Using solar thermal energy for drying of fresh food products in Algeria (original) (raw)

Solar Drying—A Sustainable Way of Food Processing

In a developing country like India, having the second largest population and agriculture as the source of income to nearly 60 % of the total population, post-harvest and storage loss is a major quandary, which needs to be addressed in due diligence. Many food preservation techniques like cold storage, drying, etc., have been evolved out over the years to tackle the above losses. The major constraint is that almost all the technologies are utilizing fossil fuel resources, which are depleting very fast and wise use of these precious resources are preferred for long-term energy sustainability. Therefore, sustainable methods for food preservation are the need of the hour. Solar drying is one of the best choices in this context. Different models of solar dryers have been developed and good quantum of research is progressing in most of the countries to propagate the solar drying technology for value addition of agriculture products. The solar drying technology is a classical example to showcase how sun’s free energy could be effectively utilized for the benefit of mankind. This chapter explains the different types of dryers, different aspects of solar drying, parameters involved in the drying process and the economic analysis to analyse the feasibility of the solar drying system. Case studies of a few of the successful installations are also included.

Solar dryer with thermal energy storage systems for drying agricultural food products: A review

Renewable and Sustainable Energy Reviews, 2010

Developing efficient and cost effective solar dryer with thermal energy storage system for continuous drying of agricultural food products at steady state and moderate temperature (40–75 °C) has become potentially a viable substitute for fossil fuel in much of the developing world. Solar energy storage can reduce the time between energy supply and energy demand, thereby playing a vital role in energy conservation. The rural and urban populations, depend mainly, on non-commercial fuels to meet their energy needs. Solar drying is one possible solution but its acceptance has been limited partially due to some barriers. A great deal of experimental work over the last few decades has already demonstrated that agricultural products can be satisfactorily dehydrated using solar energy. Various designs of small-scale solar dryers having thermal energy storage have been developed in the recent past, mainly for drying agricultural food products. Therefore, in this review paper, an attempt has been taken to summarize the past and current research in the field of thermal energy storage technology in materials as sensible and latent heat in solar dryers for drying of agricultural food products. With the storage unit, agricultural food materials can be dried at late evening, while late evening drying was not possible with a normal solar dryer. So that, solar dryer with storage unit is very beneficial for the humans and as well as for the energy conservation.

Solar Drying - Sustainable Food Processing

Food spoilage is one of the critical problems the world is facing today. A majority of food spoilage is happening in the post-harvest period due to inadequate storage and processing facilities. Cold storage is a good option but it is very much expensive and energy intensive. Hence food drying comes to lime light. Drying is one of the oldest methods used for food preservation. It is method by which the moisture will be removed, thereby restricting microbial and fungal growth. Direct sun drying has some disadvantages like exposure to dust, colour change, pigmentation, insects attack etc. Use of fossil fuel derived energy for drying has been used for getting good quality products. But fossil fuel usage is too costly and will add up to the energy demand and climate problems. Hence, solar drying is best suited sustainable way for food drying. This paper explains the concept of solar drying with case studies and economic feasibility is also discussed.

Solar drying of natural and food products: a review

Natural and food products are dried to improve self-life, reduce packaging cost, increase shipping capacity, enhance appearance, encapsulate original flavor and maintain nutritional value. The main objective of drying is to withdraw moisture from the food so that bacteria, yeast and mold cannot grow and spoil the food. Mostly fossil fuel is used for heating air for drying purpose. Due to exponential rise in the price of fuel and depletion of fossil fuel, there is a need to look for other alternatives like nonconventional energy resources viz. solar energy. India is blessed with good sunshine hours. A review is made to use solar energy for drying of agricultural and food products with different dryers available and with various parameters affecting the drying process and the product. Effect of drying on texture and oil content of the natural products are discussed. A comparison is made between conventional drying and solar energy assisted drying. Work done on different solar dryers with different natural agricultural products along with parameters, result obtained are compared from different literatures.

CONSRUCTION OF A DIRECT SOLAR DRYER FOR PERISHABLE FARM PRODUCTS

International Journal of Scientific Research Engineering & Technology (IJSRET), 2017

The use of the solar resource for food drying has always been a food preservation technique which is widely practiced in this part of the world but unfortunately some of the methods practiced in the rural areas, have been wrought with many disadvantages few of which are the poor quality of food derived and long drying time due to many external factors. The research looked into construction of a less technical direct solar dryer, which combined the concept of black body and thermodynamics with the aim of increasing the overall drying rate of the dryer. The dryer was designed primarily as a direct solar dryer. A set of selected samples of perishable farm produce were dried with the drier and another set in an open sun in a period of three days and was conducted at the same weather condition. The sample perishable farm produce used were Tomatoes, Okra and onion. The overall performance of the dryer after the total drying time reveals that the drying rate of the solar dryer was 2.1g/h, 3.8g/h, 2.4g/h faster than the open sun drying, and therefore requires less time for drying. This implies that the open sun drying rate is not satisfactory when compare to that of the dryer.

Performance characteristics of solar drying system for agricultural products

Drying has important influences on agricultural products' quality and storage. Drying characteristics of different agricultural products vary. Temperature and velocity of drying airflow affect greatly drying quality and drying efficiency of agricultural products. Two types of solar drying systems for different drying temperature requirement were designed and characterized in this paper: solar air drying system with plate air collector and solar parabolic trough concentrating drying system. In solar air drying system with plate air collector, the drying oven has two ventilation modes. With top inlet and bottom outlet ventilation mode, the overall temperature in drying oven is relatively high, however large vertical temperature difference exists in drying oven. With bottom inlet and top outlet ventilation mode, the temperature in drying oven is uniformity, however relatively low. In notoginseng drying experiment, the drying time is shortened to half of that in nature drying. The average thermal efficiency is 66.5%. The solar trough concentrating drying system utilizes a low cost and reliable V-type metal cavity to collect solar irradiation. In the system, the heat conducting oil can be heated to 230℃, and the air flow from heat exchanger reaches above 200℃. The tobacco shred drying experiments verifies that the drying temperature of the system meets the tobacco shred drying requirement. Solar trough concentrating drying system matchts the drying temperature scope of 80℃~200℃.

Solar drying of agricultural products: A review

The use of solar energy in recent years had reached a remarkable edge. The continuous research for an alternative power source due to the perceived scarcity of fuel fossils is its driving force. It had become even more popular as the cost of fossil fuel continues to rise. Of all the renewable sources of energy available, solar energy is the most abundant one and is available in both direct as well as indirect forms. Solar energy applications were divided mainly into two categories: the first is the direct conversion to electricity using solar cells (electrical applications). The second is the thermal applications. The latter include solar heating, solar cooling, solar drying, solar cooking, solar ponds, solar distillation, solar furnaces, solarthermal power generation, solar water heating, solar air heating, etc. Detailed description, fundamentals and previous work performed on solar dryers and solar air heaters, as the vital element for the indirect and mixed modes of solar dryers, were presented in the present review paper.

Solar Drying Technology: Potentials and Developments

Energy, Environment and Sustainable Development, 2011

This paper presents developments and potentials of solar drying technologies for drying of fruits, vegetables, spices, medicinal plants, and fish. Previous efforts on solar drying and recent developments of different types of solar dryers for drying of cereal grains, fruits, vegetables, spices, medicinal plants, and fish in the rural areas of the tropics and subtropics are critically examined in terms of drying performances and product quality, and economics. Experimental performances of different types of solar dryers which have demonstrated their potentialities for drying of fruits, vegetables, spices, medicinal plants, and fish in the tropics and subtropics are addressed. Simulated performances of solar tunnel dryer were assessed for drying fruits, vegetables, spices, medicinal plants, and fish. The agreement between the simulated and experimental results was very good. Energy and exergy analyses of solar drying of jackfruit leather in a solar tunnel dryer are also presented. A multilayer neural network approach to predict the performance of the solar tunnel dryer is presented. The prediction of the performance of the dryer was found to be excellent after it was adequately trained. Finally, prospects of solar dryers for drying of fruits, vegetables, spices, medicinal plants, and fish in the tropics and subtropics are discussed.

Preservation of Food Items Using Solar Dryers: A Review

In order to conserve the food products like chillies, grapes, potatoes & other agricultural products, for a longer period of time & with same the quality they need to be dried by using any form of energy, for example heat energy from fossil fuels or solar energy etc. This is done to reduce the moisture content to a predetermined level which prevents the growth & reproduction of micro organisms like bacteria, yeasts etc. that causes many moisture mediated deterioration reactions. One of the drying methods involves drying the produce with the help of direct sun light by spreading them in an open space. This process is labor intensive & requires a large area for spreading the produced to dry out. The disadvantage of this method involves uneven heating, loss of produce due to birds, animals, bad weather etc. Another method of drying involves artificial mechanical drying which is an energy intensive, expensive and costly method. Green house drying or solar drying gives the best results as it does not compromise the product quality, aesthetic etc. Moreover it makes the transportation process easy as the volume of dried product reduces. This paper reviews the solar drying process & gives complete in depth of all the elements involve in solar drying.