Solar Dryer

is work presents the regulation of temperature in an indirect multitrays solar dryer with oriented flux under the irradiance fluctuation. e temperature regulator using a negative temperature coefficient (NTC) as a sensor and fans is designed, and a similar device is also used to measure humidity through a sensor. Inlet and outlet dryer temperature and temperature on the three trays have been recorded with the regulation system according to different airflow modes. Irradiance and humidity have also been recorded. e model of outlet temperature with energy storage was given by using heat transfer equations. e results have shown that in the linking airflow mode, the average temperature on the three trays is 51.3 ± 1.5 a°C , 52.18 ± 1.4 a°C , and 51.9 ± 1.2 a°C , respectively, with 52°C as setpoint temperature and NTC fixed on tray number 2. With temperature sensor in the same tray and 51°C as setpoint temperature, the average temperatures on the three trays are 51.86 ± 1.54°C, 51.60 ± 1.16°C, and 50.42 ± 1.13°C, respectively, in mixed mode, whereas in crossing airflow mode, the temperature gradient does not allow regulation on all trays. e regulation is possible when the temperature in the dryer chamber exceeds the set point temperature by more than 5%. e proportional type corrector is suitable for the temperature controller in indirect solar dryers. When the energy source is unstable, humidity which is a variable parameter is used to mark the end of drying instead of time.

The use of solar energy in open sun drying in
traditional way of drying crops, fruits, vegetables etc. The
greenhouse drying is one of the techniques which overcome the
problems associated with open sun drying. In the present work,
an effort is made to improve the drying rate of traditional
greenhouse dryer. An experimental investigation using tomato
flakes has been done to compare the drying rates of both
traditional as well as modified greenhouse dryers. Better drying
conditions- high temperature & low relative humidity are found
out to be for modified greenhouse dryer. Experiments were
performed in October 2016.

This paper presents the design, construction and testing of a simple solar dryer for food preservation. Its construction was accomplished using mainly inexpensive locally available materials to make it relatively affordable to the average poor farmer dwelling in the rural area. The dryer temperature was found to be above the ambient temperature by an average of 51 % throughout the day-light time and the temperature rise was up to 75 % for about three hours immediately after 12.00 h (noon). The drying rate and the system efficiency were 0.46 kg/h and 59 % respectively. The rapid rate of drying in the dryer reveals its ability to dry food items reasonably rapidly to a safe moisture level and simultaneously it ensures a superior quality of the dried product. The results obtained indicate that solar dryers have a future especially in food preservation.

A prototype direct solar dryer has been fabricated and tested in no load, partial load and full loading conditions under forced convection mode. Experiment has been conducted in different cases. Case-1 is when no load is used inside the dryer and air velocity is 2-10 m/s, case 2 is when partial load is used inside the dryer and air velocity 2-10 m/s. Case-3 when full load is used inside the dryer and air velocity is 2-10 m/s. Ambient temperature, solar radiation, solar dryer temperature and air velocity have been evaluated in thermal performance analysis and calculating the mass flow rate. The results also showing the effectiveness of moisture reduced and reduced weight per hour. In this paper, a direct solar dryer prototype is designed, constructed and performance tested for the analysis of the drying kinetics of these by products and their possible efficiency evaluation. The characteristics of the prototype are presented together with the variations of the properties of temperature, air velocity and mass flow rate for direct solar dryer. The analysis of the drying kinetics of the tomato or potato slices shows the performance of the direct solar dryer obtaining reductions of the drying time than the conventional drying.

RESUMEN En este trabajo se presenta un deshidratador solar indirecto por convección forzada, está diseñado, en base de la aplicación del canal concentrador parabólico compuesto (CPC) como colector solar. Esta aplicación se basa en el buen rendimiento óptico que presenta el CPC, con respecto a otros colectores de concentración. La convección forzada se realiza por medio de unos extractores que se alimentan por un pequeño sistema fotovoltaico. Se han obtenido las curvas de secado de la fresa. Los tiempos de secado son de aproximadamente 3 horas. Se observa que la temperatura en la cámara de secado no tiene variaciones altas, en caso de nubosidades no muy prolongadas. PALABRAS CLAVE: deshidratador solar, CPC, convección forzada. ABSTRACT In this project, an indirect solar dehydrator by forced convection is presented, which was designed on the basis of the application of the compound parabolic concentrator (CPC) channel as a solar collector. This application is based on the good optical performance of the CPC, with respect to other concentration collectors. The forced convection takes place a small photovoltaic system. Drying rate curve has been obtained of the strawberry. The drying times are approximately three hours. It is observed that the temperature in the drying chamber does not have high variations in the case of not very prolonged cloudiness.

This paper presents direct solar dryer for drying application likes as fruits, vegetables, and spices. Previous efforts on solar drying and recent developments of direct solar dryer for drying of cereal grains, fruits, vegetables and spices in the rural areas of the tropic and sub-tropic are critically examined in terms of drying performance and product quality and economic. The unpredictable rise and frequent scarcity of fossil fuel accelerated the continuous search for an alternative power source. Solar is one of the renewable and sustainable sources of power that attracted a large community of researches from all over the world. This is largely due to its abundant in both direct and indirect form. As such the development of efficient and inexpensive equipment for the drying of agricultural products using solar power evolved thereby improving the quality of the product as well as improving the quality of life. In this paper a review of direct solar is presented. It has been observed that use of direct solar dryer under natural convection and forced convection reduces moisture in very less time as well as drying rate is very fast than the sun drying.

— A hybrid photovoltaic solar dryer was designed, constructed and tested in the Department of Food Science and Technology, Modibbo Adama University of Technology Yola, Nigeria. The thin layer drying behaviour of tomato slices using a hybrid drying method compared to solar and open sun drying was investigated. The dryer consists of solar collector, photovoltaic solar panel, battery and drying chamber. The dryer was operated as both a solar-energy dryer and as a hybrid solar dryer. The drying performance of the dryer was evaluated with fresh tomato slice and compared with open sun drying under the same climatic conditions. The dryer recorded a raised temperature of 62℃ attainable in the drying chamber of hybrid dryer and 54 o C attainable in the drying chamber of solar dryer. The moisture content of tomato slices was reduced from 94.22 % wet basis to 10 % in 6 hours for hybrid drying method while it took 9 hours to achieve the same moisture content reduction in the solar dryer. The average drying rate and the efficiency was computed as 0.0800kg/h and 71% for hybrid dryer and 0.0578kg/h and 65% for solar-energy dryer respectively. The quality of the tomato samples dried using the hybrid dryer was superior to those of solar and sun drying methods. From the result of this study it shows that a hybrid solar-energy dryer using photovoltaic (PV) solar panel suggested a promising process for adoption to preserve tomato which can prevent it from spoilage and post-harvest losses. The good quality and shelf stable dried tomato slices is indicative for a sustainable productivity that will create a sound avenue for economic growth in tomato producing regions of the world. Keywords— design, hybrid dryer, photovoltaic solar panel, solar dryer and tomatoes.

This study was conducted to evaluate performance of modified hybrid solar dryer for drying paddy (Oryza Sativa L.) seed, evaluate quality of seed and fit experimental data to thin layer drying equations. A modified hybrid solar dryer having capacity of 500 kg was constructed to carry out the study. Performance of the dryer was evaluated based on the drying rate, collector performance, collector efficiency, drying efficiency and quality of seed. A flat plate concentrating solar collector was placed on each legs of the dryer with wheel to turn the solar collector horizontally and change its direction with sun's

This paper contains the results of a study in which the solar energy potential for drying has been assessed, and the effects of some important design parameters on the performance ofa box type direct solar dryer have been investigated with an objective to optimize the design for maximum drying rate. From hourly values of solar radiation measured at BAU in 1984, monthly average of daily total insolations were calculated which ranged from 7.74 to 19.30 MJ/m2/day. These amounts of solar energy were capable of removing at least 0.7 to 1.72 kg water per m2 per day. The average dryer temperature and the temperature rise in a box type solar dryer were found to vary widely with the area ofair openings. Maximum temperatures were obtained when the area of air openings were below 2% of the collector area. Maximum evaporations were observed at 4 to 5% air openings; below and above this range, the evaporation rates declined. A box type dryer, when provided with a chimney, increased the air temperature by 3.20C and increased the drying rate by 2.3% as compared to those of a dryer without a chimney.

The presents work is based on the working of dryers, the basic aim of this experiment is to design a dryer which meets the basic requirements of dryer which are improved by a modification in the design of indirect forced solar dryer. The concept behind the construction of a dryer is energy conservation and food preservation by the moisture removal process in solar dryer. In this experiment the dryer which is designed works by using solar energy as well as electrical energy that is why the name of the dryer is ‘Hybrid Solar Dryer’. In this hybrid solar dryer a recirculating duct is added from the motor fan assembly to the drying chamber that the hot air which goes through the passage of air flow that is firstly hot air passes through the rectangular duct then in divergent duct and finally reaches in the drying chamber but in between them some amount of hot is wasted but by the recirculating duct this air is reutilized for heating the food product in drying chamber. After working on this dryer the drying time reduces, drying rate increases ,removal rate of moisture content increases in comparison to indirect solar dryer without air recirculation.

Solar drying is an emerging technology to preserve wide range of products from agriculture to animal-based products. The application of solar dryers, however must be evaluated to determine its benefit and effectiveness. In the evaluation of solar dryer performance, three criteria which are most important to look at are thermal performance, economic cost and environmental implications. Therefore, this paper attempts to review the thermoeconomic analysis and environmental evaluation on various solar drying system. Performance equations in energy-economic-environment analyses for solar drying syistems evaluation are presented. The CO2 emission, carbon mitigation, and earned carbon credit of various solar drying syistem are also presented.

To separate the tumble dryer belt warming component itself, search for two screws that will be holding it set up. These will in all likelihood be at the best. There is likewise a connect connector to the base left corner. tumble dryer belt warming - http://www.bombinobelts.com/product/dryer-belts

Abstract— Different drying methods viz., Sun drying, shade drying and tray drying (temperature 45, 55 and 65 0C) were used for dehydration of curry (Murraya koenigii) leaves for optimal retention of color and its constituents. It was observed that the time required for tray drying was less (27%), when compared to sun and shade drying. Tray dried (550C) curry leaves had maintained nutritional constituents up to acceptable limit with superior green color and a more porous and uniform structure than those obtained from sun and shade drying. Dehydrated curry leaves showed good consumer acceptance as well as shelf life.

A solar dryer used for agricultural produce has been developed. Major components of the dryer include: (i) flat plate collector, (ii) glass cover (iii) drying chamber, and (iv) lagging material. The flat plate collector was made with corrugated iron sheet coated dull black. The absorber is insulated with 50mm thick fibre glass. The solar collector has a surface area of 0.315m2, mounted on a frame tilted to an angle of 45 degrees. Performance test showed that the dryer recorded a maximum temperature of 660C at an average heat gain of 9176.06KJ.

This paper deals with current practices of drying agricultural products in most of developing nations like India. It also try to coin the concept of utilization of Solar dryer at farm side. 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 longterm 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. The effect of temperature to moisture contents against time and rate of dr...

This study is concerned with the analyses of performance on a solar dryer integrated with solid desiccant coloums using water based solar collector. The dryer consists of a solar water collector, two solid desiccant coloums, a water storage tank, two heat exchangers, an air heater, and a drying chamber. The dryer decreased the Centella asiatica L moisture content from 88.3% (wb) to 15.9% (wb) within 12 hours, with an average temperature and relative humidity of 45.4°C and 25.8%, respectively. The rate of moisture evaporation and the specific moisture evaporation rate were in the range of 0.001-1.762kg/h and 0.02-0.482 kg/kWh, with 0.594kg/h and 0.169kg/kWh in average values, respectively. The dryer efficiency was in the range of 0.62%-30.4%, with 15.4% in average value. The energy required for moisture evaporation and total energy input to the dryer were in the range of 26.9-1132.2W and 3638.0-4329.7W, with 601.8 W and 3967.4 W in average values, respectively. The efficiency of collector and the heat exchanger effectiveness were in the range of 38.1-50.5% and 65.1-79.7%, with 45.0% and 73.0% in average values, respectively. The result shows that the dryer is suitable for drying Centella asiatica L, this is due to the low temperature of drying air and high moisture evaporation rate.

This paper presents the design, construction and testing of a simple solar dryer for food preservation. Its construction was accomplished using mainly inexpensive locally available materials to make it relatively affordable to the average poor farmer dwelling in the rural area. The dryer temperature was found to be above the ambient temperature by an average of 51 % throughout the daylight time and the temperature rise was up to 75 % for about three hours immediately after 12.00 h (noon). The drying rate and the system efficiency were 0.46 kg/h and 59 % respectively. The rapid rate of drying in the dryer reveals its ability to dry food items reasonably rapidly to a safe moisture level and simultaneously it ensures a superior quality of the dried product. The results obtained indicate that solar dryers have a future especially in food preservation.

Drawbacks associated with natural convection solar dryers are encouraging the development of low-capacity hybrid drying systems which integrate renewable energy in their operation. However, information on the cost-effectiveness of such drying systems for decision-making by investors is lacking. This study seeks to assess the financial and economic feasibility of a solar-biomass hybrid dryer for maize drying. A cost-benefit analysis was done using net present value (NPV), benefit-cost ratio (BCR), and internal rate of return (IRR) as well as payback period to measure the financial viability of the dryer operation and the profitability of the investment. The results show that the total capital expenditure required to establish the drying system is $ 5,263 with a running cost of $ 1,166 per year. Using an economic utilisation period of 10 years, the investment in the dryer was determined to be viable with an NPV of $ 4,876 and an IRR of 38% at a capital cost of 24%. At a drying charge ...

This work aims to improve an indirect solar dryer by adding a biomass energy source with a storage system. A Hybrid Biomass-Indirect Solar Dryer (HBISD) was designed and made from local materials. Solar energy and improved charcoal (30 MJ/kg) stove (Jambar type) with a thermal storage system using pozzolan supply the drying chamber. Measurements of irradiance and in and out dryer chamber temperatures were carried out in three drying modes with and without energy storage: indirect solar, biomass, and hybrid. The solar collector designed has an area of 0.2 m², and the drying chamber volume is 0.402 mP 3 P. The volume of the fireplace is 0.012 mP 3 P. The experimental results show that the highest drying room temperature is 52 °C at 940 W / m² for the solar collector test, while for the different masses of charcoal (200, 400, 600, and 800 g) in the fireplace, it is 40.6 °C, 55.33 °C, 63.2 °C, and 62.31 °C respectively. Using a mixture of charcoal and pozzolan in the mass proportion of 20%, 30%, and 50% of pozzolan, it is shown that the temperature in the drying room reaches 71.37 °C, 64.28 °C, and 60.02 °C, respectively. The autonomy due to the storage system is 02 hours 05 minutes, 01 hours 20 minutes, and 01 hours 15 minutes respectively for temperatures above 50 °C. The quantity of charcoal used in the storage case is less than that in its absence for the same duration and drying room temperature. In hybrid mode, the drying of guava has a shorter drying duration (7 hours) than that obtained in indirect solar mode (26 hours).

Among the most important components of solar energy systems, solar collectors are devices that receive solar energy and convert it into thermal energy, as most essential components of solar dryer. This review presents description and previous work performed on performances of solar air collector for agricultural produce. In addition, various solar collectors are classified and described. Solar air collectors for drying application of agricultural produce are presented and summarize. The energy and exergy efficiency of the solar air collector ranges from 28% to 62% and from 30% to 57%, respectively.

The objective of this study is to find an optimized thin layer mathematical model suitable for drying kinetics of turmeric. Turmeric has high moisture content which necessitates effective drying. A 10 Kg, sample batch, of turmeric was dried in a solar dryer. Drying air temperatures and air velocity were observed in the range of 55 0 C-68 0 C and 0.7 m/sec-1.4 m/sec respectively in the drying experiments. It is seen that the moisture content of the turmeric is reduced from 77% to 11.93% in 22 hours when compared to open sun drying, which required 60 hours for the same reduction in the moisture content. Scheffler dish was used to generate steam for the dryer. Seven thin layer mathematical models, cited in the literature, had been used for the study. These models were applied for different trays placed in the dryer. The result of the research and experimentation showed that the Page Model fits best for drying in the steam-based dryer and open sun drying. Experimental results showed 63.33% saving in drying time, and the drying efficiency was found as 29.85%. Uncertainty in the drying efficiency was observed as 0.67%. Experimental investigation and the findings from the mathematical modeling are presented in this paper.

Particularly in the low drying temperature drying is an energy intensive process and requires a suitable optimization technique. This work represents the kinetic simulation and energy efficient optimization technique for drying long grain, i.e. rice. At 30-60 degrees C temperature the grains have been dried in a solar powered air dryer. After certain time interval the enzymatic activity and the moisture content have been measured. Genetic Algorithm (GA) has been used for the simulation and the optimization process while the experimental data have been used to fit the thin layer drying model. The results indicate that between 40 and 50 degrees C temperature and the 1.3-1.5 m/s air flow rate the drying time for the rice is around 120-180 min. The kinetic simulation and the quality analysis confirm that the dried products have a better enzymatic activity which resembles the quality standard and the required energy for the optimized drying process is lower than the others.

Link to Full-Text Articles :
http://www.tandfonline.com/doi/pdf/10.1080/15435075.2014.890106

Solar crops drying as a process has currently become a decisive factor to improve the efficiency in the industrial, residential and farm sectors. Given its considerable importance, different researchers have proposed and developed a great number of theoretical and experimental models to predict the drying kinetics of the process, including the machine and the product. In the use of solar thermic driers, there have been great advances on developing models; however, the major part of these works has concentrated in driers of industrial scale. The unified models that allow predicting temperature profiles and moisture content for many types of crops, using handmade driers to small scales have been less applied. It has been mainly due to the wide diversity of products and the big differences between the existing processes. The purpose of this research is offering a panoramic about the state of the art related to models and present the basic theoretical foundations to develop a model for ...

A hybrid dryer fuelled by the combination of solar energy and energy from kerosine stove, was developed in NSPRI and assessed for drying local "Ogbomosho" mango cultivar in comparison with the following hybrid mango cultivars; Peter, Peach, Joulie, and Indicina. Their physicochemical properties were assessed. Peter has the highest in ascorbic acid and total sugar levels. The physicochemical properties of Ogbomosho variety are comparable to that of hybrid mangoes. Effective drying of the mango chips with the hybrid dryer; to moisture level of 16.336 ± 1.303 was attained.

Aim of this paper is to study an effect of evaporative capacity by evaluating a performance of solar air heater and dryer. This is also a performance indicator of the solar collector like a widely-used ‘‘collector efficiency’’. The comparison of variation in evaporative capacity with other properties and thermal efficiency are analyzed. The effect of meteorological conditions on performance of solar dryer can be found. Importance of the evaporative capacity and methods for determining the evaporative capacities are presented.

Sun drying" is the earliest method of drying farm produce ever known to man and it involves simply laying the agricultural products out open in the sun. This has several disadvantages since the farm produce are laid in the open sky and there is greater risk of spoilage due to adverse climatic situations and insects. Solar dryer is a device which are used to dry substances, mostly food products. A solar dryer is of two types-direct and indirect. In this paper the main idea is to construct a hybrid solar dryer by using the excess heat generated around the solar panel. We have learnt from various researches that as the temperature rises, the panels generate less voltage and become less efficient in producing electricity. So, to overcome this problem we have proposed a system such that a solar dryer can be constructed by using the excessive hot air generated near the solar panels. This will also keep the solar panel cool and maintain the efficiency. The electricity generated from the solar panel will be used in drip irrigation. This system will help the farmers to irrigate their farm and dry their food products with the help of solar energy.

This paper is present the construction of mobile solar dryer that is used in more difficult access mountain areas in the Republic of Macedonia where the most common herbs and mushrooms, so you need to make a series of modifications to the design and selection of another source of extra energy. The development and the application of the science designing led to the use of the methodical construction where the designing direction is carried out into phases and present an act of solving all constructive assignments. This methodical construction is applied on the construction methodology of combined mobile solar dryer.

Abstract Indirect solar dryer is used to dry food products. The dried product quality and the drying air temperature distribution are inter-related parameters. Therefore, obtaining a suitable air distribution in the drying chamber via parametric studies is essential to ensure uniform drying of products. Since parametric and optimization investigations by physical experiments are usually expensive and time consuming, computational fluid dynamics (CFD) being a flexible and less expensive tool can be employed to perform such studies. In the current paper, the best design and operating conditions are highlighted through a parametric study using an experimentally validated CFD model and image processing techniques. The effect of adding a passive chimney and the effect of three mass flow rates on the drying air distribution is tested by using ANSYS FLUENT software. The average temperature increased by 16, 11 and 8 K for the mass flow rate of ṁ = 0.0141, 0.0636, and 0.0872 kg.s−1, respectively. The air temperature uniformity was improved significantly by 21.7 and 20.3% for the mass flow rate of ṁ=0.0141 and 0.06 kg.s−1, respectively, while it was marginally increased for ṁ = 0.08 kg.s−1. Using solar chimney improved the drying air temperature by 7 degrees.