’s Chemical Engineering Handbook 8th Ed

Any Questions ???