- Email: [email protected]
Drying of copra in a forced convection solar drier
ARTICLE IN PRESS BIOSYSTEMS ENGINEERING
99 (2008) 604 – 607
Available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/issn/15375110
Research Note: PH—Postharvest Technology
Drying of copra in a forced convection solar drier M. Mohanraj, P. Chandrasekar Mechanical Engineering Department, Dr. Mahalingam College of Engineering and Technology, Pollachi-642003, India
ar t ic l e i n f o
A forced convection solar drier was designed, fabricated and tested for the drying copra under Indian climatic conditions. Drying copra in the drier reduced its moisture content
Article history:
from about 51.8% to 7.8% and 9.7% in 82 h for trays at the bottom and top, respectively. The
Received 22 June 2007
copra obtained was graded as 76% milling grade copra (MCG1), 18% (MCG2) and 6% (MCG3)
Received in revised form
according to Bureau of Indian standards (BIS: 6220-1971). The thermal efficiency of the solar
13 December 2007
drier was estimated to be about 24%.
Accepted 19 December 2007
& 2008 IAgrE. Published by Elsevier Ltd. All rights reserved.
Available online 12 February 2008
1.
Introduction
India ranks as the third largest coconut-producing country in the world. It annually produces 14.37 billion nuts (Singh & Remany, 2002). Copra is one of the major traditional products processed from coconuts. Fresh coconut contains a moisture content of about 52% (wet basis), which should be reduced down to about 7% by drying in order to concentrate the oil content. On an average, 5–7 coconuts are required to produce 1 kg of copra, although this depends on the source. The traditional methods followed in India are sun and kiln drying. They produce poor-quality copra and are time consuming. With kiln drying, smoke is in direct contact with the coconut cups. As a result, high-quality copra is not produced and smoke deposits may form polycyclic aromatic hydrocarbons in the copra (Thiruchelvam et al., 2007). Sun drying takes about 7 days and if the weather is rainy the copra produced will be contaminated with fungi which produce a grey rancid product. Furthermore sun drying requires more space, is labour intensive and there can be deteriorations in quality from deposits of dirt and dust. Also, microorganisms can increase the acid content, cause rancidity and reduce the amount of extractable oil resulting in
low-quality coconut oil. The oil extracted from poor-quality copra also requires additional refinement to meet international standards. Several experimental and theoretical studies have been reported on the development of various types of solar driers for drying agricultural products (e.g. Kadam & Samuel, 2006; Shanmugam & Natarajan, 2006; Ivanova and Andonov, 2001). The main objective of the present work was to study the drying characteristics and quality of copra produced in a forced convection solar drier so that it could be recommended to farmers for high-quality copra production.
2.
Material and methods
The experiments were carried out at the coconut farm in Pollachi, India, from January to April 2007.
2.1.
Forced convection solar drier
A schematic diagram of a forced convection solar drier is shown in Fig. 1(a) and a cross-sectional view of a solar air heater in Fig. 1(b). The solar drier consisted of a flat plate solar air heater of area 2 m2 (2 m 1 m) connected to a drying
Corresponding author. Tel.: +91 9486411896; fax: +91 4259 236070
E-mail address: [email protected] (M. Mohanraj). 1537-5110/$ - see front matter & 2008 IAgrE. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.biosystemseng.2007.12.004
ARTICLE IN PRESS BIOSYSTEMS ENGINEERING
605
99 (2008) 604– 607
Humid air Exit
0.4m
Glass wool insulation
Ambient Dry and wet bulb temperature
0.6m Loading
Copra V
Velocity of air at tray entry Wet bulb temperature Dry bulb temperature
Door 1.5m
Drying chamber
Trays Solar air heater A Absorber plate
V
Sand Glass cover Control valve
1m
A1
Orificemeter
Blower
Insulation
50 100
5
25
Manometer
1000
All dimensions are in mm Fig. 1 – (a) Schematic view of the solar drier used for copra drying. (b) Sectional view A–A1 of a solar air heater.
chamber. The solar air heater had a 2 mm thick copper absorber plate coated with black paint to absorb the incident solar radiation. The absorber plate was placed directly behind the transparent cover (glass) with a layer of air separating it from the cover. The air to be heated passed between the transparent cover (glass) and the absorber plate. To reduce the losses from topside of the absorber plate and to increase the temperature of air using the greenhouse effect, a 5 mm thick glass cover was placed over the absorber. The gap between the glass and the absorber surface was maintained at 25 mm for air circulation. One side of the collector was connected to a 0.75 kW (1 HP) centrifugal fan with an airflow rate up to 300 m3 h1 and the other side with a drying chamber. A divergent section was provided at the entry of the solar air heater to provide uniform air circulation over the absorber surface. The 100 mm gap between the absorber and the insulation was filled with sand to store heat. The drying chamber was made up of a 2 mm thick mild steel sheet with a width, depth and height of 1 m 1 m 1.5 m, respectively. The drying chamber was insulated with 10 mm thick glass wool. The solar air heater was tilted to an angle about 251 with respect to the horizontal, which is considered to be an optimum angle for year-round performance of the system at Pollachi (Shariah et al., 2002). The system was oriented to face the south to maximise the incident solar radiation on the solar collector. On the basis of measurements, Pollachi
(latitude of 10.391N, longitude of 77.031E), where the experiment was conducted, had about 11 h 30 min of daylight, with typically about 8 h per day of sunshine available for drying. Four calibrated thermocouples (Pt 100) with70.25 1C accuracy were fixed at different locations (as shown in Fig. 1) of the solar drier to measure the temperature of drying air through a digital scanner having a 0.1 1C resolution connected with a rotary selector switch. Power input to the blower was measured with an energy meter having 70.4% accuracy. A U-tube manometer was fixed in the path of the air circuit to measure the velocity of air entering the drier. The velocity of air at the inlet of the tray was measured with the help of a vane-type anemometer having70.01 m/s accuracy. Solar intensity was measured using a solar intensity meter having an accuracy of about 72%. A digital electronic balance of 1 kg capacity having an accuracy of 70.001 g was used to weigh the samples. The humidity of the ambient air was measured using standard non-aspirated wet and dry bulb mercury thermometers with sensitivities of 0.5 1C.
2.2.
Experimental procedure
Broken coconuts were loaded over the trays of a drier chamber. For hot air circulation over the products to be dried, the wire mesh trays had a porosity of about 90% . Then the fan was switched on and the air velocity adjusted to an
ARTICLE IN PRESS
2.3.
Data analysis
The quantity of moisture content in a material can be represented on a wet basis and expressed in percentage. About 10 g samples were chopped from randomly selected five cups and kept in a convective electrical oven, which was maintained at 10571 1C for 4 h. The initial (Wi) and final (Wf) mass of the samples was recorded with the help of an electronic balance. The moisture content (Mwb) on a wet basis was calculated by Mwb
ðWi Wf Þ ¼ 100. Wi
(1)
1200
600 400 200
Fig. 2 – Variation of solar intensity and ambient relative humidity.
70 60 50 40 30 20
Tda Tamb
10 0 0
8
16
24
32 40 48 56 Drying time (h)
64
72
80
(2)
where cp is the specific heat of air in J kg1 K, ma is the mass flow rate of air in kg s1; Ta is the ambient temperature and To is the outlet air temperature. A is the surface area of the solar collector in m2 and I is the solar intensity in W m2.
3.
800
0 6 12 18 24 30 36 42 48 54 60 66 72 78 Drying time (h)
Results and discussion
The variation of solar radiation and ambient relative humidity during experimentation is shown in Fig. 2. A maximum solar intensity of 932 W m2 was observed. The ambient relative humidity varied between 55% and 72% with an average of about 68% . Temperature variations of the drying air and ambient are shown in Fig. 3. The average drying air temperature recorded at the inlet of the drier was 43 1C. The maximum drying air temperature recorded during peak sunshine hours was 63 1C. The average temperature reduced to 31 1C outside the hours of sunshine and during the night. At the outlet of the drying chamber, a high relative humidity of about 90% was recorded during the initial stages of drying but this gradually reduced to about 34% at the end of drying. The variation of moisture content (wet basis) with drying time is shown in Fig. 4. The average moisture content of the coconut was reduced from about 51.8% to 7.8% and 9.7% in the bottom and the top tray, respectively, after 82 h. The moisture reduction during the first and the second day of drying was found to be about 33% and 20%, respectively. The higher
Fig. 3 – Variation of ambient and drying air temperature as a function of drying time.
Moisture content (wet basis) (%)
cp ma ðTo Ta Þ 100 AS I
1000
0
The instantaneous thermal efficiency of the solar air heater was estimated by using Eq. (2) according to (Kadam & Samuel, 2006) Zth ¼
100 90 80 70 60 50 40 30 20 10 0
Solar intensity Ambient relative humudity
Relative humudity (%)
optimum of 1.2 m/s at the tray inlet. The velocity of the air at the tray was adjusted by using a control valve. During the experiments, temperatures at various locations in the solar collector and the drier chamber, ambient dry and wet bulb temperatures were measured at hourly intervals. The relative humidity of air was calculated from measured wet and dry bulb temperatures using a psychometric chart. After the moisture content was reduced to 40%, the copra kernels were scooped from the shells and dried further without shells. Moisture contents were determined by using Eq. (1). To assure the quality of copra obtained, three experiments were carried out. At the end of each experiment, the dried copra was graded according to Bureau of Indian standards (BIS: 6220-1971). The average grade value is presented. Experiments were only conducted during daylight hours.
99 (2008) 604 – 607
Solar radiation (W m-2)
BIOSYSTEMS ENGINEERING
Temperature (°C)
606
60 50
Top Bottom
40 30 20 10 0 0
8
16
24
32 40 48 56 Drying time (h)
64
72
80
Fig. 4 – Variation of moisture content as a function of drying time.
moisture reduction during the first day was observed because of the evaporation of free moisture migrating from the outer surface layers. This then reduced due to the internal migration of moisture from inner layers to the surface producing a uniform dehydration of wet kernel. Typically, 10 h a day of drying occurred during sunshine. Without
ARTICLE IN PRESS BIOSYSTEMS ENGINEERING
sunshine desorption of moisture took place and the moisture content increased by about 0.5–1.5%. The reduction in the moisture content of copra at the bottom tray was about 5–8% higher than that of the top tray. A high drying rate at a rate of 4.2 g of water/g of dry matter was observed during the initial stage of drying. The drying rate decreased with an increase in the drying time. Drying occurs in the falling rate period with a steep fall in the moisture content in the initial stages of drying which becomes very slow in the later stages. The drying rate of copra in the solar dryer was high compared to sun drying due to its high heat and mass transfer coefficients. About 50 kg of moisture was removed from 300 nuts to obtain about 60 kg of copra. The initial weight of 300 nuts with shells was measured to be about 160 kg. The thermal efficiency of the solar air heater was estimated to be about 24% by using Eq. (2). About 60 kg of copra was produced from 300 nuts. The copra obtained was graded as 76% MCG1, 18% MCG2 and 6% MCG3. Based on the grading of copra, it could be concluded that more than 75% of high-quality MCG1 could be produced in the solar drier. Unlike with kiln and sun drying, the copra obtained was free from smoke, dust, bird and rodent damage.
4.
Conclusion
A forced convection solar drier was designed, fabricated and tested for drying copra. It can be concluded that a
99 (2008) 604– 607
607
forced convection solar drier is more suitable for producing high-quality copra for small holders. About 75% of high-quality copra (MCG1) could be produced. The average thermal efficiency of the solar air heater was estimated to be about 24%. R E F E R E N C E S
Shariah A; Al-Akhras M -A; Al-Omari I A (2002). Optimizing the tilt angle of solar collectors. Renewable Energy, 26, 587–598 Ivanova D; Andonov K (2001). Analytical and experimental study of combined fruit and vegetable dryer. Energy Conversion and Management, 42, 975–983 Kadam D M; Samuel D V K (2006). Convective flat plate solar heat collector for cauliflower drying. Biosystems Engineering, 93, 189–198 Thiruchelvam T; Nimal D A D; Upali S (2007). Comparison of quality and yield of copra processed in CRI improved kiln drying and sun drying. Journal of Food Engineering, 78, 1446–1451 Shanmugam V; Natarajan E (2006). Experimental investigation of forced convection and desiccant integrated solar dryer. Renewable energy, 31, 1239–1251 Singh H P; Remany G (2002). Approaches for increasing the farm income through product diversification and product utilization. In: Sustainable Products and Utilization of Coconut (Singh HP; Mathew MT, eds), pp 1–11. Coconut Development Board, Kochi
99 (2008) 604 – 607
Available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/issn/15375110
Research Note: PH—Postharvest Technology
Drying of copra in a forced convection solar drier M. Mohanraj, P. Chandrasekar Mechanical Engineering Department, Dr. Mahalingam College of Engineering and Technology, Pollachi-642003, India
ar t ic l e i n f o
A forced convection solar drier was designed, fabricated and tested for the drying copra under Indian climatic conditions. Drying copra in the drier reduced its moisture content
Article history:
from about 51.8% to 7.8% and 9.7% in 82 h for trays at the bottom and top, respectively. The
Received 22 June 2007
copra obtained was graded as 76% milling grade copra (MCG1), 18% (MCG2) and 6% (MCG3)
Received in revised form
according to Bureau of Indian standards (BIS: 6220-1971). The thermal efficiency of the solar
13 December 2007
drier was estimated to be about 24%.
Accepted 19 December 2007
& 2008 IAgrE. Published by Elsevier Ltd. All rights reserved.
Available online 12 February 2008
1.
Introduction
India ranks as the third largest coconut-producing country in the world. It annually produces 14.37 billion nuts (Singh & Remany, 2002). Copra is one of the major traditional products processed from coconuts. Fresh coconut contains a moisture content of about 52% (wet basis), which should be reduced down to about 7% by drying in order to concentrate the oil content. On an average, 5–7 coconuts are required to produce 1 kg of copra, although this depends on the source. The traditional methods followed in India are sun and kiln drying. They produce poor-quality copra and are time consuming. With kiln drying, smoke is in direct contact with the coconut cups. As a result, high-quality copra is not produced and smoke deposits may form polycyclic aromatic hydrocarbons in the copra (Thiruchelvam et al., 2007). Sun drying takes about 7 days and if the weather is rainy the copra produced will be contaminated with fungi which produce a grey rancid product. Furthermore sun drying requires more space, is labour intensive and there can be deteriorations in quality from deposits of dirt and dust. Also, microorganisms can increase the acid content, cause rancidity and reduce the amount of extractable oil resulting in
low-quality coconut oil. The oil extracted from poor-quality copra also requires additional refinement to meet international standards. Several experimental and theoretical studies have been reported on the development of various types of solar driers for drying agricultural products (e.g. Kadam & Samuel, 2006; Shanmugam & Natarajan, 2006; Ivanova and Andonov, 2001). The main objective of the present work was to study the drying characteristics and quality of copra produced in a forced convection solar drier so that it could be recommended to farmers for high-quality copra production.
2.
Material and methods
The experiments were carried out at the coconut farm in Pollachi, India, from January to April 2007.
2.1.
Forced convection solar drier
A schematic diagram of a forced convection solar drier is shown in Fig. 1(a) and a cross-sectional view of a solar air heater in Fig. 1(b). The solar drier consisted of a flat plate solar air heater of area 2 m2 (2 m 1 m) connected to a drying
Corresponding author. Tel.: +91 9486411896; fax: +91 4259 236070
E-mail address: [email protected] (M. Mohanraj). 1537-5110/$ - see front matter & 2008 IAgrE. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.biosystemseng.2007.12.004
ARTICLE IN PRESS BIOSYSTEMS ENGINEERING
605
99 (2008) 604– 607
Humid air Exit
0.4m
Glass wool insulation
Ambient Dry and wet bulb temperature
0.6m Loading
Copra V
Velocity of air at tray entry Wet bulb temperature Dry bulb temperature
Door 1.5m
Drying chamber
Trays Solar air heater A Absorber plate
V
Sand Glass cover Control valve
1m
A1
Orificemeter
Blower
Insulation
50 100
5
25
Manometer
1000
All dimensions are in mm Fig. 1 – (a) Schematic view of the solar drier used for copra drying. (b) Sectional view A–A1 of a solar air heater.
chamber. The solar air heater had a 2 mm thick copper absorber plate coated with black paint to absorb the incident solar radiation. The absorber plate was placed directly behind the transparent cover (glass) with a layer of air separating it from the cover. The air to be heated passed between the transparent cover (glass) and the absorber plate. To reduce the losses from topside of the absorber plate and to increase the temperature of air using the greenhouse effect, a 5 mm thick glass cover was placed over the absorber. The gap between the glass and the absorber surface was maintained at 25 mm for air circulation. One side of the collector was connected to a 0.75 kW (1 HP) centrifugal fan with an airflow rate up to 300 m3 h1 and the other side with a drying chamber. A divergent section was provided at the entry of the solar air heater to provide uniform air circulation over the absorber surface. The 100 mm gap between the absorber and the insulation was filled with sand to store heat. The drying chamber was made up of a 2 mm thick mild steel sheet with a width, depth and height of 1 m 1 m 1.5 m, respectively. The drying chamber was insulated with 10 mm thick glass wool. The solar air heater was tilted to an angle about 251 with respect to the horizontal, which is considered to be an optimum angle for year-round performance of the system at Pollachi (Shariah et al., 2002). The system was oriented to face the south to maximise the incident solar radiation on the solar collector. On the basis of measurements, Pollachi
(latitude of 10.391N, longitude of 77.031E), where the experiment was conducted, had about 11 h 30 min of daylight, with typically about 8 h per day of sunshine available for drying. Four calibrated thermocouples (Pt 100) with70.25 1C accuracy were fixed at different locations (as shown in Fig. 1) of the solar drier to measure the temperature of drying air through a digital scanner having a 0.1 1C resolution connected with a rotary selector switch. Power input to the blower was measured with an energy meter having 70.4% accuracy. A U-tube manometer was fixed in the path of the air circuit to measure the velocity of air entering the drier. The velocity of air at the inlet of the tray was measured with the help of a vane-type anemometer having70.01 m/s accuracy. Solar intensity was measured using a solar intensity meter having an accuracy of about 72%. A digital electronic balance of 1 kg capacity having an accuracy of 70.001 g was used to weigh the samples. The humidity of the ambient air was measured using standard non-aspirated wet and dry bulb mercury thermometers with sensitivities of 0.5 1C.
2.2.
Experimental procedure
Broken coconuts were loaded over the trays of a drier chamber. For hot air circulation over the products to be dried, the wire mesh trays had a porosity of about 90% . Then the fan was switched on and the air velocity adjusted to an
ARTICLE IN PRESS
2.3.
Data analysis
The quantity of moisture content in a material can be represented on a wet basis and expressed in percentage. About 10 g samples were chopped from randomly selected five cups and kept in a convective electrical oven, which was maintained at 10571 1C for 4 h. The initial (Wi) and final (Wf) mass of the samples was recorded with the help of an electronic balance. The moisture content (Mwb) on a wet basis was calculated by Mwb
ðWi Wf Þ ¼ 100. Wi
(1)
1200
600 400 200
Fig. 2 – Variation of solar intensity and ambient relative humidity.
70 60 50 40 30 20
Tda Tamb
10 0 0
8
16
24
32 40 48 56 Drying time (h)
64
72
80
(2)
where cp is the specific heat of air in J kg1 K, ma is the mass flow rate of air in kg s1; Ta is the ambient temperature and To is the outlet air temperature. A is the surface area of the solar collector in m2 and I is the solar intensity in W m2.
3.
800
0 6 12 18 24 30 36 42 48 54 60 66 72 78 Drying time (h)
Results and discussion
The variation of solar radiation and ambient relative humidity during experimentation is shown in Fig. 2. A maximum solar intensity of 932 W m2 was observed. The ambient relative humidity varied between 55% and 72% with an average of about 68% . Temperature variations of the drying air and ambient are shown in Fig. 3. The average drying air temperature recorded at the inlet of the drier was 43 1C. The maximum drying air temperature recorded during peak sunshine hours was 63 1C. The average temperature reduced to 31 1C outside the hours of sunshine and during the night. At the outlet of the drying chamber, a high relative humidity of about 90% was recorded during the initial stages of drying but this gradually reduced to about 34% at the end of drying. The variation of moisture content (wet basis) with drying time is shown in Fig. 4. The average moisture content of the coconut was reduced from about 51.8% to 7.8% and 9.7% in the bottom and the top tray, respectively, after 82 h. The moisture reduction during the first and the second day of drying was found to be about 33% and 20%, respectively. The higher
Fig. 3 – Variation of ambient and drying air temperature as a function of drying time.
Moisture content (wet basis) (%)
cp ma ðTo Ta Þ 100 AS I
1000
0
The instantaneous thermal efficiency of the solar air heater was estimated by using Eq. (2) according to (Kadam & Samuel, 2006) Zth ¼
100 90 80 70 60 50 40 30 20 10 0
Solar intensity Ambient relative humudity
Relative humudity (%)
optimum of 1.2 m/s at the tray inlet. The velocity of the air at the tray was adjusted by using a control valve. During the experiments, temperatures at various locations in the solar collector and the drier chamber, ambient dry and wet bulb temperatures were measured at hourly intervals. The relative humidity of air was calculated from measured wet and dry bulb temperatures using a psychometric chart. After the moisture content was reduced to 40%, the copra kernels were scooped from the shells and dried further without shells. Moisture contents were determined by using Eq. (1). To assure the quality of copra obtained, three experiments were carried out. At the end of each experiment, the dried copra was graded according to Bureau of Indian standards (BIS: 6220-1971). The average grade value is presented. Experiments were only conducted during daylight hours.
99 (2008) 604 – 607
Solar radiation (W m-2)
BIOSYSTEMS ENGINEERING
Temperature (°C)
606
60 50
Top Bottom
40 30 20 10 0 0
8
16
24
32 40 48 56 Drying time (h)
64
72
80
Fig. 4 – Variation of moisture content as a function of drying time.
moisture reduction during the first day was observed because of the evaporation of free moisture migrating from the outer surface layers. This then reduced due to the internal migration of moisture from inner layers to the surface producing a uniform dehydration of wet kernel. Typically, 10 h a day of drying occurred during sunshine. Without
ARTICLE IN PRESS BIOSYSTEMS ENGINEERING
sunshine desorption of moisture took place and the moisture content increased by about 0.5–1.5%. The reduction in the moisture content of copra at the bottom tray was about 5–8% higher than that of the top tray. A high drying rate at a rate of 4.2 g of water/g of dry matter was observed during the initial stage of drying. The drying rate decreased with an increase in the drying time. Drying occurs in the falling rate period with a steep fall in the moisture content in the initial stages of drying which becomes very slow in the later stages. The drying rate of copra in the solar dryer was high compared to sun drying due to its high heat and mass transfer coefficients. About 50 kg of moisture was removed from 300 nuts to obtain about 60 kg of copra. The initial weight of 300 nuts with shells was measured to be about 160 kg. The thermal efficiency of the solar air heater was estimated to be about 24% by using Eq. (2). About 60 kg of copra was produced from 300 nuts. The copra obtained was graded as 76% MCG1, 18% MCG2 and 6% MCG3. Based on the grading of copra, it could be concluded that more than 75% of high-quality MCG1 could be produced in the solar drier. Unlike with kiln and sun drying, the copra obtained was free from smoke, dust, bird and rodent damage.
4.
Conclusion
A forced convection solar drier was designed, fabricated and tested for drying copra. It can be concluded that a
99 (2008) 604– 607
607
forced convection solar drier is more suitable for producing high-quality copra for small holders. About 75% of high-quality copra (MCG1) could be produced. The average thermal efficiency of the solar air heater was estimated to be about 24%. R E F E R E N C E S
Shariah A; Al-Akhras M -A; Al-Omari I A (2002). Optimizing the tilt angle of solar collectors. Renewable Energy, 26, 587–598 Ivanova D; Andonov K (2001). Analytical and experimental study of combined fruit and vegetable dryer. Energy Conversion and Management, 42, 975–983 Kadam D M; Samuel D V K (2006). Convective flat plate solar heat collector for cauliflower drying. Biosystems Engineering, 93, 189–198 Thiruchelvam T; Nimal D A D; Upali S (2007). Comparison of quality and yield of copra processed in CRI improved kiln drying and sun drying. Journal of Food Engineering, 78, 1446–1451 Shanmugam V; Natarajan E (2006). Experimental investigation of forced convection and desiccant integrated solar dryer. Renewable energy, 31, 1239–1251 Singh H P; Remany G (2002). Approaches for increasing the farm income through product diversification and product utilization. In: Sustainable Products and Utilization of Coconut (Singh HP; Mathew MT, eds), pp 1–11. Coconut Development Board, Kochi