Essay: ENHANCED AIR FINNED WATER COOLING SYSTEM – A PROJECT REPORT

1.1 INTRODUCTION TO PROBLEM
Nowadays looking to current scenario, in few years, industries are going to face scarcity of water. Industries have applied vision 2020 for their betterment in growth and solving problems. As per their vision and survey, the amount of water that they are using should be reduced.
Water is mainly used in industries as cooling media. Water absorbs heat in large amount and releases it to the open atmosphere in cooling towers. During this lots of water is wasted in form of vaporization. That is huge loss.
When water is transported from one place to another place, there is loss of water in terms of leakages at joints, seals of penstock and ducts.
For better effect of cooling, we need to circulate water continuously around the heat source. For that external energy should be supplied. That costs high.
When water is continuously flowing in system, it causes fouling and scale formation around heat transfer surfaces. That reduces heat transfer rate after some years. And hence it is less efficient.
When this type of cooling system is applied to any power plant or industry, maintenance cost becomes considerable factor. This type of system also needs high constructional cost and floor area.
Taking cooling water and rejecting hot water to reservoirs is also damaging or harmful to environment.
Hence this conventional system should be replaced that reduces amount of water that is used, cost of circulation, cost of maintenance and should be eco friendly.
11
1.2 AIM & OBJECTIVE
 To reduce water usage
 To increase heat transfer
 To reduce scale formation and fouling
 To reduce operating cost of system
 To reduce maintenance cost
 To improve efficiency
 To reduce floor area
 To reduce complexity
 To decrease production cost
1.3 LITERATURE REVIEW
The literature available, sites Air Cooling Methods as well as Water Cooling Procedures. Different API (American Petroleum Institute) Plans are used to dissipate this generated heat and cool the seal faces thus extending the seal life.
Flushing is required to cool and lubricate the seal. Controlling Flush Fluid Temperature is critical to the life of a mechanical seal. Cooling of the product also may be needed to improve the margin to vapour formation, to meet secondary sealing element temperature limits, to reduce coking or polymerizing, or to improve lubricity (as in hot water).
Burgmann deviced an air cooling procedure for the cooling of mechanical seals. In this method, the heat exchanger is made up of finned tubes, to provide natural air circulation. So, for this reason, it is to be installed in well ventilated places, indoors or else outdoors with vertical installation.
There are four finned tubes through which process fluid is circulated and cooling is done by air. It is assumed here that through all these four tubes, an equal amount of fluid is being passed, which is not exactly the case. The figures below describe the method.
Flow Serve has devised another Cooling method, which provides a reliable means of reducing the temperatures surrounding the mechanical seal without the use of cooling water. Air is used as the coolant, providing economy by eliminating the water as well as the water related problems. Use of other expensive coolants also gets eliminated.
12
They have devised both, the Natural Convection and Forced Convection Models. In Forced Convection Model, an electric motor or air motor is used to drive the blower to circulate the air. The figure below shows these models.
Another type of Heat Exchanger, available in the literature is a Helical Coiled Heat Exchanger, from Graham Corporation. Helically coiled heat exchangers offer certain advantages, such as: compact size, higher film coefficient (the rate at which heat is transferred through a wall from one fluid to another) and more effective use of available pressure drop. These combined features result in more efficient and less expensive designs.
Stainless steel is the standard material of construction. Other frequently used materials include copper, titanium, Alloy 20, Alloy825, Alloy 400 and Admiralty. The casing material is usually made of cast iron or cast steel. Other materials are available as well, such as stainless steel and other corrosion resistant metals.
In case of water cooling methods for mechanical seals, a pump for high temperature liquid includes duct means interconnecting the suction inlet space, and the annular clearance space between the shaft and the pressure housing at a point immediately adjacent to the seal around the shaft. During hot stand-by uniform thermosiphon circulation of liquid occurs from the suction inlet space through the annular clearance space and back to the suction inlet via the duct means, which helps prevent thermal stresses being set up in the shaft.
TOMIOKA JUN and HASHIZUME TAKEHIRO a centrifugal blood pump has been developed as an implantable left ventricular assist device. A newly designed mechanical seal with a recirculating cooling water system is used for the shaft seal. The mechanical seal separate cooling water and blood in the sealing face. The objective of this study is to establish the measuring method of bi-directional leakage of the sealed fluid and the cooling-water through the sealing face, especially when blood is used as the sealed fluid. The leakage of the blood to the cooling-water side was measured by the atomic emission spectroscopy. The leakage of the cooling-water to the blood side was measured by using the atomic absorption spectroscopy, by using the standard addition method, by the correction of hemolysis caused by leakage of the cooling water. As the results of the experiments, the leakage rate of both the cooling water and the blood were below 0.4[ml/6h]. Therefore, the mechanical seal performed acceptably well to support its use in the centrifugal blood pump.
13
CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 CHAPTER 2 DESIGNDESIGNDESIGNDESIGNDESIGNDESIGN OF SOLUTIONOF SOLUTIONOF SOLUTIONOF SOLUTIONOF SOLUTIONOF SOLUTIONOF SOLUTIONOF SOLUTIONOF SOLUTIONOF SOLUTIONOF SOLUTION
2.1 VARIOUS EXISTING COOLING SYSTEMS FOR SEALS
2.1.1) Shell and Tube Heat Exchanger Method
To avoid flushing of mechanical seals, we use water cooled heat exchangers. Shell and tube type heat exchangers are used as water cooled system.
Fig.1: Cooling Arrangement No. I
2.1.2)Water Jacketing Method
In this method of cooling seals, water at atmospheric temperature is circulated continuously in the jacket present outside the Heat Transfer Media (HTM) and therefore the cooling of the HTM oil is obtained.
The below type of the cooling arrangement is present in this particular case study, for which alternate has been proposed.
14
Fig.2: Cooling Arrangement No. II
2.1.3)AIR COOLER METHOD
In the standard Air Cooler Method, air is the medium to cool the process fluid. Air is circulated either by natural circulation or by forced circulation. Fins are provided for higher heat transfer rate. But, still, because of less efficiency compared to the water cooling method this method has not been in use frequently.
Fig.3: Cooling Arrangement
15
The figure above shows typical Air cooling system.
2.2) WATER COOLING METHOD – A FORESEEN PROBLEM
In certain process industry, the Heat Transfer Media (HTM) is normally in a temperature range of 200ºC – 330ºC. And to avoid the chances of leakage from pump gland, Mechanical Seals are being used as already discussed. Oil from pump section travels along the shaft, to the mechanical seal parts and heats them. To cool the mechanical seal, water is circulated continuously in the jacket of seal, which is costly. Apart from the continuous circulation of water required, it is also necessary to create an inert environment so that the HTM does not come in contact with the atmosphere in any way and become hazardous by combining with the oxygen of the atmosphere. To avoid such chances of HTM leakage, Nitrogen Flushing is also done continuously, Nitrogen being an inert gas. This again is a very costly affair and the total annual cost for both, the above sited factors, turns out to be very – very high.
To reduce this cost, an alternate is proposed, i.e. to install an Enhanced Air Finned Cooler instead of jacketed water cooling method. This new system will have cold oil as the media which will be circulated in the seal jacket.
2.3)ADDITIONAL DISADVANTAGE OF WATER COOLING METHOD
There are numerous other disadvantages of the water cooling method, which are as follows –
1. Dissolved salts in water get deposited on the outer surface of the tube and reduce the thermal conductivity, the thickness of the tube also increases due to scaling and due to all these, the out-let temperature increases and may cause seal failure. Also water consumption increases after scale formation.
2. Circulation of fluid stops due to improper vented coils on the surface of heat exchangers in coil type Heat Exchangers which fails the Mechanical seals.
3. Due to scaling and fouling there may arise problems of un-scheduled shut down of the pump which ultimately causes production loss.
16
4. Fouling can be very costly in process industry, refinery and petrochemical plants since it increases fuel usage, results in interrupted operation, production losses and increases maintenance costs as well.
For all the above sited reasons, it is very much important to find an alternate method to be able to avoid all the water related problems, so that the industry can get rid of the high cost factors incurred to it.
2.4) PROPOSED SOLUTION
As an alternate to the present water jacketing procedure in this industry, an Enhanced Air Finned Cooler has been proposed.
In the proposed system i.e. the Enhanced air finned cooler the heat transfer is being done by a working fluid which does not require any continuous feed and instead only a very small quantity is sufficient to serve the same purpose.
The hot oil, coming out from the pump discharge will exchange heat with low temperature boiling point liquid in the air finned cooler. In turn this hot oil i.e. HTM will get cooled and then it will be circulated to the seal cavity. The system will dissipiate heat from the seal area and will keep temperatue of the seal to desired level.
Advantatage of this system is that there is no recurring cost to cool the seal parts.
17
CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: CHAPTER 3: INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO INTRODUCTION TO ENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLERENHANCED AIR FINNED COOLER
Enhanced Air Finned Cooler is an equipment proposed to eliminate all cost related problems as well as all water related problems. In this system only small amount of working fluid is required in a closed loop which will be responsible for the heat transfer from the HTM i.e. the process fluid.
3.1) BASIC CONCEPT
The proposed system works on the principle of thermosiphon two phase pipe system, with the finned condenser, with natural circulation of air to enhance the heat transfer rate. Thermosiphon operate on a closed two phase cycle and utilize the latent heat of vaporization to transfer heat with very small temperature gradients.
In this system the working fluid is made to flow inside the tubes and outside is the process fluid which is to be cooled.
As illustrated in the figure below, heat is added, by the process fluid, to the bottom portion of the apparatus, there by vaporizing the working fluid. During this phase change process, the working fluid picks up the heat associated with its latent heat of vaporization. Now, as the vapor in the evaporator region is at a higher temperature and hence at a higher pressure than that in the condenser, the vapor rises and flows to the cooler condenser where it gives up the latent heat of vaporization. Here, buoyancy forces assist the process. Gravitational forces then cause the condensate film to flow back down the inside of the pipe wall where it can again be vaporized.
Hence, this equipment, is principally based on the thermo siphon effect which rely upon the local gravitational acceleration for the return of the liquid from the evaporator to the condenser.
A very small quantity of the working fluid is required, inside the tube.
The vapor gets condensed as the tube in this region is in contact with the atmosphere.
18
Here fins are used in the condenser region to enhance heat transfer rate by natural convection, air cooling process. So, this vapor gets converted to liquid form by dissipating its heat. As it is cooled now so it moves back to the down portion of the tube because of gravity by natural circulation. Hence, it completes a cycle.
This cycle is continued and repeated.
So, in this way, The Enhanced Air Finned Cooler is unique in design. The condenser tubes consist of sealed Stainless Steel tubes with Aluminium fins around it, to condense the working fluid by natural air circulation..
Condenser
Fins
Working Fluid
Vapor
Evaporator
19
3.2)SELECTION CRITERION
3.2.1) Selection Of Working Fluid
The design and manufacture of this equipment is governed by the different operational considerations as the effective operational temperature range, which is determined by the selection of the working fluid; the maximum power it is capable of transporting and the maximum evaporator heat flux, which is determined by the point at which the nucleate boiling occurs.
As the basis of operation here is the vaporization and condensation of the working fluid, selection of a suitable working fluid is perhaps the most important aspect of the design and manufacturing process.
Factors that affect the selection of an appropriate working fluid include the operating temperature range, the vapor pressure, thermal conductivity, the compatibility with the vessel material, the stability and the toxicity.
The theoretical, operating temperature range here is typically between the critical temperature and the triple state of the working fluid. Above the critical temperature, the
working fluid exists in a vapor state and no increase in the pressure will force it to return it to a liquid state. Similarly, when the operating temperature is below the triple state, the working fluid exists in the solid and vapor states. Hence, operating in this temperature range is to be avoided.
20
The actual optimum operating temperature range is significantly less than the region defined by these temperatures. The typical operating temperature range for various heat pipe working fluid is shown in the following table.
The presence of impurities in the working fluid can have significant detrimental effects on the operation of heat pipes and thermo siphons. Performance Degradation caused by the presence or formation of non condensable gases (NCG) and performance degradation caused by solid or liquid impurities have detrimental effects.
3.2.2) SELECTION OF CONTAINER/CASE MATERIAL
For the selection of Case or Container Materials the factors that should be considered are the operating temperature range of the proposed solution, compatibility with the working fluid, internal operating pressure, evaporator and condenser sizes and the possibility of external corrosion. Formation of NCG typically limits the operational lifetime of thermo siphons. Degradation or contamination of the container material can lead to chemical reactions with the working fluid and hence generation of NCGs. This can also cause the formation of corrosive films and corrosion on the internal surface of the pipe.
Basic requirements include a container capable of maintaining a leak proof seal and structural integrity throughout the entire pressure range. Possible materials include pure metal alloys such as alluminium, stainless steel, copper, composite materials or for higher temperature applications, refractory materials or linings to prevent corrosion.
Basillis et al (1976) conductive extensive compatibility tests with several combinations of working fluids, the results of which are given below in the table.
21
TABLE 1. WORKING FLUID AND CONTAINER COMPATIBILITY DATA
Material Water Acetone Ammonia Methanol Dow- A Dow – E Freon 11 Freon 12 Copper RU RU NU RU RU RU RU RU Aluminum GNC RL RU NR UK NR RU RU Stainless Steel GNT PC RU GNT RU RU RU RU Nickel PC PC RU RL RU RL UK UK Refrasil RU RU RU RU RU UK UK
Abbreviations:
RU – recommended by past successful usage; RL – recommended by literature; PC – probably compatible; NR – not recommended; NU – not used; UK – unknown; GNC – generation of gases at all temperatures; GNT – generation of gases at elevated temperatures when oxides present.
Based on the above considerations, it was decided to choose water as the working fluid and stainless steel i.e. SS316 as the container material. As the working temperature range of the working fluid is between 5C – 230C.
SS316 is the optimal choice for the container (pipe and tubes) material as it is a non corrosive metal which is compatible with the process fluid i.e. the Heat Transfer Medium (HTM). Aluminium can not be used with water as the working fluid hence also SS has been considered.
22
Material shall be Aluminium unless specified or agreed by the purchaser, as per the API (American Petroleum Institute) standards (API 661 Code) and hence copper is not a suitable choice for the fins. And so, the only choice was Aluminium.
For the Heat Transfer calculations the different correlations for boiling and condensation have been considered.
To find the heat transfer coefficient for the evaporation process, the relation proposed by Jacob has been used, which is as follows –
h = 2.54 (Δ Te)3 e (p/1.351) W/m2 – K
where p is the pressure in MPa., and Δ Te is the temperature difference between the surface temperature and the saturation temperature.
After finding for the heat transfer coefficient the rate of heat transfer is to be calculated using Newton’s Law of Cooling.
Similarly, during the condensation process, the heat transfer coefficient has been found with the help of the formula proposed by Mc Adams as
hL = 1.13 [{g ρl (ρl – ρv ) kl3 hfg}/ {μl (Tsat – Ts) L}] ^0.25
hL – heat transfer coefficient
g – acceleration due to gravity
ρl – density of saturated liquid at average film temperature
ρv – density of saturated vapor
23
kl – thermal conductivity of the saturated liquid
hfg – Latent Heat of condensation
μl – dynamic viscosity of saturated liquid
Tsat – saturation temperation
Ts – surface temperature
L – Length of the condenser section
The rate of heat transfer has been calculated by the Newton’s Law of Cooling in both these cases.
The rate of heat transfer through fins has also been calculated separately by the following formula by considering the fins to be of a finite length and the heat is transferred by convection from its end to the surrounding fluid.
Q = (hPkA)0.5 . θ [{tanh(mL) + (h/mk)} / {1 +((h/mk) tanh(mL))}]
Q – rate of heat transfer through fins
h – heat transfer coefficient
P – Perimeter
k – thermal conductivity of the fin material
A – Surface Area
θ – the temperature difference between the surface temperature and the atmosphere.
m – (hP/kA)0.5
L – length of the fins
The rate of heat transfer through the SS tube has also been calculated separately using Fourier’s Law of Heat Conduction.
24
Finally, the design has been based on the minimum of the above calculated values.
We have taken 500 mm long tube, with internal diameter of 19 mm and external diameter of 38 mm depending upon the availability in the market. The evaporator section is of 100 mm and rest is the condenser section.
The fins are decided of 0.3 mm thickness and the pitch has been taken as 3 mm. As the thickness of the fin shall not be too less to become very thin and at the same time, shall not be too high to not to give the efficient cooling, so
TABLE 2. HEAT TO BE REMOVED(LIQUID HTM)
Heat To be removed(liquid HTM) Sr no. Parameters Values Unit 1 Flow selected 3 lpm 2 Sp.Gr 0.94
3 Sp.heat 0.5
4 Inlet temp to cooler 220 deg C 5 Expected outlet temp from cooler 140 deg C 6 Heat to be removed mxsXΔ T 112.8 kcal/min
7858.4 W
TABLE 3. VALUES CONSIDERED
VALUES CONSIDERED Sr no. Parameters Values Unit 1 Fin OD 3.8 cm 2 Fin ID/ Tube OD 1.9 cm 3 Fin Thickness 0.03 cm 4 No of Fins on each tube 120
5 Tube ID 1.6 cm 6 Length of the tube ( Condensation section) 40 cm 7 No. of Tubes 19
25
8 Ambient temperature 40 deg C 9 Fin Temp 132 deg C 10 Film heat transfer coefficient h 15 W/m2degK 11 Length of tube covered by Fins 3.6
12 Thermal conductivity of SS 316 13.8 W/mdegK 13 Length of the tube (Evaporator section) 10 cm 14 Temperature inside the tube 150 deg C 15 Temperature out side the tube 220 deg C
TABLE 4. HEAT TRANSFER CALCULATIONS FOR EVAPORATOR SECTION
Heat Transfer Calculations For Evaporator Section Parameters Values Unit P = Pr. in MPa 0.101325 Mpa Ts 220 ⁰ C Tsat 100 ⁰ C Δ Te = Ts -Tsat 120 ⁰ C De 0.019 m h = heat transfer coeff. = 2.54*(ΔTe)^3*e^(P/1.351) 3644.046064 W/m^2-K A 0.000283 m^2 Q = h*A*Δ T for 1 tube 113650.095 W
TABLE 5. HEAT TRANSFER CALCULATIONS FOR EVAPORATOR SECTION THROUGH THE SS316 TUBE
Heat Transfer Calculations For Evaporator Section through the SS316 tube Parameters Velues Unit
26
Kss 13.8 W/m-K Le 0.1 m ln r2/r1 0.693147
T1 -T2 70 ⁰ C Q 875.2083 W Q for 19 tubes 16628.96 W
TABLE 6. HEAT TRANSFER CALCULATIONS FOR CONDENSER SECTION
Heat Transfer Calculations For Condenser Section Parameters Values Units G 9.81 m/sec^2 den. Liq. 913.75 kg/m^3 den.vap. 2.95 kg/m^3 KL liq.thermal cond. 0.68 W/m-K Hfg 2090.25 KJ/Kg Ul liq. Vis. 179.95*10^6 N-s/m^2 Δ T 10 ⁰ C L 0.4 m Hl 10499.93 W/m^2-K A = 3.14*D*L 0.023864 m2 D2 0.019 m Q for 1 tube 2505.704 W mass flow rate = Q/hfg 1.198758 gm/sec
TABLE 7. HEAT TRANSFER CALCULATIONS FOR CONDENSER SECTION THROUGH SS316 TUBE
Heat Transfer Calculations For Condenser Section through SS316 tube Parameters Values Units Lc 0.04 m Ta 40 ⁰ C
27
TABLE 8. HEAT TRANSFER THROUGH FINS
Heat transfer through fins Parameters Values Units
H 15 W/m2K
P 0.05966 m
A 0.20414117 m2
K 204.2 W/mK
No.of Fins 120
m = (hP/kA)^0.5 0.14651905
Ts 132 ⁰ C
Ta 40 ⁰ C
Δ T = Ts – Ta 92 ⁰ C
L = P*No. of fins 7.1592 m
Ml 1.04895917
tanh(mL) 0.9999
h/mk 0.50135048
(tanh(ml)+h/mk)/(1+h/mk*tanh(mL) 0.99996679
Q (hpka)^0.5*ΔT 561.911924 W Q For 19 Tubes
10676.3266 W
Q 550.1309 W Q for 19 tubes 10452.49 W
28
CHAPTER 4 FABRICATION
For the design & fabrication of the enhanced air finned cooler we have first taken a 12” stainless steel pipe & welded the bottom plate over it. Next, the partition plate was welded on the bottom plate.
Next on the upper plate at the very first the holes were marked & drilled. As through these holes will enter the finned pipes, hence fixing arrangement was also done for the tubes. After this, the baffle plate was welded on the upper plate and in the last the upper plate itself was welded on the tube.
The finned tubes are fabricated by the fabricator. In all there are 19 tubes with 120 fins of 3 mm thickness and 3 mm pitch. The fins used here, are of Aluminium and on the tubes the wrapping has been done with only the ends being welded. This process is done completely by the machines. Finned tubes have been fabricated separately. The Evaporator section of the complete tube has also been done separately and after the completion of the finned tubes both have been welded together. All these tubes are later on connected on the upper plate and are fixed and tightened with the circlips at the end. Inner tube has been designed separately in which O – ring has been inserted to avoid leakage and give it a perfect sealing.
After completing the structure, the three passages, for the inlet, the outlet and the drain are welded. For this, first the flanges were welded and then at the upper, down and bottom position, the pipes are connected, respectively. These pipes are of 15 mm outer diameter.
At last the stand was done which again is of steel only.
As stainless steel 316 has been used as the material except for the fins, the welding everywhere was done using ss316 welding rods only.
29
30
CHAPTER 5 EXPERIMENTAL SET UP AND TRIAL PROCEDURE
5.1) EXPERIMENTAL SET UP
In the above arrangement shown, the hot process liquid coming out from the discharge of the pump is made to pass through the Enhanced Air Finned Cooler (EAFC), where it gets cooled by coming in contact with the working fluid and simultaneously transferring its heat to the working fluid. As a result, the process fluid becomes cool and then is made to pass through the outlet at the downstream, from EAFC, into the seal cavity. From the seal cavity it then passes back to the suction line of the pump. This whole loop is shown by the blue color in the picture.
31
5.2) TRIAL PROCEDURE
A temperature gauge is installed in the outlet section through the EAFC to measure the outlet temperature of the process fluid to verify the results.
The flow of the HTM can be changed by controlling it to pass through a valve. By using a flow meter, the different flow rates entering in to EAFC through the discharge of the pump, can be measured. For a particular flow rate a specific outlet temperature will be achieved, which can be observed by the temperature gauge installed for the purpose.
In this manner, for various flow rates different values of outlet temperatures will be obtained and a graph can be plotted between these two parameters.
32
CHAPTER 6 RESULTS AND ANALYSIS
6.1) RESULT TABLE
NO.
TIME
INLET TEMPERATURE
OUTLET TEMPERATURE
1
68
–
2
2.5
67
56
3
5
67
55
4
7.5
65
52
5
10
65
52
6
12.5
64
50
7
15
60
46
8
17.5
56
43
9
20
56
43
6.2) ANALYSIS
X : TIME Y: TEMPERATURE
10
20
30
40
50
60
70
80
2.5
5
7.5
10
12.5
15
17.5
20
INLET
OUTLET
33
The outlet temperature has been measured using the thermometers and various readings have been taken till the temperature attains the steady state.
There is a difference, in the assumed value of the outlet temperature, with the experimental results.
The reason for this is, that in the present condition, the position of the Enhanced Finned Air Cooler was, between two hot vessels.
Although the vessels are insulated, but still due to the lack of proper air circulation, the condenser region is not giving the efficient cooling and hence there is a difference in outlet temperature values.
The difference is of the order of 5% which is well acceptable.
6.3) FUTURE SCOPE
There is every possibility of improvement, in the designed apparatus. Change of working fluid, change of compatible container material can always give different outlet temperatures depending upon the requirement.
Heat Pipe principle can also be used using a wick, which will be a costly affair but at the same time, may be more efficient.
34
CHAPTER 7 CONCLUSION
7.1)BENEFITS OF ENHANCED AIR FINNED COOLER
RELIABILITY:
Any equipment which depends on the reliability of other equipment is not reliable or less reliable. Air Finned Cooler cools the product with natural draft. It does not have any moving parts, needs no external power source.
Air Finned Cooler does not depend on the cooling water, therefore risk of shut down due to poor quality/ quantity of water is eliminated.
DIRECT SAVING
Cost of Water : With Air Fin Coolers no water is required hence cost of water is saved. To get desired amount of cooling normally for water-cooled heat exchangers 40 to 50 lpm water is required @ Rs. 5 per cubic meter approximate saving will be about Rs. 1,10,000/- per year.
Cost of circulation of water: The energy is saved using this cooler as no un-scheduled shut down is to be done by limitation of water circulated.
Preventive Maintenance: Water causes scaling problem, and due to scaling, temperature to the seal goes up, the pump needs to be taken for removal of scale. Cost of removal of scale and loss of production is saved with Air Fin Coolers.
Shut down Maintenance: If seal fails because of poor cooling in addition to the production and maintenance loss, cost of replacement seal components add to the loss.
35
INDIRECT SAVING
Fouling: In absence of water, no scaling can take place. Because of scaling heat transfer gets reduced, hence either water consumption goes up or temperature in seal area goes up which reduces the seal life.
Better circulation of flushing fluid: In absence of coil, friction loss reduces hence there is better circulation of flushing liquid. The seal will be more comfortable with increased amount of flushing liquid, as there is no friction.
Cooling Tower Water Contamination: In the process of scale removal the water cooled heat exchanger tube gets eroded / corroded and becomes week and some time may get punctured. Identification of leaking cooler takes enormous time. Also entire cooling tower water needs to be drained. In Air Cooler such possibility does not arise because of absence of water.
Fire Hazard: In the event of seal failure, the hot liquid leak to the atmosphere. If it is at the self ignition temperature, it catches fire.Where as in Enhanced Air Finned Cooler, cool product reaches to the seal as long as the pump is running. Therefore in the event of leakage only cool product will come out of the stuffing box and no chance of catching fire.
36
CHAPTER 8CHAPTER 8CHAPTER 8CHAPTER 8CHAPTER 8CHAPTER 8CHAPTER 8CHAPTER 8CHAPTER 8 REFEREREFEREREFEREREFEREREFEREREFERENCE S
1. Brenan, P.J. and Krolijeck, E.J. , Heat Pipe Design Handbook, B& K Engg. , 1979.
2. Brigida, Carlo J. (Convent Station, NJ), Bow, William J. (Morristown, NJ) Wet/dry steam condenser, Publication Date: 05/03/1983 Document Type and Number: United States Patent 4381817.
3. Burgmann India Pvt. Ltd., Mechanical Seals for Pumps, Compressors and Agitators. , Design Manual 14
4. Dunn, P. D. and Raey, D.A.,1982, Heat Pipes, 3rd Edition, Pergamon, Oxford.
5. Holman, J. P., 1997, Heat Transfer , 8th Edition. Mcgraw Hill , N. Y. , pp 310 – 312
6. Peterson G. P. 1994, An Introduction To Heat Pipes : modeling, testing and applications, John Wiley & Sons, Inc. pp 230 – 239, 246 – 250
7. Robert H. Perry & Cecil h. Chilton , Chemical Engineer’s Handbook , Fifth Edition , Mcgraw Hill Book Company , 1973 pp no. 9 – 48
8. Sealol Hindustan Ltd., Mechanical Seal Handbook , Fluid Sealing Association 1994
9. Therminol 66 Heat Transfer Fluid By Solutia , Catalogue
10. Tomioka Jun(Waseda Univ.,JPN) and Hashizume Takehiro, Journal Title;Nihon Kikai Gakkai Nenji Taikai Koen Ronbunshu Title;The Sealing Characteristics of a Mechanical Seal for a Centrifugal Blood Pump Vol.2002;No.Vol.1;pp..53-54(2002)