DESIGN AND FABRICATION OF PERMEABILITY APPARATUS FOR DETERMINATION OF PERMEABILITY OF POROUS CERAMICS
Permeability measurement determines the pore size and pore connectivity is an important characterization for porous materials. For the measurement of permeability highly sophisticated & expensive instrument are commercially available for research purpose but for undergraduate level research the purchase of this equipment is an expensive affair though the working principle of the apparatus is very simple. So an attempt has been made to design and fabricate a permeability measurement set up for undergraduate level research work at very low cost using Darcy’s equation as basic principle. Initial sketches and designs were drawn manually on the basis of text book diagrams and research papers. Subsequently the designs were analysed with respect to ease of fabrication, cost and adaptability to various size of samples. Finally the final design was selected out of 3 designs and the three dimensional design of the final design was made using CATIA (version 5) software, after which the equipment was fabricated using brass. Brass is used for its easy machinability and long life. The measured permeability showed similar trend for similar sample measured by other equipment (Mercury porosimetry).
LIST OF FIGURES
Figure no. Figure Caption Page no.
2.1 Commercially available permeability apparatus 13
2.2 Commercially available permeability apparatus 13
3.1 Design-1 of permeability the apparatus 16
3.2 Design-2 of permeability the apparatus 17
3.3 Design-3 of permeability the apparatus 18
3.4 The final design of the apparatus 19
3.5 Isometric view of sample holder 20
3.6 Isometric view of sample holder with bolt 21
3.7 Isometric view of the final design 21
3.8 Sectional view of the final design 22
4.1 Picture of sample holder and bolt to tight the sample 24
4.2 O-ring inside the sample holder 24
4.3 Sample inside the sample holder 24
4.4 Variable size of sample holder 25
4.5 Picture of complete permeability set up 25
5.1 Flow chart for HA powder preparation 27
5.2 Process flow chart for gel casting sample 29
5.3 Flow chart of polymer sponge method 31
6.1 Variation of volume flow rate with pressure 37
6.2 Pore size distribution of 60% naphthalene gel casting sample 38
6.3 Pore size distribution of 50% naphthalene gel casting
6.4 Pore size distribution of 50 (vol.%) solid loading polymer
sponge replication sample 39
LIST OF TABLES
Figure no. Table Caption Page no.
6.1 Bulk density and apparent porosity of the sample prepared by different method 35
6.2 Specific permeability coefficient calculation for sample prepared by different method 36
6.3 Summary of apparent porosity, average pore radius and average pore diameter of the sample prepared by different
List of Figures
List of tables
CHAPTER 1: INTRODUCTION 8
1.1. Introduction 10
1.2. The guiding Principle-Darcy’s equation 10
CHAPTER 2: LITERATURE REVIEW
2.1 Permeability and its applications 12
2.2 Objective and novelty of work
CHAPTER 3: DESIGN OF APPARATUS 14
3.1 Design-1 16
3.2 Design-2 17
3.3 Design-3 18
3.4 Three dimensional designs
CHAPTER 4: FABRICATION OF APPARATUS 20
CHAPTER 5: PREPARATION OF POROUS SAMPLE 24
5.1 Sample Preparation by Pellet Pressing method 27
Sample Preparation by Gel casting method28
Sample preparation by Polymer replication method30
CHAPTER 6: EXPERIMENTAL WORK
Apparent Porosity, Bulk Density Measurement34
Measurement of Permeability36
Study of effect of pressure on volume flow rate.37
Pore Size Distribution by Porosimetry Test38
CHAPTER 7: RESULTS & DISCUSSION
7.1 Results and discussion 43
CHAPTER 8: CONCLUSION
8.1 Conclusion 45
Permeability is a most important material property which defines the resistance to the passage of the fluid, and it depends on the porosity and pore connectivity. Therefore the permeability is correlated with the type of pores and pore size distribution. The permeability is determined from Darcy’s equation. The permeability measurement gives an idea of the packing behaviour of the particles in the body. The correct measurement of permeability is very important in many physics and engineering fields such as soil science, particulate systems, reactive reactor medium, fabrics, porous ceramic and filter processing and their applications.
The usual apparatus for permeability measurements essentially contain a set up where a fluid is forced to pass through a porous medium.
The guiding Principle-Darcy’s equation :
This semi empirical equation describes fluid transport in porous media based on one or more fluid.
Q=volume flow rate
Kp= specific permeability coefficient ΔP= pressure drop across the sample
L=flow length or thickness of the test sample A=area of cross-section of the sample
η= fluid viscosity
The permeability coefficient Kp depends on the combination of the fluid and porous material used. The greater the value of Kp the higher will be the rate of flow of a fluid through a material .
CHAPTER-7: RESULTS &DISCUSSION
Results and Discussion:
The main aim of the study was to design, fabricate and test a permeability measurement apparatus. The second aim was to calibrate the apparatus with some standard sample and to correlate the permeability value obtained from the fabricated permeability equipment with that obtain from a commercially available equipment.
From the study following could be concluded
· A simple design for the permeability measurement apparatus could be prepared.
· The apparatus could be fabricated with the help of Central Workshop using the design.
· The apparatus was leak proof.
· Some porous samples were tested in the apparatus and the permeability value was recorded for these samples.
· Although no calibration was made because of lack of the standard sample but from the permeability value measured by the apparatus the following could be concluded that permeability depends (1) On the sample property (2) Flow rate vs. pressure show the linear relationship in accordance with the standard equation.
· Although apparatus was not calibrated the permeability of the different samples corresponded well with the data obtain from other system. For example a sample prepared by the pellet pressing method with naphthalene as pore former although had higher porosity did not show interconnected pores in the microstructure. Such a sample is expected to have low permeability and the result obtained from the fabricated apparatus exhibited similar trend. On the other hand sample prepared by gel casting method and polymer sponge replication method has shown high pore connectivity in the SEM microstructure. Such sample has also shown higher permeability measured by this apparatus.
Therefore it can be said that although the absolute value may become different if the instrument is calibrated, the present study showed that the apparatus can measure the permeability with relative ease and probably with accuracy. However the last part needs to verified with the standard samples having known porosity, permeability and pore size.
A simple and low cost permeability measurement apparatus was designed and the permeability obtained from the fabricated apparatus show similar trend when measured by the other equipment (Mercury porosimetry). The equipment needed to be calibrated using standard sample with known permeability and porosity. Another interesting feature is that, this apparatus can be used for pressure casting provided that we put the slurry in a tubular mesh container and apply air pressure..