Technical brief
Construction and maintenance of Solar Fish Drier
This Technical brief details the basic construction techniques as well as the material, equipment, skills and labour requirements necessary to construct a low cost solar fish drier suitable for the small scale dry fish producers of Sri Lanka.
Introduction
Initiatives to improve the productivity and quality standards of the local dry fish industry is important for several reasons. Firstly, fish, including dry fish, is the most important source of protein, ac counting for 65% of the protein intake of the average Sri Lankan consumer. With the gradual increase in population, the demand for fish and processed fish is also steadily increasing. Secondly, it is estimated that Sri Lanka imports about 28,000t of dry fish annually, (Ministry of Fisheries and Aquatic Resources - Fisheries Strategy Document 2005), amounting to a significant outflow of foreign currency from the country. Improving the local dry fish industry can help save at least a portion of this outflow of foreign currency. Thirdly, dry fish is an important source of income for the small scale coastal fisheries communities of Sri Lanka Dry fish production mainly consists of micro level cottage enterprises, carried out predominantly by fisherwomen as a supplementary source of income. As such, the quantities produced tend to be low. Furthermore due to the long drawn drying process, the moisture retained creates an ideal environment for growth of fungi. The practice of drying the fish in the open under the sun affects the hygienic conditions of the dried fish, due to the high risk of contamination with dust particles and harmful contaminants. However, the scale of the average dry fish enterprise precludes the introduction of sophisticated methods of fish preservation. The high capital requirement and the fuel cost of many of the high-tech dryers makes it unaffordable and impractical for the small scale dry fish producer. Furthermore, social factors such as attitudes, lifestyle and behaviour makes it difficult to introduce radical changes to conventional drying methods. Practical Action started with the general understanding that there was a need for a low cost, low technology means for producing larger quantities of high quality dry fish. Through a combination of community and expert consultation, Practical Action innovated a solution in the form of a solar powered fish dryer. The use of solar energy means that the cost of energy is zero. It’s simple design makes the cost of installation low, especially since most of the material can be easily sourced locally. The dryer is sealed to avoid contamination. The maintenance cost is minimal, and it allows for faster drying compared to the conventional drying methods.
Who to contact: Project Manager – Fisheries or the Resource Desk at
Practical Action (formerly ITDG)
No 5, Lionel Edirisinghe Mw, Colombo 5, Sri Lanka. T +94 (11) 2829412 F +94 (11) 2856188 W www.practicalaction.org www.janathakshan.org E srilanka@practicalaction.org.lk
Technical brief
The two models of driers developed are, • • Stationary Drier Mobile (Collapsible) Drier ¾” in height. The floor is elevated from the ground level and constructed of paved brick and covered with a cement rendering. Brick walls with a height of 2’6” are erected on the four sides to support the structure. The inner side of the walls is plastered to prevent breeding and harbouring of insects while the outer side is painted black, for greater heat absorption and retention. Two ducts and two chimneys are fixed on the upper ends of the roof ventilators. These are also painted black so as to augment the expulsion of the spent air. The heat collection device is made of 08 metal trenches, painted black on the inner side, facing the sun. The roof is covered with a polythene cover and is supported on a weather proof, seasoned timber framework. These trenches are located 1’3” below the eaves. The idea behind designing the heat collector in the form of trenches (each trench loaded with black coloured metal chips), is to facilitate storage and releasing of heat during cloudy spells, thus offsetting the vagaries of temperature fluctuations. The capacity of this drier is 100 Kg per batch.
Stationary Drier
Picture: stationary type solar drier
A bove: stationary solar drier The structure of this drier is very similar to a gable roofed green house. It is a structure 25. 4ft in length and 15. 4ft in width. The height of the eaves is 8.6ft and the ridge is 12’
Isometric view of the drier
Practical Action Construction and maintenances of solar fish drier Technical brief
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Technical brief
Practical Action Construction and maintenances of solar fish drier Technical brief
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Technical brief
Practical Action Construction and maintenances of solar fish drier Technical brief
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Technical brief
Mobile (collapsible) Drier
sits on a 12” high 9” thick wall, and is protected by a rodent guard. I t has four moveable, wooden racks with cascading shelves , each fixed with seven shelves made of plastic netting, which serves as the drying surfaces . The space provision i n and around the racks facilitates easy loading and unloading. The capacity of this drier is 50 kg per batch.
Above: Mobile (collapsible) solar dryer The structure of this dryer is very similar to the conventional agricultural poly tunnels. It is 12’6” in length and 10’4” in width. The height at the apex is 6’4”. The door is polythene clad, and is lockable. The floor is elevated from ground level and is rendered using black cement. The base of the drier
Isometric drawing of the drier
Practical Action Construction and maintenances of solar fish drier Technical brief
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