IJAET International Journal of Application of Engineering and Technology

Vol-2 No.-2

ISSN: 2395-3594

DESIGN AND ANALYSIS OF AN EFFICIENT STOVE FORCOOKING AND DRYING OF ERI SILK USINGCOMPUTATIONAL FLUID DYNAMICS (CFD)

A. Sinha1, R. Gupta2 and B. J. Bora3

1Assistant Professor, Mechanical Engg. Deptt, LNCT group of colleges, Gwalior, India,2Director, NIT Srinagar, J&K, India

3Research Scholar, Mechanical Engg. Deptt, IIT Guwahati, Assam, India

E-mail: abhinit05@gmail.com

I. INTRODUCTION

Geographically, Asia is the main producer of silk in theworld and produces over 95 % of the total global output.But, bulk of it is produced in China, India, Japan, Braziland Korea. India is ranked as the second major raw silkproducer in the world. It contributes about 18% to the totalworld raw silk production. Assam produces 90% of the Erisilk produced in India. It is grown in Assam, Meghalaya,Nagaland, Manipur and some small villages in India. Erisilk cocoons contain two types of proteins, namely Fibronand Sericin. Fibron protein helps silk to be drawn into finethread where Sericin is the gummy substance present in theraw silk. In order to remove Sericin, Eri silk cocoons areneeded to be boiled in soda water for 15 to 20 minutes at atemperature 85ºC to 95ºC [1]. Therefore, the dried Eri

cocoons are boiled in soda water in a stainless steel vessel.The boiled Eri cocoons are then washed with water andreeled into fibre. Eri silk are then re-reeled. The re-reeledEri fibre undergoes lancing and skeining operations. Thus,the Eri fibre that is obtained after these operations is woveninto silk fabric with the help of handlooms and powerlooms. The main energy transfer of the whole Eri silkmanufacturing process takes place mainly in the Cookingprocess. But the existing system is a bit crude. Hence,modification of the existing system needs to be done sothat the efficiency can be increased which will in turnlower the cost of production. But before making anymodification, the efficiency of the existing system needs tobe found out. Hence, energy and exergy analysis of thecooking process needs to done to find out the out theefficiency of the existing process.

ABSTRACT

India is the second largest producer of silk in the world after china. The silk produced by Philosamia ricini is calledEri silk. Eri Silk comes from the worm Samia Cynthia ricini, found in North East of India and some parts of Chinaand Japan. However, production of silk in Assam follows an age old process which is energy inefficient. The existingcooking process of silk cocoons consists of boiling of silk cocoons in a stainless steel vessel along with water and sodain an open fireplace. In this paper, a case study was undertaken for energy and exergy analysis using data for 12months of the cooking process involved in the Eri silk production at Assam, a unit under KVIC. From the analysis,the energy and exegetic efficiencies were found to be 18.2% and 3.99%.Therefore,one system is designed for cookingand drying of Eri cocoons simultaneously in a single oven, having square combustion chamber and spherical boilingchamber. The main reason for this type of design is to maximize the utilization of heat carried by the combustiongases. Then, the system is analyzed by using computational fluid dynamics (CFD).

Keywords: - Energy, Exergy, Eri silk, CFD.

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II. DESCRIPTION OF THE PROCESS,

Eri silk is obtained from semi domesticated silk wormcalled Philosamia ricini that feeds on castor leaves. Thecaterpillars are placed on the trees and when they havestripped the tree of foliage, the caterpillar will make a massexit down the trunk. They are collected by the keepers andplaced on another tree. When ready to spin their cocoons,these caterpillars once again exit the tree where they werefeeding. This behavior allows the keepers to collect andcontrol the caterpillars. Each caterpillar is placed into ajail, a container made of dried twigs. The peduncle (silkthat anchors the cocoon) is very weak; the caterpillarsprefer a low place with numerous twigs to protect themwhile in their cocoons. The caterpillars within the Ericocoon are now known as Pupae and after 28 days, mothemerges out of the Eri cocoon. The Eri cocoons are thencollected for Eri silk manufacturing. The Eri silk is calledAhimsa silk because there is no killing of life in form mothto obtain this silk. The matured Eri cocoons are collectedand then are the first dried in the sun and then dried withcombustion gases produced by the burning of firewood atdifferent range of temperatures. Eri silk cocoons containtwo types of proteins, namely Fibron and Sericin. Fibronprotein helps silk to be drawn into fine thread whereSericin is the gummy substance present in the raw silk. Inorder to remove Sericin, Eri silk cocoons are needed to beboiled in soda water. Therefore, the dried Eri cocoons areboiled in soda water in a stainless steel vessel. The boiledEri cocoons are then washed with water and reeled intofibre. Eri silk are then re-reeled. The re-reeled Eri fibreundergoes lancing and skeining operations. Thus, the Erifibre that is obtained after these operations is woven intosilk fabric with the help of handlooms and power looms.

III. FORMULATION OF THE PROBLEM

Figure 1 showing a closed cooking vessel in which silkcocoons are boiled along with water and soda as per thecooking recipe. As the vessel is not insulated, someamount is lost to the surrounding. Thus, the efficiency interms of heat gained by the Products is given by:

η = (1)

The control volume exergy rate balance for a system isgiven by:

= ∑ (1 − ) ̇ - ( ̇ - ) + ∑ ̇ - ∑ ̇- ̇ (2)

Where

= rate of exergy change

Fig. 1 showing the energy transfer of the system

∑ (1 − ) ̇ = exergy transfer rate due to heat transfer

( ̇ - ) = exergy transfer rate due to time rate change

of volume∑ ̇ - ∑ ̇ = change of rate of exergy transfer

accompanying mass flow and flow work between inlet and

exit.̇ = rate of exergy destruction

The control volume exergy rate balance for the cookingprocess of the silk manufacturing process is given by

= [(1- ) ̇ -(1- ) ̇ -(1- ) ̇ ]-[ ̇ - ] -̇ (3)

Assuming that the system operates at steady state and thereis no work, the system exergy balance reduces to:

(1- ) ̇ = (1- ) ̇ + (1- ) ̇ + ̇ (4)

As =0, [ ̇ - ] =0

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II. DESCRIPTION OF THE PROCESS,

Eri silk is obtained from semi domesticated silk wormcalled Philosamia ricini that feeds on castor leaves. Thecaterpillars are placed on the trees and when they havestripped the tree of foliage, the caterpillar will make a massexit down the trunk. They are collected by the keepers andplaced on another tree. When ready to spin their cocoons,these caterpillars once again exit the tree where they werefeeding. This behavior allows the keepers to collect andcontrol the caterpillars. Each caterpillar is placed into ajail, a container made of dried twigs. The peduncle (silkthat anchors the cocoon) is very weak; the caterpillarsprefer a low place with numerous twigs to protect themwhile in their cocoons. The caterpillars within the Ericocoon are now known as Pupae and after 28 days, mothemerges out of the Eri cocoon. The Eri cocoons are thencollected for Eri silk manufacturing. The Eri silk is calledAhimsa silk because there is no killing of life in form mothto obtain this silk. The matured Eri cocoons are collectedand then are the first dried in the sun and then dried withcombustion gases produced by the burning of firewood atdifferent range of temperatures. Eri silk cocoons containtwo types of proteins, namely Fibron and Sericin. Fibronprotein helps silk to be drawn into fine thread whereSericin is the gummy substance present in the raw silk. Inorder to remove Sericin, Eri silk cocoons are needed to beboiled in soda water. Therefore, the dried Eri cocoons areboiled in soda water in a stainless steel vessel. The boiledEri cocoons are then washed with water and reeled intofibre. Eri silk are then re-reeled. The re-reeled Eri fibreundergoes lancing and skeining operations. Thus, the Erifibre that is obtained after these operations is woven intosilk fabric with the help of handlooms and power looms.

III. FORMULATION OF THE PROBLEM

Figure 1 showing a closed cooking vessel in which silkcocoons are boiled along with water and soda as per thecooking recipe. As the vessel is not insulated, someamount is lost to the surrounding. Thus, the efficiency interms of heat gained by the Products is given by:

η = (1)

The control volume exergy rate balance for a system isgiven by:

= ∑ (1 − ) ̇ - ( ̇ - ) + ∑ ̇ - ∑ ̇- ̇ (2)

Where

= rate of exergy change

Fig. 1 showing the energy transfer of the system

∑ (1 − ) ̇ = exergy transfer rate due to heat transfer

( ̇ - ) = exergy transfer rate due to time rate change

of volume∑ ̇ - ∑ ̇ = change of rate of exergy transfer

accompanying mass flow and flow work between inlet and

exit.̇ = rate of exergy destruction

The control volume exergy rate balance for the cookingprocess of the silk manufacturing process is given by

= [(1- ) ̇ -(1- ) ̇ -(1- ) ̇ ]-[ ̇ - ] -̇ (3)

Assuming that the system operates at steady state and thereis no work, the system exergy balance reduces to:

(1- ) ̇ = (1- ) ̇ + (1- ) ̇ + ̇ (4)

As =0, [ ̇ - ] =0

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II. DESCRIPTION OF THE PROCESS,

Eri silk is obtained from semi domesticated silk wormcalled Philosamia ricini that feeds on castor leaves. Thecaterpillars are placed on the trees and when they havestripped the tree of foliage, the caterpillar will make a massexit down the trunk. They are collected by the keepers andplaced on another tree. When ready to spin their cocoons,these caterpillars once again exit the tree where they werefeeding. This behavior allows the keepers to collect andcontrol the caterpillars. Each caterpillar is placed into ajail, a container made of dried twigs. The peduncle (silkthat anchors the cocoon) is very weak; the caterpillarsprefer a low place with numerous twigs to protect themwhile in their cocoons. The caterpillars within the Ericocoon are now known as Pupae and after 28 days, mothemerges out of the Eri cocoon. The Eri cocoons are thencollected for Eri silk manufacturing. The Eri silk is calledAhimsa silk because there is no killing of life in form mothto obtain this silk. The matured Eri cocoons are collectedand then are the first dried in the sun and then dried withcombustion gases produced by the burning of firewood atdifferent range of temperatures. Eri silk cocoons containtwo types of proteins, namely Fibron and Sericin. Fibronprotein helps silk to be drawn into fine thread whereSericin is the gummy substance present in the raw silk. Inorder to remove Sericin, Eri silk cocoons are needed to beboiled in soda water. Therefore, the dried Eri cocoons areboiled in soda water in a stainless steel vessel. The boiledEri cocoons are then washed with water and reeled intofibre. Eri silk are then re-reeled. The re-reeled Eri fibreundergoes lancing and skeining operations. Thus, the Erifibre that is obtained after these operations is woven intosilk fabric with the help of handlooms and power looms.

III. FORMULATION OF THE PROBLEM

Figure 1 showing a closed cooking vessel in which silkcocoons are boiled along with water and soda as per thecooking recipe. As the vessel is not insulated, someamount is lost to the surrounding. Thus, the efficiency interms of heat gained by the Products is given by:

η = (1)

The control volume exergy rate balance for a system isgiven by:

= ∑ (1 − ) ̇ - ( ̇ - ) + ∑ ̇ - ∑ ̇- ̇ (2)

Where

= rate of exergy change

Fig. 1 showing the energy transfer of the system

∑ (1 − ) ̇ = exergy transfer rate due to heat transfer

( ̇ - ) = exergy transfer rate due to time rate change

of volume∑ ̇ - ∑ ̇ = change of rate of exergy transfer

accompanying mass flow and flow work between inlet and

exit.̇ = rate of exergy destruction

The control volume exergy rate balance for the cookingprocess of the silk manufacturing process is given by

= [(1- ) ̇ -(1- ) ̇ -(1- ) ̇ ]-[ ̇ - ] -̇ (3)

Assuming that the system operates at steady state and thereis no work, the system exergy balance reduces to:

(1- ) ̇ = (1- ) ̇ + (1- ) ̇ + ̇ (4)

As =0, [ ̇ - ] =0

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Equation (4) shows that the exergy carried into the systemaccompanying the heat is either transferred from thesystem accompanying the heat transfers and or destroyedby irreversibilities within the system [2,3]. This can bedescribed by efficiency in the form product/ input as:

ε =( ) ̇( ) ̇

=( )( ) η (5)

Heat gained by silk cocoons is given by:

= × × ( ̵ ) (6)

Heat gained by Soda is given by:

= × × ( ̵ ) (7)

Heat gained by Water is given by:

= × ×( ̵ ) (8)

Total heat gained by the silk cocoons and alkaline water:

= + + (9)

Total heat produced due to combustion the fuel is given by:

= × CV (10)

DATA COLLECTION

The data is collected from Dakshin Kamrup SamagraVikash Parishad, an Eri silk production unit under KVIC,located at Bijoynagar, Kamrup in Assam for the year:2009-2010.

FOR THE YEAR: 2009-2010

Table 1 showing the data for Eri cocoons

Serial No. Parameter Quantity

1Mass of Eri silk

cocoons7085950 kg

2 Mass of Soda used 58550 kg

3Mass of Fuel (wood)

burnt5925720 kg

4Mass of water used

for cooking of Eri silkcocoons

64835500 kg

Table 2 showing the value taken from heat and mass transfer handbook[4]

Serial No. Parameter Quantity1 1.38 kJ/kg.K2 1.45 kJ/kg.K3 4.131 kJ/kg.K4 C.V 18MJ/kg5 298K6 368K7 2253K

IV. RESULTS & DISCUSSION

Using the value from Table 1 and Table 2 in Eq. (1) andEq. (5), we get:

η=18.2%ε =3.99%

Thus, the energy and exegetic efficiencies are found out as18.2% and 3.99% respectively. From the above analysis, itcan be concluded that the present cooking system is not atall energy efficient. Thus, there is a need for a modifiedsystem which will be energy efficient than the existingsystem so that the cost of silk production can be decreased.As the system is not energetically efficient, more fuel isneeds to be burn which in turn increases the cost ofproduction of Eri Silk. Hence, a more efficient system forthe cooking of Eri cocoons in Eri silk manufacturingprocess needs to be found out.

MODIFIED SYSTEM

A modified system is designed which comprises of afurnace, cooking vessel heating chamber and silk cocoonsheating chamber [Fig. 2]. A modified system having squarecombustion chamber of 12cm×12cm, cooking vessel of22cm diameter and 15cm height and cocoon heatingchamber of size 20cm×20cm is used for computationalfluid dynamics analysis using fluent software. Thecombustion chamber is square. All the parts of themodified system exposed to the ambient should be wellinsulated. In the cooking vessel heating chamber, silkcocoons are cooked in a cooking vessel where as in the silkcocoons heating chamber, silk cocoons are dried by usinghot combustion gases .To maximize heat transfer to thecooking vessel, the hot combustion gases formed due tocombustion of the fuel is passed through a narrow gapbetween cooking vessel and the chamber enclosing thecooking vessel. As the hot gases pass through the narrow

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gap, its velocity increases. The high velocity hotcombustion gases heats up the cooking vessel faster due tofriction between the cooking vessel and hot combustiongases [5], the combustion gases coming out from chamberenclosing the cooking vessel are then passed throughanother chamber called Cocoon heating chamber used fordrying of the silk cocoons. In the existing system, theheating process of the silk cocoons and cooking processare done separately where in the modified system bothheating process and the cooking process of the Eri silkcocoons can be done simultaneously.

Fig. 2 Showing the design of the modified system. All dimensions are incentimeters

COMPUTATIONAL FLUID DYNAMICS ANALYSISOF THE MODIFIED SYSTEM

The modified system is modeled in the pre-processorGambit 2.3.16 and then analyzed in Fluent 6.3.16.Steadyand k–є model is taken and for carrying out combustion,UDF file is created using injection system in fluentsoftware.

Table 3 Boundary conditions

parameters ValueVelocity of air 1m/s

Velocity of wood 0.5m/sSize of the wood 0.1mWall thickness 0.01m

Fig. 3 showing the view of the modified systemhaving square combustion chamber in gambit

Figure 4 Grid inpendence test for the modified systemhaving square combustion chamber

Fig. 5 Showing the contours of temperature for a modified system havinga square chamber furnace

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gap, its velocity increases. The high velocity hotcombustion gases heats up the cooking vessel faster due tofriction between the cooking vessel and hot combustiongases [5], the combustion gases coming out from chamberenclosing the cooking vessel are then passed throughanother chamber called Cocoon heating chamber used fordrying of the silk cocoons. In the existing system, theheating process of the silk cocoons and cooking processare done separately where in the modified system bothheating process and the cooking process of the Eri silkcocoons can be done simultaneously.

Fig. 2 Showing the design of the modified system. All dimensions are incentimeters

COMPUTATIONAL FLUID DYNAMICS ANALYSISOF THE MODIFIED SYSTEM

The modified system is modeled in the pre-processorGambit 2.3.16 and then analyzed in Fluent 6.3.16.Steadyand k–є model is taken and for carrying out combustion,UDF file is created using injection system in fluentsoftware.

Table 3 Boundary conditions

parameters ValueVelocity of air 1m/s

Velocity of wood 0.5m/sSize of the wood 0.1mWall thickness 0.01m

Fig. 3 showing the view of the modified systemhaving square combustion chamber in gambit

Figure 4 Grid inpendence test for the modified systemhaving square combustion chamber

Fig. 5 Showing the contours of temperature for a modified system havinga square chamber furnace

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gap, its velocity increases. The high velocity hotcombustion gases heats up the cooking vessel faster due tofriction between the cooking vessel and hot combustiongases [5], the combustion gases coming out from chamberenclosing the cooking vessel are then passed throughanother chamber called Cocoon heating chamber used fordrying of the silk cocoons. In the existing system, theheating process of the silk cocoons and cooking processare done separately where in the modified system bothheating process and the cooking process of the Eri silkcocoons can be done simultaneously.

Fig. 2 Showing the design of the modified system. All dimensions are incentimeters

COMPUTATIONAL FLUID DYNAMICS ANALYSISOF THE MODIFIED SYSTEM

The modified system is modeled in the pre-processorGambit 2.3.16 and then analyzed in Fluent 6.3.16.Steadyand k–є model is taken and for carrying out combustion,UDF file is created using injection system in fluentsoftware.

Table 3 Boundary conditions

parameters ValueVelocity of air 1m/s

Velocity of wood 0.5m/sSize of the wood 0.1mWall thickness 0.01m

Fig. 3 showing the view of the modified systemhaving square combustion chamber in gambit

Figure 4 Grid inpendence test for the modified systemhaving square combustion chamber

Fig. 5 Showing the contours of temperature for a modified system havinga square chamber furnace

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Fig. 7 showing the temperature distribution plot

From the above analysis following conclusions are drawn:

(a) In case of the modified system, the surroundingtemperature around the cooking vessel (580K) is more thanambient temperature (300K). Therefore, losses will be lessas compared to the existing system whose surroundingtemperature is ambient.

(b) Result shows that velocity of combustion gases 19.2m/s. This means that the fluid friction will be more in caseof new system having square combustion chamber. Thefast combustion gases punch through a boundary layer ofstill air that keeps slower moving gases from scrappingagainst the surface of the pot.

(c) The velocity (19.2m/s) and temperature (759K) of thecombustion gases are sufficiently high to be used for thedrying process of the Eri silk cocoons.

Thus, it can be concluded that the new system is moreenergy efficient than existing system and if this system isused in silk production, it will surely lower the cost ofproduction of silk.

ACKNOWLEDGEMENT

The authors sincerely acknowledge the support renderedby Directorate of Science and Technology, Khadi &Village Industries Commission (KVIC), Mumbai andKVIC, Bijoynagar, Guwahati for carrying out this project

NOMENCLATURE=initial temperature of the product=

η=Efficiency of the processε= Exergetic efficiency of the process=Mass of silk cocoons=Mass of soda=Mass of the water=Mass of the fuel (Wood)C.V=Calorific value of the fuel

=Specific of the silk=Specific heat of soda

Specific heat of water=Heat lost to the surrounding=Heat gained by the product (i.e.

Eri cocoons)=Heat supplied by the fuel=Temperature of the

Ambient=Temperature of the product= Temperature of the source

REFERENCES

[1] Directorate of Sericulture, Sericulture Manual-StandardOperating Manual, Assam, pp. 1-93, 2005.

[2] Moran & Shapiro, Fundamental of EngineeringThermodynamics, John Willey & Sons, Inc, New York, pp.346-347, 2000.

[3] B.Mudgal, Rakesh Roshen, Upendra parashar, “CFD Analysisof temperature dissipation from a hollow metallic pipe throughcircular fins using Ansys 14.5”, International Journal ofApplication of Engineering and Technology, Dec. 2014, Vol.-1 No.-2, Pg.-54-61.

[4] Nag, Basic and Applied Thermodynamics, Tata McGraw-HillPublishing Company Limited, New Delhi, pp. 243-245, 2008.

[5] Kothandaraman and Subramanyan, .Heat and Mass transferData Book, New Age International Limited Publishers, NewDelhi, pp. 1-190, 1995.

[6] Bryden et al., Design Principles for Wood Burning CookStoves, Aprovecho Research Center Shell Foundation, U.S.A,pp. 1-40.

Fig. 6 Showing the contours of wall temperature for the modifiedsystem having square combustion chamber

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Fig. 7 showing the temperature distribution plot

From the above analysis following conclusions are drawn:

(a) In case of the modified system, the surroundingtemperature around the cooking vessel (580K) is more thanambient temperature (300K). Therefore, losses will be lessas compared to the existing system whose surroundingtemperature is ambient.

(b) Result shows that velocity of combustion gases 19.2m/s. This means that the fluid friction will be more in caseof new system having square combustion chamber. Thefast combustion gases punch through a boundary layer ofstill air that keeps slower moving gases from scrappingagainst the surface of the pot.

(c) The velocity (19.2m/s) and temperature (759K) of thecombustion gases are sufficiently high to be used for thedrying process of the Eri silk cocoons.

Thus, it can be concluded that the new system is moreenergy efficient than existing system and if this system isused in silk production, it will surely lower the cost ofproduction of silk.

ACKNOWLEDGEMENT

The authors sincerely acknowledge the support renderedby Directorate of Science and Technology, Khadi &Village Industries Commission (KVIC), Mumbai andKVIC, Bijoynagar, Guwahati for carrying out this project

NOMENCLATURE=initial temperature of the product=

η=Efficiency of the processε= Exergetic efficiency of the process=Mass of silk cocoons=Mass of soda=Mass of the water=Mass of the fuel (Wood)C.V=Calorific value of the fuel

=Specific of the silk=Specific heat of soda

Specific heat of water=Heat lost to the surrounding=Heat gained by the product (i.e.

Eri cocoons)=Heat supplied by the fuel=Temperature of the

Ambient=Temperature of the product= Temperature of the source

REFERENCES

[1] Directorate of Sericulture, Sericulture Manual-StandardOperating Manual, Assam, pp. 1-93, 2005.

[2] Moran & Shapiro, Fundamental of EngineeringThermodynamics, John Willey & Sons, Inc, New York, pp.346-347, 2000.

[3] B.Mudgal, Rakesh Roshen, Upendra parashar, “CFD Analysisof temperature dissipation from a hollow metallic pipe throughcircular fins using Ansys 14.5”, International Journal ofApplication of Engineering and Technology, Dec. 2014, Vol.-1 No.-2, Pg.-54-61.

[4] Nag, Basic and Applied Thermodynamics, Tata McGraw-HillPublishing Company Limited, New Delhi, pp. 243-245, 2008.

[5] Kothandaraman and Subramanyan, .Heat and Mass transferData Book, New Age International Limited Publishers, NewDelhi, pp. 1-190, 1995.

[6] Bryden et al., Design Principles for Wood Burning CookStoves, Aprovecho Research Center Shell Foundation, U.S.A,pp. 1-40.

Fig. 6 Showing the contours of wall temperature for the modifiedsystem having square combustion chamber

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Fig. 7 showing the temperature distribution plot

From the above analysis following conclusions are drawn:

(a) In case of the modified system, the surroundingtemperature around the cooking vessel (580K) is more thanambient temperature (300K). Therefore, losses will be lessas compared to the existing system whose surroundingtemperature is ambient.

(b) Result shows that velocity of combustion gases 19.2m/s. This means that the fluid friction will be more in caseof new system having square combustion chamber. Thefast combustion gases punch through a boundary layer ofstill air that keeps slower moving gases from scrappingagainst the surface of the pot.

(c) The velocity (19.2m/s) and temperature (759K) of thecombustion gases are sufficiently high to be used for thedrying process of the Eri silk cocoons.

Thus, it can be concluded that the new system is moreenergy efficient than existing system and if this system isused in silk production, it will surely lower the cost ofproduction of silk.

ACKNOWLEDGEMENT

The authors sincerely acknowledge the support renderedby Directorate of Science and Technology, Khadi &Village Industries Commission (KVIC), Mumbai andKVIC, Bijoynagar, Guwahati for carrying out this project

NOMENCLATURE=initial temperature of the product=

η=Efficiency of the processε= Exergetic efficiency of the process=Mass of silk cocoons=Mass of soda=Mass of the water=Mass of the fuel (Wood)C.V=Calorific value of the fuel

=Specific of the silk=Specific heat of soda

Specific heat of water=Heat lost to the surrounding=Heat gained by the product (i.e.

Eri cocoons)=Heat supplied by the fuel=Temperature of the

Ambient=Temperature of the product= Temperature of the source

REFERENCES

[1] Directorate of Sericulture, Sericulture Manual-StandardOperating Manual, Assam, pp. 1-93, 2005.

[2] Moran & Shapiro, Fundamental of EngineeringThermodynamics, John Willey & Sons, Inc, New York, pp.346-347, 2000.

[3] B.Mudgal, Rakesh Roshen, Upendra parashar, “CFD Analysisof temperature dissipation from a hollow metallic pipe throughcircular fins using Ansys 14.5”, International Journal ofApplication of Engineering and Technology, Dec. 2014, Vol.-1 No.-2, Pg.-54-61.

[4] Nag, Basic and Applied Thermodynamics, Tata McGraw-HillPublishing Company Limited, New Delhi, pp. 243-245, 2008.

[5] Kothandaraman and Subramanyan, .Heat and Mass transferData Book, New Age International Limited Publishers, NewDelhi, pp. 1-190, 1995.

[6] Bryden et al., Design Principles for Wood Burning CookStoves, Aprovecho Research Center Shell Foundation, U.S.A,pp. 1-40.

Fig. 6 Showing the contours of wall temperature for the modifiedsystem having square combustion chamber

172