MITIJME-August-2015, Full Volume

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MIT International Journal of Mechanical Engineering, Vol. 5, No. 2, August 2015, pp. 63-66 63

ISSN 2230-7680 MIT Publications

Fracture Based Analysis of Pressure Vessel:Application of Fracture Mechanics in Ultrasonic Testing

Nomesh Kumar

Advanced Systems Laboratory

Defence R&D Organisation

Hyderabad, India

V. Venkateswara Rao

Advanced Systems Laboratory

Defence R&D Organisation

Hyderabad, India

Abhishek Saxena*

Mechanical Engineering Department

Moradabad Institute of Technology

Moradabad, U.P., India

Email ID: [email protected]

I. INTRODUCTION

Fracture mechanics can be divided into linear elastic fracture

mechanics (LEFM) and non-linear fracture mechanics (NLEFM).

LEFM gives excellent results for brittle-elastic materials like

high-strength steel, glass, ice, concrete etc, however, NLEFM

gives excellent results for ductile materials like low carbon

materials like steel, stainless steel, certain aluminum alloys and

polymers [1 and 12]. In small strain regimes, it is better to prefer

linear fracture mechanics as it provides a good approximation

to the physical problem. Usually fractures are dangerous andcostly with respect to structural failure mode in the eld of aero-structures, automobile chassis, railway bridges, pressure vessel,

ships and pipeline explosions [2 and 12-13]. The term fracture

mechanics refers to a vital specialization within solid mechanics

in which the presence of a crack is assumed and quanties rela-tions between the crack length, the materials inherent resistance

to crack growth and the stress at which the crack propagates at

high speed to cause structural failure and hence it deals with

fracture phenomenon and events [14].

In a pressure vessel, the major factors responsible for occurrence

of failure are the combinations of poor weld properties with

stress concentrations and poor choice of brittle materials in theconstruction. A major achievement in the theoretical foundation

of LEFM was the introduction of the stress intensity factor (SIF)

as a parameter for the intensity of stresses close to the crack tip

and related to the energy release rate. Stress intensity factors

are a measure of the change in stress within the vicinity of the

crack tip [2].

Therefore, it is important to know the crack direction and

when the crack stops propagating. The stress intensity factor is

compared with the critical stress intensity factor KIC

(material

fracture toughness value) to determine whether or not the crack

will propagate.The presence of undetected cracks on the walls of a pressure

vessel can severely reduce the strength of the structure and can

cause sudden failure at nominal tensile stresses less than the

materials yield strength. Crack appearance and growth can

seriously endanger the reliability of structures and components

in operation [4]. Therefore, it is important to assess their inu-ence on the structural integrity. To ensure the integrity of a

structure when a aw is present, the designer should understandand adequately apply the mechanics of fracture, particularly

the relation between structure loading (applied stress), the awsize and the fracture toughness. Ultrasonic Testing (UT) is one

of the measure techniques to monitor the aws in the pressurevessel wall[11]. However, it is very important to the designer

Fracture Mechanics is a set of theories describing the behavior of structures with geometrical discontinuity. The discontinuity

features may be in the form of line discontinuities in two dimensional media (such as plates and shells) and surface discontinuities

in three-dimensional (3D) media. One of the important aspects of fracture mechanics is the fracture parameter stress intensity

factor (SIF). SIF is used for structural integrity assessment of structures containing cracks and singular stress elds. In this

framework, fracture mechanics is applied to determine the ultrasonic test references for cylindrical pressure vessels. High

notch reference provides faulty inspection and a very tight notch reference generates a lot of noise, by which it is difcult to

determine the presence of crack and size of crack. Here, this problem has been monitored and attempt has been made to resolve

this through an analysis.

ABSTRACT


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to know, which type of reference specimen to be used to detect

the aws. Ultrasonic references are required for all inspectionto establish the performance of the inspection and to interrelate

the test result with reference reectors. Because of thin mate-rial testing involves many special problems in various type of

materials, it is preferred that the ultrasonic references shall bemade from the same material and same conguration as the partunder test so that same ultrasonic properties are ensured. The

references which most nearly approximate the part/product under

test shall be used. Ultrasonic references may be made in a variety

of thickness, however, the three standard notches E, F and G for

angle beam ultrasonic reference blocks are preferred. In present

paper, it is studied to choose appropriate reference notch for the

given pressure vessel problem[15].

In this framework, fracture mechanics is applied to determine the

ultrasonic test references for cylindrical pressure vessel. High

notch reference provide faulty inspection, however, very tight

notch reference gives a lot of noise, by which it is difcult todetermine the presence of crack and size of crack.

II. FORMULATION OF THE PROBLEM

Consider semi elliptical crack is in X Y plane as shown in

Figure 1.

Fig. 1:Detail of crack

Where,

a - initial surface crack depth (half of minor axis of ellipse)

c - Semi crack length (semi major axis of ellipse)

d - Internal diameter of cylindrical pressure vessel

R - Internal radius of cylindrical pressure vessel

t - Case thickness

p - Internal Pressure (MPa)

According to Grifth theory [11] of failure the fracture in brittle

material face plane when the elastic energy supplied at thecrack tip is equal or greater than the energy required to create

new crack, surface. But additional conditions required in crackextension are as:

1. The stress a head of the tip must reach a critical magnitude.

2. The total energy of the system must be reduced during

crack extension.For this, two approaches can be used;

1. Plain stress approach

2. Plain stain approach

The state of stress exists in thin shells is plane stress condition,

where as in thick shells, it is plane strain condition.

A. Plain Stress Approach

Plain stress is dened as a state of stress in which one of theprincipal stresses is zero[13]. This condition is applied where

the thickness of structural element is small as compared to other

dimensions.

z

VSx

E

VSy

E=

(1)

(G E) S a0.5 =

(2)

where G is the energy release rate.

B. Plain Stain Approach

It is dene as a state of a constraint in the vicinity of the cracktip. i.e. the strain in z- direction is zero.

E =

S

E

VS

E

VS

E

z x y = 0

(3)

Sz = V(S

x+ S

y) (4)

G.E. = S a v ( )1 2 (5)

The minimum thickness to achieve the plane strain condition

is given by

tp = 2 5.

kic

ys

2

(6)

If pressure vessel thickness is less than tp, plane stress criterion

should be used, but for pressure vessel, plane strain condition isconsidered due to following reasons.

1. The plane strain fracture toughness is a material property

like UTS, yield strength etc. and it is independent of

thickness of material and aw geometry for high strengthmaterial.

2. The plane stress fracture toughness (Kc) is not material

properties and it depends on the thickness of material, awgeometry.

3. K1C

of the given material will be lower than KC. Hence

K1C

for design is more conservative and the number of

allowable crack sizes can also be reduced.


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Assumptions

1. The plane strain fracture toughness of weldment is 80%

of the parent material.

2. Flow present is in such an orientation that it would tend

to open up under the technical stress. 3. Elliptical surface aws have been considered, as then send

to propagate at faster rate than embedded aws.

3. The stress intensity factor is more in elliptical surface

aws.

Methodology

Crack in cylindrical thin pressure vessel often initiated on

exposed surface and tend to grow inward assuming semi elliptical

crack. When such a crack is subjected to both direct pressure

and a eld stress, their individual effect must be superpositionedto obtain resultant stress intensity factor. Hence stress intensity

factor KIfor semi-elliptical crack at the inside surface subjected

to internal pressure Piis given as

Ki =M P

ak h i

( )

+

(7)

Where, - Shape factor determine by elliptical integral, which

is a function of aw aspect ratio (a/c) and can be determined by;

= 1 22 2

2

0

2

1

2

c a

cdsin

(8)

and variation of with a/c ratio is given in Figure 2.

Fig. 2. Variation of with a/c ratio

Mk Back correction factor based on aw depth to thickness ratio

which is; Mk= 1 for a/t 0.5.

Mk=1 0 1 2 0 5 0 5. . . .

+

>

a

t for

a

i (9)

And hisHoop stress, which can be determined by;

sh =

Pd

t

d

t

i

21 3+

(10)

Criterion for Leak before Break

Kic

s ty

2

11 (11)

If this condition is satised, pressure vessel will be leak beforeburst, otherwise it will burst without leak.

III. CASE STUDY

Rocket motor case is made up of Maraging -250 steel materi-

als with casing thickness 3.0 mm. It is decided to do ultrasonic

testing of motor case to monitor health over a period of time.

Motor case is shown in Figure 1. Sensitivity for fracture of this

motor is studied. Material properties and geometric parameter-

sare considered as:

A. Material Parameters

K1C

on parent material for Plain strain condition = 90 Mp m

K1C

on weld material for Plain strain condition = 75 Mpa m

KC

on parent material for Plain stress condition = 120 Mp m

Yield strength of the Maraging steel = 1650 Mpa

Yield strength in weld region = 1560 Mpa

B. Geometric Parameters

Thickness of casing (t) = 3.0 mm

Radius of cylindrical portion (R) = 360 mm

Maximum Internal Pressure (Pi) = 65 bar

Proof Pressure = 1.1x65= 71.5 72 bar

Hoop stress (h) = 1050 Mpa

Minimum thickness required achieving plain strain condition

is given by

T = 2 5 5 2

2

. .K

s

ic

y

= mm (12)

Critical crack size (acr)is given by

acr = 0 25 1000 1 32

2

. .

=

K

s

ic

h

mm (13)

However motor case thickness is 3.0 mm, plain strain approach

is used for fracture based analysis of pressure vessel. Failure

boundary curve is generated as crack size (a) as abscissa and

crack size ratio as ordinate and is shown that motor case will

leak before burst as depicted in Fig. 3. Notches E, F and G with

equivalent tight cracks are also plotted in Fig. 3. Critical crack

size is also determined to qualify the pressure vessel for given

pressure through ultrasonic testing.


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Fig. 3:Failure curve with notches and tight crack size

IV. RESULT AND DISCUSSION

Figure 3 shown that notch Gis in safe zone, however equivalent

tight crack is in failure region. If, one will use G notch as

ultrasonic reference, it would not capture even critical crack size.

Hence used of Gnotch as reference is void. Notch Fas well as

equivalent tight cracks are in safe zone. Also notch Fis close to

Failure boundary curve. Furthermore the equivalent crack size

4 1.5 mm square is more close to failure boundary curve than

6 1 mm square. The use of notch F with equivalent crack size

of 4 1.5 is good option. Notch E as well as equivalent tight

cracks are in safe zone, however they are much far from Failure

boundary curve. NotchEcan be used but it will give a lot ofsignal noise and it would be difcult to explicitly determine thecrack and crack size.

V. CONCLUSION

Ultrasonic references are required for inspection of all pressure

vessels to establish the performance of the inspection and to

interrelate the test result with reference reectors. The referenceswhich most nearly approximate the part/product under test shall

be used. The three standard notches E, F andGfor ultrasonic

reference blocks are preferred. In given case study, notch Fhave

preference over notch GandHas notch Fis very close to failure

boundary and give nearly approximation. The critical crack sizealso helps the inspector to clear the pressure vessel with given

condence level.

REFERENCES

1. [M.A. Guerrero, C. Betego, J. Belzunce, Fracture analysis of apressure vessel made of high strength steel (HSS), Engineering

Failure Analysis (2007).

2. Shaque, M.A. Khan, Stress distributions in a horizontal pressureand the saddle supports.pressure vessels and piping (2010).

3. M.K. Samal, J.K. Chakravart ty, M. Seidenfuss, E. Roos c,Evaluation of fracture toughness and its scatter in the DBTT regionof different types of pressure vessel steels, Engineering Failure

Analysis (2010).

4. S. Kotrechko,Yu. Meshkov, A new approach to estimate irradiationembrittlement of pressure vessel steels, pressure vessel and piping

(2007).

5. J.C. Newman Fracture analysis of surface and through cracks incylindrical pressure vessel (1976).

6. Hervandil Morosini Sant, Anna, Murilo Fonseca Leal, A practicalprocedure to assess critical defects in pressure vessels subjectedto

fatigue loads (2010).

7. Kee Bong Yoon, Tae Gyu Park, Ashok Saxena Creep crack rowthanalysis of elliptic surface cracks in pressure vessels (2003).

8. JaroslavMackerle Finite elements in the analysis of pressure vesselsand piping an addendum: A bibliography (20012004).

9. T. Aseer Brabin, T. Christopher, B. Nageswara Rao, Finite elementanalysis of cylindrical pressure vessels having a misalignment in a

circumferential joint, pressure vessels and piping (2010).

10. Andreas Sandvik, Erling Ostby, Christian Thaulow, Probabilistic

fracture assessment of surface cracked pipes using strain-basedapproach (2006).

11. SAE Standard, AMS 2631 A.

12. Mundhe N. D. and Utpat Abhay A., Analysis of cracked cylindricalpressure vessel by using experimental approach, International

Journal of Latest Trends in Engineering and Technology (IJLTET),

vol. Vol. 2 Issue 3, pp. 155-160, 2013.

13. Anderson T.L, Fracture Mechanics Fundamentals and Applications.

CRC Press, second ed., 1995.

14. Osama A., Terfas and Abdusalam A. A., Ductile crack growthinsurface cracked pressure vessel, International Journal of

Mechanical, Aerospace, Manufacturing, Industrial Science and

Engineering, vol. 7 No:1, pp. 27-33, 2013.

15. Nomesh Kumar and B.V. Papa Rao; DRDO Report, 2008.


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assumptions. The assumptions are mandatory for deriving the

analytical expressions and therefore the deection computed doesnot fall very closely to the deection measured by experimentalmeans (by using dial gauge, micrometer or vibrating reed).

Computational methods are being applied earlier to the deectionrelated investigations of the dial gauged force transducers and

some results have been discussed. The results for some of ring

shaped force transducers of different nominal capacity have

been reported and bring out the anomalies between the deviation

of deection between analytical means to computational andexperimental means.

Fig. 1:A typical ring shaped dial gauged force

transducer (or, Proving Ring) [1]

For more rigorous study, a comparison has been made

between the analytical and experimental methods for 30

ring shaped force transducers of different nominal capacity

ranging from 500 N to 3000,000 N. The reasons behindthe deviations are attempted to be unearthed.

II. EXPERIMENTAL PROCEDURE

For, analytical investigations, the dimensions of the dial

gauged force transducers like inner radii, outer radii,

width, thickness etc. are noted. The material of the dial

gauged force transducer is generally EN 24 steel and

properties of EN 24 are taken into consideration. The

analytical expressions for deection of the ring shapedforce transducers are well established are already discussed

earlier. Those expressions are taken into account to

compute the deection. Equation 1 describes the expressionfor calculation of deection by analytical mean.

=

FR

EI

2

4

2 (1)

The ring shaped force transducers are calibrated according

to the standard guidelines of the standard IS 4169-1988

(reafrmed 2003) and the mean deection for the ratedcapacity of the force transducer, say for 500 N capacity

force transducer, deection at 500 N is noted and multipliedby the resolution of the dial gauge to get the deection inmm. The information in the form of dimensions of the force

transducer, deection by analytical method and experi-mental methods are summarized in Table 1. Deviation of

deection from analytical method also has been computedand shown in Table 1.

III. RESULTS AND DISCUSSIONS

The ndings of the Table 1 may be summarized in the formof Figures 2-5. Figures 2-3 discuss the capacity of the ring

shaped force transducers as a function of thickness to mean

radii (t/R) ratio. The ratio is also an indicator of thin ring or

thick ring. If the ratio falls below 0.1, the ring is classiedas very thin ring and if goes beyond 0.3, it is considered a

thick ring. Figures 4-5 discusses the deviation of deec-tion from analytical method to the experimental method

for different t/R ratio. The gures 2-5 are shown below:

Fig. 2:Force transducers of nominal capacity up to 100 kNagainst t/R ratio


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Table 1: Observations for deection of force transducers of differentdimensions and nominal capacity

C R t b t/R () D

Anal Exp

500 89.00 3.0 30.0 0.03 3.709 1.982 46.57

750 90.00 4.0 30.0 0.04 2.427 2.121 42.16

1000 88.00 4.0 35.0 0.05 2.593 1.662 35.91

1500 87.50 5.0 35.0 0.06 1.958 1.262 35.54

2000 87.25 5.5 35.0 0.06 1.944 1.314 32.42

2500 88.00 6.0 30.0 0.07 2.241 2.122 36.55

3000 87.00 6.0 35.0 0.07 2.227 2.186 33.28

5000 86.50 7.0 35.0 0.08 2.298 1.502 34.63

10000 90.75 8.5 50.0 0.09 2.075 1.368 34.06

10000 90.00 8.0 40.0 0.09 3.034 1.948 35.80

15000 90.25 9.5 50.0 0.11 2.192 1.348 38.52

20000 90.50 9.0 50.0 0.10 3.467 2.342 32.44

20000 89.75 9.5 45.0 0.11 3.194 2.132 33.26

25000 90.50 11.0 40.0 0.12 2.967 1.988 32.99

30000 90.75 10.5 50.0 0.12 3.302 2.176 34.10

40000 89.00 12.0 40.0 0.13 3.477 2.318 33.34

50000 89.50 13.0 48.0 0.15 2.897 1.972 31.94

50000 93.00 14.0 50.0 0.15 2.499 1.684 32.60

50000 91.25 13.5 50.0 0.15 2.632 1.722 34.58

70000 94.50 16.0 50.0 0.17 2.459 1.542 37.28

80000 96.50 17.0 45.0 0.18 2.772 1.748 36.93

100000 85.50 17.0 50.0 0.20 2.169 2.152 33.05

100000 87.00 18.0 47.0 0.21 2.048 1.368 33.19

500000 90.00 35.0 40.0 0.39 1.812 1.206 33.43

1000000 90.00 40.0 55.0 0.44 1.765 1.156 34.52

1000000 87.75 39.5 50.0 0.45 1.869 1.238 33.76

1000000 89.50 39.0 55.0 0.44 1.873 1.186 36.68

2000000 95.00 50.0 60.0 0.53 1.949 1.286 34.01

2000000 99.00 52.0 60.0 0.53 1.961 1.274 35.02

3000000 100.00 60.0 60.0 0.60 1.973 1.284 34.92

It is clear from the Figures 2-3 that as the capacity of the

force transducers tends to increase, the t/R ratio tends to

increase. It is also noticed from Table I, that the increase

in capacity is hardly having any signicant impact over themean radii of the force transducer, while on the other side;

the width has been enhanced signicantly. It is also visiblefrom careful investigations of Figures 4-5 that deviation of

deection is above 35 % for t/R ratio up to 0.05.

Fig. 3:Force transducers of nominal capacity 100 kN

onwards against t/R ratio

A recent investigation reported to take computational

investigations into consideration for deection relatedinvestigations. The study reveals that there is about 35

% of deviation reported, if the comparison is made for

deection in case of analytical and computational means.This way, the expression for deection of ring shaped force

transducer needs to be modied.Hence, the proposed expression for deection may be takenas given below by Equation 2:

=

0 65

4

23

. FR

EI (2)

Fig. 4:Deviation of deection for force transducers of nominalcapacity up to 100 kN


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Fig. 5: Deviation of deection for force transducers of nominal

capacity 100 kN onwards

Table 2: Deviation of deection by different analytical expressions toexperimentally measured deection of force transducer

Sl. No. C D (throuh Eq. 1) D (by Eq. 2)

1. 500 46.57 17.80

2. 750 42.16 9.94

3. 1000 35.91 1.40

4. 1500 35.54 0.83

5. 2000 32.42 -3.96

6. 2500 36.55 2.38

7. 3000 33.28 -2.64

8. 5000 34.63 -0.57

9. 10000 34.06 -1.44

10. 10000 35.80 1.23

11. 15000 38.52 5.41

12. 20000 32.44 -3.93

13. 20000 33.26 -2.68

14. 25000 32.99 -3.09

15. 30000 34.10 -1.39

16. 40000 33.34 -2.55

17. 50000 31.94 -4.71

18. 50000 32.60 -3.69

19. 50000 34.58 -0.64

20. 70000 37.28 3.51

21. 80000 36.93 2.98

22. 100000 33.05 -3.00

23. 100000 33.19 -2.78

24. 500000 33.43 -2.42

25. 1000000 34.52 -0.75

26. 1000000 33.76 -1.90

27. 1000000 36.68 2.59

28. 2000000 34.01 -1.52

29. 2000000 35.02 0.03

30. 3000000 34.92 -0.12

IV. CONCLUSIONS

In the present paper, a comparison of the deection of thering shaped force transducers for nominal capacity from

500 N to 3000 kN. The deection has been measured

by the analytical expressions available, which has beengenerally used and the experimental method. A signicantdeviation of about 35% is found on an average basis after

careful investigation of data. The analytical expression for

deection is proposed to have multiplied by a factor of 0.65for coherence of analytical and experimental ndings. Ithas been found that the average deviation is reduced to

0.14 % for throughout range of force transducers taken

into account.

Acknowledgement

Authors are thankful to Director, CSIR - National Physical

Laboratory, New Delhi, India and Dean, University

School of Engineering & Technology, Guru Gobind Singh

Indraprastha University, Delhi, India for their kind support.

REFERENCES

[1] Kumar, H. and Kumar, A.: Investigations of measurement

uncertainty and stability studies of dial gauged force proving

instruments.NCSLI Measure the Journal of Measurement Science,

Vol. 6, No. 2, (2011), pp. 64-68.

[2] Godwin, R.J.: An extended octagonal ring transducer for use intillage studies.Journal of Agricultural Research, Vol. 20, No. 4,

1975, pp. 347-352.

[3] Kumar, H., Sharma, C. and Kumar, A.: The development and

metrological characterization of a square ring shaped force

transducer.Measurement Science and Technology, Vol. 24, No. 9,

2013.

[4] Pardeep, Kumar, H., Kaushik, M. and Kumar, A.: Preliminary

investigations of hexagonal ring shaped force transducer. In:

Proceeding of the 4thNirma University International Conference

on Engineering Nuicone 2013, Ahmadabad, India.

[5] ISO 376-2011. (2011). Metallic materials Calibration of force

proving instruments used for verification of uniaxial testing

machines.

[6] Method for calibration of force proving instruments used for

verication of uniaxial testing machines, IS 4169-1988 (re-afrmed2003).

[7] Chen, B., Wu, X. and peng, X.: Finite element analysis of ring strainsensor. Sensor and Actuators A: Physical, Vol. 139, No. 1-2, 2007,

pp. 66-69.

[8] Kumar, H., Sharma, C. and Kumar, A.:Deection analysis of a forcetransducer. Sensor Letters, Vol. 10, No. (3/4), 2012, pp. 723-728.

Abbreviations

Capacity C (N)

Mean Radius- R (mm)

Thickness t (mm)

Width b (mm)

Thickness to Mean Radii ratio - (t/R)

Deection - (mm)Deviation- D (%)


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Performance Studies of a Hybrid Solar Heater

for Water and Space Heating and Lighting

Vishal BhasinDepartment of Mechanical Engineering,

K.I.M.T., Moradabad, U.P., India

Abhishek SaxenaDepartment of Mechanical Engineering

M.I.T., Moradabad, U.P., India

Email ID: [email protected]

List of Symbols/Abbreviations

Ac= Gross area of solar collector, m2

Aa= Absorber area of solar collector, m2

Ap= Total outside surface area of the connecting pipes, m2

As= Outside surface area of storage tank, m2

Cp= Specic heat of water, J/kg K

C = Concentration ratio

F = Collector efciency factor

GT = Solar irradiance on the inclined plane of the solar collector,

W/m2

GT = Average value of solar irradiance on the inclined plane of

the solar collector during day test, W/ m2

(MC)s= Thermal capacitance of the water in the storage tank

only (J/K).

Q = Total energy collected by the solar collector during period

of the day-test (kWh)

Qc = The total solar irradiance on the collector during test

period, (J)

t = Time, s

Tamb

= Ambient air temperature, C

Tm= Cold water temperature from mains, C

Tpf

= Temperature of water in pipes, C

Ttf= Temperature of water in storage tank, C

Tps

= Temperature of pipe surface, C

Usd

=Overall heat loss coefcient of the system during day-test,W/ m2K

UL =Overall heat loss coefcient of solar collector, W/ m2K

Usn

=Overall heat loss coefcient of system during night-test,W/ m2K

Up=Overall heat loss coefcient of piping, W/ m2K

Ut=Overall heat loss coefcient of storage tank, W/ m2

t = Time duration of solar test, s

sys,o

= Maximum efciency of the system

sys

= Efciency of solar hot water system averaged over thetest period

cooling= Cooling time constant during no radiation period, day

A lot o research and work has been carried to increase the efficiency o solar thermal systems by innovating new ideas which are continued.Here, an attempt has been made to analyze the easibility o new application, which can be perormed on solar energy as well as backup powerin any climatic condition and can also save a good amount o other ossil uels using purposely or heating tasks and lighting. Te system will notonly provided the continuous hot water supply round the year but in winters it is easible or space heating with good lighting around the place oinstallation. In the present work, the methodology o the evaluation o hybrid solar water heater and room heater cum room lighting system hasbeen discussed with design and the easibility o the present system. Besides this, some additional benefits over the designs o solar hybrid systemsused or water and space heating have been outlined. Te observational results concludes that system is efficiently working with multiple applicationswhich result in a slightly increase in overall efficiency.

Keywords:Solar energy, hybrid, heating, lighting.

ABSTRACT


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Subscripts

amb = Ambient Conditions

c = Collector

d = Day time

f = Final value

I = Initial Value

max = Maximum

n = Night time

o = Overall

p = Pipe

s=System

t=Storage tank

I. INTRODUCTION

With the advancement of technologies day by day and increasing

requirement of energy resources of the world, there is a need of

non-conventional sources of energy as the conventional sources

of energy such as oil, fossil fuels, coal etc., are depleting day by

day which are major source for fuel requirement in almost every

activity of man. All the machines, industries, household appli-

ances works either based on electricity or based on fuels. The

generation of electricity is based mostly in thermal power plant

where coal is used as raw material. Such conventional source of

energy is limited in nature. With the increase in population there

is an increase in energy consumption such as fuels, electricity

etc. which is the basic requirements of all machines and electric

devices. Without the use of it we cannot imagine the present life.

For this there is a need to nd the alternative source of energywhich can fulll the current energy requirements of the marketor another way is increase the efciency of present applications.There are various hybrid systems which perform for water heat-

ing and space heating individually. As per the latest technologies

compact machines are in demand and for this other type of heat

exchangers are required which are light in weight, transfer the

heat easily, simple in construction, less response time, efcientand economical. Solar water heating system (SWH) is renewable

energy technology and has been used in numerous countries of

the world. Solar heater is a device which is used for heating the

water, for producing steam for domestic and industrial purposes

by utilizing the solar energy.

Hot water is important for bathing and for washing utensils and

other domestic purpose in urban as well as in country areas.

Solar water heaters (SWHs) of 100-300 liters capacity are suited

for domestic use and easily heated water to a temperature of

60-80oC. A 100 liters capacity SWH can replace an electric geyser

for residential use and may save approximately 1500 units of

electricity annually. The use of 1000 SWHs of 100 liters capacity

each can contribute to a peak load saving of approximately 1 MW.

The efciency of solar thermal conversion is around 70% whencompared to solar electrical direct conversion system which has

an efciency of only 17% [2]. A SWH of 100 liters capacity canprevent the emission of 1.5 tonnes of carbon dioxide per year

[1]. If green house gases emissions continue to grow at current

rates, it is almost certain that the atmospheric levels of carbon

dioxide will increase twice or thrice during the 21 century. In an

already highly crowded and stressed earth, millions of peopledepend on weather patterns, such as monsoon rains, to continue

as they have in the past. Even minimum changes will be disrup-

tive and difcult. Carbon dioxide is responsible for 60 percentof the enhanced greenhouse effect [8]. Humans are burningcoal, oil and natural gas at a rate that is much faster than the

rate at which these fossil fuels were created. This is releasing

the carbon stored in the fuels into the atmosphere and upsetting

the carbon cycle (a precise balanced system by which carbon

is exchanged between the air, the oceans and land vegetation

taking place over millions of years). Currently, carbon dioxide

levels in the atmosphere are rising by over 10 percent every 20

years.The solar radiation incident on the surface of the earth canbe conveniently utilized for the benet of human society. Oneof the popular devices that harness the solar energy is solar hot

water system (SHWS) [10].

Broadly, the solar water heating systems are of two categories.They are closed loop system and open loop system [16]. In the

rst one, heat exchangers are installed to protect the system fromhard water obtained from bore wells or from freezing tempera-

tures in the cold regions. In the other type, either thermosyphon

or forced circulation system, the water in the system is open to

the atmosphere at one point or other. The thermosyphon systems

are simple and relatively inexpensive. They are suitable for

domestic and small institutional systems, provided the water is

treated and potable in quality. The forced circulation systems

employ electrical pumps to circulate the water through collec-

tors and storage tanks.

II. LITERATURE SURVEY

Akyuthas been analyzed that the heat pipes perform satisfactorily

as heat transfer elements in solar water heaters. In it the

maximum allowable temperature drop along the heat pipe was

taken as 6C [3]. Bong represented a theoretical model for thedetermination of the efciency, the heat removal factor, and

the outlet water temperature of a single collector and an arrayof at plate heat pipe collectors [10]. Parkhas been studiedon the thermal performance of heat pipe to optimize the heat

distribution of satellite equipment and conclude that the outer

wall temperature can be controlled by redistribution of heat

sources and the heat source closer to the condenser can carry

more heat while maintaining lower temperatures at the outer

wall [13]. Wang et.al., has been observed that the temperature

along the heat pipe wall surfaces is quite uniform and they also

suggested the idea of time constant to describe the transient

characteristics of the at plate heat pipe [14]. Shah et. al., hasinvestigated theoretically and experimentally that the tubular

collector can utilize solar radiations coming from all directions

[15]. Facao et. al., has analyzed the thermal behavior of a plate


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heat pipe solar collector in which the numerical model is based

on energy balance equations by assuming a quasi- steady state

condition [16]. Wang et. al., has been developed a novel atplate collector and concluded the results that the maximum heat

transfer capacity of the at heat pipe was affected by the mesh

number, wire diameter, number of layers, and tilt angle, as wellas the sintering process utilized, i.e., the compact coefcient ofthe sintered screen mesh wick [17].

Zhang et. al., has investigateda case of supercritical CO2 the

annually averaged collector efciency is above 60% whichis much higher than that of water based solar collector [19].

It was also concluded that the CO2 temperature and pressure

increase with the solar radiation and the CO2mass ow rate

in the loop also increases with the solar radiation. Bin et. al.,has been conducted an experiment on turbulent convective

heat transfer with molten salt in a circular tube and the average

forced convective heat transfer coefcients of molten salt weredetermined by least-squares method [23]. Tundeehas conductedsome experimental and theoretical analysis on the heat extraction

process from solar pond by using the heat pipe heat exchanger

[25]. Jianfeng et. al., has been proposed the basic physicalmodel of solar receiver pipe with solar selective coating and

heat transfers and exergic performances was also analyzed. The

solar selective coating with low emissivity will increase the wall

temperature and energy absorption efciency of heat pipe. Atthe same time as the pipe radius decreases or ow velocity rises,the wall temperatures drops and the heat absorption efciencyincreases [26]. Ma. et. al., has been investigated the thermal

performance of the individual two layered glass tube evacuated

solar collector by analytical means and studied the inuence ofair layer and solar radiation intensity on the heat efciency inwhich the results showed that the efciency of solar collectorincreases 10%, and the outlet uid temperature increases 16%if the synthetically conductance increases from 5 to 40 W/m

K [28]. Hayek et. al., had experimentally investigated that the

efciency of heat pipe based collector is 15-20% higher than thatof water in glass design [29]. Cheng has been made efforts to

trace the origins of the thermodynamic aspects of the heat pipe

operations to the limiting case of the innitesimal (differential)Carnot vapor cycle (Carnot heat pipe) [30]. Within the context of

the idealized Carnot heat pipe, it is shown that thermodynamics,

uid mechanics and heat transfer (thermal sciences) are closelycoupled in heat pipe operation. It is of interest to note that theCarnot vapor cycle provides the basic principle for heat pipe and

two-phase thermosyphon in addition to the classical cases of heat

engine, refrigeration machine and heat pump [30].

Kishor et.al. [31] has been provided a grey-box modeling

approach based on fuzzy system to predict the outlet water

temperature of a solar water heating system. Articial NeuralNetwork Technique is used to determine its performance. Fuzzy

modeling technique is used to predict the outlet water temperature

accurately utilizing 3 parameters as inputs, namely inlet water

temperature, ambient temperature, solar insolation received.

The black-box/grey-box modeling has been successfullyinvestigated in great extent to study the performance of SWH

system. Cruickshank and Harrison [32] have been carried out

a computer simulation to predict the performance of solar

domestic hot water (SDHW) systems. Thermal Storage heat

loss characteristic is one of the important features of heat loss

characteristics. In addition, the validity of the basic assumptions

typically used in the computer modeling of storage heat losses(e.g., one dimensional temperature proles, minimal tank wallconduction, uniform wall heat loss) were examined, mainly for

a thermally stratied thermal storage. The economic benets ofutilizing solar water heating systems for low-income dwellings

in Brazil have been analyzed by Naspolini et.al., [33]. It is anatural choice of technology for residential buildings in Brazilas because solar radiation resource is evenly distributed with

small annual variability. Brazil, at present is one of the largestusers of solar water heating system. Water heating is one of the

largest single contributors to the total residential electricity bill

averaging over 22% of the monthly bill.

Juanico [34] has been developed a new design of roof-integratedwater solar collector by integrating the collector into roof. Its

main concept is based on the use of water redistribution for

changing the roof conguration. The design provides a low-costsystem for household heating and cooling that could be even

cheaper than conventional roofs with similar thermal qualities,

by using fully its congurable property. Author also proposedto maximize the degree of adaptability of the building to the

environment. New piping technologies (continuous lines, ttingswithout elbows, etc.) can be used to minimize leakage problems.

New developments in low-conductivity windows (triple glazing

lled with low-conductivity gases, low-emissivity coating, etc.provides a way to obtain very good insulation by using multiple-

glass windows.

(A) SOLAR WATER HEATER

The most common application for the utilization of solar

energy is solar water heater. With the advancement of solar

technology solar water heater popularity rises rapidly as it is

very economical than PV modules. Even though the initial cost

is high, its operating and maintenance cost is negligible. Solar

water heater is eco-friendly in nature and its efciency is basedon inlet water temperature. It consist of three major components

i.e. collectors, storage tank and electric pumps. In simple solar

heaters, electric pumps are not necessary but it is useful to

increase the efciency of system [39]. For efcient operation itshould be properly installed and in direct sunlight facing towards

the sun and the supply of unheated water should be maintained.

It can be categorized as open loop system (or direct system) and

closed loop system (or indirect system). For higher temperature

closed loop system is preferred and vice versa. The solar heater

can also be classied as active system and passive system. Inactive system external source of energy such as electric pumps

are required. The various parameters to consider while installing

a solar heater are its size, sunlight, proper installation, tilt angle

and the orientation of collector.


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Fig. 1:Simple solar water heater installations

As shown in Figure 2.1, when the sun rays falls on the solar

collector the temperature of the working uid inside it startedto increase. Due to this the hot uid started to move upwardstowards the upper end of storage tank and in the same time the

cold uid from the bottom end of storage tank will started tomove towards the collector tubes. Thus a circulation will start

due to thermosyphon effect and heating of uid continues up toavailability of sun light [40].

(B) Parabolic Trouh Collectors

Parabolic trough collectors are high temperature devices which

has an operating temperature of about 400

0

C. It consists oflong parabolic reectors which concentrates solar light on anabsorber tube placed on a focal line. The absorber tube consists

of a working uid such as thermo oil which is used to generatesteam at 3900C for the generation of electricity. The steam can

also generate directly through absorber tube which consist

evacuated glass tube alongwith antifriction coating. Parabolic

trough collectors are having simple geometry and are used mostly

in solar based thermal power plants (SEGS).

Fig. 2:Parabolic trough collector

The Figure 2.2 represents a parabolic trough collectors placed in

an array in which absorber tube which is also known as dewar

tube is interconnected with solar eld piping and a uid suchas thermal oil ow through it. The reectors are used to collectthe solar energy which reects back towards the absorber tube

to increase the temperature of owing uid which then used togenerate steam to produce electricity. For better efciency atracking system can also be used.

(C) Dish Collectors

Dish collector also known as point focusing collector consists of

parabolic reector mirrors having a receiver at the focal centerwhich can concentrate the sunlight up to 1000 times and have

the ability to melt the steel at sharp focal point.

Fig. 3: Dish collector

It is similar to large satellite dish antenna including dual axis

tracking having various small mirrors on its reecting surface.Sometimes the reecting surface is also covered with inexpensivethin aluminium foil which serves the same purpose efciently.Dish collectors are used to generate electricity through steam

generated at focal point or placing sterling engine directly at the

centre. It can also be used as solar dish cooker which is relatively

small and generate temperature of about 2000C but generally

not preferred to heat water as it is large in size and high cost. Dish

collectors consist of four major parts which are (1) Parabolic reect-

ing surface, (2) receiver and (3) supporting rods and (4) supportingframe with tracking mechanism.

III. EXPERIMENTAL SETUP

To construct the hybrid system the following components and

instruments are required along with the prescribed testing consid-

erations. The experimental data is collected in two phases i.e. rstduring the sunshine and other is without sunshine only by using

heating element. The system comprises of following elements:

A SWH frame or a collector which is made up of aluminumpipes of size (90 120 cm) having eight rods of diameter

9 mm and of length 900 mm and two rods of diameter

15 mm and of length 1200 mm forming net structure like


13/60



SWH frame of total area of 100 cm2 to collect the solar

radiation for heating the water and act as a collector which

is mounted on a reector of diameter 140 cm and of focallength 40 cm by help of wires and insulated threads.

Fig. 4:Installation of solar hybrid system

For the installation of SWH an insulated water container isrequired which will supply the regular water to the collec-

tor or solar heater frame and is required for the circulationof uid due to thermosyphon effect. In the present systemwe are using a container of 30 liter in volume of galvanized

cast iron with proper insulation having inlet and outlet

passages. To connect the collector and water tank PVC

pipes are used which is required to form a closed loop

system. Here PVC pipes are used and to connect with

the metal frame or collector a exible pipe is also used toact as intermediate between metal frame and PVC pipe

and alongwith it metal clips are used to prevent leakage.

To regulate the supply of uid in between metal framecollector and water storage tank various valves are needed.

Presently three valves are used to control uid from watertank to collector, collector to water tank and collector to

outlet respectively. For the drainage of uid for cleaningpurpose of metal frame collector or during any unwanted

leakage a drainage valve is also added. This leakage of

uid will drop the efciency of a system to a great extentand it can be removed by using appropriate means.

The system is also used as a room heater and room light-ing and for this heating element is required. For a hybrid

system we are using a halogen of 500 W which will act

as a room heater and also be used for room lighting. The

500 W halogen light is sufcient for lighting a room of

size 1212 square feet.

Fig. 5:Representation of PVC tting in SWH

The present SWH including halogen/bulb for hybrid system is

insulated as shown in Figure 3.1. The uid is supplied to theSWH frame via PVC and exible pipe. The system is made in away so that it acts like a simple thermosyphon and it should be

properly insulated and leak proof. When the sun rays fall on the

SWH, the uid in it gets heated and this heated uid gets startedto move upwards and thus proper circulation of uid will start

between SWH and uid container due to thermosyphon effect.In this way the temperature of uid of whole system will riseand thus hot water will obtain by proper usage of solar energy.

In the case, if there is less sunshine in day hours and no sunshineduring the night hours, the uid can be heated by using extraheating element which can also become a source of light during

night. Thus the system is made hybrid by using solar energy as

well as electricity and its additional advantage is also use it as

source of light during night. In this way the same system can be

used for water heating, space heating as well as for room lighting.

For the testing purpose we have measure the temperature varia-

tion of the tank temperature, room temperature, bulb temperature,

solar radiation intensity in a regular interval of time. As the sys-

tem is hybrid with various applications so we divide the testing

procedures in two halves i.e. one in a closed room during night

and another during the sunshine. Other measuring instrumentis also required for testing purpose to calculate solar radiation,

uid temperature etc. For the measurement of solar radiation onepyranometer is necessary. The main component of pyranometer

is a thermopile. A thermopile is an electronic device that converts

thermal energy into electrical energy. It is composed of several

thermocouples connected usually in series or, less commonly, in

parallel. Thermopiles do not respond to absolute temperature, but

generate an output voltage proportional to a local temperature

difference or temperature gradient.

The surrounding air speed need to be measured on the collec-

tor surface at every half an hour with an accuracy of 0.1 m/s.

For this purpose one anemometer is necessary. Thermocouplesare used to measure the temperature of the system at various


14/60



points simultaneously. Six wire thermocouple which is used in

the current project. For measuring of length, height, and width

a meter rule was used while for short length a Vernier scale (0-

125 mm) was used with a least count of + 0.02 mm. For circular

measurement a micro meter of (50-100 mm) with an accuracy

of + 0.01 mm.

(B) Testin Procedure

The tests shall be carried out in the following sequence:

1. PRE-CONDITIONING TEST

Fully assembled system lled with water shall be kept exposedto weather conditions for 15 days having daily solar irradiation

on the plane of solar collectors more than 16 MJ/m2. The dayswith solar irradiance lesser than this value shall not be counted.

After pre-conditioning of fteen days, all parts of the system shallbe inspected for any visual sign of degradation, deformation,

ingress of moisture/dust, etc. and shall be reported.

Fig. 6:Installation of hybrid solar heater for water & space

heating and room lighting

2. STATIC PRESSURE LEAKAGE TEST

The purpose of this test is to ensure the integrity of Solar HotWater System particularly its tank to withstand the pressure,

which it might meet in service. Initially, air bleed valve is kept

open. For solar water heating systems, it is to be ensured that all

air is removed from the collector by circulating water though it.

Thereafter, the solar water heating system (tank + collector), is

lled to its full capacity (as per claims of the manufacturer) withwater at a temperature of 60 2 C. After lling, the bleed valveand all other valves are closed, and specied hydraulic pressureis applied. For at plate collector systems, the specied pressureis 5.0 kg/cm2while for ETC based systems it is 0.2 kg/cm2. The

system is kept pressurized for a period of 30 min. All parts of

the system, especially the storage tank, shall be inspected for

visual sign of leakages. Results of the test in terms of the initial

and nal reading of the pressure gauge, temperature of the water,duration of the test and the result of inspection shall be reported.

3. THERMAL MODELING

The test method is based on a lumped capacitance model, where

it is assumed that average water temperature in the storage tank

characterizes the behaviour of the whole system whether the

storage is well mixed or stratied. The test procedure envisagescharacterizing the thermal performance of the system without

any withdrawal of hot water from the storage tank. This strategy

is adopted because the performance of the solar water heating

system strongly depends on the pattern of withdrawal of hot

water from the storage tank, and there could be wide variation

in the withdrawal pattern. The solar collector and part of piping

would not play role in loosing heat from the tank during night

as it does during the day. However, nighttime test would account

for all thermal losses from the system.

4. THERMAL ANALYSIS OF CPC

If the acceptance angle is 2max

, the concentration ratio (maxi-

mum) Cmax

is given by

C Dmax'max

sin2

1=

(4.1)

For a linear 2D collector, the maximum value of C is 212. For

dish concentrator (3D collector), the maximum value of C can

be expressed as

CDmax'

maxsin

2 2

1=

(4.2)

The maximum value of C for a 3D collector (dish having an

compound curvature) is about 40,000 considering that the sun

subtends an angle of 0.The solar PTC optical efciency isdened in the following form:

op

r

b

S

I= (4.3)

Jaffe presented the method for calculating and optimizing theperformance of parabolic dish solar collectors and for optimizing

their cost/output ratio[1]. The most important performance opti-mization is that of the receiver aperture. The efciency maximaassociated with focal length and, if a heat engine is used, with

receiver temperature, are relatively broad; it may be desirable

to design somewhat off these maxima. It presents methods for

calculating collector and system performance and for optimizing

performance and cost/output ratio.

The equation used for net rate of heat collection is

Q IA G A T T h T T A h T T r r a c r a w k r a= ( ) + ( ) [ ( )4 4

(4.4)

The collector efciency


15/60



coll opt r Q

IA= = (4.5)

Where the optical efciency of the concentrator

opt G= (4.6)

The heat collected Q and the collector efciencyare maximizedwhen

= ( ) + ( ) 1 2 2 4 4

f r a c r aT T h T T I G/ (4.7)

The geometric concentration ratio at this intercept factor is

affected by the design of the secondary, and may be written as

C C C= 1 2 (4.8)

The C that can be attained by using a secondary is limited in two

ways. C cannot exceed the theoretical limit

C1 21= / sin (4.9)

Thermal Performance Studies of Solar Water Heater

Mean water temperature increases as the day progressed, as

expected. The temperature remained steady towards the even-

ing and drops off at night. The mean system efciency at theend-of-day is dened as:

=

VC T

A H

p100% (4.10)

However the mean temperature rise depends upon the collector

area/storage volume ratio of the system. Large collector areasand small tank volumes would result in higher temperature rise.

The mean system efciency would take this into to account.The pro-rated expected mean water temperature rise could be

calculated from Eq., viz.,

=

T

H

c

A

Vp

100

(4.11)

The total energy incident on the collector during the time period

from t1d

to t2d

is given by the expression:

Q A G dt c c t

d

d

= 2

1 (4.12)

IV. FEASIBILITY STUDY

SWHsare now using globally all over the world for the daily

purpose availability of hot water to utilize the maximum of solar

energy. As the running cost of SWH is negligible and initial

cost is high but now a day initial cost are also getting lower due

to newly incoming techniques and also due to policies made

by the government to encourage solar energy. Solar energy is

becoming a practical experience in day to day life and we aretrying to improve the applications of SWH by using it in a newer

way i.e. to use the SWH to for water heating, space heating as

well as for space lighting. One of the problems associated with

the SWH is that in day time the water gets hot but during that

time the requirement of hot water is less i.e. most of the hot

water required in the morning. Also the unused water whose

temperature rises up during day gets cooled down during the

night hours and in the next morning the water obtains is of normal

temperature. To improve the efciency of the system variousmethods are available and the most common method is properly

insulation of water storage tank especially for the night hours

but it increased the cost the system and the heat losses are also

associated with them.

We have tried to improve the system efciency by using an extraheating element such as 500 W halogen or bulb. The heating

element heat up the water temperature during night as well as it

also helps to maintain the hot water temperature as per require-

ment. Thus such type of system can be used for 24 hours, i.e.,during the day as well as during night. The heating element is

also useful for space heating. This can be made by placing the

system including heating element outside of room but near the

window. Thus the temperature of room rises from the ambient

temperature. The rising temperature of the room depends on the

position of the system with respect to the window of the room.

The same system can also be used for lighting purposes dur-

ing night especially in commercial buildings such as hospitals,

hostels, public places, and parks and in campus of the residential

society and corporate ofces as there is always a need of lightduring whole night for security or other reasons. Some peoples

are used dim light in night inside the room also and it can also

be possible by the present system if it kept near the window.

Thus the same system is using for water heating, space heat-

ing as well as for room and campus lighting without made any

physical changes in the system. This hybrid system will be easily

adopted by the society due to their multiple applications without

any additional cost.

V. RESULT AND DISCUSSION

The present work conducted in Moradabad Institute of Technol-

ogy in Moradabad-244001. Performance of any solar water heater

depends on design of solar water heater, capacity of tank and the

collector area. As in typical north Indian weather conditions, on

a sunny winter day, one sq.m. of collector area can be expected

to heat approximately 50 liters of water by a temperature of 30-

40C. The thermal performance of solar water and space heating

room heating system is investigated with water as a working uidon both sunny day and cloudy day. For economic feasibility the

system was installed in a way such that it can be used for other

purposes as the heater element which serves as a backup for the

system during night can also be served as a room heater at the

same time in colder regions and along with it also used as room

lighting. Thus the multi-function system will obtain at the samecost without any degradation of energy.


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The system has been installed according to above construction

details without any leakage and proper insulation in Moradabad

in the month of July, 2014 towards south direction. In the preconditioning test the whole system was installed and ll withwater and kept it in the same conditions for 5 days to check the

leakage of the collector. The leakage of the system was checked

during rst two days and then kept the system lled with waterfor next ve days.

In the static pressure leakage test pressurized water was made to

ow through the collector to check the leakage of water due topressure as during system operation the water inside the collector

gets heated and of high pressure during the circulation of uid.For the pressure leakage test one end of collector was connected

with tap water of high pressure and other end of the collector was

made blocked. The system was checked every one hour during

whole day and the leakage which emerged was removed. To

increase the absorptivity of the collector it was then painted with

thick black paint. After that the collector was ready to install with

the bowl reector and with the storage water tank via PVC pipettings. In our system three valves are used to control the uidinside the system. The bowl reector was taken from the solarcooker reector system due to its easily availability and simplein construction. The PVC pipes were used due to its light weight

and corrosion resistance and easy installation and exibility. Thejoining ends in pipes were xed with insulating threads as mostof the heat losses occur at the joint ends. The water container

was then lled with water and system was made leak proof in

a closed loop. Again the system checked for two days to checkstatic leakage test.

As discussed before the testing of the system was made in two

phases, one during the day time and another during the night

time as the present system are made to work for both i.e. day

as well as for night time. In the rst testing phase the systemwas installed in the campus outside the window of room which

was glass mirrored in a way that the system was available for

water heating, space heating as well as for lighting. The test

was performed from 20:00 hours in the evening to 6:00 hours

in the morning and the rst reading was taken after two hour

and remaining after every half hour. A halogen of 500 W wasused and ux of it was measured at every interval of time includ-ing the measurement of T

amb, tank uid temperature, pipe uid

temperature, pipe surface temperature, room temperature and

the velocity of wind.

THERMAL PERFORMANCE OF HYBRID SWH

DURING NIGHT

During the rst day, i.e. on 21.07.2014,the system was operatedusing the heating element. The whole set-up was installed in the

day and tested. At 6:00 PM in the evening the system was lledfull of water and allowed the system to remain standstill for two

hours. From 8:00 PM the reading was measured at every interval

of 30 minutes of various temperatures i.e. ambient temperature,

tank uid temperature, pipe uid temperature, pipe surfacetemperature, room temperature including velocity of wind and

ux of heating element.

The observational data collected during the night are as follows:

Fig. 7:Performance curves of system during night (Day 1)

At starting Tamb

was measured as 32.2oC with 450 W/m2 uxof heating element and ended up with 29.5oC and 560 W/m2

heating element ux. The readings were noted and Tpf

was rises

from 32.4oC to 57.9oC from 20 hours in evening to 6 hours in

morning. The temperature of tank uid i.e. the Ttfwas also risenfrom 32.9oC to 36.8oC. The room temperature T

roomwas risen

from 32.4oC to 37.5oC. The ux was measured of average valueof 540 W/m2. The same procedures were followed on the next

day i.e. 22.07.2014 and Tpf

was increased from 32.8oCto 58.6oC

with an average ux of 480 W/m2and the Troom

was increased

from 32.8oC to 37.8oC.

Fig. 8:Performance curves of system during night (Day 2)


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THERMAL PERFORMANCE OF HYBRID SWH

DURING SUNSHINE

During the daytime there is no requirement of heating element.

On the 3rdday of experiment the observational readings were

measured in the presence of sunshine. The test was performed

in between 10:00 AM to 6:00 PM at an ambient temperature of

31.4oC at 600 W/m2solar radiations. The temperature of the uidin the pipe rises from 31.6oC to 68.2oC and the temperature of

tank uid rises from 31.9oC to 40.1oC. The observational dataduring the day time are as follows:

Fig. 9:Performance curves of system during daytime (Day 3)

On the fourth day the same procedures were repeated and data

were collected at Tamb

of 30.90C with an average solar radiation

of 650 W/m2. The Tpf

was increased from 30.6 to 64.50C and

the temperature in the tank uid increases from 30.9 to 38.80C.

Fig. 9:Performance curves of system during daytime (Day 4)

VI. CONCLUSION

Wide spread utilization of solar water heaters can reduce a sig-

nicant portion of the conventional energy being used for heatingwater in homes, factories and other commercial and institutional

establishments. Internationally the market for solar water heatershas expanded signicantly during the last decade.

For increasing the applications of solar water heater a new type of

system is introduced in which hybrid SWH is used which is work-

ing by the help of solar energy as well as by using electricity as

an external supply. The same system can be used as room heater

in winter season as well as used for lighting in night in the room

or in an open campus. The observational results concludes thatsystem is efciently working with multiple applications whichresult in a slightly increase in overall efciency. The additionalapplications of the system help to minimize its initial cost and

further experiments are needed to bring the solar products in the

market at competitive price.

REFERENCES

[1] Solar Water Heater, Delhi Energy Efciency & RenewableEnergy Management Centre, New Delhi.

[2] Ahsan, Amimul, Kh. M. Shafiul Islam, Teruyuki Fukuhara,

and Abdul HalimGhazali, Experimental study on evaporation,condensation and production of a new Tubular Solar Still

Desalination, 2010.

[3] M. Akyurt,Development of heat pipes for solar water heaters,Solar energy, vol. 32, Saudi Arabia, 1984.

[4] Abhishek Saxena and G. Srivastava, Potential and Economics ofSolar Water Heating, MIT International Journal of MechanicalEngineering Vol. 2, No. 2, Aug. 2012, pp. (97-104).

[5] BP energy outlook 2030 www.bp.com/.../bp...energy.../2030_energy_outlook_booklet.pdf

[6] Indian Energy Scenario indiastatistical.wordpress.com/2006/10/03/

indian-energyscenario/

[7] http://www.utopiasolarsolutions.com/solar_radiation_in_india.html

[8] Ministry of Power India ofcial website.

[9] Ministry of new and renewable energy ofcial website.

[10] T.Y. Bong et al., Thermal performance of a at plate heat pipecollector array, Solar Energy, vol. 50, Singapore, 1993.

[11] A. Akbarzadeh, Heat pipe based cooling systems for photovoltaiccells under concentrated solar radiation, Applied thermal

engineering, vol. 16, Australia, 1995.

[12] Robert S. Reid, Heat pipe transient response approximation,lib-www.lanl.gov, Los Alamos, 1996.

[13] J. Heung Park, A study on thermal performance of heat pipe foroptimum placement of satellite equipment,ETRI Journal, 1997.

[14] Y. Wang et. al., An experimental investigation of the thermalperformance of an asymmetrical at plate heat pipe,InternationalJournal of Heat and Mass Transfer, U.S.A, 2000.

[15] L.J. Shah et. al., Vertical evacuated tubular-collectors utilizingsolar radiations coming from all directions, Applied Energy,

Denmark, 2004.

[16] Jorge Facao et al., Analysis of a plate heat pipe solar collector,International Journal of Low Carbon Technologies, Portugal,

2005

[17] Y. Wang et al, Investigation of a novel at heat pipe, Journalof Heat Transfer, vol. 127, 2005


18/60



[18] David B. sarrafet al., Heat pipes for high temperature thermalmanagement, ASME InterPACK,07, Lancaster, 2007.

[19] X.R. Zhang et al, An experimental study on evacuated tube solarcollector using supercritical CO

2,Applied Thermal Engineering,

28, Japan, 2008.

[20] Hua Zhu et al., Theoretical and experimental research on heattransfer performance of the semi-open heat pipe, J. Zhejiang

Univ. Science A, 2008.

[21] H. Li (in 2012). Experimentally investigated the solar powered

air conditioning system using desiccant wheel.

[22] Randeep Singh et al.,Effect of wick characteristics on the thermal

performance of the miniature loop heat pipe,Journal of heat

transfer, vol.131, 2009.

[23] L. Bin et al., Turbulent convective heat transfer with molten saltin a circular pipe,International communications in heat and mass

transfer, China, 2009.

[24] P. Naphon et. al., Experimental investigation of titanium

nano uids on the heat pipe thermal efciency, Internationalcommunications in heat and mass transfer, Thailand, 2010.

[25] S. Tundee et al., Heat extraction from salinity gradient solar pondsusing heat pipe heat exchangers, Solar energy,84, 2010.

[26] Lu Jianfeng et al., Heat transfer performance and exergeticoptimization for solar receiver pipe,Renewable energy35, 2010.

[27] C.B. Shobhan et al., A review and comparative study of theinvestigations on micro heat pipes, International Journal of

Energy Research, India, 2007.

[28] Liangdong Ma et al., Thermal performance analysis of theglass evacuated tube solar collector with U-tube,Building and

Environment, 45 (2010).

[29] M. Hayek, Experimental Investigation of the performance ofevacuated tube solar collectors under eastern mediterranean

climate conditions,Energy Procedia6, Lebanon, 2011.

[30] K.C. Cheng, Some observations on carnot cycle as the genesisof the heat pipe and thermosyphon, International Journal of

Mechanical Engineering Education, Vol. 28, Canada, 1998.

[31] NandKishor, Mihir Kr. Das, AnirudhaNarain, Vibhaw Prakash

Ranjan: Fuzzy model representation of thermosyphon solar waterheating system : Solar Energy 84 (2010) 948955

[32] Cynthia A. Cruickshank, Stephen J. Harrison :Heat losscharacteristics for a typical solar domestic hot water storage ,

Energy and Buildings, 42 (2010) 17031710.

[33] H.F. Naspolini, H.S.G. Milito, R. Rther: The role and benetsof solar water heating in the energy demands of low-income

dwellings in Brazil, Energy Conversion and Management 51(2010) 28352845.

[34] Luis Juanico: A new design of roof-integrated water solarcollector for domestic heating and cooling: Solar Energy 82

(2008) 481492.

[35] Price H. Lu Pfert E., Kearney D., Zarza E., Cohen G., Gee R., et

al., Advances inparabolic trough solar power technology.J. Sol.

Energy, Eng 2002;124:10917.

[36] Albiasa. http://www.albiasasolar.com; 2009.

[37] Kearney, D.W. Parabolic trough collector overview In: Parabolicthrough workshop 2007, NREL; 2007.

[38] Kimura D.,High efficiency power generation using lowtemperature water In: CSP today, 2nd conc sol therm power

summit; 2008.

[39] B.L. Price. Jr., Heat pipe technology for energy conservationin the process industry, Proceedings from the seventh national

industrial energy technology conference, Houston, 1985.

[40] S. Tundee, P. Terdtoon, P. Sakulchangsatjatai, R. Singh, A.

Akbarzadeh, Heat extraction from salinity gradient solar pondsusing heat pipe heat exchangers, Solar Energy, 84, Thailand, 2010.

[41] Zhaohui qi, Study on hybrid system of solar powered water heaterand adsorption ice maker,International Journal on Architectural

Science,, China, 2006.

[42] S.A. Kalogirou, Y. Tripanagnostopoulos, Hybrid PV/T solarsystems for domestic hot water and electricity production,Energy

Conversion and Management, Greece, 2006.

[43] R. Z. Wang, m. Li, y. X. Xu and j. Y. Wu, An energy efcienthybrid system of solar powered water Heater and adsorption ice

maker, Solar Energy, Vol. 68, 2000.


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Design and Fabrication of

Hydraulic Scissor Lift

Doli Rani*

Faculty of Mechanical Engineering Department,

Sunderdeep Group of Institutions,

Ghaziabad, U.P., India

e-mail:[email protected]

Nitin Agarwal


MIT, Moradabad, U.P., India

Vineet Tirth


MIT, Moradabad, U.P., India

. INTRODUCTION

Elevated work platforms are mechanical devices that are used

to give access to areas that would previously be out of reach,

mostly on buildings or building sites. They are also known as

Aerial Work Platforms (AWPs). They usually consist of the work

platform itself often a small metal base surrounded by a cage

or railings and a mechanical arm used to raise the platform. The

user then stands on the platform and controls their ascent or

descent via a control deck situated there[1].

Some forms of aerial work platform also have separate controls

at the bottom to move the actual AWP itself while others are

controlled entirely on the platform or towed by other vehicles.

Most are powered either pneumatically or hydraulically.This

then allows workers to work on areas that dont include public

walkways, such as top-story outdoor windows or gutters to

provide maintenance. Other uses include use by re brigade andemergency services to access people trapped inside buildings,

or other dangerous heights. Some can be tted with specialistequipment, for example allowing them to hold pieces of glass to

install window planes. They are temporary measures and usually

mobile, making them highly exible as opposed to things suchas lifts or elevators [2].

However generally they are designed to lift fairly light loads

and so cannot be used to elevate vehicles, generators or pieces

of architecture for which a crane would more likely be used. In

some cases however elevated work platforms can be designed

to allow for heavier loads. Depending on the precise task there

are various different types of aerial work platform which utilize

separate mechanisms and fuel sources. The most common type

is the articulated Elevated Work Platform, (EWP) or hydraulicplatforms (and also known as boom lifts or cherry picker).

The following paper describes the design as well as analysis of a hydraulic scissor lift having two levels. Conventionally a scissor lift or jack

is used for lifting a vehicle to change a tire, to gain access to go to the underside of the vehicle, to lift the body to appreciable height, and

many other applications. A Scissor lift is the type platform that can usually move vertically. This mechanism is achieved by the use of link,

folding support in crisscross pattern known as a Pantograph. The upward motion is achieved by the application of pressure to outside of thelowest set of support elongating the crossing pattern and propelling the work platform vertically. This paper describes the complete study of

components (hydraulic cylinder, scissor arms, spacing shaft and platform), selection of materials and analyzes the dimensions of components

along with their sketches with the help of design software CATIA V5 followed by stress analysis on COMSOL. Further fabrication of all the

parts and assembly is carried out.

Keywords:Hydraulic Scissor, COSMOL, Scissor lif, Hydraulic circuit, sofware CAIA V5.

ABSTRACT


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A pantographis connected in a manner based onparallelograms

so that the movement of one pen, in tracing an image, produces

identical movements in a second pen. If the rst point traces aline drawing, an identical, enlarged, or a pen will draw miniatur-

ized copy xed to the other. Using the same principle, different

kinds of pantographs are used for other forms of duplication inareas such as sculpture, minting, engraving and milling [1-3].

Fig. 1

. WORkINg PRINCIPLE

Because of the shape of the original device, a pantograph alsorefers to a kind of structure that can compress or extend like

an accordion,forming a characteristic rhomboidalpattern. This

can be found in extension arms for wall-mounted mirrors, tem-

porary fences,scissor lifts, and otherscissor mechanismssuch

as thepantographused in electric locomotives and trams [3].

A Scissors lifts provide the most economical, dependable, and

versatile method of lifting heavy loads. Scissors lifts have few

moving parts, are well lubricated, and provide many years of

trouble free operation. These lift tables raise the loads smoothly

to any desired height, and can be easily congured to meetthe specic speed, capacity, and foot print requirement of anyhydraulic lifting application. Each scissors lift is designed and

manufactured to meet the industry safety requirements set forth

in ANSI MH2 9.1, and is by far the most popular and efcient ofall styles of scissors tables used in material handling applications.

Fig. 2

Fig. 3

COMPONENTS OF SCISSOR LIFT

SCISSOR ARMS

PLATFORM

BASE FRAMEPINNED JOINTS

SPACING SHAFT

HYDRAULIC CIRCUIT

1.Scissors arms

Leg deection due to bending is a result of stress, which is drivenby total weight supported by the legs, scissors leg length, and

available leg cross section. The longer the scissors legs are, the

more difcult it is to control bending under load. Increased legstrength via increased leg material height does improve resistance

to deection, but can create a potentially undesirable increasedcollapsed height of the lift.


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2. Platform Structure

Platform bending will increase as the loads center of gravity

moves from the center (evenly distributed) to any edge (eccentri-

cally loaded) of the platform. Also, as the scissors open during

rising of the lift, the rollers roll back towards the platform hinges

and create an increasingly unsupported, overhung portion of the

platform assembly. Eccentric loads applied to this unsupported

end of the platform can greatly impact bending of the platform.

Increased platform strength via increased support structure

material height does improve resistance to deection, but alsocontributes to an increased collapsed height of the lift.

3.Base Frame

Normally, the lifts base frame is mounted to the oor and shouldnot experience deection. For those cases where the scissors liftis mounted to an elevated or portable frame, the base frame must

be rigidly supported from beneath to support the point loading

created by the two scissors leg rollers and the two scissors leghinges.

4.Pinned Joints

Scissors lifts are pinned at all hinge points, and each pin has a

running clearance between the O.D. of the pin and the I.D. of

its clearance hole or bushing. The more scissors pairs, or pan-

tographs, that are stacked on top of each other, the more pinned

connections there are to accumulate movement, or deection,when compressing these designed clearances.

5.Hydraulic Circuit Air Entrapment

All entrapped air must be removed from the hydraulic circuit

through approved bleeding procedures air is very compress-ible and is often the culprit when a scissors lift over-compresses

under load, or otherwise bounces (like a spring) during operation.

6.Hydraulic Circuit Fluid Compressibility

Oil or hydraulic uid will compress slightly under pressure. Andbecause there is an approximate 5:1 ratio of lift travel to cylinder

stroke for most scissors lift designs (with the cylinders mounted

horizontally in the legs), there is a resulting 5:1 ratio of scissors

lift compression to cylinder compression[4].

7.Hydraulic Circuit Hose Swell

All high pressure, exible hosing is susceptible to a degree ofhose swell when the system pressure is increased. System pres-

sure drops slightly because of this increased hose volume, and

the scissors table compresses under load until the maximum

system pressure is reestablished. And, as with compressibility,

the resulting lift movement is 5 times the change in oil column

height in the hose.

8. Cylinder Thrust Resistance

Cylinders lay nearly at inside the scissors legs when the lift isfully lowered and must generate initial horizontal forces up to

10 times the amount of the load on the scissors lift due to the

mechanical disadvantage of their lifting geometry. As a result,

there are tremendous stresses (and resulting deection) placedon the scissors inner leg member(s) that are designed to resist

these cylinder forces. And, as already mentioned above with any

change in column length of the lifting actuator/cylinder, resulting

vertical lift movement is 5 times that amount of change.

9.Load Placements

Load placement also plays a large part in scissors lift deection.Off-centered loads because the scissors lift to deect differentlythan with centered, or evenly distributed, loads. End loads (in-

line with the scissors) are usually shared well between the two

scissors leg pairs. Side loads (perpendicular to the scissors),

however, are not shared well between the scissors leg pairs and

must be kept within acceptable design limits to prevent leg twist

(unequal scissors leg pair deection) which often results inpoor roller tracking, unequal axle pin wear, and misalignment

of cylinder mounts.

10.Lift Elevations during Transfer

As mentioned above, degree of deection is directly related tochange in system pressure and change in component stress as a

result of loading and unloading. Scissors lifts typically experience

their highest system pressure and highest stresses (and therefore

the highest potential for deection) within the rst 20% of totalavailable vertical travel (from the fully lowered position).

. DESIgN ANALYSIS

Design ConsiderationsConsiderations made during the design and fabrication of a port-

able work platform being elevated by two hydraulic cylinders

is as follows:

(a) Functionality of the design

(b) Manufacturability

Economic availability, that is general cost of materials and

fabrication techniques employed.

Design Analysis

1. Cylinder

Bore = 80

Fig. 4: Standards for single acting cylinders.


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Pressure = 315 bar; Material structure steel st-42 hollow tube;

Tensile strength = 42kgf/mm2= 412.02 N/mm2; FOS = 4 [5].

Hoop stress induced can be found by

t = di/2 {st + (1 2)p / st-(1+)p 1} (1)

Outer Diameter = d + 2 to (2)

Where to = stress imparted on the tube. But the standard size is

75; therefore a cylinder of 75 / 50 is used; since the availablesize is 75mm then Thickness t,

t = (D d) (3)

2. Design of Piston Rod

For piston rod material of mild steel EN 8, t = 541.9856 N/ mm2. But the piston rod diameter is rounded off to 32 mm in

order to sustain buckling load. The internal resistance of pistonis given by;

Force F= Area Stress (4)

3. Design of End Cover

Material used Mild steel; Based on strength basis

F = d tc t (5)

The thickness is found by industrial formula

tc = d (3 w / 16 P) (6)

Where w = working stress

4. Piston Head

Piston head diameter is 49.794 49.970 mm the clearance is

given as the piston is used to slide forward and backward. The

piston head length is chosen based on piston seals to fox and

width also no of seals to x.

To check the piston rod for column action

When a structure is subjected to compression it undergoes visibly

large displacements transverse to the load then it is said to

buckle, for small lengths the process is elastic since the bucklingdisplacements disappear when the load is removed. For one end

xed and other end free C = 0.25 Let Fcr = Critical buckling

load; y= yield point; L = length of rod; I = radius of gyration;K = Minimum radius of gyration and is given by

K = I / A (7)

Critical load using Eulers Formula

Fcr= C 2 E / (L / K) 2 (8)

Fcr= 2 E I / 4 L2 (9)

Where the Slenderness ratio, L / K is 73.75,

5. Base

The base structure is built-up of C channels and hollow bars

are usually used in engineering applications due to their high

rigidity, strength as compared to the other bars, the chosen C

channel is ISMC (Indian standard medium weight channel).

The supports and the two cylinders are exibly coupled to the

base there by not transmitting the full load on to the base. The

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