Numerical and experimental investigation of direct solar crop dryer for farmers

Science.gov (United States)

Kareem, M. W.; Habib, Khairul; Sulaiman, S. A.

2015-07-01

This article presents a theoretical and experimental investigation on effects of weather on direct solar crop drying technique. The SIMULINK tool was employed to analyze the energy balance equations of the transient system model. A prototype of the drying system was made and data were collected between the months of June and July in Perak, Malaysia. The contribution of intense sunny days was encouraging despite the wet season, and the wind velocity was dynamic during the period of investigation. However, high percentage of relative humidity was observed. This constitutes a hindrance to efficient drying process. The reported studies were silent on the effect of thick atmospheric moisture content on drying rate of agricultural products in tropic climate. This finding has revealed the mean values of insolation, wind speed, moisturized air, system performance efficiency and chili microscopy image morphology. The predicted and measured results were compared with good agreement.

Technique of solar drying the linden

International Nuclear Information System (INIS)

Fonseca Fonseca, Susana; Andión Torres, Ronald; Espinosa Borges, Ruberlando; Torres Ten, Alonso; Arzuaga Machado, Yusnel; Fuentes lombá, Osmay

2017-01-01

In Santiago of Cuba exists interest in the utilization of medicinal plants for the manufacture of flowed abstract and Tinturas, and this requires the dry product. At the present time this process is done in houses roofed. This product will be dried at 10 or 12 days. Having in account than in the Center of investigation of Solar Energy was developed a prototype of solar drier, which enables the drying of the anamu with the required quality, in this work is done a study, for the utilization of the aforementioned drier, for the drying of others medicinal plants. It is determine and evaluated experimentally a Procedure of drying of linden in this solar drier. The dry plants were sent to the UBPC La Rosita of medicinal plants, which manifested conformity with the obtained results, showing contentment with the quality of the dry product. (author)

Practical use of solar heating-dehumidification dry kiln

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Yoshinori

1988-06-01

In order to decrease the energy cost for drying, a solar-dehumidification dry kiln which used the dehumidification dry process together with the solar thermal drier was developed and tested. In the daytime the drying temperature rose up to 60/sup 0/C in summer and 40/sup 0/C in winter, and it was kept higher by 15 to 20/sup 0/C than the outside temperature at night. Owing to the adoption of the combination of direct solar heating and exhausting highly humid air, it was not necessary to operate the dry kiln in the day time. Average electrical energy consumption which was consumed to 15% moisture content from the raw lumber was about 73kWh/m/sup 3/ in summer which was lowest, about 87kWh/m/sup 3/ in winter. Energy cost required for the solar dehumidification dry kiln is 1/2 to 2/3 of that of the conventional dehumidification dry kiln. The solar-dehumidification dry kiln has a merit of cheaper operating cost in the low energy cost and reduced drying time. (7 figs, 1 tab, 6 refs)

Determination of pistachio drying behaviour and conditions in a solar drying system

Energy Technology Data Exchange (ETDEWEB)

Midilli, Adnan [Karadeniz Technical Univ., Mechanical Engineering Dept., Trabzon (Turkey)

2001-07-01

The main object of this study is to determine the drying behaviour and conditions of shelled and unshelled pistachio samples using both solar assisted and open sun drying. For each drying experiment, 100 g each of unshelled and shelled pistachio were used. The least-squares method was applied to find the drying curve equation of pistachio. During the experiments, shelf temperatures, weight loss of pistachio, moisture content of air, and distribution of solar radiation were measured; and presented depending on the drying time. Also, the mass shrinkage ratios of shelled and unshelled pistachio samples were determined, and the experimental uncertainty ratio was calculated as 15-16.5 per cent based on the experimental results. It was deduced that the shelled and unshelled pistachio samples in the solar assisted forced convection dryer were perfectly dried at temperatures of 50{+-}10degC in the time period of 6 h. Whereas, the samples in the open sun drying were not sufficiently dried at temperatures of 28{+-}4degC in the same time period. Hence, it is suggested that the pistachio samples with approximately 29.0 per cent of moisture are dried in the solar assisted convection dryer at 50{+-}10degC of temperature in the time period of approximately 6 h in order to protect from the negative climatic and environmental effects. However, it is not desirable to dry the pistachio samples in the open sun because of greater drying time, dirt, dust and harmful insects. (Author)

Development of Solar Drying Model for Selected Cambodian Fish Species

OpenAIRE

Hubackova, Anna; Kucerova, Iva; Chrun, Rithy; Chaloupkova, Petra; Banout, Jan

2014-01-01

A solar drying was investigated as one of perspective techniques for fish processing in Cambodia. The solar drying was compared to conventional drying in electric oven. Five typical Cambodian fish species were selected for this study. Mean solar drying temperature and drying air relative humidity were 55.6°C and 19.9%, respectively. The overall solar dryer efficiency was 12.37%, which is typical for natural convection solar dryers. An average evaporative capacity of solar dryer was 0.049 kg·h...

Effect of solar radiation on drying house performance

International Nuclear Information System (INIS)

Rachmat, R.

2000-01-01

Solar drying is one of thermal utilization where radiation energy can be utilized efficiently. Solar drying of all sorts of agricultural products have been thoroughly studied and reported in literature, but brown rice drying system has not yet done as many as other products. The aim of the present study is to investigate the effect of solar radiation on drying house performance and brown rice drying characteristics. A construction of drying house is made from FRP sheets with 30 deg. of root slope faces southern part and inside the drying house is installed a flat bed dryer. The site of construction has 136 deg. 31.4'E in longitude and 34 deg. 43.8N in latitude with 3 m in elevation from sea level. The investigated parameters are global solar radiation, absorbed and net radiation and brown rice drying characteristics. The results showed that in unload condition, the air temperature inside drying house was higher (10 deg. C - 12 deg. C) than ambient air when there was not collector and temperature rise become higher (16 deg. C) when there was a black FRP collector inside drying house. The effect of solar radiation on temperature rise has the trend as a linear function. The heat collection efficiency of drying house with black FRP collector was two times higher (36.9 percent) than that without collector (16.3 percent). These phenomena exhibited significant result of collector utilization to the advantageous condition for a drying purpose [in

Solar drying in sludge management in Turkey

Energy Technology Data Exchange (ETDEWEB)

Kamil Salihoglu, Nezih; Pinarli, Vedat; Salihoglu, Guray [Faculty of Engineering and Architecture, Environmental Engineering Department, Uludag University, 16059, Bursa (Turkey)

2007-08-15

Two main wastewater treatment plants in Bursa city in Turkey will start to operate and produce at least 27,000 tons of dry solids per year by the end of 2006. The purpose of this study was to investigate an economical solution to the sludge management problem that Bursa city would encounter. The general trend in Turkey is mechanical dewatering to obtain a dry solid (DS) content of 20%, and liming the mechanically dewatered sludge to reach the legal land filling requirement, 35% DS content. This study recommends limited liming and solar drying as an alternative to only-liming the mechanically dewatered sludge. Open and covered solar sludge drying plants were constructed in pilot scale for experimental purposes. Dry solids and climatic conditions were constantly measured. Faecal coliform reduction was also monitored. The specially designed covered solar drying plant proved to be more efficient than the open plant in terms of drying and faecal coliform reduction. It was found that, if the limited liming and solar drying method was applied after mechanical dewatering instead of only-liming method, the total amount of the sludge to be disposed would be reduced by approximately 40%. This would lead to a reduction in the transportation, handling, and land filling costs. The covered drying system would amortize itself in 4 years. (author)

Desorption isotherms, drying characteristics and qualities of glace tropical fruits undergoing forced convection solar drying

Energy Technology Data Exchange (ETDEWEB)

Jamradloedluk, Jindaporn; Wiriyaumpaiwong, Songchai [Mahasarakham Univ. Khamriang, Kantarawichai, Mahasarakham (Thailand)

2008-07-01

Solar energy, a form of sustainable energy, has a great potential for a wide variety of applications because it is abundant and accessible, especially for countries located in the tropical region. Drying process is one of the prominent techniques for utilization of solar energy. This research work proposes a forced convection solar drying of osmotically pretreated fruits viz. mango, guava, and pineapple. The fruit cubes with a dimension of 1cm x 1cm x 1cm were immersed in 35% w./w. sucrose solution prior to the drying process. Drying kinetics, color and hardness of the final products obtained from solar drying were investigated and compared with those obtained from open air-sun drying. Desorption isotherms of the osmosed fruits were also examined and five mathematical models were used to fit the desorption curves. Experimental results revealed that solar drying provided higher drying rate than natural sun drying. Color of glace fruit processed by solar drying was more intense, indicated by lower value of lightness and higher value of yellowness, than that processed by sun drying. Hardness of the products dehydrated by both drying methods, however, was not significantly different (p>0.05). Validation of the mathematical models developed showed that the GAB model was most effective for describing desorption isotherms of osmotically pretreated mango and pineapple whereas Peleg's model was most effective for describing desorption isotherms of osmotically pretreated guava. (orig.)

Solar drying of jack fruit almonds Secagem solar de amêndoas de jaca

Directory of Open Access Journals (Sweden)

Alexandre J. de M Queiroz

2011-12-01

Full Text Available Dryers heated by solar energy have been constructed and used in drying whole and half jack fruit almonds. The samples were dried during the day in direct sun and in the conventional solar dryer prepared for this purpose. Another piece of equipment was built for reception and accumulation of sun energy in a body of water, which was used as a heat source for night drying. The drying with the sun energy was compared with artificial drying. The jack fruit almonds were dried whole, half, with pellicle and without it. The storage of solar energy in water was technically viable for use in night drying. The drying by combining solar dryers in the day and night periods were completed in approximately 35 hours, and were equivalent to artificial drying between 40ºC and 70ºC. Almond cut in half and the pellicle removed reduced the drying time.Secadores com aquecimento por energia solar foram construídos e utilizados em secagens de amêndoas de jaca inteiras e em metades. As secagens no período diurno foram realizadas por exposição direta ao sol e em secador solar convencional, elaborado para este fim. Construiu-se também um equipamento para captação e acumulação de energia solar em uma massa de água, a qual foi utilizada como fonte de calor para realização de secagens no período noturno. As secagens com o uso de energia solar foram comparadas com secagens artificiais. As amêndoas de jaca foram secadas inteiras, em metades, com e sem película. O armazenamento da energia solar em corpo de água mostrou-se viável do ponto de vista técnico para utilização em secagens noturnas. As secagens combinando secadores por energia solar nos períodos diurno e noturno foram concluídas em tempos aproximados de 35 horas e equivaleram a secagens artificiais entre 40 ºC e 70 ºC. O corte das amêndoas e a retirada das películas reduziram o tempo de secagem.

Drying hot red pepper using solar tunnel drier

International Nuclear Information System (INIS)

Hossain, M.A; Bala, B.K.

2006-01-01

A solar tunnel drier was used to dry red hot pepper under the tropical weather conditions of Bangladesh in order to investigate its performance and the quality of the drier product. The drier comprises a plastic sheet-covered flat plate collector and a drying tunnel. The drier is arranged to supply hot air to the drying tunnel using two small fans powered by a 40 watt PV module. Fresh red pepper was water blanched before drying. In each drying batch in the solar tunnel drier, 20 kg of dried red pepper with 4 to 6% moisture content (wb) was obtained from 80 kg of fresh red pepper with initial moisture content of 73 to 75% (wb) in 20 to 22 hours of drying while it took 32 to 34 hours to bring down the moisture content of similar sample to 8 to 10% (wb) in sun drying methods. The pepper dried in the solar tunnel drier was completely protected from dust, dirt, rain, insects, birds, rodents and microorganisms and it was a quality-dried product in term of colour and pungency. The solar tunnel drier is recommended for drying of pepper as well as vegetables and fruits in developing countries especially in Bangladesh

Solar Drying in Hot and Dry Climate of Jaipur

OpenAIRE

Parikh, Darshit; Agrawal, G. D.

2016-01-01

Objective of the present study was to design, develop and to carry out detail experimentation and then analyze solar cabinet dryer. For these various types of solar dryer, their principles and design methods, modeling, drying temperature, efficiency, utilization of dryer and payback period were reviewed. In the present study, solar cabinet dryer is constructed at Mechanical Engineering Department, M.N.I.T, Jaipur, latitude (26.01° N). The measurement of solar intensity, temperatures, relative...

Silk cocoon drying in forced convection type solar dryer

International Nuclear Information System (INIS)

Singh, Panna Lal

2011-01-01

The thin layer silk cocoon drying was studied in a forced convection type solar dryer. The drying chamber was provided with several trays on which the cocoons loaded in thin layer. The hot air generated in the solar air heater was forced into drying chamber to avoid the direct exposure of sunlight and UV radiation on cocoons. The drying air temperature varied from 50 to 75 o C. The cocoon was dried from the initial moisture content of about 60-12% (wb). The drying data was fitted to thin layer drying models. Drying behaviour of the silk cocoon was best fitted with the Wang and Singh drying model. Good agreement was obtained between predicted and experimental values. Quality of the cocoons dried in the solar dryer was at par with the cocoons dried in the conventional electrical oven dryer in term of the silk yield and strength of the silk. Saving of electrical energy was about 0.75 kWh/kg cocoons dried. Economic analysis indicated that the NPV of the solar dryer was higher and more stable (against escalation rate of electricity) as compare to the same for electrical oven dryer. Due to simplicity in design and construction and significant saving of operational electrical energy, solar cocoon dryer seems to be a viable option.

Development of Solar Drying Model for Selected Cambodian Fish Species

Science.gov (United States)

Hubackova, Anna; Kucerova, Iva; Chrun, Rithy; Chaloupkova, Petra; Banout, Jan

2014-01-01

A solar drying was investigated as one of perspective techniques for fish processing in Cambodia. The solar drying was compared to conventional drying in electric oven. Five typical Cambodian fish species were selected for this study. Mean solar drying temperature and drying air relative humidity were 55.6°C and 19.9%, respectively. The overall solar dryer efficiency was 12.37%, which is typical for natural convection solar dryers. An average evaporative capacity of solar dryer was 0.049 kg·h−1. Based on coefficient of determination (R 2), chi-square (χ 2) test, and root-mean-square error (RMSE), the most suitable models describing natural convection solar drying kinetics were Logarithmic model, Diffusion approximate model, and Two-term model for climbing perch and Nile tilapia, swamp eel and walking catfish and Channa fish, respectively. In case of electric oven drying, the Modified Page 1 model shows the best results for all investigated fish species except Channa fish where the two-term model is the best one. Sensory evaluation shows that most preferable fish is climbing perch, followed by Nile tilapia and walking catfish. This study brings new knowledge about drying kinetics of fresh water fish species in Cambodia and confirms the solar drying as acceptable technology for fish processing. PMID:25250381

Drying kinetics and characteristics of dried gambir leaves using solar heating and silica gel dessicant

Science.gov (United States)

Hasibuan, R.; Hidayati, J.; Sundari, R.; Wicaksono, A. S.

2018-02-01

A drying combination of solar heating and silica gel dessicant has been applied to dry gambir leaves. The solar energy is captured by a collector to heat the air and the hot air is used to dry gambir leaves in a drying chamber. An exhaust fan in drying chamber assists to draw water molecules from gambir leaves accelerated by silica gel dessicant. This study has investigated the drying kinetics and drying characteristics of gambir leaves drying. In drying operation the air velocity is tuned by a PWM (pulse width modulation) controller to adjust minimum and maximum level, which is based on the rotation speed of the exhaust fan. The results show that the air velocity influenced the drying kinetics and drying characteristics of gambir leaves using solar-dessicant drying at 40 cm distance between exhaust fan and silica gel dessicant.

Force convective solar drying system

International Nuclear Information System (INIS)

Ruslan, M.H.; Othman, M.Y.; Baharuddin Yatim; Kamaruzzaman Sopian; Ibarahim, Z.

2006-01-01

This paper presents design and performance of V-groove back-pass solar collector for solar drying system. In this study three V-groove back-pass solar collector each with dimension of 4.6 m x 1.0 m x 0.15 m have been fabricated for solar drying system. An outdoor test at mean solar intensity for 600-800 Wm -2 by using 0.15m 3 s -1 of air flow rate which also been suggested by (Zeroul et al. 1994) was carried out at Solar Research Energy Park. Universiti Kebangsaan Malaysia. Analysis on the collector performance based on daily data was reported that the value of FR ) e and FRUL was 0.709 ± 0.001 and 5.89 ± 0.31 Wm -2o C -1 respectively with 60-70 o C of output temperature (Ruslan et al. 2001). The three V-groove collectors each with dimension 4.6 m x 0.15 m were connected in series array mounted on the roof of a solar assisted drying system. By using two electric fans of 85W and 2700 rpm each, the speed of air was regulated at 0.11 kgs -1 to 0.31 kgs -1 using a voltage regulator. Performance of the collector based on the thermal analysis showed that at mean daily solar radiation 700 Wm -2 , the output temperature of 52 o C to 73 o C could be achieved using 0.11-0.31 kgs -1 of flow rate. Thermal analysis also showed that the efficiencies of 45% to 61% could be obtains using the same flow rate and solar radiation. Analysis of daily data showed that for radiation from 300 Wm -2 to 1000 Wm -2 the power generated from the collector was within 1.5 kW to 8.9 kW. The study concluded that the levels of the levels of the solar radiation and flow rate used influenced the performance of the collector

Test of solar dryers in Ghana

Energy Technology Data Exchange (ETDEWEB)

Oestergaard Jensen, S. [Teknologisk Institut. SolEnergiCentret, Taastrup (Denmark); Floejgaard Kristensen, E. [Danmarks JordbrugsForskning, Tjele (Denmark); Agyei, F. [FAGOD Ltd. (Ghana); Larsen, T. [Clipper Design Ltd. (Ghana); Nketiah, K.S. [FORIG (Ghana)

2002-06-01

The report describes the tests carried out in Ghana on three solar dryers as part of the project 'Test and Research Project into the Drying of Food and Wood Products with Solar Heat' financed by DANIDA. The main objective of the project was to develop and test solar dryers for crop, fish and wood in Ghana. Three dryers were erected: 1. Solar crop dryer: The solar crop dryer was erected at Silwood Farms at Pokuase about 30 km north of Accra. Silwood Farms grows primarily maize for seed and pineapples, 2. Solar fish dryer: The solar fish dryer was erected at Elite Enterprise Ltd. at Tema about 35 km east-north-east of Accra. Elite Enterprise Ltd. buys and dries fish, 3. Solar wood dryer: The solar wood dryers were erected at Clipper Design Ltd. at Mankoadze about 65 km west-south-west of Accra. Clipper Design Ltd. produces mainly doors. (BA)

Mathematical and computational modeling simulation of solar drying Systems

Science.gov (United States)

Mathematical modeling of solar drying systems has the primary aim of predicting the required drying time for a given commodity, dryer type, and environment. Both fundamental (Fickian diffusion) and semi-empirical drying models have been applied to the solar drying of a variety of agricultural commo...

Development of Solar Drying Model for Selected Cambodian Fish Species

Directory of Open Access Journals (Sweden)

Anna Hubackova

2014-01-01

Full Text Available A solar drying was investigated as one of perspective techniques for fish processing in Cambodia. The solar drying was compared to conventional drying in electric oven. Five typical Cambodian fish species were selected for this study. Mean solar drying temperature and drying air relative humidity were 55.6°C and 19.9%, respectively. The overall solar dryer efficiency was 12.37%, which is typical for natural convection solar dryers. An average evaporative capacity of solar dryer was 0.049 kg·h−1. Based on coefficient of determination (R2, chi-square (χ2 test, and root-mean-square error (RMSE, the most suitable models describing natural convection solar drying kinetics were Logarithmic model, Diffusion approximate model, and Two-term model for climbing perch and Nile tilapia, swamp eel and walking catfish and Channa fish, respectively. In case of electric oven drying, the Modified Page 1 model shows the best results for all investigated fish species except Channa fish where the two-term model is the best one. Sensory evaluation shows that most preferable fish is climbing perch, followed by Nile tilapia and walking catfish. This study brings new knowledge about drying kinetics of fresh water fish species in Cambodia and confirms the solar drying as acceptable technology for fish processing.

Timber drying kilns using solar energy

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-12-15

The objective of this project was to research the potential for solar kilns for drying timber in tropical countries (Guyana, Honduras and Belize) and produce a manual which will provide the knowledge necessary to build and operate a solar kiln. The main output of the project is the manual Solar Heated Timber Drying Kilns - a Manual on their Design and Operation. The manual covers:- background information; selection of construction materials; methods of kiln construction; kiln operation and maintenance procedure. The manual has been designed to provide the necessary knowledge and confidence to build and operate a solar kiln, and ultimately benefit from an improved product. Specifically, the manual will benefit small building construction units, furniture and joinery manufacturers and sawmill operators in developing and developed countries worldwide. (author)

Development and Evaluation of Solar Tunnel Dryer for Commercial Fish Drying

Science.gov (United States)

Mohod, A. G.; Khandetod, Y. P.; Shrirame, H. Y.

2014-01-01

The local practice of drying fish in open sun drying poses problems such as high moisture content, uncontrolled drying and contamination. These problems can be avoided by proper use of improved methods such as the solar tunnel dryer, which results in faster drying of fish. The semi cylindrical walk-in type natural convection solar tunnel dryer, having drying area of 37.5 m2 was developed and evaluated for the drying of fish products in comparison with the conventional method of open sun drying. The experiments were conducted without fish and with fish to evaluate the performance of solar tunnel dryer. The average rise in temperature inside the solar tunnel dryer was found to be 11.24 °C and 18.29 °C over the ambient temperature during no load test in winter and summer respectively. The average 28 % saving in time was observed for selected fish drying using solar tunnel dryer over open sun drying method with average drying efficiency of 19 %. The economics was calculated for drying of prawns ( Parapaeneopsis stylifera) by solar tunnel dryer and open sun drying system on the basis of business as a whole. The economics of the solar tunnel dryer is presented in term of Net present worth, Benefit-Cost Ratio, Payback period, Profitability index and Internal rate of return. The pay back period for solar tunnel dryer was found to be 2.84 years.

Solar air heaters for industrial drying; Aquecedor solar de ar para secagem industrial

Energy Technology Data Exchange (ETDEWEB)

Braga, Everaldo Mendes [Governo do Estado da Paraiba, Joao Pessoa, PB (Brazil). Secretaria de Planejamento e Gestao

2008-07-01

The objective of this study is to encourage the use of solar energy in industrial drying of fruits, with the producers poles, at the same time, promote the rational use of energy for heat, or replacing the hydroelectric and oil derivatives for this purpose. This study is presented in the following chapters: availability of solar energy; details of constructive solar heated air; drying fruit; market. (author)

Performance of a forced convection solar drier integrated with gravel as heat storage material

Energy Technology Data Exchange (ETDEWEB)

Mohanraj, M. [Dr Mahalingam College of Engineering and Technology, Pollachi (India). Dept. of Mechanical Engineering; Chandrasekar, P. [Swinburne Univ. of Technology, Sarawak (Malaysia). School of Engineering Sciences

2009-07-01

Sun drying is the most common method used in India to dry agricultural products such as grains, fruits and vegetables. The rate of drying depends on solar radiation, ambient temperature, wind velocity, relative humidity, initial moisture content, type of crops, crop absorptivity and mass product per unit exposed area. However, this method of spreading the crop in a thin layer on the ground has several disadvantages. This paper reported on a study that focused on developing a forced convection solar drier integrated with heat storage materials for drying various agricultural crops. The indirect forced convection solar drier, integrated with gravel as a sensible heat material, was used to dry pineapple slices under conditions similar to those found in Pollachi, India. The performance of the system was discussed along with the drying characteristics, drying rate, and specific moisture extraction rate. The results showed that the moisture content (wet basis) of pineapple was reduced from about 87.5 to 14.5 per cent (equilibrium moisture content) in about 29 hours in the bottom tray and 32 hours in the top tray. The thermal efficiency of the solar air heater was also reviewed. 9 refs., 5 figs.

Usage of hybrid solar collector system in drying technologies of medical plants

International Nuclear Information System (INIS)

Čiplienė, Aušra; Novošinskas, Henrikas; Raila, Algirdas; Zvicevičius, Egidijus

2015-01-01

Highlights: • Solar radiation energy utilization in drying technologies. • Accumulation of solar radiation energy. • The system comprising two different solar collector types. • Preparation of the drying agent by employing solar radiation energy around the clock. • The energy resources saving technology for medicinal plants’ raw material processing and drying. - Abstract: In the temperate climate zone under natural conditions, medicinal plants drying up to 8–12% moisture content and preparation of the quality medicinal plant’s raw material are complicated tasks. In many cases drying process of medicinal plants raw material, particularly rich in volatile compounds, needs the optimal drying temperatures of 30–45 °C and relative humidity not higher than 50–60%. In Lithuania, located in the northern part of the temperate climate zone, in summer the average temperature of ambient air is 16.1 ± 0.5 °C, and relative humidity is 77.3 ± 1.8%. In order to improve the sorption properties of ambient air, it is heated up to the admissible drying temperature. The experimental dryer was developed comprising two different solar collectors: the air type solar collector with area 12 m 2 for direct heating of the drying agent and the flat-plate type solar collector (8 m 2 ) for accumulation of converted heat energy. The research of motherwort (Leonurus cardiaca L.) drying was carried out in the dryer. It was determined that by combining operation of two different solar collectors, the solar radiation energy for drying agent’s heating could be used continuously around the clock by employing the accumulated energy, in order to compensate the solar irradiance variability and to ensure stability of the drying process. In the daytime the air-type solar collector at an airflow equal to 367 m 3 h −1 , i.e. at comparative flow of the drying agent per ton of dried medicinal plant raw material – 2450 m 3 h −1 , heats the air up to 30 °C when the solar

Yields of Selected Catch Crops in Dry Conditions

Directory of Open Access Journals (Sweden)

Martina Handlířová

2016-01-01

Full Text Available Catch crops mainly reduce soil erosion and leaching of nutrients as well as enrich the soil organic matter. The aim of this research is to evaluate the yields of catch crops of Sinapis alba, Phacelia tanacetifolia, Fagopyrum esculentum, Carthamus tinctorius and Secale cereale v. multicaule, and thus determine the possible applicability of catch crops in areas with high average annual temperature and low precipitation totals. The small-plot field experiment was performed on clay-loam gleyic fluvisol at the Field Experimental Station in Žabčice, Southern Moravia, Czech Republic, within the period of 2006-2014. The catch crops were set up after winter wheat in mid-August. The results have shown a statistically significant difference among different catch crops in yield of dry matter and even among years. The yield of catch crops is mainly dependent on a sufficient supply of water in the soil and the appropriate amount and distribution of rainfall over the growing season. Sinapis alba and Phacelia tanacetifolia regularly reached the highest yields. High yields were also achieved with Fagopyrum esculentum. Due to the method of crop rotation in the Czech Republic, with a predominance of Brassica napus var. napus, it is inappropriate to include Sinapis alba. It is the best to grow Phacelia tanacetifolia and even Fagopyrum esculentum, or a mixture thereof, depending on the use of catch crops.

Experimental Investigation of Solar Drying for Orange Peels by Forced convection

International Nuclear Information System (INIS)

Ben Slama, Romdhane; Mechlouch, Fethi; Ben Daoud, Houcine

2009-01-01

Solar drier does not degrade any more the dried products with the manner of the products dried at the natural sun. The drying unit is composed mainly of a solar air collector and an enclosure of drying. The transformation of the solar radiation into heat is done thanks to the solar collector whose effectiveness is increased by the addition of suitable baffles in the mobile air vein. The efficiency of the collector reaches then 80. The hot air on the outlet side of the collector arrives in the enclosure of drying where the heat transfer with the product to be dried is done by convection. The kinetics drying study shows that in addition to the dependence of the temperature and air velocity of drying, the speed of drying also depends on fragmentation on the product to dry, and mainly, of the product surface in contact with the drying air. Thus, the hygrometry is reduced from 76 to 13 pour cent in one day.. The total efficiency of the drier reached 28 pour cent

Suitability of locally constructed solar dryers for vegetable drying

International Nuclear Information System (INIS)

Seidu, J.M.; Tevor, W.J.; Kotei, R.; Mahama, A.A.; Amoah, R.S.

2008-01-01

Indigenous vegetables and spices are usually common and abundant during the rainy season but unfortunately, almost disappear during the dry season due to inadequate processing because of their high moisture content, poor storage and marketing facilities. A study was therefore conducted to find the possibilities of drying vegetables using locally constructed solar dryers at the Mechanisation section of the University of Education, Mampong Campus. The study was done during the months of March to September, 2004 and six designs of solar panels were used. The panels were constructed using hard wood, binding materials (nails), chicken mesh, nylon net, and black and white polythene sheets. Variations in panels resulted from the type of polythene sheet used (white, black or both), drying platform and shape of the roof. The panels with their interior lined with the black polythene sheet recorded higher temperatures than those with their bases covered with only the chicken mesh and nylon nettings. All the designs recorded higher temperatures than the ambient temperature. The drying of vegetables was observed to be faster in the panels with their drying platforms lined with the black polythene sheet than those with their bases covered with only the chicken mesh and nylon net. Appearance of the vegetables after drying in the solar panels was almost the same as before drying as compared to the open sun drying that got mouldy after drying. Those vegetables that were dried directly on the black polythene sheet however were slightly darker in colour. Solar drying with these locally constructed panels would be a better means of drying vegetables by rural folks. (au)

Nitrogen deficiency in maize. I. Effects on crop growth, development, dry matter partitioning, and kernel set

International Nuclear Information System (INIS)

Uhart, S.A.; Andrade, F.H.

1995-01-01

Variations in N availability affect growth and development of maize (Zea mays L.) and may lead to changes in crop physiological conditions at flowering and in kernel set. The objectives of this study were (i) to establish the effect of N availability on crop development, crop radiation interception, radiation use efficiency, and dry matter partitioning; and (ii) to study the relationship between kernel number and crop growth at flowering and between kernel number and crop N accumulation at flowering. Three experiments with a commercial hybrid (DK636) were carried out under field conditions at the INTA Balcarce Experimental Station, Argentina, without water limitations. The treatments consisted of different radiation levels, obtained by shading, combined with different levels of N availability obtained by the addition of N fertilizer or organic matter to immobilize N. Nitrogen deficiencies delayed both vegetative and reproductive phenological development, slightly reduced leaf emergence rate, and strongly diminished leaf expansion rate and leaf area duration. Nitrogen deficiencies reduced radiation interception as much as radiation use efficiency and their effects on the ear dry mater/total dry matter ratio at harvest were associated with crop growth rate reductions at flowering. Dry matter partitioning to reproductive sinks at flowering and the ear dry matter/total dry matter ratio at harvest were reduced by N shortages. Significant relationships between kernel number and N accumulation rate or crop growth rate at flowering were fitted by linear + plateau functions with thresholds above which kernel number and grain yield did not increase

Better lumber drying process with a non-greenhouse type solar kiln

Energy Technology Data Exchange (ETDEWEB)

Yang, K C

1979-01-01

The preliminary study of using solar energy for lumber drying in NW Ontario is proven applicable and practical by the evidence of data collected. It was found that lumber seasoning using solar energy in the region is more favorable in the summer than in the winter. The most significant advantages of lumber drying with a solar kiln are: (1) low percentage of drying defect lumber produced; (2) higher strength properties of lumber produced; (3) unlimited sources of heat energy from the sun are available. The longer drying periods with a solar kiln as compared to a conventional steam kiln can be overcome by utilizing a supplemental heat system, e.g., wood residue burner to shorten the drying period. However, some improvements and modification of the existing kiln should be done in order to increase the efficiency of the lumber drying system.

A comparative study of direct and indirect solar drying of mango ...

African Journals Online (AJOL)

A comparative study of direct and indirect solar drying of mango. ... Thus, indirect solar dryer was found to be suitable for industrial or semi industrial mango drying, whereas direct solar dryer was appropriate to a family ... HOW TO USE AJOL.

Performance studies of solar tunnel dryer for drying aonla (Embilica Officinalis) pulp

International Nuclear Information System (INIS)

Seveda, M. S.

2012-01-01

A solar tunnel dryer was constructed and evaluated the performance for drying aonla pulp. The dryer consists of a transparent UV stabilized plastic covered solar collector cum drying unit. Evaluation parameters are air temperature, solar insolation, moisture content, relative humidity and airflow rate. A minimum of 111.18 m 2 solar collector area is required to dry a batch 1000 kg aonla pulp in 16 hours (two days drying period). The initial and final moisture content considered were 424.93 and 10.08% dry basis, respectively. It was observed that on an average 43 per cent of higher temperature was obtained in solar tunnel dryer over the ambient temperature. The results obtained during the test period denoted that the maximum gained energy occurred at 13 o'clock hour and then gradually declined since the maximum solar radiation occurred at this time. (author)

Solar heating - a major source of renewable energy

International Nuclear Information System (INIS)

Bosselaar, L.

2001-01-01

Actions that can be taken to increase the uptake of technology for solar water heaters and solar buildings are discussed. An overview of existing technology covers solar water heating, solar buildings, space heating, solar cooling, solar drying, solar desalination. Solar water heating, solar buildings and solar crop drying are discussed individually under the sub-headings of (a) the technology; (b) the market; (c) potential; (d) economics and (e) market acceleration strategies. Other subjects discussed are market acceleration, main opportunities, R and D needs and conclusions. The IEA solar heating and solar cooling programme is described

Mushroom drying with solar assisted heat pump system

International Nuclear Information System (INIS)

Şevik, Seyfi; Aktaş, Mustafa; Doğan, Hikmet; Koçak, Saim

2013-01-01

Highlights: • Experimental investigation of a simple and cost effective solar assisted heat pump system. • Developing of a computer program for a drying system with different scenarios by using PLC. • Obtained less energy input with high coefficients of performance of system and more quality products. • Determination of mushroom drying properties such as moisture content, moisture ratio and drying ratio. - Abstract: In this study, a simple and cost effective solar assisted heat pump system (SAHP) with flat plate collectors and a water source heat pump has been proposed. Mushroom drying was examined experimentally in the drying system. Solar energy (SE) system and heat pump (HP) system can be used separately or together. A computer program has been developed for the system. Drying air temperature, relative humidity, weight of product values, etc. were monitored and controlled with different scenarios by using PLC. This system is cheap, good quality and sustainable and it is modeled for good quality product and increased efficiency. Thus, products could be dried with less energy input and more controlled conditions. Mushrooms were dried at 45 °C and 55 °C drying air temperature and 310 kg/h mass flow rate. Mushrooms were dried from initial moisture content 13.24 g water/g dry matter (dry basis) to final moisture content 0.07 g water/g dry matter (dry basis). Mushrooms were dried by using HP system, SE system and SAHP system respectively at 250–220 min, at 270–165 min and at 230–190 min. The coefficients of performance of system (COP) are calculated in a range from 2.1 to 3.1 with respect to the results of experiments. The energy utilization ratios (EURs) were found to vary between 0.42 and 0.66. Specific moisture extraction rate (SMER) values were found to vary between 0.26 and 0.92 kg/kW h

solar dryer with biomass backup heater for drying fruits

African Journals Online (AJOL)

SOLAR DRYER WITH BIOMASS BACKUP HEATER FOR DRYING FRUITS: DEVELOPMENT AND PERFORMANCE ANALYSIS. ... Journal of Science and Technology (Ghana) ... Most solar dryers rely on only solar energy as the heat source.

Effect of Cover Crops on Vertical Distribution of Leaf Area and Dry Matter of Soybean (Glycine max L. in Competition with Weeds

Directory of Open Access Journals (Sweden)

seyyedeh samaneh hashemi

2017-08-01

Full Text Available Introduction Amount and vertical distribution of leaf area are essential for estimating interception and utilization of solar radiation of crop canopies and, consequently dry matter accumulation (Valentinuz & Tollenaar, 2006. Vertical distribution of leaf area is leaf areas per horizontal layers, based on height (Boedhram et al., 2001. Above-ground biomass is one of the central traits in functional plant ecology and growth analysis. It is a key parameter in many allometric relationships (Niklas & Enquist, 2002. The vertical biomass distribution is considered to be the main determinant of competitive strength in plant species. The presence of weeds intensifies competition for light, with the effect being determined by plant height, position of the branches, and location of the maximum leaf area. So, this experiment was conducted to study the vertical distribution of leaf area and dry matter of soybean canopy in competition with weeds and cover crops. Materials and methods This experiment was performed based on complete randomized block design with 3 replications in center of Agriculture of Joybar in 2013. Soybean was considered as main crop and soybean and Persian clover (Trifolium resupinatum L., fenugreek (Trigonella foenum–graecum L., chickling pea (Lathyrus sativus L. and winter vetch (Vicia sativa L. were the cover crops. Treatments were included cover crops (Persian clover, fenugreek, chickling pea and winter vetch and cover crop planting times (simultaneous planting of soybean with cover crops and planting cover crops three weeks after planting of soybeans and also monoculture of soybeans both in weedy and weed free conditions were considered as controls. Soybean planted in 50 cm row spacing with 5 cm between plants in the same row. Each plot was included 5 rows soybeans. Cover crop inter-seeded simultaneously in the main crop. Crops were planted on 19 May 2013 for simultaneous planting of soybean. The dominant weed species were green

Utilization of parabolic solar collector in wood drying; Utilizacao de coletor solar parabolico na secagem de madeira

Energy Technology Data Exchange (ETDEWEB)

Souza Mendes, Alfredo de

1986-12-31

This study was concerned to concept, to project and to build a parabolic solar collector as a generation source of thermic energy to the conventional drying of wood, jointed to a drying environment and to evaluate its efficiency. In this sense, prototypes of a solar collector and a conventional dry kiln were built. The collector with linear focus, was provided with a solar photoelectric tracking system. The dry kiln had semiautomatic control of temperature and a capacity to dry 0,3 m deg 3 of wood. All the steps of the construction of the system are presented with details. (author). 14 figs., 8 tabs., 73 refs

Drying firewood in a temporary solar kiln: a case study.

Science.gov (United States)

George R. Sampson; Anthony F. Gasbarro

1986-01-01

A pilot study was undertaken to determine drying rates for small diameter, unsplit paper birch firewood that was dried: (1) in a conventional top-covered pile; (2) in a simple, temporary solar kiln; and (3) in tree length. Drying rates were the same for firewood piles whether they were in the temporary solar kilns or only covered on top to keep rain or snow from...

Design of a solar-assisted drying system using the double-pass solar collector

International Nuclear Information System (INIS)

Sopian, K.; Daud, W.R.; Supranto; Othman, M.Y.; Yatim, B.

2000-01-01

A solar-assisted drying system that uses the double-pass solar collector with porous media in the second channel has been designed and constructed at the Solar Energy Research Park, Universiti Kebangsaan Malaysia. The drying system has a total of six double-pass solar collectors. Each collector has a length of 240 cm and a width of 120 cm. The upper channel depth is 3.5 cm and the lower channel depth is 10.5 cm. The lower channel is filled up with steel wool as the porous media. The solar collectors are arranged as 2 banks of 3 collectors each in series. Internal manifold are used to connect the collectors. An auxiliary heater source is installed to supply heat under unfavourable solar radiation conditions. An on/off controller is used to control the startup and shutdown of the auxiliary heater. An outlet temperature of 80-90 0 C can be achieved at a solar radiation range of 800-900 W/m 3 , ambient temperature of 29 degree C and flow rate of O.20 kg/s. (Author)

Mycotoxin risks and toxigenic fungi in date, prune and dried apricot among Mediterranean crops

Directory of Open Access Journals (Sweden)

Hayrettin OZER

2012-05-01

Full Text Available Dried fruit is fruit that is preserved by removing the original water content naturally, through sun drying or artificially, by the use of specialized dryers or dehydrators. Dried fruit has a long tradition of use dating back to the fourth millennium BC in Mesopotamia and is prized because of its sweet taste, nutritive value and long shelf life. Traditional dried fruits such as raisins, figs, dates, apricots and prunes have been a staple of Mediterranean diets for millennia. The Mediterranean region is very favourable for production of dried fruits, not only with its climatic conditions, but also its exceptional fertile lands. Additionally, proximity to trade routes historically has allowed Mediterranean countries more access to dried fruits than landlocked countries. Today, dried fruit consumption is widespread. Nearly half of the dried fruits sold throughout the world are raisins, followed by dates, prunes (dried plums, figs, apricots, peaches, apples and pears. Dates, prunes, apricots, figs and raisins are the major dried fruits produced in the Mediterranean area. Dried fruits are not perishable but can support mold growth, some of which can produce mycotoxins. Occurence of toxigenic molds and mycotoxins on these dried fruits can be a problem in the Mediterranean basin, as in the other parts of the world, being a health hazard to the population as well as a trade issue for the export of local products. Although the most important mycotoxins occuring in Mediterranean crops are aflatoxins (B1, B2, G1 and G2 and ochratoxin A, the type and level of mycotoxins and toxigenic molds vary by crop and also by country and in some cases geographic location within a country. In this review mycotoxin risks and toxigenic fungi in date, prune and dried apricot among Mediterranean crops are reported and discussed.

Performance of a solar dryer using hot air from roof-integrated solar collectors for drying herbs and spices

Energy Technology Data Exchange (ETDEWEB)

Janjai, S.; Tung, P. [Silpakorn University, Pathom (Thailand). Dept. of Physics

2005-11-01

A solar dryer for drying herbs and spices using hot air from roof-integrated solar collectors was developed. The dryer is a bin type with a rectangular perforated floor. The bin has a dimension of 1.0 m x 2.0 m x 0.7 m. Hot air is supplied to the dryer from fiberglass-covered solar collectors, which also function as the roof of a farmhouse. The total area of the solar collectors is 72 m{sup 2}. To investigate its performance, the dryer was used to dry four batches of rosella flowers and three batches of lemon-grasses during the year 2002-2003. The dryer can be used to dry 200 kg of rosella flowers and lemon-grasses within 4 and 3 days, respectively. The products being dried in the dryer were completely protected from rains and insects and the dried products are of high quality. The solar air heater has an average daily efficiency of 35% and it performs well both as a solar collector and a roof of a farmhouse. (author)

Energy and exergy analyses of solar drying process of pistachio

International Nuclear Information System (INIS)

Midilli, A.; Kucuk, H.

2003-01-01

This paper is concerned with the energy and exergy analyses of the drying process of shelled and unshelled pistachios using a solar drying cabinet. Using the first law of thermodynamics, energy analysis was carried to estimate the amounts of energy gained from solar air collectors and the ratios of energy utilization. However, exergy analysis was accomplished to determine the location, type, and magnitude of exergy losses during the solar drying process by applying the second law of thermodynamics. It was deduced that the exergy losses took place mostly in the 15th shelf where the available energy was less utilized. Moreover, the shelled and unshelled pistachios are sufficiently dried in the ranges between 40 and 60 deg. C and 37 and 62% of relative humidity at 1.23 m s -1 of drying air velocity in 6 h despite the exergy losses of 0.15-3.08 kJ kg -1

Mathematical modeling of thin layer drying of pistachio by using solar energy

Energy Technology Data Exchange (ETDEWEB)

Midilli, A [University of Nigde (Turkey). Dept. of Mechanical Engineering; Kucuk, H [Karadeniz Technical Univ., Trabzon (Turkey). Dept. of Mechanical Engineering

2003-05-01

This paper presents a mathematical modeling of thin layer forced and natural solar drying of shelled and unshelled pistachio samples. In order to estimate and select the suitable form of solar drying curves, eight different mathematical models, which are semi-theoretical and/or empirical, were applied to the experimental data and compared according to their coefficients of determination (r,{chi}{sup 2}), which were predicted by non-linear regression analysis using the Statistical Computer Program. It was deduced that the logarithmic model could sufficiently describe thin layer forced solar drying of shelled and unshelled pistachio, while the two term model could define thin layer natural solar drying of these products in evaluation by considering the coefficients of determination, r{sub sfsd}=0.9983, {chi}{sup 2}{sub sfsd}=2.697x10{sup -5}; r{sub ufsd}=0.9990, {chi}{sup 2}{sub ufsd}=1.639x10{sup -5} for thin layer forced solar drying and r{sub snsd}=0.9990, {chi}{sup 2}{sub snsd}=3.212x10{sup -6}; r{sub unsd}=0.9970, {chi}{sup 2}{sub unsd}=4.590x10{sup -5} for thin layer natural solar drying. (Author)

Modelling and experimental validation of thin layer indirect solar drying of mango slices

Energy Technology Data Exchange (ETDEWEB)

Dissa, A.O.; Bathiebo, J.; Kam, S.; Koulidiati, J. [Laboratoire de Physique et de Chimie de l' Environnement (LPCE), Unite de Formation et de Recherche en Sciences Exactes et Appliquee (UFR/SEA), Universite de Ouagadougou, Avenue Charles de Gaulle, BP 7021 Kadiogo (Burkina Faso); Savadogo, P.W. [Laboratoire Sol Eau Plante, Institut de l' Environnement et de Recherches Agricoles, 01 BP 476, Ouagadougou (Burkina Faso); Desmorieux, H. [Laboratoire d' Automatisme et de Genie des Procedes (LAGEP), UCBL1-CNRS UMR 5007-CPE Lyon, Bat.308G, 43 bd du 11 Nov. 1918 Villeurbanne, Universite Claude Bernard Lyon1, Lyon (France)

2009-04-15

The thin layer solar drying of mango slices of 8 mm thick was simulated and experimented using a solar dryer designed and constructed in laboratory. Under meteorological conditions of harvest period of mangoes, the results showed that 3 'typical days' of drying were necessary to reach the range of preservation water contents. During these 3 days of solar drying, 50%, 40% and 5% of unbound water were eliminated, respectively, at the first, second and the third day. The final water content obtained was about 16 {+-} 1.33% d.b. (13.79% w.b.). This final water content and the corresponding water activity (0.6 {+-} 0.02) were in accordance with previous work. The drying rates with correction for shrinkage and the critical water content were experimentally determined. The critical water content was close to 70% of the initial water content and the drying rates were reduced almost at 6% of their maximum value at night. The thin layer drying model made it possible to simulate suitably the solar drying kinetics of mango slices with a correlation coefficient of r{sup 2} = 0.990. This study thus contributed to the setting of solar drying time of mango and to the establishment of solar drying rates' curves of this fruit. (author)

Estimation of paddy water temperature during crop development

International Nuclear Information System (INIS)

Centeno, H.G.S.; Horie, T.

1996-01-01

The crop meristem is in direct contact with paddy water during crop's vegetative stage. Ambient air temperature becomes an important factor in crop development only when internodes elongate sufficiently for the meristem to rise above the water surface. This does not occur until after panicle initiation. Crop growth at vegetative stage is affected more by water temperature than the most commonly measured air temperature. During transplanting in 1992 dry season, the maximum paddy water temperature was 10 deg C higher than the maximum air temperature. For rice crop models, the development of a submodel to estimate water temperature is important to account the effect of paddy water temperature on plant growth. Paddy water temperature is estimated from mean air temperature, solar radiation, and crop canopy. The parameters of the model were derived using the simplex method on data from the 1993 wet- and dry-season field experiments at IRRI

Energy and exergy analyses of solar drying process of pistachio

Energy Technology Data Exchange (ETDEWEB)

Midilli, A [University of Nigde (Turkey). Dept. of Mechanical Engineering; Kucuk, H [Karadeniz Technical Univ., Trabzon (Turkey). Dept. of Mechanical Engineering

2003-05-01

This paper is concerned with the energy and exergy analyses of the drying process of shelled and unshelled pistachios using a solar drying cabinet. Using the first law of thermodynamics, energy analysis was carried to estimate the amounts of energy gained from solar air collectors and the ratios of energy utilization. However, exergy analysis was accomplished to determine the location, type, and magnitude of exergy losses during the solar drying process by applying the second law of thermodynamics. It was deduced that the exergy losses took place mostly in the 15th shelf where the available energy was less utilized. Moreover, the shelled and unshelled pistachios are sufficiently dried in the ranges between 40 and 60{sup o}C and 37 and 62% of relative humidity at 1.23 m s{sup -1} of drying air velocity in 6 h despite the exergy losses of 0.15-3.08 kJ kg{sup -1}. (Author)

Estimating Water Footprints of Vegetable Crops: Influence of Growing Season, Solar Radiation Data and Functional Unit

Directory of Open Access Journals (Sweden)

Betsie le Roux

2016-10-01

Full Text Available Water footprint (WF accounting as proposed by the Water Footprint Network (WFN can potentially provide important information for water resource management, especially in water scarce countries relying on irrigation to help meet their food requirements. However, calculating accurate WFs of short-season vegetable crops such as carrots, cabbage, beetroot, broccoli and lettuce presented some challenges. Planting dates and inter-annual weather conditions impact WF results. Joining weather datasets of just rainfall, minimum and maximum temperature with ones that include solar radiation and wind-speed affected crop model estimates and WF results. The functional unit selected can also have a major impact on results. For example, WFs according to the WFN approach do not account for crop residues used for other purposes, like composting and animal feed. Using yields in dry matter rather than fresh mass also impacts WF metrics, making comparisons difficult. To overcome this, using the nutritional value of crops as a functional unit can connect water use more directly to potential benefits derived from different crops and allow more straightforward comparisons. Grey WFs based on nitrogen only disregards water pollution caused by phosphates, pesticides and salinization. Poor understanding of the fate of nitrogen complicates estimation of nitrogen loads into the aquifer.

Drying of mint leaves in a solar dryer and under open sun: Modelling, performance analyses

International Nuclear Information System (INIS)

Akpinar, E. Kavak

2010-01-01

In this study was investigated the thin-layer drying characteristics in solar dryer with forced convection and under open sun with natural convection of mint leaves, and, performed energy analysis and exergy analysis of solar drying process of mint leaves. An indirect forced convection solar dryer consisting of a solar air collector and drying cabinet was used in the experiments. The drying data were fitted to ten the different mathematical models. Among the models, Wang and Singh model for the forced solar drying and the natural sun drying were found to best explain thin-layer drying behaviour of mint leaves. Using the first law of thermodynamics, the energy analysis throughout solar drying process was estimated. However, exergy analysis during solar drying process was determined by applying the second law of thermodynamics. Energy utilization ratio (EUR) values of drying cabinet varied in the ranges between 7.826% and 46.285%. The values of exergetic efficiency were found to be in the range of 34.760-87.717%. The values of improvement potential varied between 0 and 0.017 kJ s -1 . Energy utilization ratio and improvement potential decreased with increasing drying time and ambient temperature while exergetic efficiency increased.

Investment opportunity : the FPL low-cost solar dry kiln

Science.gov (United States)

George B. Harpole

1988-01-01

Two equations are presented that may be used to estimate a maximum investment limit and working capital requirements for the FPL low-cost solar dry kiln systems. The equations require data for drying cycle time, green lumber cost, and kiln-dried lumber costs. Results are intended to provide a preliminary estimate.

Dimensioning, construction and commissioning of a coffee beans drying system with use of solar collectors

International Nuclear Information System (INIS)

Mora Vindas, Allan Gerardo

2014-01-01

A system of low-cost solar drying of coffee beans is dimensioned, built and commissioned by using solar collectors based on recycled aluminum cans. The information is collected from literature about the drying of coffee, types of drying and the various types of solar dryers.The coffee beans drying system is conceptualized and sized based on a solar collector constructed of aluminum cans as solar radiation absorbing material. The grain drying system is then built in coffee benefit CoopeTarrazu to all provided by the company and help materials and labor facilities. A guide to implementation of solar drying technology with general information is tailored to implement, select, build and maintain a solar grain dryer in Central America. The launch of the drying system was made by checking the proper functioning of the system and measurement instruments variables selected to calculate the efficiency of the system. The drying system is tested with a load of 45 kg of coffee bean, using a flow of air through natural convection to operate the system with the exclusive use of renewable energy. The grain is drying from a humidity of 50% (b.n), up to a humidity between 11% and 13% (b.n), which is the range generally used for the safe storage of grain. Facts of solar radiation, temperature, air velocity, relative humidity and grain humidity were taken to determine the behavior of the sized system. The maximum thermal efficiency achieved by the solar collector is determined constructed of 18%, with an air flow of 0.013 kg/s and a solar radiation 1138 W/m 2 . The average drying efficiency during experimentation was 17.8%, which is among the range of efficiencies for the type of drying equipment. Best thermal efficiencies were obtained from the solar collector built that the commercial solar collector compared. Controlling the flow of air into the equipment is recommended in order to improve the thermal efficiency and drying equipment, using blowers, fans or induced draft chimney

Thin layer convective solar drying and mathematical modeling of prickly pear peel (Opuntia ficus indica)

International Nuclear Information System (INIS)

Lahsasni, Siham; Kouhila, Mohammed; Mahrouz, Mostafa; Idlimam, Ali; Jamali, Abdelkrim

2004-01-01

This paper presents the thin layer convective solar drying and mathematical modeling of prickly pear peel. For these purposes, an indirect forced convection solar dryer consisting of a solar air collector, an auxiliary heater, a circulation fan and a drying cabinet is used for drying experiments. Moreover, the prickly pear peel is sufficiently dried in the ranges of 32 to 36 deg. C of ambient air temperature, 50 to 60 deg. C of drying air temperature, 23 to 34% of relative humidity, 0.0277 to 0.0833 m 3 /s of drying air flow rate and 200 to 950 W/m 2 of daily solar radiation. The experimental drying curves show only a falling drying rate period. The main factor in controlling the drying rate was found to be the drying air temperature. The drying rate equation is determined empirically from the characteristic drying curve. Also, the experimental drying curves obtained were fitted to a number of mathematical models. The Midilli-Kucuk drying model was found to satisfactorily describe the solar drying curves of prickly pear peel with a correlation coefficient (r) of 0.9998 and chi-square (χ 2 ) of 4.6572 10 -5

Solar radiation availability for tomato cropping during winter in Santa Maria, RS, Brazil

International Nuclear Information System (INIS)

Estefanel, V.; Buriol, G.A.; Andriolo, J.L.; Lima, C.P.; Luzzi, N.

1998-01-01

The probability of occurrence of days with solar radiation bellow the critical value for the development of tomato inside greenhouse in Santa Maria, Rio Grande do Sul State, were calculated during May, June, July and August. It was considered the flue density of solar radiation of 200 cal cm -2 dia -1 as the lowest value to tomato growth and 180 cal cm -2 dia -1 as the low value reference of solar radiation for crop growth. Daily values of solar radiation were estimated by sunshine duration during the time period from 1912 to 1996. Results showed that the availability of solar radiation in Santa Maria was lower than the required by tomato crop inside plastic greenhouse during Winter, mainly in June and July. (author) [pt

Thin layer convective solar drying and mathematical modeling of prickly pear peel (Opuntia ficus indica)

Energy Technology Data Exchange (ETDEWEB)

Lahsasni, S.; Mahrouz, M. [Unite de Chimie Agroalimentaire (LCOA), Faculte des Sciences Semlalia, Marrakech (Morocco); Kouhila, M.; Idlimam, A.; Jamali, A. [Ecole Normale Superieure, Marrakech (Morocco). Lab. d' Energie Solaire et Plantes Aromatiques et Medicinales

2004-02-01

This paper presents the thin layer convective solar drying and mathematical modeling of prickly pear peel. For these purposes, an indirect forced convection solar dryer consisting of a solar air collector, an auxiliary heater, a circulation fan and a drying cabinet is used for drying experiments. Moreover, the prickly pear peel is sufficiently dried in the ranges of 32 to 36 {sup o} C of ambient air temperature, 50 to 60 {sup o}C of drying air temperature, 23 to 34% of relative humidity, 0.0277 to 0.0833 m{sup 3}/s of drying air flow rate and 200 to 950 W/m{sup 2} of daily solar radiation. The experimental drying curves show only a falling drying rate period. The main factor in controlling the drying rate was found to be the drying air temperature. The drying rate equation is determined empirically from the characteristic drying curve. Also, the experimental drying curves obtained were fitted to a number of mathematical models. The Midilli-Kucuk drying model was found to satisfactorily describe the solar drying curves of prickly pear peel with a correlation coefficient (r) of 0.9998 and chi-square ({chi}{sup 2}) of 4.6572 10{sup -5}. (Author)

Solar-assisted drying of timber at industrial scale: management paper

African Journals Online (AJOL)

While ambient air drying depends on the weather conditions, conventional hightemperature dryers cause high investments and energy costs. Up to now, solar dryers could not be established in industrial timber production, due to their insufficient drying capacity and the lack of an adequate control of the drying conditions.

Investigation into solar drying of potato: effect of sample geometry on drying kinetics and CO2 emissions mitigation.

Science.gov (United States)

Tripathy, P P

2015-03-01

Drying experiments have been performed with potato cylinders and slices using a laboratory scale designed natural convection mixed-mode solar dryer. The drying data were fitted to eight different mathematical models to predict the drying kinetics, and the validity of these models were evaluated statistically through coefficient of determination (R(2)), root mean square error (RMSE) and reduced chi-square (χ (2)). The present investigation showed that amongst all the mathematical models studied, the Modified Page model was in good agreement with the experimental drying data for both potato cylinders and slices. A mathematical framework has been proposed to estimate the performance of the food dryer in terms of net CO2 emissions mitigation potential along with unit cost of CO2 mitigation arising because of replacement of different fossil fuels by renewable solar energy. For each fossil fuel replaced, the gross annual amount of CO2 as well as net amount of annual CO2 emissions mitigation potential considering CO2 emissions embodied in the manufacture of mixed-mode solar dryer has been estimated. The CO2 mitigation potential and amount of fossil fuels saved while drying potato samples were found to be the maximum for coal followed by light diesel oil and natural gas. It was inferred from the present study that by the year 2020, 23 % of CO2 emissions can be mitigated by the use of mixed-mode solar dryer for drying of agricultural products.

Convective drying of chilies using a concentrating solar collector

International Nuclear Information System (INIS)

Hanif, M.; Khattak, M.K.; Aamir, M.

2015-01-01

A concentrating solar collector was developed for convective drying of green chilies by providing optimum drying environment. A temperature in the range of 45-65 degree C and relative humidity of less than 10% was observed during the drying period provided by the solar collector from 9.00 am to 5.00 pm. Different levels of drying temperature and air mass flow rates were tested to find their effect on drying time of the chilies. The experiment was laid out as a randomized complete block design with a factorial arrangement of the treatments consisting of 3 levels of temperature and 3 levels of air mass flow rate, replicated 3 times. Drying temperature and air mass flow rates effected the drying time significantly. The means comparison showed that minimum drying time of 17.96 h was recorded at high temperature of 65 degree C followed by a drying time of 20.27 and 21.43 h at temperatures of 55 and 45 degree C. The means of air mass flow rates showed that minimum drying time of 18.49 h was noted at high air mass flow rate of 3.50 kg min-1 followed by 20.32 and 20.86 h at air mass flow rates of 1.5 and 2.30 kg min-l. Chilies dried at temperature of 65 degree C and air mass flow rate of 3.5 kg min-1 showed an average drying rate of 0.02 g(H20)hrl cm-2as compared to the slow drying rates at 55 and 45 degree C. It was concluded that chilies must be dried at high temperature and high air mass flow rates to get on time quality dried chilies. (author)

Thin layer modelling of Gelidium sesquipedale solar drying process

International Nuclear Information System (INIS)

Ait Mohamed, L.; Ethmane Kane, C.S.; Kouhila, M.; Jamali, A.; Mahrouz, M.; Kechaou, N.

2008-01-01

The effect of air temperature and air flow rate on the drying kinetics of Gelidium sesquipedale was investigated in convective solar drying. Drying was conducted at 40, 50 and 60 deg. C. The relative humidity was varied from 50% to 57%, and the drying air flow rate was varied from 0.0277 to 0.0833 m 3 /s. The expression for the drying rate equation is determined empirically from the characteristic drying curve. Thirteen mathematical models of thin layer drying are selected in order to estimate the suitable model for describing the drying curves. The two term model gives the best prediction of the drying curves and satisfactorily describes the drying characteristics of G. sesquipedale with a correlation coefficient R of 0.9999 and chi-square (χ 2 ) of 3.381 x 10 -6

Solar drying of rose (Rosa sp.) petals

Energy Technology Data Exchange (ETDEWEB)

Balladin, D.A.; Headley, Oliver [University of the West Indies, Center for Resource Management and Environmental Studies, St. Michael (Barbados)

1999-10-01

The rose (Rosa sp.) petals can be dried after 2 days at about 30degC reaching an equilibrium moisture content after 16 h using the solar wire basket dryer. The initial moisture content (wet wt basis) and final moisture content (dry wt basis), determined by the Dean-Stark toluene were 65.7 and 25.2% respectively. The intensity of the rose red coloured pigment (pelargonidin) decreased by a factor of 2.5 after drying. The pelargonidin ethanoic extract as an acid-base indicator, has a K{sub 4} value of 1 x 10{sup -4} mol 1{sup -1} and pH of end point 4 and imbibed on filter paper and allowed to air dry for 5 min showed excellent properties as acid-based test tapes. (Author)

Study on effectiveness of continuous solar dryer integrated with desiccant thermal storage for drying cocoa beans

Directory of Open Access Journals (Sweden)

Sari Farah Dina

2015-03-01

Full Text Available The main objective is to assess effectiveness of continuous solar dryer integrated with desiccant thermal storage for drying cocoa beans. Two type of desiccants were tested, molecular sieve 13× (Na86 [(AlO286·(SiO2106]·264H2O as an adsorbent type and CaCl2 as an absorbent type. The results revealed that during sunshine hours, the maximum temperature within the drying chamber varied from 40 °C to 54 °C. In average, it was 9–12 °C higher than ambient temperature. These temperatures are very suitable for drying cocoa beans. During off-sunshine hours, humidity of air inside the drying chamber was lower than ambient because of the desiccant thermal storage. Drying times for intermittent directs sun drying, solar dryer integrated with adsorbent, and solar dryer integrated with absorbent were 55 h, 41 h, and 30 h, respectively. Specific energy consumptions for direct sun drying, solar dryer integrated with adsorbent, and solar dryer integrated with absorber were 60.4 MJ/kg moist, 18.94 MJ/kg moist, and 13.29 MJ/kg moist, respectively. The main conclusion can be drawn here is that a solar dryer integrated with desiccant thermal storage makes drying using solar energy more effective in term of drying time and specific energy consumption.

Thin layer modelling of Gelidium sesquipedale solar drying process

Energy Technology Data Exchange (ETDEWEB)

Ait Mohamed, L. [Laboratoire d' Energie Solaire et des Plantes Aromatiques et Medicinales, Ecole Normale Superieure, BP 2400, Marrakech (Morocco); Faculte des Sciences Semlalia, BP 2390, Marrakech (Morocco); Ethmane Kane, C.S. [Faculte des Sciences de Tetouan, BP 2121, Tetouan (Morocco); Kouhila, M.; Jamali, A. [Laboratoire d' Energie Solaire et des Plantes Aromatiques et Medicinales, Ecole Normale Superieure, BP 2400, Marrakech (Morocco); Mahrouz, M. [Faculte des Sciences Semlalia, BP 2390, Marrakech (Morocco); Kechaou, N. [Ecole Nationale d' Ingenieurs de Sfax, BPW 3038 (Tunisia)

2008-05-15

The effect of air temperature and air flow rate on the drying kinetics of Gelidium sesquipedale was investigated in convective solar drying. Drying was conducted at 40, 50 and 60 C. The relative humidity was varied from 50% to 57%, and the drying air flow rate was varied from 0.0277 to 0.0833 m{sup 3}/s. The expression for the drying rate equation is determined empirically from the characteristic drying curve. Thirteen mathematical models of thin layer drying are selected in order to estimate the suitable model for describing the drying curves. The two term model gives the best prediction of the drying curves and satisfactorily describes the drying characteristics of G. sesquipedale with a correlation coefficient R of 0.9999 and chi-square ({chi}{sup 2}) of 3.381 x 10{sup -6}. (author)

Development of a Solar Assisted Drying System Using Double-Pass Solar Collector with Finned Absorber

International Nuclear Information System (INIS)

Azmi, M S M; Sopian, K; Ruslan, M H; Fudholi, A; Majid, Z A A; Yasin, J M; Othman, M Y

2012-01-01

The Solar Energy Research Group, Universiti Kebangsaan Malaysia, International Islamic University Malaysia and Yayasan FELDA has designed and constructed a solar assisted drying system at OPF FELDA Factory, Felda Bukit Sagu 2, Kuantan, Pahang. The drying system has a total of six double-pass solar collectors. Each collector has a length of 480 cm and a width of 120 cm. The first channel depth is 3.5 cm and the second channel depth is 7 cm. Longitudinal fins made of angle aluminium, 0.8 mm thickness were attached to the bottom surface of the absorber plate. The solar collectors are arranged as two banks of three collectors each in series. Internal manifold are used to connect the collectors. Air enters through the first channel and then through the second channel of the collector. An auxiliary heater source is installed to supply heat under unfavourable solar radiation condition. An on/off controller is used to control the startup and shutdown of the auxiliary heater. An outlet temperature of 70–75 °C can be achieved at solar radiation range of 800–900 W/m 2 and flow rate of 0.12 kg/s. The average thermal efficiency of a solar collector is approximately 37%.

Development of a Solar Assisted Drying System Using Double-Pass Solar Collector with Finned Absorber

Science.gov (United States)

Azmi, M. S. M.; Othman, M. Y.; Sopian, K.; Ruslan, M. H.; Majid, Z. A. A.; Fudholi, A.; Yasin, J. M.

2012-09-01

The Solar Energy Research Group, Universiti Kebangsaan Malaysia, International Islamic University Malaysia and Yayasan FELDA has designed and constructed a solar assisted drying system at OPF FELDA Factory, Felda Bukit Sagu 2, Kuantan, Pahang. The drying system has a total of six double-pass solar collectors. Each collector has a length of 480 cm and a width of 120 cm. The first channel depth is 3.5 cm and the second channel depth is 7 cm. Longitudinal fins made of angle aluminium, 0.8 mm thickness were attached to the bottom surface of the absorber plate. The solar collectors are arranged as two banks of three collectors each in series. Internal manifold are used to connect the collectors. Air enters through the first channel and then through the second channel of the collector. An auxiliary heater source is installed to supply heat under unfavourable solar radiation condition. An on/off controller is used to control the startup and shutdown of the auxiliary heater. An outlet temperature of 70-75 °C can be achieved at solar radiation range of 800-900 W/m2 and flow rate of 0.12 kg/s. The average thermal efficiency of a solar collector is approximately 37%.

Preservation of fruits and vegetables using solar dryers. A comparative study for solar and natural drying of grapes, figs, tomatoes and onions. IV. temperature measurements, calculating the generated energy and dryer efficiency during drying

International Nuclear Information System (INIS)

Sehery, A.A.; Gallali, Y.M.; Shoshan, H.

2000-01-01

This study has taken four axis, first, design and construction of the dryer, secondly, microbial load determination, thirdly, chemical and sensory evaluation data. The results of these three parts were published earlier at the International Congress on Application of Solar and Renewable Energy, Food Science and Technology and World Renewable Energy Congress V, Cairo, Egypt, 1992, 1996 and Florence, Italy, 1998, respectively. The whole study was oriented towards comparing the solar (three modes, direct, indirect, and mixed) and natural drying. The fourth part of the study is dealing with some parameters affecting drying as temperature measurement, calculating the generated energy and the dryer efficiency during drying periods. Drying temperature is considered the most important factor in the drying operation, since the accuracy of temperature measurement gives the correct results and right indication for the approval of these scientific methods in the drying operation and the design of solar dryers. In this project, we depended on temperature measurements at different points by means of thermocouples fixed in the heat collector and the drying chamber. The average temperature outside the dryer ranged from 21-41 degree C. That of the heat collector were 40-75 degree C and those of the drying chamber were in the range of 40-73 degree C. The radiation measurements calculated depending on the results recorded by the solar center instruments from 5/8/95 - 16/10/95. The thermal energy existing from the heat collector to the drying chamber during the drying period was measured using the equation of Holland. From the investigation results, we can conclude that in all trials, solar drying was a more efficient method for drying all samples of fruits and vegetables, especially for grapes, figs and onion. Grapes dried using mixed mode from 83 % to 30 % moisture in 4 days at an average temperature of 55 degree C while natural drying reduced the moisture to 57% for the same period

a comparative study of direct and indirect solar drying of mango

African Journals Online (AJOL)

BARTH EKWUEME

appropriate to a family scale traditional mango drying. ... before its marketing. Also, direct ..... measured using a digital probe thermohygrometer of ...... Comparison of direct and indirect solar drying kinetics Amelie and Brooks mango varieties.

Optimization design of solar enhanced natural draft dry cooling tower

International Nuclear Information System (INIS)

Zou, Zheng; Guan, Zhiqiang; Gurgenci, Hal

2013-01-01

Highlights: • We proposed a cost model for solar enhanced natural draft dry cooling tower. • We proposed an optimization scheme for this new cooling system. • We optimally designed one for a 50 MW EGS geothermal plant as a demonstration. • Results proved its economic advantages for EGS geothermal application. - Abstract: This paper proposed an optimization scheme for solar enhanced natural draft dry cooling tower design, in which a detailed cost model was proposed including capital, labour, maintenance and operation costs of each component. Based on the developed cost model, the optimal design option can be identified in terms of the relatively lower annual cost and the relatively higher total extra income over the Solar Enhanced Natural Draft Dry Cooling Tower (SENDDCT) lifetime. As a case study, a SENDDCT was optimally designed to meet the cooling demand for a 50 MW geothermal power plant with Engineered Geothermal System (EGS) technology. The results showed that the optimized SENDDCT not only has better cooling performance during the daytime but also is a cost effective option for EGS geothermal power plants

Solar drying: An appropriate technology for the north Argentina; Secado solar: Una tecnologia apropiada para el norte argentino

Energy Technology Data Exchange (ETDEWEB)

Zurlo, Hugo D; Vergara, Liliana; Spotorno, Ruben; Benitez, Francisco; De Pedro, Jorge; Cervino, Veronica; Monzon, Sergio [Universidad Tecnologica Nacional, Chaco (Argentina)

2000-07-01

The results concerning to solar drying of nutritious products for rehearsed a low cost solar dryer, adapted to the area, composed by a plane solar collector of 2 m{sup 2} and a drying camera with capacity for, approximately, 5 kg of product. The objectives of the work were: a) to develop a low cost solar dry, capable to dehydrate products for human alimentary use; b) to transfer the developed technology to low resources rural communities through the INCUPO (Institute of Popular Culture) and to small producers through the INTA (National Institute of Agricultural Technology) and c) to diffuse the practice of the solar drying among small producers. The diffusion and transfer of the developed technology to small rural producers, contribute to improve their quality of life when facilitating them additional revenues for productive diversification, besides the contribution to the sustainable use of the forest like source of non conventional nutritious resources contributing to the task of cultural rescue faced by organizations like the INCUPO. [Spanish] Se exponen los resultados concernientes al secado solar de productos alimenticios para consumo humano. Se diseno, construyo y ensayo un secador solar de bajo costo, adaptado a la zona, compuesto por un colector solar plano de 2m{sup 2} y una camara de secado con capacidad para, aproximadamente, 5 kg de producto fresco. Los objetivos del trabajo fueron: a) desarrollar un secadero solar de bajo costo, apto para deshidratar productos para uso alimentario humano; b) transferir la tecnologia desarrollada a comunidades rurales de bajos recursos a traves del INCUPO (Instituto de Cultura Popular) y a pequenos productores a traves del INTA (Instituto Nacional de Tecnologia Agropecuaria) y c) difundir la practica del secado solar entre productores frutihorticolas. La difusion y transferencia de la tecnologia desarrollada a pequenos productores rurales, contribuye a mejorar su calidad de vida al posibilitarles ingresos adicionales

Adaptation to a warming-drying trend through cropping system adjustment over three decades: A case study in the northern agro-pastural ecotone of China

Science.gov (United States)

Zhang, Jingting; An, Pingli; Pan, Zhihua; Hao, Baozhen; Wang, Liwei; Dong, Zhiqiang; Pan, Xuebiao; Xue, Qingwu

2015-06-01

Long-term field monitoring data and historical crop data are useful to assess the impacts of climate change and to manage cropping systems. The objectives of this study are to understand the cropping system response to a warming-drying trend in the northern agro-pastural ecotone (NAE) of China and to document how farmers can adapt to the warming-drying trend by changing cropping system structure and adjusting planting date. The results indicate that a significant warming-drying trend existed in the NAE from 1980 to 2009, and this trend significantly decreased crop (spring wheat, naked oat, and potato) yields. Furthermore, the yield decreased by 16.2%-28.4% with a 1°C increase in maximum temperature and decreased by 6.6%-11.8% with a 10% decrease in precipitation. Considering food security, water use efficiency, and water ecological adaptability in the semi-arid NAE, cropping system structure adjustment (e.g., a shift from wheat to potato as the predominant crop) and planting date adaptation (e.g., a delay in crop planting date) can offset the impact of the warming-drying trend in the NAE. Based on the successful offsetting of the impact of the warming-drying trend in the NAE, we conclude that farmers can reduce the negative effects of climate change and minimize the risk of crop failure by adapting their cropping system structure at the farming level.

Natural convection solar crop dryers in Kenya: Theory and practical application. African Energy Programme research report series no. 3

International Nuclear Information System (INIS)

Othieno, H.

1987-01-01

The African Energy Programme (AEP) was established by the Commonwealth Science Council (CSC) to strengthen Africa's scientific and technical capabilities to develop and utilise the continent's enormous renewable energy resources to assist its socio-economic development. The AEP was conceived at a regional workshop held at Arusha, Tanzania in 1979, at which African researchers met to share their experiences of and explored the feasibility of establishing a collaborative regional R and D programme to develop and adapt technologies appropriate to the specific needs of the participating countries. The AEP researchers accorded the highest priority to seeking solutions to the energy problems of Africa's predominantly rural populations and identified eight project areas as the nodes for regional collaborative research and development: 1. Biogas for rural development; 2. Wood/Charcoal production and utilisation; 3. Solar crop drying; 4. Solar thermal heating and cooling; 5. Wind electricity generation; 6. Wind water pumping; 7. Resources Assessments; 8. Energy policy and planning. The primary goal of the AEP activities were to develop indigenous national capabilities to enable the examination and application of technological solutions appropriate to the unique problems and socio-cultural environments of each country. However, the severe limitations on expertise and the broad similarity of many of the critical problems favoured regional R and D cooperation around common techniques and methodologies in each project area. This work has made a significant contribution to Science and Technology. Prior to this work there was no detailed information in natural convection solar dryers. This work has exposed a number of critical design factors which must be considered in order to design an efficient dryer. Buoyancy-induced pressure inside the dryer, problems of multiple radiative heat exchange in the heater and cooling effects of wind have been studied in detail. The final dryer

Natural convection solar crop dryers in Kenya: Theory and practical application. African Energy Programme research report series no. 3

Energy Technology Data Exchange (ETDEWEB)

Othieno, H [Kenyatta University, Nairobi (Kenya)

1987-07-01

The African Energy Programme (AEP) was established by the Commonwealth Science Council (CSC) to strengthen Africa's scientific and technical capabilities to develop and utilise the continent's enormous renewable energy resources to assist its socio-economic development. The AEP was conceived at a regional workshop held at Arusha, Tanzania in 1979, at which African researchers met to share their experiences of and explored the feasibility of establishing a collaborative regional R and D programme to develop and adapt technologies appropriate to the specific needs of the participating countries. The AEP researchers accorded the highest priority to seeking solutions to the energy problems of Africa's predominantly rural populations and identified eight project areas as the nodes for regional collaborative research and development: 1. Biogas for rural development; 2. Wood/Charcoal production and utilisation; 3. Solar crop drying; 4. Solar thermal heating and cooling; 5. Wind electricity generation; 6. Wind water pumping; 7. Resources Assessments; 8. Energy policy and planning. The primary goal of the AEP activities were to develop indigenous national capabilities to enable the examination and application of technological solutions appropriate to the unique problems and socio-cultural environments of each country. However, the severe limitations on expertise and the broad similarity of many of the critical problems favoured regional R and D cooperation around common techniques and methodologies in each project area. This work has made a significant contribution to Science and Technology. Prior to this work there was no detailed information in natural convection solar dryers. This work has exposed a number of critical design factors which must be considered in order to design an efficient dryer. Buoyancy-induced pressure inside the dryer, problems of multiple radiative heat exchange in the heater and cooling effects of wind have been studied in detail. The final dryer

A study of the drying effect on lemon slices using a closed-type solar dryer

Energy Technology Data Exchange (ETDEWEB)

Ho-Hsien Chen; Hernandez, C.E.; Tzou-Chi Huang [National Pingtung University of Science and Technology (China). Dept. of Food Science

2005-01-01

An experimental closed-type dryer associated with a photovoltaic system (PV) was developed. The transparent drying cabinet was designed with high transmittance glass to decrease the reflection of direct sunlight and to offer extra direct solar heating on the raw material during drying. Parallel wiring with a local electrical grid was necessary for switching purposes if there is insufficient battery backup during peak operation. Lemon slices were dried using the closed-type solar dryer and results were compared with hot air drying at 60{sup o}C. The results indicate that the dried lemon slices using a closed-type solar dryer has better general levels of quality in terms of sensory parameters. (author)

Thin layer drying characteristics of curry leaves (Murraya koenigii in an indirect solar dryer

Directory of Open Access Journals (Sweden)

Vijayan Selvaraj

2017-01-01

Full Text Available In this work, the thin layer drying characteristics of curry leaves (Murraya koenigii has been studied in an indirect forced convection solar dryer with constant air mass flow rate of 0.0636 kg/s. Twelve thin layer drying models were tested for its suitability to describe the drying characteristics of curry leaves. The dryer has reduced the initial moisture content of curry leaves from 67.3% (wet basis to the final moisture content of 4.75% (wet basis in 3.5 hours. The pickup efficiency of indirect solar dryer for drying curry leaves was varied between 4.9% and 23.02%. Based on the statistical parameters, the Modified Henderson and Pabis model and Wang and Singh model were selected for predicting the drying characteristics of curry leaves. The payback period for the solar dryer was evaluated as 8 months, which is found to be much lower when compared with the entire life span of 15 years. The payback evaluation confirms that the solar dryer is economically viable in rural applications.

Solar drying and organoleptic characteristics of two tropical African fish species using improved low-cost solar driers.

Science.gov (United States)

Mustapha, Moshood K; Ajibola, Taiye B; Salako, Abdulbashir F; Ademola, Sunmola K

2014-05-01

This study was done to evaluate the drying performance, efficiency, and effectiveness of five different types of improved low-cost solar driers in terms of moisture loss from two tropical African fish species Clarias gariepinus (African sharp tooth catfish) and Oreochromis niloticus (Nile tilapia) and testing the organoleptic characteristics of the dried samples. The driers used were made from plastic, aluminum, glass, glass with black igneous stone, and mosquito net, with traditional direct open-sun drying as a control. A significant (P < 0.05) decrease in weight resulting from moisture loss in the two fish species was observed in all the driers, with the highest reduction occurring in the glass drier containing black stone. The rate of weight loss was faster in the first 4 days of drying with black stone-inserted glass drier showing the fastest drying rate with a constant weight in C. gariepinus attained on the 11th day and in O. niloticus on the eighth day. The slowest drier was plastic where a constant weight of the species were recorded on and 13th day and 11th day, respectively. Volunteers were used to assess the organoleptic characteristics of the dried samples and they showed lowest acceptability for the open-sun drying, while samples from the glass drier containing black stone had the highest acceptability in terms of the taste, flavor, appearance, texture, odor, palatability, and shelf-life. The low-cost solar driers were effective found in removing water from the fish resulting in significant loss of weight and moisture. The highest drying time, efficient performance, drying effectiveness, and high acceptability of the organoleptic parameters of the dried products from the black stone-inserted glass drier were due to the ability of the glass and the black stone to retain, transmit, and radiate heat to the fish sample all the time (day and night). These low-cost driers are simple to construct, materials for its construction readily available, easy to

Modelling the drying kinetics of green peas in a solar dryer and under open sun

Energy Technology Data Exchange (ETDEWEB)

Sunil [Department of Mechanical Engineering, BRCM CET Bahal, Haryana–127028 (India); Varun [Department of Mechanical Engineering, NIT Hamirpur, (H.P.)–177005 (India); Sharma, Naveen [Department of Mechanical and Industrial Engineering, IITR, (U.K.)–247667 (India)

2013-07-01

The drying kinetics of green peas was investigated in an indirect solar dryer and under open sun. The entire drying process took place exclusively in falling rate period. The constant rate period was absent from the drying curves. The rehydration capacity was also determined for peas dried in solar dryer and under open sun. The rehydration capacity of solar dried peas was found higher than open sun dried peas. The drying data obtained from experiments were fitted to eight different mathematical models. The performance of these models was examined by comparing the coefficient of correlation (R2), sum of squares error (SSE), mean squared error (MSE) and root mean square error (RMSE) between observed and predicted values of moisture ratios. Among these models, the thin layer drying model developed by Page showed good agreement with the data obtained from experiments for bottom tray. The Midilli et al. model has shown better fit to the experimental data for top tray and open sun than other models.

Comparison of the histology of (I) fresh, (II) solar dried and (III) solar dried/steam distilled ginger (Zingiber officinale Roscoe) rhizome tissue prior to the extraction of its pungent principles

Energy Technology Data Exchange (ETDEWEB)

Balladin, D.A.; Headley, O. [University of the West Indies, Bridgetown (Barbados). Centre for Resource Management and Environmental Studies; Chang-yen, I.; Duncan, E.J. [University of the West Indies, (Trinidad and Tobago). Faculty of Agriculture and Natural Sciences; McGaw, D.R. [University of the West Indies, (Trinidad and Tobago). Faculty of Engineering

1999-06-01

The histological analysis of the rhizome cells of West Indian ginger (Zingiber officinale Roscoe), has revealed some information about the cell`s design. Comparisons have shown that the oleoresin (pungent principles - gingerols and shogaols) were not observable in cell sections of the fresh ginger rhizomes. However, the number of the oleoresin organelles increased in the order of solar dried and solar dried/steam distilled ginger rhizomes, the latter having a high oleoresin extraction yield with acetone of 8.0 g per 100 g ginger rhizome (dry wt.). (author)

Mathematical modelling of the thin layer solar drying of banana, mango and cassava

Energy Technology Data Exchange (ETDEWEB)

Koua, Kamenan Blaise; Fassinou, Wanignon Ferdinand; Toure, Siaka [Laboratoire d' Energie Solaire, Universite de Cocody- Abidjan, 22 BP 582 Abidjan 22 (Ivory Coast); Gbaha, Prosper [Laboratoire d' Energie Nouvelle et Renouvelable, Institut National Polytechnique, Felix HOUPHOUET - BOIGNY de Yamoussoukro (Ivory Coast)

2009-10-15

The main objectives of this paper are firstly to investigate the behaviour of the thin layer drying of plantain banana, mango and cassava experimentally in a direct solar dryer and secondly to perform mathematical modelling by using thin layer drying models encountered in literature. The variation of the moisture content of the products studied and principal drying parameters are analysed. Seven statistical models, which are empirical or semi-empirical, are tested to validate the experimental data. A non-linear regression analysis using a statistical computer program is used to evaluate the constants of the models. The Henderson and Pabis drying model is found to be the most suitable for describing the solar drying curves of plantain banana, mango and cassava. The drying data of these products have been analysed to obtain the values of the effective diffusivity during the falling drying rate phase. (author)

An experimental study on the application of polyalcohol solid-solid phase change materials in solar drying with cross-corrugated solar air collectors

Science.gov (United States)

Gao, W. F.; Lin, W. X.; Liu, T.; Li, M.

2017-11-01

In this paper, two identical solar driers with the same cross-corrugated solar air collectors and drying chamber were developed, one with phase-change materials (PCMs) and the other without PCMs. These two solar drying systems were tested in typical sunny and cloudy days in Kunming and their thermal performances were analyzed. The experimental results show that the temperature changing is smoother in the collector with the PCMs, which is beneficial for the drying as the useful drying time was prolonged. The same trend was also found in the chamber with the PCMs. The PCMs in solar drying system was found to play a role in temperature regulating. There were several cycles of heat charging-discharging in a cloudy testing day while the temperatures on collectors and in chambers with the polyalcohol PCMs is higher than each phase-change temperature. Nevertheless, there was only one cycle of heat charging-discharging in a sunny testing day. The collector with PCMs has higher daily useful heat gain than the collector without PCMs.

Rhizosphere microorganisms affected by soil solarization and cover cropping in Capsicum annuum and Phaseolus lunatus agroecosystems

Science.gov (United States)

Field experiments were conducted to evaluate the effects of soil solarization or cover cropping on bell pepper (Capsicum annuum) and lima bean (Phaseolus lunatus, L.) rhizosphere microorganisms. In Experiment I, flat surface solarization (FSS), raised bed solarization (RBS), cowpea (Vigna unguiculat...

Drivers of solar radiation variability in the McMurdo Dry Valleys, Antarctica

Science.gov (United States)

Obryk, Maciej; Fountain, Andrew G.; Doran, Peter; Lyons, Berry; Eastman, Ryan

2018-01-01

Annually averaged solar radiation in the McMurdo Dry Valleys, Antarctica has varied by over 20 W m−2 during the past three decades; however, the drivers of this variability are unknown. Because small differences in radiation are important to water availability and ecosystem functioning in polar deserts, determining the causes are important to predictions of future desert processes. We examine the potential drivers of solar variability and systematically eliminate all but stratospheric sulfur dioxide. We argue that increases in stratospheric sulfur dioxide increase stratospheric aerosol optical depth and decrease solar intensity. Because of the polar location of the McMurdo Dry Valleys (77–78°S) and relatively long solar ray path through the stratosphere, terrestrial solar intensity is sensitive to small differences in stratospheric transmissivity. Important sources of sulfur dioxide include natural (wildfires and volcanic eruptions) and anthropogenic emission.

Production of organic fertilizer from olive mill wastewater by combining solar greenhouse drying and composting.

Science.gov (United States)

Galliou, F; Markakis, N; Fountoulakis, M S; Nikolaidis, N; Manios, T

2018-05-01

Olive mill wastewater (OMW) is generated during the production of olive oil. Its disposal is still a major environmental problem in Mediterranean countries, despite the fact that a large number of technologies have been proposed up to date. The present work examines for the first time a novel, simple and low-cost technology for OMW treatment combining solar drying and composting. In the first step, OMW was dried in a chamber inside a solar greenhouse using swine manure as a bulking agent. The mean evaporation rate was found to be 5.2 kg H 2 O/m 2 /d for a drying period of 6 months (February-August). High phenol (75%) and low nitrogen (15%) and carbon (15%) losses were recorded at the end of the solar drying process. The final product after solar drying was rich in nutrients (N: 27.8 g/kg, P: 7.3 g/kg, K: 81.6 g/kg) but still contained significant quantities of phenols (18.4 g/kg). In order to detoxify the final product, a composting process was applied as a second step with or without the use of grape marc as bulking agent. Results showed that the use of grape marc as a bulking agent at a volume ratio of 1:1 achieved a higher compost temperature profile (60 °C) than 2:1 (solar drying product: grape marc) or no use (solar drying product). The end product after the combination of solar drying and composting had the characteristics of an organic fertilizer (57% organic carbon) rich in nutrients (3.5% N, 1% P, 6.5% K) with quite low phenol content (2.9 g/kg). Finally, the use of this product for the cultivation of pepper plants approved its fertility which was found similar with commercial NPK fertilizers. Copyright © 2018 Elsevier Ltd. All rights reserved.

Nutritional and physicochemical properties of stored solar-dried ...

African Journals Online (AJOL)

Preservation techniques for cowpea (Vigna unguiculata L.) leaves, a green leafy vegetable mainly consumed in the eastern and northern parts of Uganda, are still lacking. The study aimed at determining the effect of blanching, open sun and solar-drying on the nutrient content, organoleptic acceptability and ...

Solar radiation use efficiency and morphophysiological indices in common bean cultivars

Directory of Open Access Journals (Sweden)

Gisele Carneiro da Silva Teixeira

2015-03-01

Full Text Available Common bean crops present a broad edaphoclimatic adaptation, allowing their cultivation throughout the year. However, in order to reach good economic income levels, it is fundamental to understand the processes that affect the growth and development of the crop in various environments. This study aimed to compare two common bean cultivars (BRS Radiante and Pérola contrasting in cycle and growth behavior by using morphophysiological indices and solar radiation use efficiency. The following traits were evaluated: light extinction coefficient, radiation use efficiency, phenologic development, leaf area index, total dry matter weight, crop growth rate, relative growth rate and dry matter partitioning. The BRS Radiante cultivar shows a higher vigor, when compared to the Pérola cultivar, due to its faster initial phenologic development and higher initial and relative growth rates. Both cultivars differ for leaf area index and shoot architecture, although that does not happen for light extinction coefficient. The BRS Radiante cultivar shows a higher solar radiation use efficiency, resulting in a greater dry matter yield throughout its development.

Solar radiation distribution inside a greenhouse with south-oriented photovoltaic roofs and effects on crop productivity

International Nuclear Information System (INIS)

Cossu, Marco; Murgia, Lelia; Ledda, Luigi; Deligios, Paola A.; Sirigu, Antonella; Chessa, Francesco; Pazzona, Antonio

2014-01-01

Highlights: • The solar radiation distribution inside photovoltaic greenhouses has been studied. • A greenhouse with 50% of the roof area covered with solar panels was considered. • The yearly solar light reduction was 64%, with a transversal north–south gradient. • The reduction was 82% under the solar panels and 46% under the plastic cover. • We provided suggestions for a better agronomic sustainability of PV greenhouses. - Abstract: This study assessed the climate conditions inside a greenhouse in which 50% of the roof area was replaced with photovoltaic (PV) modules, describing the solar radiation distribution and the variability of temperature and humidity. The effects of shading from the PV array on crop productivity were described on tomato, also integrating the natural radiation with supplementary lighting powered by PV energy. Experiments were performed inside an east–west oriented greenhouse (total area of 960 m 2 ), where the south-oriented roofs were completely covered with multi-crystalline silicon PV modules, with a total rated power of 68 kWp. The PV system reduced the availability of solar radiation inside the greenhouse by 64%, compared to the situation without PV system (2684 MJ m −2 on yearly basis). The solar radiation distribution followed a north–south gradient, with more solar energy on the sidewalls and decreasing towards the center of the span, except in winter, where it was similar in all plant rows. The reduction under the plastic and PV covers was respectively 46% and 82% on yearly basis. Only a 18% reduction was observed on the plant rows farthest from the PV cover of the span. The supplementary lighting, powered without exceeding the energy produced by the PV array, was not enough to affect the crop production, whose revenue was lower than the cost for heating and lighting. The distribution of the solar radiation observed is useful for choosing the most suitable crops and for designing PV greenhouses with the attitude

Developing a hybrid solar/wind powered irrigation system for crops in the Great Plains

Science.gov (United States)

Some small scale irrigation systems (powered by wind or solar do not require subsidies, but this paper discusses ways to achieve an economical renewable energy powered center pivot irrigation system for crops in the Great Plains. By adding a solar-photovoltaic (PV) array together with a wind...

Improving the Monitoring of Crop Productivity Using Spaceborne Solar-Induced Fluorescence

Science.gov (United States)

Guan, Kaiyu; Berry, Joseph A.; Zhang, Yongguang; Joiner, Joanna; Guanter, Luis; Badgley, Grayson; Lobell, David B.

2015-01-01

Large-scale monitoring of crop growth and yield has important value for forecasting food production and prices and ensuring regional food security. A newly emerging satellite retrieval, solar-induced fluorescence (SIF) of chlorophyll, provides for the first time a direct measurement related to plant photosynthetic activity (i.e. electron transport rate). Here, we provide a framework to link SIF retrievals and crop yield, accounting for stoichiometry, photosynthetic pathways, and respiration losses. We apply this framework to estimate United States crop productivity for 2007-2012, where we use the spaceborne SIF retrievals from the Global Ozone Monitoring Experiment-2 satellite, benchmarked with county-level crop yield statistics, and compare it with various traditional crop monitoring approaches. We find that a SIF-based approach accounting for photosynthetic pathways (i.e. C3 and C4 crops) provides the best measure of crop productivity among these approaches, despite the fact that SIF sensors are not yet optimized for terrestrial applications. We further show that SIF provides the ability to infer the impacts of environmental stresses on autotrophic respiration and carbon-use-efficiency, with a substantial sensitivity of both to high temperatures. These results indicate new opportunities for improved mechanistic understanding of crop yield responses to climate variability and change.

Mathematical modelling for the drying method and smoothing drying rate using cubic spline for seaweed Kappaphycus Striatum variety Durian in a solar dryer

Energy Technology Data Exchange (ETDEWEB)

M Ali, M. K., E-mail: majidkhankhan@ymail.com, E-mail: eutoco@gmail.com; Ruslan, M. H., E-mail: majidkhankhan@ymail.com, E-mail: eutoco@gmail.com [Solar Energy Research Institute (SERI), Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Muthuvalu, M. S., E-mail: sudaram-@yahoo.com, E-mail: jumat@ums.edu.my; Wong, J., E-mail: sudaram-@yahoo.com, E-mail: jumat@ums.edu.my [Unit Penyelidikan Rumpai Laut (UPRL), Sekolah Sains dan Teknologi, Universiti Malaysia Sabah, 88400 Kota Kinabalu, Sabah (Malaysia); Sulaiman, J., E-mail: ysuhaimi@ums.edu.my, E-mail: hafidzruslan@eng.ukm.my; Yasir, S. Md., E-mail: ysuhaimi@ums.edu.my, E-mail: hafidzruslan@eng.ukm.my [Program Matematik dengan Ekonomi, Sekolah Sains dan Teknologi, Universiti Malaysia Sabah, 88400 Kota Kinabalu, Sabah (Malaysia)

2014-06-19

The solar drying experiment of seaweed using Green V-Roof Hybrid Solar Drier (GVRHSD) was conducted in Semporna, Sabah under the metrological condition in Malaysia. Drying of sample seaweed in GVRHSD reduced the moisture content from about 93.4% to 8.2% in 4 days at average solar radiation of about 600W/m{sup 2} and mass flow rate about 0.5 kg/s. Generally the plots of drying rate need more smoothing compared moisture content data. Special cares is needed at low drying rates and moisture contents. It is shown the cubic spline (CS) have been found to be effective for moisture-time curves. The idea of this method consists of an approximation of data by a CS regression having first and second derivatives. The analytical differentiation of the spline regression permits the determination of instantaneous rate. The method of minimization of the functional of average risk was used successfully to solve the problem. This method permits to obtain the instantaneous rate to be obtained directly from the experimental data. The drying kinetics was fitted with six published exponential thin layer drying models. The models were fitted using the coefficient of determination (R{sup 2}), and root mean square error (RMSE). The modeling of models using raw data tested with the possible of exponential drying method. The result showed that the model from Two Term was found to be the best models describe the drying behavior. Besides that, the drying rate smoothed using CS shows to be effective method for moisture-time curves good estimators as well as for the missing moisture content data of seaweed Kappaphycus Striatum Variety Durian in Solar Dryer under the condition tested.

Mathematical modelling for the drying method and smoothing drying rate using cubic spline for seaweed Kappaphycus Striatum variety Durian in a solar dryer

International Nuclear Information System (INIS)

M Ali, M. K.; Ruslan, M. H.; Muthuvalu, M. S.; Wong, J.; Sulaiman, J.; Yasir, S. Md.

2014-01-01

The solar drying experiment of seaweed using Green V-Roof Hybrid Solar Drier (GVRHSD) was conducted in Semporna, Sabah under the metrological condition in Malaysia. Drying of sample seaweed in GVRHSD reduced the moisture content from about 93.4% to 8.2% in 4 days at average solar radiation of about 600W/m 2 and mass flow rate about 0.5 kg/s. Generally the plots of drying rate need more smoothing compared moisture content data. Special cares is needed at low drying rates and moisture contents. It is shown the cubic spline (CS) have been found to be effective for moisture-time curves. The idea of this method consists of an approximation of data by a CS regression having first and second derivatives. The analytical differentiation of the spline regression permits the determination of instantaneous rate. The method of minimization of the functional of average risk was used successfully to solve the problem. This method permits to obtain the instantaneous rate to be obtained directly from the experimental data. The drying kinetics was fitted with six published exponential thin layer drying models. The models were fitted using the coefficient of determination (R 2 ), and root mean square error (RMSE). The modeling of models using raw data tested with the possible of exponential drying method. The result showed that the model from Two Term was found to be the best models describe the drying behavior. Besides that, the drying rate smoothed using CS shows to be effective method for moisture-time curves good estimators as well as for the missing moisture content data of seaweed Kappaphycus Striatum Variety Durian in Solar Dryer under the condition tested

Mathematical modelling for the drying method and smoothing drying rate using cubic spline for seaweed Kappaphycus Striatum variety Durian in a solar dryer

Science.gov (United States)

M Ali, M. K.; Ruslan, M. H.; Muthuvalu, M. S.; Wong, J.; Sulaiman, J.; Yasir, S. Md.

2014-06-01

The solar drying experiment of seaweed using Green V-Roof Hybrid Solar Drier (GVRHSD) was conducted in Semporna, Sabah under the metrological condition in Malaysia. Drying of sample seaweed in GVRHSD reduced the moisture content from about 93.4% to 8.2% in 4 days at average solar radiation of about 600W/m2 and mass flow rate about 0.5 kg/s. Generally the plots of drying rate need more smoothing compared moisture content data. Special cares is needed at low drying rates and moisture contents. It is shown the cubic spline (CS) have been found to be effective for moisture-time curves. The idea of this method consists of an approximation of data by a CS regression having first and second derivatives. The analytical differentiation of the spline regression permits the determination of instantaneous rate. The method of minimization of the functional of average risk was used successfully to solve the problem. This method permits to obtain the instantaneous rate to be obtained directly from the experimental data. The drying kinetics was fitted with six published exponential thin layer drying models. The models were fitted using the coefficient of determination (R2), and root mean square error (RMSE). The modeling of models using raw data tested with the possible of exponential drying method. The result showed that the model from Two Term was found to be the best models describe the drying behavior. Besides that, the drying rate smoothed using CS shows to be effective method for moisture-time curves good estimators as well as for the missing moisture content data of seaweed Kappaphycus Striatum Variety Durian in Solar Dryer under the condition tested.

Solar energy applications in different agricultural and industrial processes

International Nuclear Information System (INIS)

Agudelo Florez, Sergio; Pineda Rios, Alexander

2002-01-01

Solar thermal technology can offer so much more than just domestic hot water, in this paper it is shown some solar system that can provide process heat for many industrial and agricultural requirements, for example can dry crops, extract potable water from brackish or saline supplies, destroy hazardous contaminants and be used in the manufacture of advanced material

Assessment of satellite and model derived long term solar radiation for spatial crop models: A case study using DSSAT in Andhra Pradesh

Directory of Open Access Journals (Sweden)

Anima Biswal

2014-09-01

Full Text Available Crop Simulation models are mathematical representations of the soil plant-atmosphere system that calculate crop growth and yield, as well as the soil and plant water and nutrient balances, as a function of environmental conditions and crop management practices on daily time scale. Crop simulation models require meteorological data as inputs, but data availability and quality are often problematic particularly in spatialising the model for a regional studies. Among these weather variables, daily total solar radiation and air temperature (Tmax and Tmin have the greatest influence on crop phenology and yield potential. The scarcity of good quality solar radiation data can be a major limitation to the use of crop models. Satellite-sensed weather data have been proposed as an alternative when weather station data are not available. These satellite and modeled based products are global and, in general, contiguous in time and also been shown to be accurate enough to provide reliable solar and meteorological resource data over large regions where surface measurements are sparse or nonexistent. In the present study, an attempt was made to evaluate the satellite and model derived daily solar radiation for simulating groundnut crop growth in the rainfed distrcits of Andhra Pradesh. From our preliminary investigation, we propose that satellite derived daily solar radiation data could be used along with ground observed temperature and rainfall data for regional crop simulation studies where the information on ground observed solar radiation is missing or not available.

High pressure liquid chromatographic analysis of the main pungent principles of solar dried West Indian ginger (Zingiber officinale Roscoe)

Energy Technology Data Exchange (ETDEWEB)

Balladin, D.A.; Headley, O. [University of the West Indies, Cave Hill Campus, St. Michael, Barbados (West Indies). Centre for Resource Management and Environmental Studies; Chang-Yen, I. [University of the West Indies, St. Augustine Campus, Trinidad (West Indies). Faculty of Agriculture and Natural Sciences; McGaw, D.R. [University of the West Indies, St. Augustine Campus, Trinidad (West Indies). Dept. of Chemical Engineering

1998-12-31

The main pungent principles of West Indian ginger (Zingiber officinale Roscoe) were quantified and qualified using High Pressure Liquid Chromatography. This procedure was used to evaluate the pungency profile of fresh, solar dried and solar dried/steam distilled ginger rhizomes. In this investigation, the total oleoresin extracted was in the ratio [20: 1: 2] for [fresh ginger: solar dried: solar dried/steam distilled ginger rhizomes] with respect to the [6]-gingerol content. This simple isocratic HPLC method can be used to investigate the pungency profile of the extracted oleoresin from the ginger rhizomes. (author)

Use of geothermal heat for crop drying and related agricultural applications. Final report

Energy Technology Data Exchange (ETDEWEB)

Gordon, T.J.; Wright, T.C.; Fein, E.; Munson, T.R.; Richmond, R.C.

1978-03-01

Observations led to the selection of the alfalfa dehydration industry for in-depth analysis of the application of moderate-temperature geothermal heat. Six geothermal heat exchanger/dryer configurations were examined. A low-temperature conveyor dryer using geothermal water to supply all required heat was chosen for site-specific analysis, the retrofitting of a large alfalfa dehydration plant within the Heber KGRA in the Imperial Valley, California. Even in the most favorable scenario--sharing a geothermal pipeline with the neighboring fertilizer plant--geothermal retrofitting would increase the price of the alfalfa ''dehy'' about 40 percent. The geothermal brine is estimated to cost $2.58/million Btu's compared with a 1977 natural gas cost of $1.15. Capital cost for heat exchangers and the new dryers is estimated at $3.3 million. The Heber plant appeared to offer the only good opportunity for geothermal retrofitting of an existing alfalfa dehydration plant. Construction of new plants at geothermal resource sites cannot be justified due to the uncertain state of the ''dehy'' industry. Use of geothermal heat for drying other crops may be much more promising. The potato dehydration industry, which is concentrated in the geothermal-rich Snake River Valley of Idaho, appears to offer good potential for geothermal retrofitting; about 4.7 x 10{sup 12}Btu's are used annually by plants within 50 miles of resources. Drying together at the geothermal wellhead several crops that have interlocking processing seasons and drying-temperature requirements may be quite attractive. The best ''multicrop drying center'' site identified was at Power Ranch Wells, Arizona; 34 other sites were defined. Agricultural processing applications other than drying were investigated briefly.

Drying of Rosella (Hibiscus sabdariffa) Flower Petals using Solar Dryer with Double Glass Cover Collector

OpenAIRE

Tjukup Marnoto

2014-01-01

Chemical ingredients in rosella petals are very beneficial for health. Rosella petals needed to be drained for storage and packing purpose. The traditional drying takes 5 days and less healthy. Solar dryer technology can speed up the drying process and protect materials from dust contamination. Solar dryer with double glass covered collector has been designed and made for drying of agricultural products such as rosella flowers. Rosella petals as much as 2300 grams with initial moisture conten...

A Novel Parabolic Trough Concentrating Solar Heating for Cut Tobacco Drying System

Directory of Open Access Journals (Sweden)

Jiang Tao Liu

2014-01-01

Full Text Available A novel parabolic trough concentrating solar heating for cut tobacco drying system was established. The opening width effect of V type metal cavity absorber was investigated. A cut tobacco drying mathematical model calculated by fourth-order Runge-Kutta numerical solution method was used to simulate the cut tobacco drying process. And finally the orthogonal test method was used to optimize the parameters of cut tobacco drying process. The result shows that the heating rate, acquisition factor, and collector system efficiency increase with increasing the opening width of the absorber. The simulation results are in good agreement with experimental data for cut tobacco drying process. The relative errors between simulated and experimental values are less than 8%, indicating that this mathematical model is accurate for the cut tobacco airflow drying process. The optimum preparation conditions are an inlet airflow velocity of 15 m/s, an initial cut tobacco moisture content of 26%, and an inlet airflow temperature of 200°C. The thermal efficiency of the dryer and the final cut tobacco moisture content are 66.32% and 14.15%, respectively. The result shows that this parabolic trough concentrating solar heating will be one of the heat recourse candidates for cut tobacco drying system.

Solar drying of liquid manure. Final report; Solare Trocknung von Guelle. Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

Reuss, M.; Hainzlmeier, F.; Schulz, H.

1997-05-01

This is a report on the solar drying of manure in a simple greenhouse tunnel. As part of the research project, a pilot plant was set up at the Duernast agricultural research station of the Technical University of Munich at Weihenstephan. During a test programme of more than one year, process engineering and mode of operation were studied and optimized by means of this pilot plant. (HW) [Deutsch] Es wird berichtet ueber solare Guelletrocknung in einem einfachen Gewaechshaustunnel. Im Rahmen des Forschungsvorhabens wurde eine Versuchsanlage auf dem landwirtschaftlichen Versuchsgut Duernast den TH Muenchen/Weihenstephan errichtet. An der Anlage wurde in einem mehr als einjaehrigen Versuchsprogramm die Verfahrenstechnik und Betriebsweise untersucht und optimiert. (HW)

Daily efficiency of flat-plate solar air collectors for grain drying

Energy Technology Data Exchange (ETDEWEB)

Ting, K.C.; Shove, G.C.

1983-01-01

Single cover flat-plate solar collectors incorporated into walls and roofs of farm buildings have been used to heat ambient air for low temperature grain drying systems. Large surface area and high airflow rate are common features of these collectors. The drying period may range from several days to several weeks. Therefore, a knowledge of the variations of the collectors' daily efficiencies with respect to their design parameters would be helpful in applying solar collectors to grain drying. The objective of this study was to develop a simpler means of direct calculation of a collector's daily efficiency based on its design parameters. Many factors, such as configuration of the collector, airflow rate, weather conditions, etc. will affect the performance of solar collectors. A large number of varied conditions need to be tested in order to investigate the effect of different parameters on the collector performance. To facilitate this investigation, a computer simulation model developed by Ting was used to calculate the daily efficiencies of collectors under different operating conditions. The computer model was verified by Morrison's experimental data. Based on the simulation results, a functional relationship was developed between the daily efficiencies of collectors and their design parameters.

Solar drying of West Indian ginger (Zingiber officinale Roscoe) rhizome using a wire basket dryer

Energy Technology Data Exchange (ETDEWEB)

Balladin, D.A.; Headley, O. [University of the West Indies (Barbados). Dept. of Chemistry; Chang Yen, I. [University of the West Indies, St. Augustine (Trinidad and Tobago). Dept. of Chemistry; McGaw, D.R. [University of the West Indies, St. Augustine (Trinidad and Tobago). Dept. of Chemical Engineering

1996-09-01

A wire basket dryer (1.8 m x 0.9 m x 0.2 m) was used to dry sliced (0.15 cm) West Indian ginger (Zingiber officinale Roscoe) rhizome to an acceptable moisture content of 10.2% (dry weight basis) over a 3 day period. The optimum charge size was 14.97 kg, with a packing density of 462.04 kg m{sup -3} and a specific drying rate of 0.446 h{sup -1}. The quantities (determined by high-pressure liquid chromatography) of the main pungent principles (ginerol and shogaol) extracted from fresh, non-steam-distilled solar-dried and steam-distilled solar-dried ginger rhizomes showed increases of 0.068, 0.46 and 0.67 g [per 100 g (dry weight basis)], respectively, with a decrease in the oleoresin quality (reflected in pungency profile) of the same order. (author)

Effect of green manure crops and nitrogen fertilizer levels on dry matter remobilization efficiency in wheat (Triticum aestivum L. internodes

Directory of Open Access Journals (Sweden)

F. Gerami

2016-05-01

Full Text Available In order to evaluate the effect of nitrogen rates and green manure crops on dry matter mobilization and mobilization efficiency indices of wheat (Triticum aestivum L. a field experiment was conducted in Agricultural Faculty of Shahid Chamran University, Ahvaz during growing season of 2010-2011. The experimental design was split-plot based on randomized complete block with three replications. Main plot included four nitrogen rates (i.e. 0, 50, 100 and 150 kgN.ha-1 and sub-plot included six green manure crops containing millet (Pennisetum sp., amaranth (Amaranthus sp., sesbania (Sesbania sp., cowpea (Vigna unguiculata L., mung bean (Vigna radiata L. and fallow. This experiment was done at two stages. First, planting and turn down of green manure crops and then planting of wheat. The results showed that the maximum weight and specific weight of all stem internodes obtained from 0 to 20 days after wheat anthesis. Then, this trend decreased from 20 to 50 days after wheat anthesis due to remobilization of dry matter to grain. Mobilized dry matter was more in control (0 kg.N.h-1 than in high N application for peduncle (219 vs. 181 mg and penultimate (203 vs. 165 mg, while, was less in the lower internodes (403 vs. 407 mg. Generally, with increasing of nitrogen levels, dry matter mobilization efficiency was decreased by. So, the effect of green manure crops not limited only by soil properties, while influences the relationship between physiological sources and sink.

Optimum dry-cooling sub-systems for a solar air conditioner

Science.gov (United States)

Chen, J. L. S.; Namkoong, D.

1978-01-01

Dry-cooling sub-systems for residential solar powered Rankine compression air conditioners were economically optimized and compared with the cost of a wet cooling tower. Results in terms of yearly incremental busbar cost due to the use of dry-cooling were presented for Philadelphia and Miami. With input data corresponding to local weather, energy rate and capital costs, condenser surface designs and performance, the computerized optimization program yields design specifications of the sub-system which has the lowest annual incremental cost.

PERFORMANCE OF A FORCED CONVECTION SOLAR DRIER INTEGRATED WITH GRAVEL AS HEAT STORAGE MATERIAL FOR CHILI DRYING

Directory of Open Access Journals (Sweden)

M. MOHANRAJ

2009-09-01

Full Text Available An indirect forced convection solar drier integrated with different sensible heat storage maternal has been developed and tested its performance for drying chili under the metrological conditions of Pollachi, India. The system consists of a flat plate solar air heater with heat storage unit, a drying chamber and a centrifugal blower. Drying experiments have been performed at an air flow rate of 0.25 kg/s. Drying of chili in a forced convection solar drier reduces the moisture content from around 72.8% (wet basis to the final moisture content about 9.1% in 24 h. Average drier efficiency was estimated to be about 21%. The specific moisture extraction rate was estimated to be about 0.87 kg/kWh.

Evaluation of Pathogen Removal in a Solar Sludge Drying Facility Using Microbial Indicators

Directory of Open Access Journals (Sweden)

D. İpek Kurtböke

2010-02-01

Full Text Available South East Queensland is one of the fastest growing regions in Australia with a correspondingly rapid increase in sewage production. In response, local councils are investing in more effective and sustainable options for the treatment and reuse of domestic and industrial effluents. A novel, evaporative solar dryer system has been installed on the Sunshine Coast to convert sewage sludge into a drier, usable form of biosolids through solar radiation exposure resulting in decreased moisture concentration and pathogen reduction. Solar-dried biosolids were analyzed for selected pathogenic microbial, metal and organic contaminants at the end of different drying cycles in a collaborative study conducted with the Regional Council. Although fecal coliforms were found to be present, enteroviruses, parasites, E. coli, and Salmonella sp. were not detected in the final product. However, elevated levels of zinc and copper were still present which restricted public use of the biosolids. Dilution of the dried biosolids with green waste as well as composting of the biosolids is likely to lead to the production of an environmentally safe, Class A end-product.

Wood chip drying in connection with combined heat and power or solar energy in Finland

Directory of Open Access Journals (Sweden)

Rinne Samuli

2014-01-01

Full Text Available 20% of the Finnish district heating (DH power plant fuels are wood-based and the share is increasing. The wood fuel demand probably exceeds the potential supply in the future. The wood fuel drying with waste heat is one profitable opportunity to gain more wood fuel. If the drying energy can be produced with lower primary energy use than combusting the fuel directly, the drying potentially improves the system efficiency. In this study, the drying feasibility in the connection of a combined heat and power (CHP system, possibly with solar collectors, is calculated. The wood fuel heating can be increased profitably by 6%, using the heat from CHP for drying only when the marginal cost of the heat is low enough, i.e. the electricity price is high enough and there is free capacity after the DH demand. Although the drying is profitable, a larger heat storage can also increase the annual result similarly. The best investment choice depends on the plant properties. Here the optimal system enables 20% DH production cost savings. Solar heat may be profitable, when the solar heat has a 2–3% share of the annual heat demand. However, the dryer or larger storage tank are more profitable investments.

Design, Construction and Evaluation of a Dry Solar Sterilizer

International Nuclear Information System (INIS)

Hernández Fereira, Arcelio A.

2017-01-01

The objective of the work was the search of an alternative for sterilization using solar energy. For such purposes, a dry solar sterilizer of 4276 cm3 capacity was designed, constructed and evaluated. Potential users would be rural medical posts in areas without electricity, health posts in military units under field conditions, and experimental microbiology stations. The evaluation included the determination of the energy efficiency of the sterilizer, the economic evaluation against other variants and the biological safety assessment. The developed equipment reached the sterilization temperature for levels of the direct component of the solar radiation higher than 300 W/m2 in 14 minutes, corresponding to an average heating rate of 13 0C/minute, higher than that of an electric furnace. Its energy efficiency with direct solar radiation of 310.5 W/m2 was 53.79%. The equipment is of easy construction, simple operation and very low cost. (author)

Design of SMART waste heat removal dry cooling tower using solar energy

International Nuclear Information System (INIS)

Choi, Yong Jae; Jeong, Yong Hoon

2014-01-01

The 85% of cooling system are once-through cooling system and closed cycle wet cooling system. However, many countries are trying to reduce the power plant water requirement due to the water shortage and water pollution. Dry cooling system is investigated for water saving advantage. There are two dry cooling system which are direct and indirect cooling system. In direct type, turbine exhaust is directly cooled by air-cooled condenser. In indirect system, turbine steam is cooled by recirculating intermediate cooling water loop, then the loop is cooled by air-cooled heat exchanger in cooling tower. In this paper, the purpose is to remove SMART waste heat, 200MW by using newly designed tower. The possibility of enhancing cooling performance by solar energy is analyzed. The simple cooling tower and solar energy cooling tower are presented and two design should meet the purpose of removing SMART waste heat, 200MW. In first design, when tower diameter is 70m, the height of tower should be 360m high. In second design, the chimney height decrease from 360m to 180m as collector radius increase from 100m to 500m due to collector temperature enhancement by solar energy, To analyze solar cooling tower further, consideration of solar energy performance at night should be analyzed

Design of SMART waste heat removal dry cooling tower using solar energy

Energy Technology Data Exchange (ETDEWEB)

Choi, Yong Jae; Jeong, Yong Hoon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

2014-10-15

The 85% of cooling system are once-through cooling system and closed cycle wet cooling system. However, many countries are trying to reduce the power plant water requirement due to the water shortage and water pollution. Dry cooling system is investigated for water saving advantage. There are two dry cooling system which are direct and indirect cooling system. In direct type, turbine exhaust is directly cooled by air-cooled condenser. In indirect system, turbine steam is cooled by recirculating intermediate cooling water loop, then the loop is cooled by air-cooled heat exchanger in cooling tower. In this paper, the purpose is to remove SMART waste heat, 200MW by using newly designed tower. The possibility of enhancing cooling performance by solar energy is analyzed. The simple cooling tower and solar energy cooling tower are presented and two design should meet the purpose of removing SMART waste heat, 200MW. In first design, when tower diameter is 70m, the height of tower should be 360m high. In second design, the chimney height decrease from 360m to 180m as collector radius increase from 100m to 500m due to collector temperature enhancement by solar energy, To analyze solar cooling tower further, consideration of solar energy performance at night should be analyzed.

Solar hydrogen production: renewable hydrogen production by dry fuel reforming

Science.gov (United States)

Bakos, Jamie; Miyamoto, Henry K.

2006-09-01

SHEC LABS - Solar Hydrogen Energy Corporation constructed a pilot-plant to demonstrate a Dry Fuel Reforming (DFR) system that is heated primarily by sunlight focusing-mirrors. The pilot-plant consists of: 1) a solar mirror array and solar concentrator and shutter system; and 2) two thermo-catalytic reactors to convert Methane, Carbon Dioxide, and Water into Hydrogen. Results from the pilot study show that solar Hydrogen generation is feasible and cost-competitive with traditional Hydrogen production. More than 95% of Hydrogen commercially produced today is by the Steam Methane Reformation (SMR) of natural gas, a process that liberates Carbon Dioxide to the atmosphere. The SMR process provides a net energy loss of 30 to 35% when converting from Methane to Hydrogen. Solar Hydrogen production provides a 14% net energy gain when converting Methane into Hydrogen since the energy used to drive the process is from the sun. The environmental benefits of generating Hydrogen using renewable energy include significant greenhouse gas and criteria air contaminant reductions.

Drying of carrot slices in a triple pass solar dryer

Directory of Open Access Journals (Sweden)

Seshachalam Kesavan

2017-01-01

Full Text Available An indirect triple pass forced convection solar dryer was developed and its performance was evaluated for drying of carrot slices. The drying experiments were carried out under the meteorological conditions of Coimbatore city in India during the year 2016. The experimental set-up consists of a blower, triple pass packed bed air collector (using sand with wire mesh absorber plate, and a drying chamber. The air mass flow rate was optimized to 0.062 kg/s. The initial moisture content of the carrot slices was reduced from 87.5% (on wet basis to the final moisture content of 10% (wet basis in 6 h duration. The thin layer drying characteristics were analyzed using twelve mathematical models available in open literature. The results showed that the pick-up efficiency of the dryer was varied in the range between 14 and 43% with an average air collector thermal efficiency of 44% during the experimentation. The drying characteristics of carrot slices was predicted with good degree of accuracy using Wang and Singh drying model.

Dinâmica de crescimento da abobrinha italiana em duas estações de cultivo = Growth dynamic of summer squash in two crop seasons.

Directory of Open Access Journals (Sweden)

André Samuel Strassburger

2011-04-01

Full Text Available O objetivo deste trabalho foi quantificar os índices de crescimento, a produção e a distribuição de matéria seca da cultura da abobrinha italiana cultivada em substrato de casca de arroz in natura com solução nutritiva recirculante, em duas épocas de cultivo: primavera-verão de 2005 e verão-outono de 2006, caracterizadas, respectivamente, como períodos de alta e baixa disponibilidades de radiação solar. Cada tratamento correspondeu a uma época de amostragem, sendo a produção de matéria seca quantificada aos 0, 18, 32, 46 e 68 dias após o transplante (DAT no cultivo de primavera-verão, e aos 0, 15, 29, 43 e 55 DAT no cultivo de verão-outono.A produção de matéria seca foi maior quando a disponibilidade de radiação solar foi mais elevada. Nessa situação (alta disponibilidade de radiação solar, os frutos caracterizaram-se como os maiores drenos da cultura, não ocorrendo o mesmo em condições de baixa disponibilidade de radiação solar. As taxas de crescimento (da cultura, dos frutos, dos órgãos vegetativos aéreos e relativa também foram mais elevadas quando a radiação solar disponível foi mais elevada. A razão de área foliar e a área foliar específica apresentaram dinâmicas semelhantes à taxa de crescimento relativo, decrescendo com o decorrer do período de cultivo.The objective of this work was to quantify the growth rates, dry matter production and distribution of summer squash grown in raw rice husk medium with recirculating nutrient solution, in two crop seasons:spring-summer 2005 and summer-autumn 2006, which are periods characterized by high and low solar radiation availability, respectively. Each treatment corresponded to a sampling date and dry matter production was evaluated at 18, 32, 46 and 68 days after setting (DAS in springsummer, and 15, 29, 43 and 55 DAS in the summer-autumn crop season. Dry matter production was highest in high solar radiation availability conditions. In those

Effect of brining on the drying rate of tilapia in a solar tunnel dryer

Energy Technology Data Exchange (ETDEWEB)

Kituu, G.M.; Shitanda, D.; Kanali, C.L.; Mailutha, J.T. [Jomo Kenyatta Univ. of Agriculture and Technology, Nairobi (Kenya). BEED

2008-07-01

In addition to being a source of protein, fish is an important source of local and foreign currency earnings in Kenya. A substantial amount of fish production is exported. Approximately 30 per cent is exported to the European Union, the United States, and countries in the Middle East, but nearly half of the total annual fish harvest in Kenya goes to waste due to poor processing and preservation. Measures must be taken to ensure the fish industry is protected and waste is minimized, since the livelihood of over 500,000 people depends on fish as a source of proteins and employment. Therefore, it is necessary to implement appropriate and affordable processing and preservation techniques for fish at the artisanal landing sites in order to reduce the wastage and spoilage of fish during oversupply, and to enhance long storage. This paper presented studies that were conducted to determine the effect of brining on the drying rate of tilapia in a solar tunnel dryer. The paper discussed the materials and methods, including a description of the solar tunnel dryer system; the brining process of fish; the fish drying process; and data analysis. It was concluded that limiting the amount of salt used in brining, and subsequently dehydrating fish with a solar tunnel dryer achieves a more stable and suitable dried fish product than osmotic dehydration or solar drying process separately. 19 refs., 5 figs., 2 appendices.

Drying of fruits and vegetables using a flat plate solar collector with convective air flow

International Nuclear Information System (INIS)

Mansoor, K.K.; Hanif, M.

2011-01-01

This paper presents the analysis of drying of different fruits and vegetables dried by a flat plate solar collector developed at the Department of Agricultural Mechanization, Khyber PukhtunKhwa Agricultural University Peshawar, Pakistan. A small flat plate solar collector is designed and tested for its maximum performance in terms of efficiency with different convective flow rates. The collector assembly is divided into two parts. The flat plate solar collector and the drying chamber. The materials used for flat plate solar collector are wood, steel sheet, Insulation materials, and glass sheet as covering material. The insulation box (0.9 x 1.8 x 0.3 meter) is made up of wood of popular and deodar, to be fully isolated with the help of polystyrene. The absorber is black painted v-corrugated steel sheet. Collector has a tilt angle of 34 deg. (Equivalent to the latitude of Peshawar). The covering material is (0.9 x 1.8 meter) and 5 mm thick glass sheet placed at the top of the wooden box. The collector is supported and tilted with the help of a frame made up of iron angled arms. While the drying chamber is a (1 X 0.5 x 0.3 meter) wooden box connected to the outlet duct of the collector with the help of polyvinylchloride pipe. Experiments were conducted different fruits and vegetables and different parameters like moisture lost by the products in each hour, drying rate at each hour of drying, humidity and temperature of the drying chamber. It was observed that the products such as bitter guard and onion were dried in 10 to 2 hours up to moisture content less then 8%. These two product lost 8% to 10% moisture during each hour of drying. While grapes and Green chili are dried in 24 to 25 hours up to moisture content less then 8%. These two products lost 4% to 5% moisture in each hour of drying. The drying rate of all the products dried was very much consistent. It was observed that onion and bitter guard showed a good drying rate of 0.03[g(H/sub 2/O)/g(d.m).cm/ 2 hr] to

DESIGN AND THERMAL PERFORMANCE OF THE SOLAR BIOMASS HYBRID DRYER FOR CASHEW DRYING

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Saravanan Dhanuskodi

2014-12-01

Full Text Available Drying of Cashew nut to remove testa is one of the most energy-intensive processes of cashew nut process industry. For this reason a hybrid dryer consisting of a solar flat plate collector, a biomass heater and a drying chamber is designed and fabricated. 40 kg of Cashew nut with initial moisture of 9 % is used in the experiment. The performance test of the dryer is carried out in two modes of operation: hybrid-forced convection and hybrid-natural convection. Drying time and drying efficiency during these two modes of operation are estimated and compared with the sun drying. The system is capable of attaining drying temperature between 50º and 70ºC. In the hybrid forced drying, the required moisture content of 3% is achieved within 7 hours and the average system efficiency is estimated as 5.08%. In the hybrid natural drying, the required moisture content is obtained in 9 hours and the average system efficiency is 3.17%. The fuel consumption during the drying process is 0.5 kg/hr and 0.75 kg/hr for forced mode and natural mode, respectively. The drying process in the hybrid forced mode of operation is twice faster than the sun drying. The dryer can be operated in any climatic conditions: as a solar dryer on normal sunny days, as a biomass dryer at night time and as a hybrid dryer on cloudy days. Based on the experimental study, it is concluded that the developed hybrid dryer is suitable for small scale cashew nut farmers in rural areas of developing countries.

New climate-proof cropping systems in dry areas of the Mediterranean region

DEFF Research Database (Denmark)

Jacobsen, Sven-Erik

2014-01-01

severe consequences of climate changes, under influence of multiple abiotic stresses. These stresses are becoming even more pronounced under changing climate, resulting in drier conditions, increasing temperatures and greater variability, causing desertification. This topic has been addressed in the EU...... FP7 project entitled 'Sustainable water use securing food production in dry areas of the Mediterranean region (SWUP-MED)' working on climate-proof cropping systems in Morocco, Syria, Turkey and southern Europe, collaborating with UK, Denmark and Australia. The results are valid for other parts...

Solar drying system for tropical fruits and a model for drying bananas in a static column dryer; Sistema de secagem solar para frutos tropicais e modelagem da secagem de banana em um secador de coluna estatica

Energy Technology Data Exchange (ETDEWEB)

Costa, Antonio Raimundo da Silva

2008-01-15

An electric solar dryer consisting of a solar collector, a drying chamber, an exhaust fan and a fan to promote forced hot air convection were projected, built and tested . Banana drying experiments were also carried out in a static column dryer to model the drying and to obtain parameters that can be used as a first approximation in the modeling of an electric solar dryer, depending on the similarity of the experimental conditions between the two drying systems. From the banana drying experiments conducted in the static column dryer, we obtained food weight data as a function of aqueous concentration and temperature. Simplified mathematical models of the banana drying were made, based on Fick's and Fourier's second equations, which were tested with the experimental data. We determined and/or modeled parameters such as banana moisture content, density, thin layer drying curves, equilibrium moisture content, molecular diffusivity of the water in banana D{sub AB}, extemal mass transfer coefficient k{sub M}, specific heat C{sub p}, thermal conductivity k, latent heat of water evaporation in the food L{sub food}, time to heat food, and minimum energy and power required to heat the food and evaporate the water. When we considered the shrinkage of radius R of a banana, the calculated values of D{sub AB} and k{sub M} generally better represent the phenomenon of water diffusion in a solid. The latent heat of water evaporation in the food L{sub food} calculated by modeling is higher than the latent heat of pure water evaporation L{sub water}. The values calculated for D{sub AB} and K{sub M} that best represent the drying were obtained with the analytical model of the present paper. These values had good agreement with those assessed with a numeric model described in the literature, in which convective boundary condition and food shrinkage are considered. Using parameters such as C{sub p}, D{sub AB}, k, k{sub M} and L{sub food}, one can elaborate the preliminary

Grapes ( Vitis vinifera) drying by semitransparent photovoltaic module (SPVM) integrated solar dryer: an experimental study

Science.gov (United States)

Tiwari, Sumit; Tiwari, G. N.

2018-06-01

In present research paper, semi-transparent photovoltaic module (SPVM) integrated greenhouse solar drying system has been used for grapes ( Vitis vinifera) drying. Based on hourly experimental information namely solar intensity, moisture evaporated, ambient air temperature, grape surface temperatures, relative humidity and greenhouse air temperature etc. heat and mass transfer coefficient for the SPVM drying system have been evaluated. It has been seen that the convective heat transfer coefficients for grapes found between 3.1-0.84 W/m2 K. Also, there is a fair agreement between theoretical and practical mass transfer (moisture evaporated) during drying of grapes with a correlation coefficient (r) and root mean square percentage deviation (e) of 0.88 and 11.56 respectively. Further, nonlinear regression procedure has been used to fit various drying models namely Henderson and Pabis model, Newton's model, and Page's model. From the analysis, it was found that Page's model is best fitted for grapes drying in SPV greenhouse as well as open sun drying. Further, net electrical energy, thermal energy and equivalent thermal energy were found to be 3.61, 17.66 and 27.15 kWh during six days of drying respectively.

Grapes (Vitis vinifera) drying by semitransparent photovoltaic module (SPVM) integrated solar dryer: an experimental study

Science.gov (United States)

Tiwari, Sumit; Tiwari, G. N.

2017-12-01

In present research paper, semi-transparent photovoltaic module (SPVM) integrated greenhouse solar drying system has been used for grapes (Vitis vinifera) drying. Based on hourly experimental information namely solar intensity, moisture evaporated, ambient air temperature, grape surface temperatures, relative humidity and greenhouse air temperature etc. heat and mass transfer coefficient for the SPVM drying system have been evaluated. It has been seen that the convective heat transfer coefficients for grapes found between 3.1-0.84 W/m2 K. Also, there is a fair agreement between theoretical and practical mass transfer (moisture evaporated) during drying of grapes with a correlation coefficient (r) and root mean square percentage deviation (e) of 0.88 and 11.56 respectively. Further, nonlinear regression procedure has been used to fit various drying models namely Henderson and Pabis model, Newton's model, and Page's model. From the analysis, it was found that Page's model is best fitted for grapes drying in SPV greenhouse as well as open sun drying. Further, net electrical energy, thermal energy and equivalent thermal energy were found to be 3.61, 17.66 and 27.15 kWh during six days of drying respectively.

Mathematical modelling and simulation of solar-assisted drying of bulk farm products; Mathematische Modellierung und Simulation der solar unterstuetzten Trocknung landwirtschaftlicher Schuettgueter

Energy Technology Data Exchange (ETDEWEB)

Maltry, W.; Ziegler, T.; Richter, I.

1997-04-01

The report deals with problems associated with the harnessing of solar energy for drying bulk farm products: technical fundamentals, enthalpy diagrams, models for grain drying, experimental investigations, analysis of drying processes, benefits and applications of drying processes, advances. (HW) [Deutsch] Der Bericht behandelt die Probleme der Solarenergienutzung zur Trockung landwirtschaftlicher Massengueter: - Trocknungstechnische Grundlagen - Enthalpie-Diagramme - Modelle zur Koernertrocknung - experimentelle Untersuchungen - Analyse von Trocknungsprozesse - Nutzen und Verwertbarkeit der Trocknungsprozesse - Fortschritte. (HW)

Drying of Rhinacanthus nasutus (Linn. Kurz. using a solar dryer incorporated with a backup thermal energy storage from wood combustion

Directory of Open Access Journals (Sweden)

Perapong Tekasakul

2006-05-01

Full Text Available An indirect, natural convection, solar cabinet dryer incorporated with a backup thermal energy storage from wood combustion was designed and tested with the Thai herb, Rhinacanthus nasutus (Linn. Kurz. Most of Thai herbs are widely used as traditional medicine and drying is an initial step in the production process. Solar dryer with a biomass backup heating system is the most feasible solution to drying in Thailand. In this work, a 4 m x 5 m solar collector was used to absorb solar radiation for heating the incoming air during the daytime, while a biomass burner was used to supply heat when solar energy was not possible. Heat from fuelwood combustion was accumulated in the thermal storage system made of bricks, and was used to heat up the incoming air. Results showed that the herb was dried uniformly and the temperature inside the drying cabinet could be maintained above 50ºC for more than 10 hours. Thermal efficiency when using solar energy was 10.5%, but the value was less than 1% when using the heat from biomass burning. This resulted from the low moisture content of the products after being dried by the solar energy. The dryer is beneficial to the operators, particularly in southern Thailand, where continuous drying is required. This dryer is by no means limited to drying of the herb. Currently, four dryers of the same model have been used by farmer groups in southern Thailand for drying bananas, several types of herbs, fish, and other products. In economic consideration, its payback period is 5.5 years when compared with the LPG-equipped dryer. When the total cost and production capacity are considered, its payback period is about 6 years.

The Effect of Operating Conditions on Drying Characteristics and Quality of Ginger (Zingiber Officinale Roscoe) Using Combination of Solar Energy-Molecular Sieve Drying System

Science.gov (United States)

Hasibuan, R.; Zamzami, M. A.

2017-03-01

Ginger (Zingiber officinale Roscoe) is an agricultural product that can be used as beverages and snacks, and especially for traditional medicines. One of the important stages in the processing of ginger is drying. The drying process intended to reduce the water content of 85-90% to 8-10%, making it safe from the influence of fungi or insecticide. During the drying takes place, the main ingredient contained in ginger is homologous ketone phenolic known as gingerol are chemically unstable at high temperatures, for the drying technology is an important factor in maintaining the active ingredient (gingerol) which is in ginger. The combination of solar energy and molecular sieve dryer that are used in the research is capable of operating 24 hours. The purpose of this research is to study the effect of operating conditions (in this case the air velocity) toward the drying characteristics and the quality of dried ginger using the combination of solar energy and molecular sieve dryer. Drying system consist of three main parts which is: desiccator, solar collector, and the drying chamber. To record data changes in the mass of the sample, a load cell mounted in the drying chamber, and then connected to the automated data recording system using a USB data cable. All data of temperature and RH inside the dryer box and the change of samples mass recorded during the drying process takes place and the result is stored in the form of Microsoft Excel. The results obtained, shows that the air velocity is influencing the moisture content and ginger drying rate, where the moisture content equilibrium of ginger for the air velocity of 1.3 m/s was obtained on drying time of 360 minutes and moisture content of 2.8%, at 1.0 m/s was obtained on drying time of 300 minutes and moisture content of 1.4%, at 0, 8 m/s was obtained at 420 minutes drying time and the moisture content is 2.0%. The drying characteristics shows that there are two drying periods, which is: the increasing drying rate

Drying of Rosella (Hibiscus sabdariffa Flower Petals using Solar Dryer with Double Glass Cover Collector

Directory of Open Access Journals (Sweden)

Tjukup Marnoto

2014-10-01

Full Text Available Chemical ingredients in rosella petals are very beneficial for health. Rosella petals needed to be drained for storage and packing purpose. The traditional drying takes 5 days and less healthy. Solar dryer technology can speed up the drying process and protect materials from dust contamination. Solar dryer with double glass covered collector has been designed and made for drying of agricultural products such as rosella flowers. Rosella petals as much as 2300 grams with initial moisture content of 90.84 % be dried with this dryer until the moisture content of 7.67 % takes only 2 days, although the weather was less sunny . The temperature in the drying chamber was not more than 50° C, so it was good for drying groceries, not damaging chemical ingredients. The relative humidity in the space dryeris was about 40 % and it was still relative low. Drying rate and drying performance was expressed by the efficiency and Specific Moisture Evaporation Rate ( SMER were influenced by water content of the dried material and weather. Daily efficiency at the first and the second day: 14.931 % and 5.78%, while the daily SMER on the first and the second day: 0.222 and 0.0256 ( kg / kWh .

Experimental studies on drying of Zingiber officinale, Curcuma longa l. and Tinospora cordifolia in solar-biomass hybrid drier

Energy Technology Data Exchange (ETDEWEB)

Prasad, J.; Vijay, V.K. [Indian Institute of Technology, New Delhi (India). Center for Rural Development and Technology

2005-11-01

An integral type natural convection solar drier has been fabricated and coupled with a biomass stove. Experiments have been conducted to test the performance of the drier by drying of Zingiber officinale (ginger), Curcuma longa l. (turmeric) and Tinospora cordifolia (guduchi) during the summer climate in Delhi. It was found that, during the load test for ginger, 18 kg of fresh product with an initial moisture content of 319.74(db)% was dried to a final moisture content of 11.8(db)% within 33 h. Similarly, moisture content of turmeric and guduchi were reduced from 358.96 to 8.8 and 257.45 to 9.67(db)% during 36 and 48 h of drying, respectively. The drying of these products has also been studied under 'solar-only' and open sun in the same climatic conditions and the results indicate that for all the products, drying is faster, and is within 33-48 h in hybrid drier, against 72-120 h in 'solar-only' operation of the same drier and 192-288 h in open sun. Efficiency of the drier during its two mode (solar and biomass separately) of operation has been estimated and quality evaluation of under-studied products showed that developed drier is suitable for the drying of these products. The developed drier is a simple system, which can be manufactured locally and can be used for drying of other agricultural products. (author)

Mixed cropping of annual feed legumes with barley improves feed quantity and crude protein content under dry-land conditions

Directory of Open Access Journals (Sweden)

Khoshnood Alizadeh

2013-01-01

Full Text Available The objective of this research is to determine a suitable mixture of annual feed legumes and barley as a winter crop under dry-land conditions. Seeds of Hungarian vetch (cv. 2670, smooth vetch (cv. Maragheh, and local varieties of grass pea and field pea were mixed with barley (cv. Abidar in a 1:1 ratio and were tested, along with related monoculture. All legumes in the mixture survived winter while legumes alone, except Hungarian vetch, did not survive in the cold areas. The maximum fresh and dry forage yields (56 and 15 ton ha-1 respectively were obtained from a mixture of smooth vetch and barley in provinces with mild winter and more than 400 mm of rainfall. The mixture of barley and smooth vetch resulted in the highest mean crude protein content (17%. Autumn seeding of smooth vetch and barley in a 1:1 ratio produced more than 2 ton ha-1 of dry biomass with good quality in all studied areas and thus could serve as an alternative cropping system after wheat/barley in cold and semi-cold dry land.

Experimental investigation on energy and exergy analysis of coriander (Coriadrum sativum L.) leaves drying in natural convection solar dryer

International Nuclear Information System (INIS)

Panwar, N.L.

2014-01-01

This study deals with thin layer drying characteristics of Coriandrum sativum L. leaves in a natural convection solar dryer. The Coriandrum sativum L. leaves were dried from a moisture content of 88% (w.b.) to 4.5% (w.b.) in 7.5 hours. The obtained drying data were fitted to eight different drying kinetics models. Of these, the model suggested by Midilli et al. [20] had the best fit with the drying behavior of Coriandrum sativum L. leaves. In addition, the thermodynamic behaviour of a solar dryer was evaluated. The energy efficiency during the study varied from 7.81 to 37.93%. The exergy efficiency of the drying process ranged between 55.35 and 79.39%. (author)

Design aspects of integrated compact thermal storage system for solar dryer applications

International Nuclear Information System (INIS)

Rajaraman, R.; Velraj, R.; Renganarayanan, S.

2000-01-01

Solar energy is an excellent source for drying of crops, fruits, vegetables and other agricultural and forest products. Though the availability of solar energy is plenty, it is time dependent in nature. The energy need for some applications is also time dependent, but in a different pattern and phase from the solar energy supply. This implies that the solar dryer should be integrated with an efficient thermal storage system to match the time-dependent supply and end-use requirements. Based on the studies carried out on Latent Heat Thermal Storage (LHTS) Systems, it is observed that when air is used as the heat transfer fluid in LHTS system, nearly uniform surface heat flux can be achieved. Hence the LHTS systems are most suitable for air based solar drying applications. In the present work some major conclusions arrived from the investigations on LHTS systems and the design considerations for the integrated latent heat thermal storage for the solar dryer are reported. (Author)

Investigation the Vertical Distribution of Leaf Area and Dry Matter of Sweet Basil (Ocimum basilicum L., Borage (Borago officinalis L. and Cover Crops in Competition with Weeds

Directory of Open Access Journals (Sweden)

zeinab shirzadi margavi

2017-10-01

Full Text Available Introduction Distribution of leaf area and dry matter are the effective factors that influence on absorption the radiation, evaporation and transpiration of canopy and eventually dry matter accumulation and grain yield in plants. Plant canopy is the spatial arrangement of shoots in a plant population. In plant canopy, leaves are responsible for radiation absorption and gas exchange with the outside. Stem and branches arrange photosynthetic organs somehow, which gas exchange and light distribution best done. The effect of canopy structure on gas exchange and absorption of radiation in plant communities caused detailed study of the canopy structure to be more important. Materials and methods In order to investigate the vertical distribution of leaf area and dry matter of borage and sweet basil in competition with weeds by cover crops treatments, a field experiment was carried out in a randomized complete block design with 8 treatments and 3 replications in Agricultural Sciences and Natural Resources University of Sari in 2013. Treatments were cover crops mung bean (Vigna radiata L. and Persian clover (Trifolium resupinatum L. in the rows between the sweet basil (Ocimum basilicum L. and borage (Borago officinalis L.. Moreover, in order to evaluate the effectiveness of cover crops to control weeds, pure stand of sweet basil and borage in terms of weeding and no weed controls per replicates were used. Each plot was included 5 rows of medicinal plants. Cover crop inter-seeded simultaneously in the main crop. Estimation of leaf area and dry matter of each plant in different canopy layers (0-20, 20-40, 40-60, 80.100, 100-120 and 120-140 cm were done after 75 planting days, with 1 m × 1 m quadrate per plot. For this purpose a vertical card board frame marked in 20-cm increments was used in the field as a guide to cut standing plants (crops, cover crops and weeds into 20-cm strata increments (Mosier & Oliver, 1995. All samples were transferred to the

Dry technologies for the production of crystalline silicon solar cells; Trockentechnologien zur Herstellung von kristallinen Siliziumsolarzellen

Energy Technology Data Exchange (ETDEWEB)

Rentsch, J.

2005-04-15

Within this work, dynamic plasma etching technologies for the industrial production of crystalline silicon solar cells has been investigated. The research activity can be separated into three major steps: the characterisation of the etching behaviour of a newly developed dynamic plasma etching system, the development and analysis of dry etching processes for solar cell production and the determination of the ecological and economical impacts of such a new technology compared to standard up to date technologies. The characterisation of the etching behaviour has been carried out for two different etching sources, a low frequency (110 kHz) and a microwave (2.45 GHz) plasma source. The parameter of interest was the delivered ion energy of each source mainly determining the reachable etch rate. The etch rate turned out to be the main most critical parameter concerning the reachable wafer throughput per hour. Other points of interest in characterisation of the etching system were the material of the transport carriers, the silicon load as well as the process temperatures. The development of different dry etching processes targets the design of a complete dry production process for crystalline silicon solar cells. Therefore etching processes for saw damage removal, texturing, edge isolation as well as etching of dielectric layers have been developed and optimised. The major benefits of a complete dry production process would be the reduction of handling steps in between process steps and therefore offers a large cost reduction potential. For multicrystalline silicon solar cells a cost reduction potential of 5 % compared to a standard wet chemical based reference process could be realized only including the dry etching of a phosphorus silicate glass layer after diffusion. Further reduction potential offers the implementation of a dry texturing process due to a significant efficiency increase. (orig.)

Experimental study of pistachio drying behavior in a mixed-mode PV operated forced convection solar dryer

Energy Technology Data Exchange (ETDEWEB)

Zangiabadi, B [Univ. of Stavanger, Stavanger (Norway); Ameri, M; Mahmoudabadi, M M [Shahid Bahonar Univ., Kerman (Iran, Islamic Republic of)

2008-07-01

According to FAO statistics, Iran is the largest exporter of pistachios. Kerman province -south east of Iran- has approximately 200000 hectares of pistachio orchards, which provides practically 80% of whole country production of pistachios. After harvesting the pistachio, nuts must be washed to prevent staining. Therefore the nuts have almost 40% moisture content and it must be decreased to storage moisture of 6% or below. Simply decreasing in the moisture content of the products is called drying. In some areas where the environment conditions meet the minimum standard, solar drying can be an alternative approach for drying agricultural products. This work deals with the design, construction and testing a mixed-mode forced convection PV operated solar dryer. (orig.)

Alterations in fruit and vegetable beta-carotene and vitamin C content caused by open-sun drying, visqueen-covered and polyethylene-covered solar-dryers.

Science.gov (United States)

Ndawula, J; Kabasa, J D; Byaruhanga, Y B

2004-08-01

This study investigated the effects of three drying methods (open sun drying, visqueen-covered solar dryer and polyethylene-covered solar dryer) on b-carotene and vitamin C content of edible portions of mango fruit (Mangifera indica) and cowpea leaves (Vigna unguiculata). Commercial samples were analysed for vitamin C by titrimetry and b-carotene by spectrophotometry at 450 nm. Differences in vitamin retention and loss associated with the three drying methods were assessed by analysis of variance and least significant difference (LSD) at (pdrying. Open sun drying method caused the greatest b-carotene and vitamin C loss (58% and 84% respectively), while the visqueen-covered solar dryer caused the least loss (34.5% and 71% respectively). Blanching cowpea leaves improved b-carotene and vitamin C retention by 15% and 7.5% respectively. The b-carotene and vitamin C content of fresh ripe mango fruit was 5.9 and 164.3 mg/100g DM respectively. Similar to effects on cowpea leaves, the mango micronutrient content decreased (pdrying. The open sun drying method caused the greatest b-carotene (94.2%) and vitamin C (84.5%) loss, while the visqueen-covered solar dryer caused the least (73 and 53% respectively). These results show that the three solar drying methods cause significant loss of pro-vitamin A and vitamin C in dried fruits and vegetables. However, open sun drying causes the most loss and the visqueen-covered solar dryer the least, making the later a probable better drying technology for fruit and vegetable preservation. The drying technologies should be improved to enhance vitamin retention.

Constraints to the potential efficiency of converting solar radiation into phytoenergy in annual crops: from leaf biochemistry to canopy physiology and crop ecology

NARCIS (Netherlands)

Yin, X.; Struik, P.C.

2015-01-01

A new simple framework was proposed to quantify the efficiency of converting incoming solar radiation into phytoenergy in annual crops. It emphasizes the need to account for (i) efficiency gain when scaling up from the leaf level to the canopy level, and (ii) efficiency loss due to incomplete canopy

Advancing the climate data driven crop-modeling studies in the dry areas of Northern Syria and Lebanon: an important first step for assessing impact of future climate.

Science.gov (United States)

Dixit, Prakash N; Telleria, Roberto

2015-04-01

Inter-annual and seasonal variability in climatic parameters, most importantly rainfall, have potential to cause climate-induced risk in long-term crop production. Short-term field studies do not capture the full nature of such risk and the extent to which modifications to crop, soil and water management recommendations may be made to mitigate the extent of such risk. Crop modeling studies driven by long-term daily weather data can predict the impact of climate-induced risk on crop growth and yield however, the availability of long-term daily weather data can present serious constraints to the use of crop models. To tackle this constraint, two weather generators namely, LARS-WG and MarkSim, were evaluated in order to assess their capabilities of reproducing frequency distributions, means, variances, dry spell and wet chains of observed daily precipitation, maximum and minimum temperature, and solar radiation for the eight locations across cropping areas of Northern Syria and Lebanon. Further, the application of generated long-term daily weather data, with both weather generators, in simulating barley growth and yield was also evaluated. We found that overall LARS-WG performed better than MarkSim in generating daily weather parameters and in 50 years continuous simulation of barley growth and yield. Our findings suggest that LARS-WG does not necessarily require long-term e.g., >30 years observed weather data for calibration as generated results proved to be satisfactory with >10 years of observed data except in area with higher altitude. Evaluating these weather generators and the ability of generated weather data to perform long-term simulation of crop growth and yield is an important first step to assess the impact of future climate on yields, and to identify promising technologies to make agricultural systems more resilient in the given region. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of an Active Solar Crop Dryer: Design Analysis and Performance Evaluation

International Nuclear Information System (INIS)

Itodo, I. N.; Adewole, A.M.; Edemaku, S.K.

2002-01-01

A forced convection indirect solar dryer powered by a PVC module was designed and evaluated. The performance of the dryer was poor; its drying rate, collector and system drying efficiency were 0.74 kg/day, 12% and 10% respectively. The dryer was redesigned and modified into a direct forced convection type- Its design analysis and performance evaluation was undertaken by drying mashed cassava. The drying rate, system drying collector and pick-up efficiencies were 1,6 kg/day (14%/day), 9%, 46% and 29% respectively. Comparatively, the drying rate for sun drying was 0.9 kg/day. The collector efficiency compared very well to the designed value of 48% and may not need further improvement. The pick-up efficiency also compared well with typical averages for this dryer type. The drying rate and system drying efficiency Indicate the need for further development of this dryer. Prediction equations were developed from the results of measured differences in collector, dryer and ambient air temperatures plotted on graphs and applying regression. It is recommended that the volumetric air-flow rate across the drying unit should he improved by affecting the tan speed and air inlet area of the dryer. The improved dryer will subsequently be compared to a natural convection dryer so that an appropriate dryer technology can be recommended for the rural small-scale farmers

The utilization of solar energy for drying of agricultural products

International Nuclear Information System (INIS)

Mastekbayeva, G.A.; Kumar, S.

1999-01-01

The article presents the work done to studies the performance of the solar tunnel dryer fabricated in Asian Institute of Technology. Specifically, its performance at no load and load conditions, using fans powered by photovoltaic as well as from grid electricity; and tests on a hybrid dryer were done. The load experiments with chili, which was dried at all these three operating conditions were carried out. (author)

Effect of Tube Diameter on The Design of Heat Exchanger in Solar Drying system

Science.gov (United States)

Husham Abdulmalek, Shaymaa; Khalaji Assadi, Morteza; Al-Kayiem, Hussain H.; Gitan, Ali Ahmed

2018-03-01

The drying of agriculture product consumes a huge fossil fuel rates that demand to find an alternative source of sustainable environmental friendly energy such as solar energy. This work presents the difference between using solar heat source and electrical heater in terms of design aspect. A circular-finned tube bank heat exchanger is considered against an electrical heater used as a heat generator to regenerate silica gel in solar assisted desiccant drying system. The impact of tube diameter on the heat transfer area was investigated for both the heat exchanger and the electrical heater. The fin performance was investigated by determining fin effectiveness and fin efficiency. A mathematical model was developed using MATLAB to describe the forced convection heat transfer between hot water supplied by evacuated solar collector with 70 °C and ambient air flow over heat exchanger finned tubes. The results revealed that the increasing of tube diameter augments the heat transfer area of both heat exchanger and electrical heater. The highest of fin efficiency was around 0.745 and the lowest was around 0.687 while the fin effectiveness was found to be around 0.998.

75 FR 15777 - Common Crop Insurance Regulations, Basic Provisions; and Various Crop Insurance Provisions

Science.gov (United States)

2010-03-30

... (protection for production losses only) within one Basic Provisions and the applicable Crop Provisions to..., Macadamia Nut Crop Insurance Provisions, Onion Crop Insurance Provisions, Dry Pea Crop Insurance Provisions... (protection for production losses only) and revenue protection (protection against loss of revenue caused by...

Development and performance evaluation of a locally fabricated portable solar tunnel dryer for drying of fruits, vegetables and medicinal plants

International Nuclear Information System (INIS)

Munir, A.; Sultan, U.; Iqbal, M.

2013-01-01

The research was conducted to fabricate and develop a portable solar tunnel dryer (STD) for the drying of fruits, vegetables and medicinal plants. The system was designed as a portable system for decentralized applications at various sites to satisfy the drying requirements of small farmers and co-operatives. The cross sectional area of the solar tunnel dryer was trapezoidal in shape having 0.254 m/sup 2/ face area, with length and width of three meters and one meter respectively. It comprises a collector section (1.35 m) long and a drying section (1.65 m long) and two PV powered DC fans to provide the required air flow rate over the perishable agricultural products to be dried. Transparent polythene cover was used to close the dryer on top side to maintain the steady state air flow within the dryer. It has been observed that the drying air temperature was easily raised by some 8-14 degree C above the ambient temperature at air velocity ranges 0-1 m s/sup -1/. The efficiency of the solar tunnel dryer was found to be 40-45%. Psychrometric analysis was also carried out within the dryer and the process curves were drawn. The process curves were found similar to a conventional dryer showing that this dryer can be successfully utilized for the drying of agricultural products using solar energy. (author)

Crop and varietal diversification of rainfed rice based cropping systems for higher productivity and profitability in Eastern India.

Science.gov (United States)

Lal, B; Gautam, Priyanka; Panda, B B; Raja, R; Singh, Teekam; Tripathi, R; Shahid, M; Nayak, A K

2017-01-01

Rice-rice system and rice fallows are no longer productive in Southeast Asia. Crop and varietal diversification of the rice based cropping systems may improve the productivity and profitability of the systems. Diversification is also a viable option to mitigate the risk of climate change. In Eastern India, farmers cultivate rice during rainy season (June-September) and land leftovers fallow after rice harvest in the post-rainy season (November-May) due to lack of sufficient rainfall or irrigation amenities. However, in lowland areas, sufficient residual soil moistures are available in rice fallow in the post-rainy season (November-March), which can be utilized for raising second crops in the region. Implementation of suitable crop/varietal diversification is thus very much vital to achieve this objective. To assess the yield performance of rice varieties under timely and late sown conditions and to evaluate the performance of dry season crops following them, three different duration rice cultivars were transplanted in July and August. In dry season several non-rice crops were sown in rice fallow to constitute a cropping system. The results revealed that tiller occurrence, biomass accumulation, dry matter remobilization, crop growth rate, and ultimately yield were significantly decreased under late transplanting. On an average, around 30% yield reduction obtained under late sowing may be due to low temperature stress and high rainfall at reproductive stages of the crop. Dry season crops following short duration rice cultivars performed better in terms of grain yield. In the dry season, toria was profitable when sown earlier and if sowing was delayed greengram was suitable. Highest system productivity and profitability under timely sown rice may be due to higher dry matter remobilization from source to sink. A significant correlation was observed between biomass production and grain yield. We infer that late transplanting decrease the tiller occurrence and assimilate

Effects of solar radiation on grape (Vitis vinifera L.) composition and dried fruit colour

International Nuclear Information System (INIS)

Uhlig, B.A.

1998-01-01

Most sun-exposed fruit (Vitis vinifera L.) produced dark brown berries with low L-values, whereas most dried berries from shade fruit were acceptable in lightness although some had a green tinge. Fruit shaded by the natural vine canopy or exposed to direct solar radiation had similar drying ratios. However, berry weights were significantly higher in the shade than in the sun for both cultivars. The difference in berry weight between the two positions was less pronounced in the heat affected year. Solar radiation changed the composition of fresh berries and the colour of the dried fruit. The soluble-solid concentration was higher in fresh fruit exposed to direct solar radiation than in fruit grown in shaded conditions within the canopy. In the heat affected year the berries from both positions had the same soluble-solid concentrations, possibly due to dehydration of the fruit. No significant difference was found between the pH of sun fruit and shade fruit, but the titratable acidity was higher in shade fruit. Malate and tartrate concentrations in berry skin and the polyphenol oxidase activities had carotenoid concentrations in whole fresh berries were not significantly different for sun and shade fruit. Total phenol concentrations in berry skin were higher in sun fruit and chlorophyll concentrations in whole, fresh berries were higher in shade fruit. (author)

Agricultural water use, crop water footprints and irrigation strategies in the seasonally dry Guanacaste region in Costa Rica

Science.gov (United States)

Morillas, Laura; Johnson, Mark S.; Hund, Silja V.; Steyn, Douw G.

2017-04-01

Agriculture is the main productive sector and a major water-consuming sector in the seasonally-dry Guanacaste region of north-western Costa Rica. Agriculture in the region is intensifying at the same time that seasonal water scarcity is increasing. The climate of this region is characterized by a prolonged dry season from December to March, followed by a bimodal wet season from April to November. The wet season has historically experienced periodic oscillations in rainfall timing and amounts resulting from variations of several large-scale climatic features (El Niño Southern Oscillation, the Pacific Decadal Oscillation, the Atlantic Multidecadal Oscillation and the North Atlantic Oscillation). However, global circulation models now project more recurrent variations in total annual rainfall, changes in rainfall temporal distribution, and increased temperatures in this region. This may result in a lengthening of the dry season and an increase in water scarcity and water-related conflicts as water resources are already limited and disputed in this area. In fact, this region has just undergone a four-year drought over the 2012-2015 period, which has intensified water related conflicts and put agricultural production at risk. In turn, the recent drought has also increased awareness of the local communities regarding the regional threat of water scarcity and the need of a regional water planning. The overall goal of this research is to generate data to characterize water use by the agricultural sector in this region and asses its sustainability in the regional context. Towards this goal, eddy-covariance flux towers were deployed on two extensive farms growing regionally-representative crops (melon/rice rotation and sugarcane) to evaluate, monitor and quantify water use in large-scale farms. The two identically instrumented stations provide continuous measurements of evapotranspiration and CO2 fluxes, and are equipped with additional instrumentation to monitor

Mathematical model for solar drying of potato cylinders with thermal conductivity radially modulated

Science.gov (United States)

Trujillo Arredondo, Mariana

2014-05-01

A mathematical model for drying potato cylinders using solar radiation is proposed and solved analytically. The model incorporates the energy balance for the heat capacity of the potato, the radiation heat transfer from the potato toward the drying chamber and the solar radiation absorbed by the potato during the drying process. Potato cylinders are assumed to exhibit a thermal conductivity which is radially modulated. The method of the Laplace transform, with integral Bromwich and residue theorem will be applied and the analytic solutions for the temperature profiles in the potato cylinder will be derived in the form of an infinite series of Bessel functions, when the thermal conductivity is constant; and in the form of an infinite series of Heun functions, when the thermal conductivity has a linear radial modulation. All computations are performed using computer algebra, specifically Maple. It is expected that the analytical results obtained will be useful in food engineering and industry. Our results suggest some lines for future investigations such as the adoption of more general forms of radial modulation for the thermal conductivity of potato cylinders; and possible applications of other computer algebra software such as Maxima and Mathematica.

Optical crop sensor for variable-rate nitrogen fertilization in corn: i - plant nutrition and dry matter production

Directory of Open Access Journals (Sweden)

Jardes Bragagnolo

2013-10-01

Full Text Available Variable-rate nitrogen fertilization (VRF based on optical spectrometry sensors of crops is a technological innovation capable of improving the nutrient use efficiency (NUE and mitigate environmental impacts. However, studies addressing fertilization based on crop sensors are still scarce in Brazilian agriculture. This study aims to evaluate the efficiency of an optical crop sensor to assess the nutritional status of corn and compare VRF with the standard strategy of traditional single-rate N fertilization (TSF used by farmers. With this purpose, three experiments were conducted at different locations in Southern Brazil, in the growing seasons 2008/09 and 2010/11. The following crop properties were evaluated: above-ground dry matter production, nitrogen (N content, N uptake, relative chlorophyll content (SPAD reading, and a vegetation index measured by the optical sensor N-Sensor® ALS. The plants were evaluated in the stages V4, V6, V8, V10, V12 and at corn flowering. The experiments had a completely randomized design at three different sites that were analyzed separately. The vegetation index was directly related to above-ground dry matter production (R² = 0.91; p<0.0001, total N uptake (R² = 0.87; p<0.0001 and SPAD reading (R² = 0.63; p<0.0001 and inversely related to plant N content (R² = 0.53; p<0.0001. The efficiency of VRF for plant nutrition was influenced by the specific climatic conditions of each site. Therefore, the efficiency of the VRF strategy was similar to that of the standard farmer fertilizer strategy at sites 1 and 2. However, at site 3 where the climatic conditions were favorable for corn growth, the use of optical sensors to determine VRF resulted in a 12 % increase in N plant uptake in relation to the standard fertilization, indicating the potential of this technology to improve NUE.

Constraints to the potential efficiency of converting solar radiation into phytoenergy in annual crops: from leaf biochemistry to canopy physiology and crop ecology.

Science.gov (United States)

Yin, Xinyou; Struik, Paul C

2015-11-01

A new simple framework was proposed to quantify the efficiency of converting incoming solar radiation into phytoenergy in annual crops. It emphasizes the need to account for (i) efficiency gain when scaling up from the leaf level to the canopy level, and (ii) efficiency loss due to incomplete canopy closure during early and late phases of the crop cycle. Equations are given to estimate losses due to the constraints in various biochemical or physiological steps. For a given amount of daily radiation, a longer daytime was shown to increase energy use efficiency, because of the convex shape of the photosynthetic light response. Due to the higher cyclic electron transport, C4 leaves were found to have a lower energy loss via non-photochemical quenching, compared with C3 leaves. This contributes to the more linear light response in C4 than in C3 photosynthesis. Because of this difference in the curvature of the light response, canopy-to-leaf photosynthesis ratio, benefit from the optimum acclimation of the leaf nitrogen profile in the canopy, and productivity gain from future improvements in leaf photosynthetic parameters and canopy architecture were all shown to be higher in C3 than in C4 species. The indicative efficiency of converting incoming solar radiation into phytoenergy is ~2.2 and 3.0% in present C3 and C4 crops, respectively, when grown under well-managed conditions. An achievable efficiency via future genetic improvement was estimated to be as high as 3.6 and 4.1% for C3 and C4 crops, respectively. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Effect of Cover Crops and Nitrogen Fertilizer on Total Production of Forage Corn and Dry Weight of Weeds

Directory of Open Access Journals (Sweden)

R Fakhari

2014-10-01

Full Text Available To evaluate the effect of cover crops, split application of nitrogen and control weeds on forage corn and weed biomass a factorial experiment based on randomized complete block design with three replications and three factors was conducted at the Agricultural Research Station of Ardabil (Iran during 2012 crop year. The first factor was cover crops (consisting of winter rye, hairy vetch, berseem clover, with and without weeding as controls. The second factor was two levels of split application of 225 kg.ha-1 urea at two growth stages forage corn: the first level (N1= 1/2 at planting and 1/2 at 8-10 leaf stage, second level (N2= 1/3 at planting, 1/3 at 8-10 leaf and 1/3 one week before tasselling stage. The third factor consisted of two levels of weed control: weeding at 8 leaves and weeding one week before tasselling. Results showed that winter rye, hairy vetch and berseem clover cover crops decreased total weed dry weights up to 87, 82 and 65 % respectively as compared to control (without weeding. Cover crops and nitrogen application time had a significant effect on yield of fresh forage corn and cover crops. Based on the advantages of effective weed control and higher forage production of hairy vetch it can be recommended as proper cover crop.

MODELLING OF THIN LAYER SOLAR DRYING KINETICS AND EFFECTIVE DIFFUSIVITY OF Urtica dioica LEAVES

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A. LAMHARRAR

2017-08-01

Full Text Available Urtica dioica is an endemic plant of Morocco used for its virtues in traditional medicine. The drying kinetics of Urtica dioica leaves in a convective solar dryer was studied. The kinetics of drying is studied for three temperatures (40, 50 and 60 °C, ambient air temperature ranged from 30 to 35 °C. The experimental results are used to determine the characteristic drying curve. Nine mathematical models have been used for the description of the drying curve. The Midilli-Kuck model was found to be the most suitable for describing the drying curves of Urtica dioica leaves. The drying parameters in this model were quantified as a function of the drying air temperature. Moisture transfer from Urtica dioica leaves was described by applying the Fick’s diffusion model. Effective moisture diffusivity of the product was in the range of 9.38 – 72.92×10-11 m2/s. A value of 88,49 kJ/mol was determined as activation energy.

Crop characteristics and inulin production in chicory

International Nuclear Information System (INIS)

Meijer, W.J.M.; Mathijssen, E.W.J.M.

1992-01-01

Crop growth, dry matter partitioning, leaf area development, light interception and dry matter : radiation quotient in chicory were studied in field and glasshouse trials. Variations in root and inulin yields were related to sowing time, sowing density and cultivar. Retarded growth of first leaves appeared to be a major factor in limiting productivity. Growth of the first leaves was limited by assimilate supply and by low temperatures. Leaf area expansion exhibited a lag of 350 °Cd from emergence. From that point until crop closure, leaf area index increased exponentially with thermal time. Initially, 60 per cent of the dry matter was partitioned to the leaves; this share gradually decreased to about 10 per cent during later stages. The average dry matter: radiation quotient was 2.6 g MJ -1 for total dry matter and 2.4 g MJ -1 for root dry matter. Cultivars differed in early leaf growth, dry matter partitioning and dry matter: radiation quotient. The crop characteristics are compared with literature data for sugar beet and the prospects for breeding improved genotypes are discussed. (author)

Drying characteristics and nitrogen loss of biogas digestate during drying process

Energy Technology Data Exchange (ETDEWEB)

Maurer, C.; Muller, J. [Hohenheim Univ., Stuttgart (Germany). Inst. of Agricultural Engineering, Tropical and Subtropical Group

2010-07-01

The cost of transporting biogas digestate can be decreased by reducing its water content. However, the digestate emits volatile compounds during drying. This study investigated the drying behaviour and the change of digestate composition. Drying took place in a hybrid solar/waste-heat dryer that used solar energy as well as waste heat from a combined heat and power unit (CHP) and the exhaust air of a microturbine. The experiment involved the use of 60 t of liquid digestate. Climatic conditions were measured inside and outside the drying hall. Dry matter (DM) and organic dry matter (ODM) were also measured on a daily basis. In addition, the energy consumption of waste and solar heat were recorded and related to the quantity of dried feedstock. The total nitrogen, ammonium, phosphate, potassium oxide, magnesium oxide and calcium oxide in the digestate were subjected to chemical analysis before and after the drying process. Losses of nitrogen were calculated. Specific energy consumption depended on the climatic condition. Most of the energy consumption was covered by the waste heat of the CHP. A considerable amount of nitrogen was lost during the drying process.

Analysis of ginger drying inside a natural convection indirect solar dryer: An experimental study

Directory of Open Access Journals (Sweden)

S. K. Sansaniwal

2015-12-01

Full Text Available In this paper, a natural convection indirect solar cabinet dryer has been fabricated to study the drying behaviour of ginger rhizomes in terms of its convective heat transfer coefficient and moisture removing rate (% db. Various experiments were conducted during the months of March and April 2014 at Guru Jambheshwar University of Science and Technology, Hisar (29o5’5’’N, 75o45’55’’E, India. Experimental data obtained were used to evaluate the Nusselt number constants using linear regression method. Considering these constants, the average value of convective heat transfer coefficient was obtained and observed to decrease with increase in mass of ginger samples and progression of drying days with variation from 0.59 to 5.42 W/m2˚C for different mass of ginger samples. The moisture removing rate was reported to increase with increase in mass of ginger samples and decreases significantly with the progression of drying days. The average collector efficiency was also observed to vary from 14.97 to 16.14% under increasing and decreasing trends of solar radiations from morning to noon and noon to evening respectively. Modified page model was reported best for describing the drying behaviour of different mass of ginger samples. The experimental error in terms of percent uncertainty ranged from 29.19 to 46.25%.

Numerical characterisation of one-step and three-step solar air heating collectors used for cocoa bean solar drying.

Science.gov (United States)

Orbegoso, Elder Mendoza; Saavedra, Rafael; Marcelo, Daniel; La Madrid, Raúl

2017-12-01

In the northern coastal and jungle areas of Peru, cocoa beans are dried using artisan methods, such as direct exposure to sunlight. This traditional process is time intensive, leading to a reduction in productivity and, therefore, delays in delivery times. The present study was intended to numerically characterise the thermal behaviour of three configurations of solar air heating collectors in order to determine which demonstrated the best thermal performance under several controlled operating conditions. For this purpose, a computational fluid dynamics model was developed to describe the simultaneous convective and radiative heat transfer phenomena under several operation conditions. The constructed computational fluid dynamics model was firstly validated through comparison with the data measurements of a one-step solar air heating collector. We then simulated two further three-step solar air heating collectors in order to identify which demonstrated the best thermal performance in terms of outlet air temperature and thermal efficiency. The numerical results show that under the same solar irradiation area of exposition and operating conditions, the three-step solar air heating collector with the collector plate mounted between the second and third channels was 67% more thermally efficient compared to the one-step solar air heating collector. This is because the air exposition with the surface of the collector plate for the three-step solar air heating collector former device was twice than the one-step solar air heating collector. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation and comparing of natural and forced solar dryer for mint drying in Khuzestan province

Directory of Open Access Journals (Sweden)

J Habibi Asl

2017-05-01

Research Center during the years 2011-2013. Materials and Methods In this research an indirect cabinet solar dryer with three trays and grooved collector was constructed. To improve air convection, a chimney was mounted above the dryer. The dryer performance was evaluated by drying mint leaves in three levels of mass density of 2, 3, and 4 kg m-2 at two drying manners of natural and forced convection and compared with drying mint leaves in shade as the traditional method. Results and Discussion The results showed that total drying time required in different solar drier treatments was 3.5 to 15 h, while it was about 5 days in traditional method. Drying time in upper trays was more as the air flow decreased due to increase in mass density. Mean required drying time in forced convection was 29.7% less than that of natural convection. Maximum essences with 0.80% and 0.76% were belonged to "natural convection and 3kg m-2 mass density" and "forced convection and 4 kg m-2 mass density" treatments respectively, while minimum one with 0.30% was for "forced convection and 2 kg m-2 mass density" treatment. Also, the highest and lowest chlorophyll content with 8.51 and 4.18 mg ml-1 were measured in "natural convection and 3 kg m-2 mass density" and "forced convection and 4 kg m-2 mass density" treatments respectively. According to obtained results, 3 and 4 kg m-2 mass density can be suggested for natural and forced convection solar drying of mint leaves in Khuzestan condition respectively. Conclusions In order to reduce vegetable losses and increase Khuzestan vegetable producers income, indirect cabinet solar dryer for drying mint leaves in winter season, could be an appropriate option. For natural and forced convection drying methods, mass density of 3 and 4 kg m-2 is recommended respectively.

Reduced heat stress in offices in the tropics using solar powered drying of the supply air

DEFF Research Database (Denmark)

Gunnarsen, Lars; Santos, A M B

2002-01-01

air may facilitate personal cooling by increased evaporation of sweat. Heat acclimatized people with efficient sweating may in particular benefit from this cooling. A prototype solar powered supply system for dried-only air was made. Air from the system was mixed with room air, heated to six different...... content of room air, temperature of supply air and moisture content of supply air was developed based on the experiments. Reduction of moisture content in the supply air by 1.6 g/kg had the same effect as lowering the operative temperature by 1 degree C. The solar-powered system for supplying dry air...... is a low-cost alternative to traditional air conditioning in hot and humid regions....

Development of technology to utilize existing tobacco kilns and/or tobacco storage barns for curing (drying) and/or storage of other crops

Energy Technology Data Exchange (ETDEWEB)

VanHooren, D L; Scott, J J

1988-01-01

This report investigates methods to utilize existing bulk tobacco kilns for curing (drying) of shelled corn, peanuts, and baled hay. In recent years Ontario tobacco producers have had to reduce production levels due to a declining demand for flue-cured tobacco. Many tobacco producers are currently diversifying into other crops. Some of these crops require curing and/or storage. Because of high capital costs to purchase conventional curing and/or storage facilities, tobacco producers wish to reduce their initial diversification costs by modifying their existing tobacco kilns (tobacco drying structures) and/or tobacco storage barns for this purpose. The investigation included high profile and low profile downdraft stick kilns, bulk kilns, and tobacco storage (pack) barns. Corn, peanuts, and hay were considered in relation to bulk kiln specifications and modifications, handling, drying and storage methods, energy requirements, cost, and quality of end product. The conclusions drawn from the study of each product are presented. Results from the projects indicate that: shelled corn can be dried from about 26% moisture content (w.b.) or less; baled hay can be dried from about 27% moisture content (w.b.) or less; and peanuts cured at airflow rates ranging from 169 to 645 l/s/m/sup 3/ of peanuts exhibited no significant differences when evaluated for appearance and flavour. 1 ref., 23 figs., 15 tabs.

The Effect of Elevated Ozone Concentrations with Varying Shading on Dry Matter Loss in a Winter Wheat-Producing Region in China.

Science.gov (United States)

Xu, Jingxin; Zheng, Youfei; He, Yuhong; Wu, Rongjun; Mai, Boru; Kang, Hanqing

2016-01-01

Surface-level ozone pollution causes crop production loss by directly reducing healthy green leaf area available for carbon fixation. Ozone and its precursors also affect crop photosynthesis indirectly by decreasing solar irradiance. Pollutants are reported to have become even more severe in Eastern China over the last ten years. In this study, we investigated the effect of a combination of elevated ozone concentrations and reduced solar irradiance on a popular winter wheat Yangmai13 (Triticum aestivum L.) at field and regional levels in China. Winter wheat was grown in artificial shading and open-top-chamber environments. Treatment 1 (T1, i.e., 60% shading with an enhanced ozone of 100±9 ppb), Treatment 2 (T2, i.e., 20% shading with an enhanced ozone of 100±9 ppb), and Control Check Treatment (CK, i.e., no shading with an enhanced ozone of 100±9 ppb), with two plots under each, were established to investigate the response of winter wheat under elevated ozone concentrations and varying solar irradiance. At the field level, linear temporal relationships between dry matter loss and cumulative stomatal ozone uptake were first established through a parameterized stomatal-flux model. At the regional level, ozone concentrations and meteorological variables, including solar irradiance, were simulated using the WRF-CMAQ model (i.e., a meteorology and air quality modeling system). These variables were then used to estimate cumulative stomatal ozone uptake for the four major winter wheat-growing provinces. The regional-level cumulative ozone uptake was then used as the independent variable in field data-based regression models to predict dry matter loss over space and time. Field-level results showed that over 85% (T1: R(2) = 0.85 & T2: R(2) = 0.89) of variation in dry matter loss was explained by cumulative ozone uptake. Dry matter was reduced by 3.8% in T1 and 2.2% in T2 for each mmol O3·m(-2) of cumulative ozone uptake. At the regional level, dry matter loss in winter

The Effect of Elevated Ozone Concentrations with Varying Shading on Dry Matter Loss in a Winter Wheat-Producing Region in China.

Directory of Open Access Journals (Sweden)

Jingxin Xu

Full Text Available Surface-level ozone pollution causes crop production loss by directly reducing healthy green leaf area available for carbon fixation. Ozone and its precursors also affect crop photosynthesis indirectly by decreasing solar irradiance. Pollutants are reported to have become even more severe in Eastern China over the last ten years. In this study, we investigated the effect of a combination of elevated ozone concentrations and reduced solar irradiance on a popular winter wheat Yangmai13 (Triticum aestivum L. at field and regional levels in China. Winter wheat was grown in artificial shading and open-top-chamber environments. Treatment 1 (T1, i.e., 60% shading with an enhanced ozone of 100±9 ppb, Treatment 2 (T2, i.e., 20% shading with an enhanced ozone of 100±9 ppb, and Control Check Treatment (CK, i.e., no shading with an enhanced ozone of 100±9 ppb, with two plots under each, were established to investigate the response of winter wheat under elevated ozone concentrations and varying solar irradiance. At the field level, linear temporal relationships between dry matter loss and cumulative stomatal ozone uptake were first established through a parameterized stomatal-flux model. At the regional level, ozone concentrations and meteorological variables, including solar irradiance, were simulated using the WRF-CMAQ model (i.e., a meteorology and air quality modeling system. These variables were then used to estimate cumulative stomatal ozone uptake for the four major winter wheat-growing provinces. The regional-level cumulative ozone uptake was then used as the independent variable in field data-based regression models to predict dry matter loss over space and time. Field-level results showed that over 85% (T1: R(2 = 0.85 & T2: R(2 = 0.89 of variation in dry matter loss was explained by cumulative ozone uptake. Dry matter was reduced by 3.8% in T1 and 2.2% in T2 for each mmol O3·m(-2 of cumulative ozone uptake. At the regional level, dry matter

Solar drying of sweet pepper and garlic using the tunnel greenhouse drier

Energy Technology Data Exchange (ETDEWEB)

Condori, M.; Echazu, R.; Saravia, L. [Universidad Nacional de Salta, Inst. de Investigacion en Energia no Convencional, Salta (Argentina)

2001-04-01

A new low cost design for a forced convection greenhouse drier, the Tunnel Greenhouse Drier, has been built and tested. Its main parts are: a plastic greenhouse cover containing a drying tunnel made with transparent plastic walls; a line of carts with several stacked trays containing the product and moved manually inside the tunnel and an electrical fan that moves the hot air from the greenhouse into the tunnel. The trays receive solar radiation through the transparent walls, increasing the product temperature. Heat losses from the tunnel are low since the greenhouse temperatures are higher than ambient temperature. The main advantages of this drier are: (a) an almost continuous production since some carts with dried product come out of the tunnel every day, while the same amount of fresh product is introduced by the other tunnel extreme; (b) lower labor cost since the product handling is partly mechanized; (c) a conventional heater can be easily installed to keep a constant production rate; (d) the energy consumption is lower than in other drier types; (e) the installation can be used as a greenhouse for small production when it is not used as a drier. The prototype was built in the north of Argentina, and red sweet pepper and garlic were used as load. The drier thermal efficiency, considered as a solar collector, was calculated using the measured experimental data, and a linear relation between the drier temperature and the solar radiation was obtained. (Author)

Development of Simple Drying Model for Performance Prediction of Solar Dryer: Theoretical Analysis

DEFF Research Database (Denmark)

Singh, Shobhana; Kumar, Subodh

2012-01-01

An analytical moisture diffusion model which considers the influence of external resistance to mass transfer is developed to predict thermal performance of dryer system. The moisture diffusion coefficient, Deff that is necessary to evaluate the prediction model has been determined in terms...... of experimental drying parameters. A laboratory model of mixed-mode solar dryer system is tested with cylindrical potato samples of thickness 5 and 18 mm under simulated indoor conditions. The potato samples were dried at a constant absorbed thermal energy of 750 W/m2 and air mass flow rate of 0.011 kg...

Wood drying project with solar energy and absorption plant; Proyecto de un secador de madera con energia solar termica y una planta de absorcion

Energy Technology Data Exchange (ETDEWEB)

Corretger, J. M.; Lara, J.; Arnau, J.; Marquez, A.

2004-07-01

Wood drying processes currently are developed in tunnel dryers using an air hot flow through the wood to remove the water. These processes are interesting to dry current wood that does not require special control of the drying velocity. However, could be necessary to control drying velocity at any moment of the process in order to dry some high quality wood. This implies to combine heating processes, cooling and dehumidification processes and humidification processes. The aim of this project is to dry noble woods with a drying complex process, in order to improve the quality of the products and to increase the energy saving by free-cooling operations and advanced control strategies, increased by using solar energy to get cold and hot water. The saving of energy will produce a bill reduction and an important minimization of environmental impact. (Author)

Solar water heating and its prospect for timber drying application

Energy Technology Data Exchange (ETDEWEB)

Yin, B T

1982-01-01

The technical requirements for timber drying are discussed, and the possibility of using a solar water heating system to substitute for conventional fuel in a modern kiln is looked into from heat transfer considerations. At the moment, conventional fuel is used to generate steam for the heating of air in a kiln. If hot water is to be substitued for steam as the heating medium, the heating coil size required is larger. This size is determined relative to that of a steam coil for similar kiln operating temperatures. 5 references.

An empirical model to predict infield thin layer drying rate of cut switchgrass

International Nuclear Information System (INIS)

Khanchi, A.; Jones, C.L.; Sharma, B.; Huhnke, R.L.; Weckler, P.; Maness, N.O.

2013-01-01

A series of 62 thin layer drying experiments were conducted to evaluate the effect of solar radiation, vapor pressure deficit and wind speed on drying rate of switchgrass. An environmental chamber was fabricated that can simulate field drying conditions. An empirical drying model based on maturity stage of switchgrass was also developed during the study. It was observed that solar radiation was the most significant factor in improving the drying rate of switchgrass at seed shattering and seed shattered maturity stage. Therefore, drying switchgrass in wide swath to intercept the maximum amount of radiation at these stages of maturity is recommended. Moreover, it was observed that under low radiation intensity conditions, wind speed helps to improve the drying rate of switchgrass. Field operations such as raking or turning of the windrows are recommended to improve air circulation within a swath on cloudy days. Additionally, it was found that the effect of individual weather parameters on the drying rate of switchgrass was dependent on maturity stage. Vapor pressure deficit was strongly correlated with the drying rate during seed development stage whereas, vapor pressure deficit was weakly correlated during seed shattering and seed shattered stage. These findings suggest the importance of using separate drying rate models for each maturity stage of switchgrass. The empirical models developed in this study can predict the drying time of switchgrass based on the forecasted weather conditions so that the appropriate decisions can be made. -- Highlights: • An environmental chamber was developed in the present study to simulate field drying conditions. • An empirical model was developed that can estimate drying rate of switchgrass based on forecasted weather conditions. • Separate equations were developed based on maturity stage of switchgrass. • Designed environmental chamber can be used to evaluate the effect of other parameters that affect drying of crops

Do cover crop mixtures have the same ability to suppress weeds as competitive monoculture cover crops?

Directory of Open Access Journals (Sweden)

Brust, Jochen

2014-02-01

Full Text Available An increasing number of farmers use cover crop mixtures instead of monoculture cover crops to improve soil and crop quality. However, only little information is available about the weed suppression ability of cover crop mixtures. Therefore, two field experiments were conducted in Baden-Württemberg between 2010 and 2012, to compare growth and weed suppression of monoculture cover crops and cover crop mixtures. In the first experiment, heterogeneous results between yellow mustard and the cover crop mixture occurred. For further research, a field experiment was conducted in 2012 to compare monocultures of yellow mustard and hemp with three cover crop mixtures. The evaluated mixtures were: “MELO”: for soil melioration; “BETA”: includes only plant species with no close relation to main cash crops in Central Europe and “GPS”: for usage as energy substrate in spring. Yellow mustard, MELO, BETA and GPS covered 90% of the soil in less than 42 days and were able to reduce photosynthetically active radiation (PAR on soil surface by more than 96% after 52 days. Hemp covered 90% of the soil after 47 days and reduced PAR by 91% after 52 days. Eight weeks after planting, only BETA showed similar growth to yellow mustard which produced the highest dry matter. The GPS mixture had comparatively poor growth, while MELO produced similar dry matter to hemp. Yellow mustard, MELO and BETA reduced weed growth by 96% compared with a no cover crop control, while hemp and GPS reduced weeds by 85% and 79%. In spring, weed dry matter was reduced by more than 94% in plots with yellow mustard and all mixtures, while in hemp plots weeds were only reduced by 71%. The results suggest that the tested cover crop mixtures offer similar weed suppression ability until spring as the monoculture of the competitive yellow mustard.

Solar Drying and Sensory Attributes of Eland (Taurotragus oryx Jerky

Directory of Open Access Journals (Sweden)

Iva Kučerová

2018-01-01

Full Text Available A double-pass solar drier (DPSD and a laboratory oven (LO were used for thin-layer drying of eland and beef. Prior to drying, the physicochemical characteristics of the raw meat were determined, such as pH, dry matter content (%, Warner-Bratzler shear force (N, pigment concentration (mg·kg−1, weight loss during cooking (%, water holding capacity (%, colour (L,a,b, and crude fat content (%. Both meats were pretreated with traditional jerky marinade (TM, TM with fresh pineapple juice (TMP, TM with honey (TMH, and TM with Coca Cola© (TMCCL and compared to an untreated control (C. The sensory properties of the eland and beef jerky were assessed in a two-stage process. The surface colour values of the jerky samples were measured in the CIE L⁎  a⁎  b⁎ colour space and the effect of the different pretreatments on the overall combined colour (ΔE was calculated. Significant differences (p<0.05 between raw eland and beef samples were found in case of pH, pigment concentration, water holding capacity, crude fat content, and colour (L and b. Jerky from TMP pretreated meat had the highest scores for texture, colour, and taste. Generally, for both meats dried in both driers, TMH marinade was evaluated as the one with the highest total difference ΔE compared to meat dipped in TMP pretreatment, which had the lowest total difference ΔE.

Evaluation of convective heat transfer coefficient of various crops in cyclone type dryer

International Nuclear Information System (INIS)

Akpinar, E. Kavak

2005-01-01

In this paper, an attempt was made to evaluate the convective heat transfer coefficient during drying of various crops and to investigate the influences of drying air velocity and temperature on the convective heat transfer coefficient. Drying was conducted in a convective cyclone type dryer at drying air temperatures of 60, 70 and 80 deg. C and velocities of 1 and 1.5 m/s using rectangle shaped potato and apple slices (12.5 x 12.5 x 25 mm) and cylindrical shaped pumpkin slices (35 x 5 mm). The temperature changes of the dried crops and the temperature of the drying air were measured during the drying process. It was found that the values of convective heat transfer coefficient varied from crop to crop with a range 30.21406 and 20.65470 W/m 2 C for the crops studied, and it was observed that the convective heat transfer coefficient increased in large amounts with the increase of the drying air velocity but increased in small amounts with the rise of the drying air temperature

Evaluation of convective heat transfer coefficient of various crops in cyclone type dryer

Energy Technology Data Exchange (ETDEWEB)

Akpinar, E. Kavak [Mechanical Engineering Department, Firat University, 23279 Elazig (Turkey)]. E-mail: eakpinar@firat.edu.tr

2005-09-15

In this paper, an attempt was made to evaluate the convective heat transfer coefficient during drying of various crops and to investigate the influences of drying air velocity and temperature on the convective heat transfer coefficient. Drying was conducted in a convective cyclone type dryer at drying air temperatures of 60, 70 and 80 deg. C and velocities of 1 and 1.5 m/s using rectangle shaped potato and apple slices (12.5 x 12.5 x 25 mm) and cylindrical shaped pumpkin slices (35 x 5 mm). The temperature changes of the dried crops and the temperature of the drying air were measured during the drying process. It was found that the values of convective heat transfer coefficient varied from crop to crop with a range 30.21406 and 20.65470 W/m{sup 2} C for the crops studied, and it was observed that the convective heat transfer coefficient increased in large amounts with the increase of the drying air velocity but increased in small amounts with the rise of the drying air temperature.

Towards a Solid Foundation of Using Remotely Sensed Solar-Induced Chlorophyll Fluorescence for Crop Monitoring and Yield Forecast

Science.gov (United States)

Chen, Y.; Sun, Y.; You, L.; Liu, Y.

2017-12-01

The growing demand for food production due to population increase coupled with high vulnerability to volatile environmental changes poses a paramount challenge for mankind in the coming century. Real-time crop monitoring and yield forecasting must be a key part of any solution to this challenge as these activities provide vital information needed for effective and efficient crop management and for decision making. However, traditional methods of crop growth monitoring (e.g., remotely sensed vegetation indices) do not directly relate to the most important function of plants - photosynthesis and therefore crop yield. The recent advance in the satellite remote sensing of Solar-Induced chlorophyll Fluorescence (SIF), an integrative photosynthetic signal from molecular origin and a direct measure of plant functions holds great promise for real-time monitoring of crop growth conditions and forecasting yields. In this study, we use satellite measurements of SIF from both the Global Ozone Monitoring Experiment-2 (GOME-2) onboard MetOp-A and the Orbiting Carbon Observatory-2 (OCO-2) satellites to estimate crop yield using both process-based and statistical models. We find that SIF-based crop yield well correlates with the global yield product Spatial Production Allocation Model (SPAM) derived from ground surveys for all major crops including maize, soybean, wheat, sorghum, and rice. The potential and challenges of using upcoming SIF satellite missions for crop monitoring and prediction will also be discussed.

Advancing the climate data driven crop-modeling studies in the dry areas of Northern Syria and Lebanon: An important first step for assessing impact of future climate

Energy Technology Data Exchange (ETDEWEB)

Dixit, Prakash N., E-mail: p.dixit@cgiar.org; Telleria, Roberto

2015-04-01

Inter-annual and seasonal variability in climatic parameters, most importantly rainfall, have potential to cause climate-induced risk in long-term crop production. Short-term field studies do not capture the full nature of such risk and the extent to which modifications to crop, soil and water management recommendations may be made to mitigate the extent of such risk. Crop modeling studies driven by long-term daily weather data can predict the impact of climate-induced risk on crop growth and yield however, the availability of long-term daily weather data can present serious constraints to the use of crop models. To tackle this constraint, two weather generators namely, LARS-WG and MarkSim, were evaluated in order to assess their capabilities of reproducing frequency distributions, means, variances, dry spell and wet chains of observed daily precipitation, maximum and minimum temperature, and solar radiation for the eight locations across cropping areas of Northern Syria and Lebanon. Further, the application of generated long-term daily weather data, with both weather generators, in simulating barley growth and yield was also evaluated. We found that overall LARS-WG performed better than MarkSim in generating daily weather parameters and in 50 years continuous simulation of barley growth and yield. Our findings suggest that LARS-WG does not necessarily require long-term e.g., > 30 years observed weather data for calibration as generated results proved to be satisfactory with > 10 years of observed data except in area with higher altitude. Evaluating these weather generators and the ability of generated weather data to perform long-term simulation of crop growth and yield is an important first step to assess the impact of future climate on yields, and to identify promising technologies to make agricultural systems more resilient in the given region. - Highlights: • LARS-WG performed better than MarkSim in generating daily weather parameters. • LARS-WG can serve

Advancing the climate data driven crop-modeling studies in the dry areas of Northern Syria and Lebanon: An important first step for assessing impact of future climate

International Nuclear Information System (INIS)

Dixit, Prakash N.; Telleria, Roberto

2015-01-01

Inter-annual and seasonal variability in climatic parameters, most importantly rainfall, have potential to cause climate-induced risk in long-term crop production. Short-term field studies do not capture the full nature of such risk and the extent to which modifications to crop, soil and water management recommendations may be made to mitigate the extent of such risk. Crop modeling studies driven by long-term daily weather data can predict the impact of climate-induced risk on crop growth and yield however, the availability of long-term daily weather data can present serious constraints to the use of crop models. To tackle this constraint, two weather generators namely, LARS-WG and MarkSim, were evaluated in order to assess their capabilities of reproducing frequency distributions, means, variances, dry spell and wet chains of observed daily precipitation, maximum and minimum temperature, and solar radiation for the eight locations across cropping areas of Northern Syria and Lebanon. Further, the application of generated long-term daily weather data, with both weather generators, in simulating barley growth and yield was also evaluated. We found that overall LARS-WG performed better than MarkSim in generating daily weather parameters and in 50 years continuous simulation of barley growth and yield. Our findings suggest that LARS-WG does not necessarily require long-term e.g., > 30 years observed weather data for calibration as generated results proved to be satisfactory with > 10 years of observed data except in area with higher altitude. Evaluating these weather generators and the ability of generated weather data to perform long-term simulation of crop growth and yield is an important first step to assess the impact of future climate on yields, and to identify promising technologies to make agricultural systems more resilient in the given region. - Highlights: • LARS-WG performed better than MarkSim in generating daily weather parameters. • LARS-WG can serve

Quantifying biomass production in crops grown for energy

Energy Technology Data Exchange (ETDEWEB)

Bullard, M J; Christian, D; Wilkins, C

1997-12-31

One estimate suggests that continued CAP (Common Agricultural Policy) reform may lead to as much as 2 million hectares of land set aside from arable production by the year 2020 in the UK alone, with 20 million hectares in the EU in total. Set-aside currently occupies more than 500,000 hectares in the UK. Set-aside land is providing more opportunities for non-food crops, for example fuel crops, which provide biomass for energy. Whilst any crop species will produce biomass which can be burnt to produce energy, arable crops were not developed with this in mind but rather a specific harvestable commodity, e.g. grain, and therefore the total harvestable commodity is seldom maximised. The characteristics of an ideal fuel crop have been identified as: dry harvested material for efficient combustion; perennial growth to minimise establishment costs and lengthen the growing season; good disease resistance; efficient conversion of solar radiation to biomass energy; efficient use of nitrogen fertiliser (where required) and water; and yield close to the theoretical maximum. Miscanthus, a genus of Oriental and African C4 perennial grasses, has been identified as possessing the above characteristics. There may be other species, which, if not yielding quite as much biomass, have other characteristics of merit. This has led to the need to identify inherently productive species which are adapted to the UK, and to validate the productivity of species which have already been 'discovered'. (author)

Quantifying biomass production in crops grown for energy

Energy Technology Data Exchange (ETDEWEB)

Bullard, M.J.; Christian, D.; Wilkins, C.

1996-12-31

One estimate suggests that continued CAP (Common Agricultural Policy) reform may lead to as much as 2 million hectares of land set aside from arable production by the year 2020 in the UK alone, with 20 million hectares in the EU in total. Set-aside currently occupies more than 500,000 hectares in the UK. Set-aside land is providing more opportunities for non-food crops, for example fuel crops, which provide biomass for energy. Whilst any crop species will produce biomass which can be burnt to produce energy, arable crops were not developed with this in mind but rather a specific harvestable commodity, e.g. grain, and therefore the total harvestable commodity is seldom maximised. The characteristics of an ideal fuel crop have been identified as: dry harvested material for efficient combustion; perennial growth to minimise establishment costs and lengthen the growing season; good disease resistance; efficient conversion of solar radiation to biomass energy; efficient use of nitrogen fertiliser (where required) and water; and yield close to the theoretical maximum. Miscanthus, a genus of Oriental and African C4 perennial grasses, has been identified as possessing the above characteristics. There may be other species, which, if not yielding quite as much biomass, have other characteristics of merit. This has led to the need to identify inherently productive species which are adapted to the UK, and to validate the productivity of species which have already been 'discovered'. (author)

Scalable, "Dip-and-Dry" Fabrication of a Wide-Angle Plasmonic Selective Absorber for High-Efficiency Solar-Thermal Energy Conversion.

Science.gov (United States)

Mandal, Jyotirmoy; Wang, Derek; Overvig, Adam C; Shi, Norman N; Paley, Daniel; Zangiabadi, Amirali; Cheng, Qian; Barmak, Katayun; Yu, Nanfang; Yang, Yuan

2017-11-01

A galvanic-displacement-reaction-based, room-temperature "dip-and-dry" technique is demonstrated for fabricating selectively solar-absorbing plasmonic-nanoparticle-coated foils (PNFs). The technique, which allows for facile tuning of the PNFs' spectral reflectance to suit different radiative and thermal environments, yields PNFs which exhibit excellent, wide-angle solar absorptance (0.96 at 15°, to 0.97 at 35°, to 0.79 at 80°), and low hemispherical thermal emittance (0.10) without the aid of antireflection coatings. The thermal emittance is on par with those of notable selective solar absorbers (SSAs) in the literature, while the wide-angle solar absorptance surpasses those of previously reported SSAs with comparable optical selectivities. In addition, the PNFs show promising mechanical and thermal stabilities at temperatures of up to 200 °C. Along with the performance of the PNFs, the simplicity, inexpensiveness, and environmental friendliness of the "dip-and-dry" technique makes it an appealing alternative to current methods for fabricating selective solar absorbers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simulation of Solar Radiation Incident on Horizontal and Inclined Surfaces

Directory of Open Access Journals (Sweden)

MA Basunia

2012-12-01

Full Text Available A computer model was developed to simulate the hourly, daily and monthly average of daily solar radiation on horizontal and inclined surfaces. The measured hourly and daily solar radiation was compared with simulated radiation, and favourable agreement was observed for the measured and predicted values on clear days. The measured and simulated monthly averages of total (diffuse and beam daily solar radiation were compared and a reasonable agreement was observed for a number of stations in Japan. The simulation showed that during the rice harvesting season, September to October, there is a daily average of 14.7 MJ/m2 of solar irradiation on a horizontal surface in Matsuyama, Japan. There is a similar amount of solar radiation on a horizontal surface during the major rice harvesting season, November to December, in Bangladesh. This radiation can be effectively utilized for drying rough rice and other farm crops.

Numerical simulation of heat transfer process in solar enhanced natural draft dry cooling tower with radiation model

International Nuclear Information System (INIS)

Wang, Qiuhuan; Zhu, Jialing; Lu, Xinli

2017-01-01

Graphical abstract: A 3-D numerical model integrated with a discrete ordinate (DO) solar radiation model (considering solar radiation effect in the room of solar collector) was developed to investigate the influence of solar radiation intensity and ambient pressure on the efficiency and thermal characteristics of the SENDDCT. Our study shows that introducing such a radiation model can more accurately simulate the heat transfer process in the SENDDCT. Calculation results indicate that previous simulations overestimated solar energy obtained by the solar collector and underestimated the heat loss. The cooling performance is improved when the solar radiation intensity or ambient pressure is high. Air temperature and velocity increase with the increase of solar radiation intensity. But ambient pressure has inverse effects on the changes of air temperature and velocity. Under a condition that the solar load increases but the ambient pressure decreases, the increased rate of heat transferred in the heat exchanger is not obvious. Thus the performance of the SENDDCT not only depends on the solar radiation intensity but also depends on the ambient pressure. - Highlights: • A radiation model has been introduced to accurately simulate heat transfer process. • Heat transfer rate would be overestimated if the radiation model was not introduced. • The heat transfer rate is approximately proportional to solar radiation intensity. • The higher the solar radiation or ambient pressure, the better SENDDCT performance. - Abstract: Solar enhanced natural draft dry cooling tower (SENDDCT) is more efficient than natural draft dry cooling tower by utilizing solar radiation in arid region. A three-dimensional numerical model considering solar radiation effect was developed to investigate the influence of solar radiation intensity and ambient pressure on the efficiency and thermal characteristics of SENDDCT. The numerical simulation outcomes reveal that a model with consideration of

Eclipse effects on field crops and marine zooplankton: the 29 March 2006 total solar eclipse

Science.gov (United States)

Economou, G.; Christou, E. D.; Giannakourou, A.; Gerasopoulos, E.; Georgopoulos, D.; Kotoulas, V.; Lyra, D.; Tsakalis, N.; Tzortziou, M.; Vahamidis, P.; Papathanassiou, E.; Karamanos, A.

2008-08-01

Some effects in the biosphere from the Total Solar Eclipse of 29 March 2006 were investigated in field crops and marine zooplankton. Taking into account the decisive role of light on plant life and productivity, measurements of photosynthesis and stomatal behaviour were conducted on seven important field-grown cereal and leguminous crops. A drop in photosynthetic rates, by more than a factor of 5 in some cases, was observed, and the minimum values of photosynthetic rates ranged between 3.13 and 10.13 μmol CO2 m-2 s-1. The drop in solar irradiance and the increase in mesophyll CO2-concentration during the eclipse did not induce stomatal closure thus not blocking CO2 uptake by plants. Light effects on the photochemical phase of photosynthesis may be responsible for the observed depression in photosynthetic rates. Field studies addressing the migratory responses of marine zooplankton (micro-zooplankton (ciliates), and meso-zooplankton) due to the rapid changes in underwater light intensity were also performed. The light intensity attenuation was simulated with the use of accurate underwater radiative transfer modeling techniques. Ciliates, responded to the rapid decrease in light intensity during the eclipse adopting night-time behaviour. From the meso-zooplankton assemblage, various vertical migratory behaviours were adopted by different species.

Cover crops mitigate direct greenhouse gases balance but reduce drainage under climate change scenarios in temperate climate with dry summers.

Science.gov (United States)

Tribouillois, Hélène; Constantin, Julie; Justes, Eric

2018-02-14

Cover crops provide ecosystem services such as storing atmospheric carbon in soils after incorporation of their residues. Cover crops also influence soil water balance, which can be an issue in temperate climates with dry summers as for example in southern France and Europe. As a consequence, it is necessary to understand cover crops' long-term influence on greenhouse gases (GHG) and water balances to assess their potential to mitigate climate change in arable cropping systems. We used the previously calibrated and validated soil-crop model STICS to simulate scenarios of cover crop introduction to assess their influence on rainfed and irrigated cropping systems and crop rotations distributed among five contrasted sites in southern France from 2007 to 2052. Our results showed that cover crops can improve mean direct GHG balance by 315 kg CO 2 e ha -1  year -1 in the long term compared to that of bare soil. This was due mainly to an increase in carbon storage in the soil despite a slight increase in N 2 O emissions which can be compensated by adapting fertilization. Cover crops also influence the water balance by reducing mean annual drainage by 20 mm/year but increasing mean annual evapotranspiration by 20 mm/year compared to those of bare soil. Using cover crops to improve the GHG balance may help to mitigate climate change by decreasing CO 2 e emitted in cropping systems which can represent a decrease from 4.5% to 9% of annual GHG emissions of the French agriculture and forestry sector. However, if not well managed, they also could create water management issues in watersheds with shallow groundwater. Relationships between cover crop biomass and its influence on several variables such as drainage, carbon sequestration, and GHG emissions could be used to extend our results to other conditions to assess the cover crops' influence in a wider range of areas. © 2018 John Wiley & Sons Ltd.

The effect of dry shear aligning of nanotube thin films on the photovoltaic performance of carbon nanotube-silicon solar cells.

Science.gov (United States)

Stolz, Benedikt W; Tune, Daniel D; Flavel, Benjamin S

2016-01-01

Recent results in the field of carbon nanotube-silicon solar cells have suggested that the best performance is obtained when the nanotube film provides good coverage of the silicon surface and when the nanotubes in the film are aligned parallel to the surface. The recently developed process of dry shear aligning - in which shear force is applied to the surface of carbon nanotube thin films in the dry state, has been shown to yield nanotube films that are very flat and in which the surface nanotubes are very well aligned in the direction of shear. It is thus reasonable to expect that nanotube films subjected to dry shear aligning should outperform otherwise identical films formed by other processes. In this work, the fabrication and characterisation of carbon nanotube-silicon solar cells using such films is reported, and the photovoltaic performance of devices produced with and without dry shear aligning is compared.

Dry Phosphorus silicate glass etching and surface conditioning and cleaning for multi-crystalline silicon solar cell processing

International Nuclear Information System (INIS)

Kagilik, Ahmed S.

2014-01-01

As an alternative to the wet chemical etching method, dry chemical etching processes for Phosphorus silicate glass [PSG} layer removal using Trifluormethane/Sulfur Hexafluoride (CHF 3 / SF 6 ) gas mixture in commercial silicon-nitride plasma enhanced chemical vapour deposition (SiN-PECVD) system is applied. The dependence of the solar cell performance on the etching temperature is investigated and optimized. It is found that the SiN-PECVD system temperature variation has a significant impact on the whole solar cell characteristics. A dry plasma cleaning treatment of the Si wafer surface after the PSG removal step is also investigated and developed. The cleaning step is used to remove the polymer film which is formed during the PSG etching using both oxygen and hydrogen gases. By applying an additional cleaning step, the polymer film deposited on the silicon wafer surface after PSG etching is eliminated. The effect of different plasma cleaning conditions on solar cell performance is investigated. After optimization of the plasma operating conditions, the performance of the solar cell is improved and the overall gain in efficiency of 0.6% absolute is yielded compared to a cell without any further cleaning step. On the other hand, the best solar cell characteristics can reach values close to that achieved by the conventional wet chemical etching processes demonstrating the effectiveness of the additional O 2 /H 2 post cleaning treatment.(author)

Drying kinetics of whole and sliced turmeric rhizomes (Curcuma longa L. in a solar conduction dryer

Directory of Open Access Journals (Sweden)

A. Borah

2015-09-01

Full Text Available Drying of turmeric was carried out in a solar conduction dryer (SCD. Drying air temperature was achieved around 39–51 °C for an ambient temperature in the range of 25–28 °C. Moisture content from 78.65% (wb, was reduced to 6.36% (wb and 5.50% (wb for solid and sliced samples respectively in 12 h effective drying time. Drying curve of sliced samples showed more uniform falling in comparison to that of whole samples. The average effective moisture diffusivity was found to be 1.852 × 10−10 m2 s−1 for slab samples and 1.456 × 10−10 m2 s−1 for solid samples. Out of four models tried for simulation, Page model was found as best fitted thin layer drying model when simulation was done for all the drying data. The overall thermal efficiency of the dryer was found to be 55%. Drying of sliced rhizomes showed better drying kinetics and effective drying time could be reduced by slicing instead of drying in whole form.

Environmental and Economic Performance of Commercial-scale Solar Photovoltaic Systems: A Field Study of Complex Energy Systems at the Desert Research Institute (DRI)

Science.gov (United States)

Liu, X.

2014-12-01

Solar photovoltaic (PV) systems are being aggressively deployed at residential, commercial, and utility scales to complement power generation from conventional sources. This is motivated both by the desire to reduce carbon footprints and by policy-driven financial incentives. Although several life cycle analyses (LCA) have investigated environmental impacts and energy payback times of solar PV systems, most results are based on hypothetical systems rather than actual, deployed systems that can provide measured performance data. Over the past five years, Desert Research Institute (DRI) in Nevada has installed eight solar PV systems of scales from 3 to 1000 kW, the sum of which supply approximately 40% of the total power use at DRI's Reno and Las Vegas campuses. The goal of this work is to explore greenhouse gas (GHG) impacts and examine the economic performance of DRI's PV systems by developing and applying a comprehensive LCA and techno-economic (TEA) model. This model is built using data appropriate for each type of panel used in the DRI systems. Power output is modeled using the National Renewable Energy Laboratory (NREL) model PVWatts. The performance of PVWatts is verified by the actual measurements from DRI's PV systems. Several environmental and economic metrics are quantified for the DRI systems, including life cycle GHG emissions and energy return. GHG results are compared with Nevada grid-based electricity. Initial results indicate that DRI's solar-derived electricity offers clear GHG benefits compared to conventional grid electricity. DRI's eight systems have GHG intensity values of 29-56 gCO2e/kWh, as compared to the GHG intensity of 212 gCO2e/kWh of national average grid power. The major source of impacts (82-92% of the total) is the upstream life cycle burden of manufacturing PV panels, which are made of either mono-crystalline or multi-crystalline silicon. Given the same type of PV panel, GHG intensity decreases as the scale of the system increases

Anaerobic Soil Disinfestation (ASD) Combined with Soil Solarization for Root-Knot Nematode Control in Vegetable and Ornamental Crops in Florida

Science.gov (United States)

Anaerobic soil disinfestation (ASD) combined with soil solarization continues to be evaluated for management of plant-parasitic nematodes in vegetable and ornamental crops in Florida. ASD combines organic amendments and soil saturation to stimulate microbial activity and create anaerobic conditions...

Performance Analysis of Solar Assisted Fluidized Bed Dryer Integrated Biomass Furnace with and without Heat Pump for Drying of Paddy

Directory of Open Access Journals (Sweden)

M. Yahya

2016-01-01

Full Text Available The performances of a solar assisted fluidized bed dryer integrated biomass furnace (SA-FBDIBF and a solar assisted heat pump fluidized bed dryer integrated biomass furnace (SAHP-FBDIBF for drying of paddy have been evaluated, and also drying kinetics of paddy were determined. The SA-FBDIBF and the SAHP-FBDIBF were used to dry paddy from 11 kg with moisture content of 32.85% db to moisture content of 16.29% db (14% wb under an air mass flow rate of 0.1037 kg/s within 29.73 minutes and 22.95 minutes, with average temperatures and relative humidities of 80.3°C and 80.9°C and 12.28% and 8.14%, respectively. The average drying rate, specific energy consumption, and specific moisture extraction rate were 0.043 kg/minute and 0.050 kg/minute, 5.454 kWh/kg and 4.763 kWh/kg, and 0.204 kg/kWh and 0.241 kg/kWh for SA-FBDIBF and SAHP-FBDIBF, respectively. In SA-FBDIBF and SAHP-FBDIBF, the dryer thermal efficiencies were average values of 12.28% and 15.44%; in addition, the pickup efficiencies were 33.55% and 43.84% on average, whereas the average solar and biomass fractions were 10.9% and 10.6% and 36.6% and 30.4% for SA-FBDIBF and SAHP-FBDIBF, respectively. The drying of paddy occurred in the falling rate period. The experimental dimensionless moisture content data were fitted to three mathematical models. Page’s model was found best to describe the drying behaviour of paddy.

A greenhouse type solar dryer for small-scale dried food industries: Development and dissemination

Energy Technology Data Exchange (ETDEWEB)

Janjai, Serm [Solar Energy Research Laboratory, Department of Physics, Faculty of Science, Silpakorn University, Nakhon Pathom 73000 (Thailand)

2012-07-01

In this study, a greenhouse type solar dryer for small-scale dried food industries was developed and disseminated. The dryer consists of a parabolic roof structure covered with polycarbonate sheets on a concrete floor. The system is 8.0m in width, 20.0m in length and 3.5m in height, with a loading capacity about 1,000kg of fruits or vegetables. To ensure continuous drying operation, a 100kW-LPG gas burner was incorporated to supply hot air to the dryer during cloudy or rainy days. Nine 15-W DC fans powered by three 50-W PV modules were used to ventilate the dryer. This dryer was installed for a small-scale food industry at Nakhon Pathom in Thailand to produce osmotically dehydrated tomato. To investigate its performance, the dryer was used to dry 3 batches of osmotically dehydrated tomato. Results obtained from these experiments showed that drying air temperatures in the dryer varied from 35 C to 65 C. In addition, the drying time for these products was 2-3 days shorter than that of the natural sun drying and good quality dried products were obtained. A system of differential equations describing heat and moisture transfers during drying of osmotically dehydrated tomato was also developed. The simulated results agreed well with the experimental data. For dissemination purpose, other two units of this type of dryer were constructed and tested at two locations in Thailand and satisfactory results were obtained.

Eclipse effects on field crops and marine zooplankton: the 29 March 2006 total solar eclipse

Directory of Open Access Journals (Sweden)

G. Economou

2008-08-01

Full Text Available Some effects in the biosphere from the Total Solar Eclipse of 29 March 2006 were investigated in field crops and marine zooplankton. Taking into account the decisive role of light on plant life and productivity, measurements of photosynthesis and stomatal behaviour were conducted on seven important field-grown cereal and leguminous crops. A drop in photosynthetic rates, by more than a factor of 5 in some cases, was observed, and the minimum values of photosynthetic rates ranged between 3.13 and 10.13 μmol CO₂ m⁻² s⁻¹. The drop in solar irradiance and the increase in mesophyll CO₂-concentration during the eclipse did not induce stomatal closure thus not blocking CO₂ uptake by plants. Light effects on the photochemical phase of photosynthesis may be responsible for the observed depression in photosynthetic rates. Field studies addressing the migratory responses of marine zooplankton (micro-zooplankton (ciliates, and meso-zooplankton due to the rapid changes in underwater light intensity were also performed. The light intensity attenuation was simulated with the use of accurate underwater radiative transfer modeling techniques. Ciliates, responded to the rapid decrease in light intensity during the eclipse adopting night-time behaviour. From the meso-zooplankton assemblage, various vertical migratory behaviours were adopted by different species.

A rice husk gasifier for paddy drying

International Nuclear Information System (INIS)

Mirani, A.A.; Kalwar, S.A.; Ahmad, M.

2013-01-01

Due to energy crisis and constant increase in the price of fossil fuels, the world's trend changes to renewable sources of energy like solar, wind and biomass gasification. Substantial biomass potential is available in Pakistan in the form of agriculture or forest residue (rice straw, rice husk, cotton stalks, corn cobs, wood chips, wood saw, etc.). These can be best utilised for the production of producer gas or synthetic gas that can be used for drying of agricultural crops. The drying process is an important activity of post harvest processing for long-term storage. Rice husk is nowadays commonly used for biomass gasification and its heat content value is about 15MJ/kg. It constitutes about 30 percent of rice production. A rice husk gasifier was developed and evaluated on paddy drying at Japan International Cooperation Agency (JICA), Tsukuba International Center (TBIC), Japan. Rice husk gasifier has following major components; husk feeding system, ash chamber, burner, centrifugal fan, drying chamber, gasifier reactor, air duct and an electric motor of 0.37kW. The average drying plenum air temperature was recorded as 45 degree C during the drying process. The paddy 'IR 28' from initial moisture content of 24% was dried up to 14% moisture content for about 3.33h consuming 3kg/h of rice husk. The efficiency was found to be 58%. The rice husk gasifier can also be used for drying the fruits and vegetables, provided that heat exchanger should be attached with it. The overall performance of rice husk gasifier was satisfactory and will be beneficial for small scale farmers, food processors and millers as well. (author)

energetic performance analysis of drying agricultural products

African Journals Online (AJOL)

user

... a solar box dryer aided by a tracking device, and open air drying over an effective total drying time of 6 hours each day, for 5 days. ... cost in the use of modern dryers. Drying can be ..... speed, cloud cover and humidity respectively. 4.2 Solar ...

Dry cooling with night cool storage to enhance solar power plants performance in extreme conditions areas

International Nuclear Information System (INIS)

Muñoz, J.; Martínez-Val, J.M.; Abbas, R.; Abánades, A.

2012-01-01

Highlights: ► Solar thermo-electric power plants with thermal storage for condenser cooling. ► Technology to mitigate the negative effect on Rankine cycles of the day-time high temperatures in deserts. ► Electricity production augmentation in demand-peak hours by the use of day-night temperature difference. -- Abstract: Solar thermal power plants are usually installed in locations with high yearly average solar radiation, often deserts. In such conditions, cooling water required for thermodynamic cycles is rarely available. Moreover, when solar radiation is high, ambient temperature is very high as well; this leads to excessive condensation temperature, especially when air-condensers are used, and decreases the plant efficiency. However, temperature variation in deserts is often very high, which drives to relatively low temperatures during the night. This fact can be exploited with the use of a closed cooling system, so that the coolant (water) is chilled during the night and store. Chilled water is then used during peak temperature hours to cool the condenser (dry cooling), thus enhancing power output and efficiency. The present work analyzes the performance improvement achieved by night thermal cool storage, compared to its equivalent air cooled power plant. Dry cooling is proved to be energy-effective for moderately high day–night temperature differences (20 °C), often found in desert locations. The storage volume requirement for different power plant efficiencies has also been studied, resulting on an asymptotic tendency.

Empirical analysis of dry spells for agricultural applications in west Africa

International Nuclear Information System (INIS)

Sivakumar, M.V.K.

1992-01-01

Recurring droughts and decreased agricultural productivity during the last two decades in West Africa point to the need for a clearer understanding of the length of dry spells, their frequencies, and their probabilities. The simplest calculations of dry spells for general applications involve computation of the probabilities of maximum and conditional dry spells exceeding a user-specified threshold value from a given calendar date. For more precise applications in agriculture, it is important to consider the different periods after sowing a crop, since sowing dates in the semiarid West African regions vary from year to year. Using the specific definition of onset of rains in each year as the sowing date, the length of dry spells was calculated from the historical rainfall data. Probability distribution of time to the next wet day and the percentage frequencies of dry spells were computed for successive days after sowing (DAS) a crop. Dry-spell analysis showed a pronounced drop in the drought risk for cereal crops from the panicle initiation phase (20 DAS) to the flowering phase (60 DAS). The relationships between mean annual rainfall and average frequency of dry spells for the selected locations in West Africa showed distinct patterns and permit the prediction of the frequency of dry spells from annual rainfall totals. Applications of the dry-spell analysis for the choice of a crop/variety, supplemental irrigation, and crop water requirements have been described with examples

Solar heating of air used for the drying at medium and large scale, of forestry, fishery, agriculture, cattle and industrial products

International Nuclear Information System (INIS)

Gutierrez, F.

1991-01-01

The drying process and/or preservation of grains is improved through the previous heating of air. In many cases it is enough to raise the temperature only a few degrees (from 10 to 15 Centigrade), in order to increase their capacity to absorb dampness. This can be done using very simple solar captors. A massive use of solar energy in the drying process of products, by means of hot air, can only be done with very expensive equipment. For this reason, it is recommended the use of lower thermic heaters, which will have a lower cost too. (Author)

The Effect of Temperature and Drying Method on Drying Time and Color Quality of Mint

Directory of Open Access Journals (Sweden)

H Bahmanpour

2017-10-01

Full Text Available Introduction Mint (Mentha spicata L. cbelongs to the Lamiaceae family, is an herbaceous, perennial, aromatic and medicinal plant that cultivated for its essential oils and spices. Since the essential oil is extracted from dried plant, choosing the appropriate drying method is essential for gaining high quality essential oil.Vacuum drying technology is an alternative to conventional drying methods and reported by many authors as an efficient method for improving the drying quality especially color characteristics. On the other side, solar dryers are also useful for saving time and energy. In this study the effect of two method of dryings including vacuum-infrared versus solar at three different conventional temperatures (30, 40 and 50°C on mint plant is evaluated while factorial experiment with randomized complete block is applied. Drying time as well as color characteristics areconsidered for evaluation of each method of drying. Materials and Methods Factorial experiment with randomized complete block was applied in order to evaluate the effect of drying methods (vacuum-infrared versus solar and temperature (30, 40 and 50°C on drying time and color characteristics of mint. The initially moisture content of mint leaves measured according to the standard ASABE S358.2 during 24 hours inside an oven at 104 °C. Drying the samples continued until the moisture content (which real time measured reached to 10% wet basis. The components of a vacuum dryer consisted of a cylindrical vacuum chamber (0.335 m3 and a vacuum pump (piston version. The temperature of the chamber was controlled using three infrared bulbs using on-off controller. Temperature and weight of the products registered real time using a data acquisition system. The components of a solar dryer were consisting of a solar collector and a temperature control system which was turning the exhaust fan on and off in order to maintain the specific temperature. A date acquisition system was

a comparative study of the drying rate constant, drying efficiency

African Journals Online (AJOL)

The drying rate constants for the solar dryer and open- air sun dried bitter leaf were 0.8 and ... of cost benefit but the poorest when other considerations ... J. I. Eze, National Centre for Energy Research and Development (NCERD), University of ...

Evaluation of a solar-powered organic Rankine cycle using dry organic working fluids

Directory of Open Access Journals (Sweden)

Emily Spayde

2015-12-01

Full Text Available This paper presents a model to evaluate the performance of a solar-powered organic Rankine cycle (ORC. The system was evaluated in Jackson, MS, using five dry organic working fluids, R218, R227ea, R236ea, R236fa, and RC318. The purpose of this study is to investigate how hourly temperature change affects the electricity production and exergy destruction rates of the solar ORC, and to determine the effect of the working fluid on the proposed system. The system was also evaluated in Tucson, AZ, to investigate the effect of average hourly outdoor temperatures on its performance. The potential of the system to reduce primary energy consumption and carbon dioxide emissions is also investigated. A parametric analysis to determine how temperature and pressure of the organic working fluid, the solar collector area, and the turbine efficiency affect the electricity production is performed. Results show that the ORC produces the most electricity during the middle of the day, when the temperatures are the highest and when the solar collectors have the highest efficiency. Also, R-236ea is the working fluid that shows the best performance of the evaluated fluids. An economic analysis was performed to determine the capital cost available for the proposed system.

Full scale experimental study of a small natural draft dry cooling tower for concentrating solar thermal power plant

International Nuclear Information System (INIS)

Li, Xiaoxiao; Duniam, Sam; Gurgenci, Hal; Guan, Zhiqiang; Veeraragavan, Anand

2017-01-01

Highlights: • A 20 m high natural draft dry cooling tower is designed and tested. • The cooling tower model is refined and validated with the experimental data. • The performance of the cooling tower utilized in a CST power plant is investigated. • Ambient temperature effect on Rankine cycle and Brayton cycle is discussed. - Abstract: Concentrating solar thermal power system can provide low carbon, renewable energy resources in countries or regions with strong solar irradiation. For this kind of power plant which is likely to be located in the arid area, natural draft dry cooling tower is a promising choice. To develop the experimental studies on small cooling tower, a 20 m high natural draft dry cooling tower with fully instrumented measurement system was established by the Queensland Geothermal Energy Centre of Excellence. The performance of this cooling tower was measured with the constant heat input of 600 kW and 840 kW and with ambient temperature ranging from 20 °C to 32 °C. The cooling tower numerical model was refined and validated with the experimental data. The model of 1 MW concentrating solar thermal supercritical CO_2 power cycle was developed and integrated with the cooling tower model. The influences of changing ambient temperature and the performance of the cooling tower on efficiency of the power system were simulated. The differences of the mechanism of the ambient temperature effect on Rankine cycle and supercritical CO_2 Brayton cycle were analysed and discussed.

Technical research on sludge drying by solar energy and heat pump%太阳能热泵污泥干燥技术

Institute of Scientific and Technical Information of China (English)

饶宾期; 曹黎

2012-01-01

In order to solve the problems of sludge drying, the working principle and system structure of sludge drying-system by solar energy and heat pump were introduced firstly, and then the main equipment.of this system was calculated and designed, the system performance was analyzed comprehensively through experiment. Finally the energy efficiency and economy of solar energy heat pump drying-system were compared with that of the other drying system. The results showed that this system was energy-saving, eco-friendly and economy. Equipped with solar thermal collector, the system can save energy about 10% in average. The research can provide a reference for engineering application of sludge drying by solar energy and heat pump.%为解决当前污泥干燥存在的问题,该文研究利用太阳能热泵对污泥进行干燥,阐述了太阳能热泵污泥干燥系统的结构与工作原理,对系统的主要设备进行了计算设计并进行试验及性能分析,最后对太阳能热泵干燥与其他几种典型干燥方式的能耗及经济性做了比较.该系统具有节能、环保、经济等优点,配备太阳能系统平均可节省电量10％左右.该研究可为太阳能热泵干燥污泥的工程应用提供参考.

Implications of drying temperature and humidity on the drying kinetics of seaweed

Science.gov (United States)

Ali, Majid Khan Majahar; Fudholi, Ahmad; Muthuvalu, M. S.; Sulaiman, Jumat; Yasir, Suhaimi Md

2017-11-01

A Low Temperature and Humidity Chamber Test tested in the Solar Energy Laboratory, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Selangor, Malaysia. Experiments are attempted to study the effect of drying air temperature and humidity on the drying kinetics of seaweed Kappaphycus species Striatum besides to develop a model to estimate the drying curves. Simple method using a excel software is used in the analysis of raw data obtained from the drying experiment. The values of the parameters a, n and the constant k for the models are determined using a plot of curve drying models. Three different drying models are compared with experiment data seaweed drying at 30, 40, 50 and 60°C and relative humidity 20, 30 and 40% for seaweed. The higher drying temperatures and low relative humidity effects the moisture content that will be rapidly reduced. The most suitable model is selected to best describe the drying behavior of seaweed. The values of the coefficient of determination (R2), mean bias error (MBE) and root mean square error (RMSE) are used to determine the goodness or the quality of the fit. The Page model is showed a better fit to drying seaweed. The results from this study crucial for solar dryer development on pilot scale in Malaysia.

Control of volunteer soybean plants in sunflower crop

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Alexandre Magno Brighenti

2015-09-01

Full Text Available Sunflower (Helianthus annuus sown offseason, after soybean crop (Glycine max, is affected by the competition imposed by volunteer plants. Two experiments were carried out to evaluate the control of volunteer soybean plants in sunflower crops. The sulfentrazone herbicide (75 g ha-1, 100 g ha-1 and 250 g ha-1 causes phytotoxicity to sunflower immediately after application, however, plants recover, with no yield losses. These doses do not cause the total death of volunteer soybean plants, but temporarily paralyzes their growth, avoiding the competition with the sunflower crop. The glufosinate ammonium and ametryn herbicides are effective in controlling volunteer soybean plants, however, symptoms of phytotoxicity in the sunflower crop are high, reflecting in losses of dry weight biomass and crop yield. The other treatments do not provide satisfactory control of volunteer soybean plants and even reduce the sunflower dry weight biomass and yield.

Solar radiation interception of various planting space patterns of maize and its relation to yields

International Nuclear Information System (INIS)

Akhir, N.

2003-01-01

A research was carried out to study solar radiation interception and its relation to yield of maize in various plant spacing patterns at high elevation. The goal of this research was to contribute the development of crop science, especially the plant ecophysiology. A field experiment was executed from March to August 1998 at Assessment Institute of Agricultural Technology, Sukarami, West Sumatra. The experiment was arranged in Randomized Block Design and each treatment was replicated three times. The experiment data was analyzed by ANOVA and path analysis. The results of experiment indicated that the percentage of solar radiation interception gave high contribution to the dry grain yield for Pioneer-7 cultivar, and the solar radiation interception was depend on LAI and leaf angle

Effect of weed management and seed rate on crop growth under direct dry seeded rice systems in Bangladesh.

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Sharif Ahmed

Full Text Available Weeds are a major constraint to the success of dry-seeded rice (DSR. The main means of managing these in a DSR system is through chemical weed control using herbicides. However, the use of herbicides alone may not be sustainable in the long term. Approaches that aim for high crop competitiveness therefore need to be exploited. One such approach is the use of high rice seeding rates. Experiments were conducted in the aman (wet seasons of 2012 and 2013 in Bangladesh to evaluate the effect of weed infestation level (partially-weedy and weed-free and rice seeding rate (20, 40, 60, 80, and 100 kg ha(-1 on weed and crop growth in DSR. Under weed-free conditions, higher crop yields (5.1 and 5.2 t ha(-1 in the 2012 and 2013 seasons, respectively were obtained at the seeding rate of 40 kg ha(-1 and thereafter, yield decreased slightly beyond 40 kg seed ha(-1. Under partially-weedy conditions, yield increased by 30 to 33% (2.0-2.2 and 2.9-3.2 t ha(-1 in the 2012 and 2013 seasons, respectively with increase in seeding rate from 20 to 100 kg ha(-1. In the partially-weedy plots, weed biomass decreased by 41-60% and 54-56% at 35 days after sowing and at crop anthesis, respectively, when seeding rate increased from 20 to 100 kg ha(-1. Results from our study suggest that increasing seeding rates in DSR can suppress weed growth and reduce grain yield losses from weed competition.

Effect of Weed Management and Seed Rate on Crop Growth under Direct Dry Seeded Rice Systems in Bangladesh

Science.gov (United States)

Ahmed, Sharif; Salim, Muhammad; Chauhan, Bhagirath S.

2014-01-01

Weeds are a major constraint to the success of dry-seeded rice (DSR). The main means of managing these in a DSR system is through chemical weed control using herbicides. However, the use of herbicides alone may not be sustainable in the long term. Approaches that aim for high crop competitiveness therefore need to be exploited. One such approach is the use of high rice seeding rates. Experiments were conducted in the aman (wet) seasons of 2012 and 2013 in Bangladesh to evaluate the effect of weed infestation level (partially-weedy and weed-free) and rice seeding rate (20, 40, 60, 80, and 100 kg ha−1) on weed and crop growth in DSR. Under weed-free conditions, higher crop yields (5.1 and 5.2 t ha−1 in the 2012 and 2013 seasons, respectively) were obtained at the seeding rate of 40 kg ha−1 and thereafter, yield decreased slightly beyond 40 kg seed ha−1. Under partially-weedy conditions, yield increased by 30 to 33% (2.0–2.2 and 2.9–3.2 t ha−1 in the 2012 and 2013 seasons, respectively) with increase in seeding rate from 20 to 100 kg ha−1. In the partially-weedy plots, weed biomass decreased by 41–60% and 54–56% at 35 days after sowing and at crop anthesis, respectively, when seeding rate increased from 20 to 100 kg ha−1. Results from our study suggest that increasing seeding rates in DSR can suppress weed growth and reduce grain yield losses from weed competition. PMID:25000520

Effect of weed management and seed rate on crop growth under direct dry seeded rice systems in Bangladesh.

Science.gov (United States)

Ahmed, Sharif; Salim, Muhammad; Chauhan, Bhagirath S

2014-01-01

Weeds are a major constraint to the success of dry-seeded rice (DSR). The main means of managing these in a DSR system is through chemical weed control using herbicides. However, the use of herbicides alone may not be sustainable in the long term. Approaches that aim for high crop competitiveness therefore need to be exploited. One such approach is the use of high rice seeding rates. Experiments were conducted in the aman (wet) seasons of 2012 and 2013 in Bangladesh to evaluate the effect of weed infestation level (partially-weedy and weed-free) and rice seeding rate (20, 40, 60, 80, and 100 kg ha(-1)) on weed and crop growth in DSR. Under weed-free conditions, higher crop yields (5.1 and 5.2 t ha(-1) in the 2012 and 2013 seasons, respectively) were obtained at the seeding rate of 40 kg ha(-1) and thereafter, yield decreased slightly beyond 40 kg seed ha(-1). Under partially-weedy conditions, yield increased by 30 to 33% (2.0-2.2 and 2.9-3.2 t ha(-1) in the 2012 and 2013 seasons, respectively) with increase in seeding rate from 20 to 100 kg ha(-1). In the partially-weedy plots, weed biomass decreased by 41-60% and 54-56% at 35 days after sowing and at crop anthesis, respectively, when seeding rate increased from 20 to 100 kg ha(-1). Results from our study suggest that increasing seeding rates in DSR can suppress weed growth and reduce grain yield losses from weed competition.

Leaf area development, dry weight accumulation and solar energy conversion efficiencies of Phaseolus vulgaris L. under different soil moisture levels near Nairobi, Kenya

NARCIS (Netherlands)

Muniafu, M.M.; Macharia, J.N.M.; Stigter, C.J.; Coulson, G.L.

1999-01-01

Leaf area development, dry weight accumulation and solar energy conversion efficiencies of Phaseolus vulgaris L. cv GLP-2 under two soil moisture levels in two contrasting seasons near Nairobi, Kenya were investigated. The experiment confirms that dry weights and yields of Phaseolus vulgaris are

Effect of solar radiation and temperature on grain number definition in maize

International Nuclear Information System (INIS)

Didonet, A.D.; Rodrigues, O.; Mario, J.L.; Ide, F.

2002-01-01

The objective of this experiment was to study the effect of solar radiation and temperature regime between emergence and silking on the crop development rate and the number of grain per growing rate unit of the crop, and the relationships of such parameters with the grain yield of corn hybrids. The experiments were carried out in the years 1994/95 to 1996/97, using the commercial hybrids C-901, XL-560, and XL-678 in 1994/95 and the hybrids C-901, XL-212, and XL-370 in the remaining years. The treatments consisted of sowing dates from September to December, in 1994/95, and from August to December, in 1995/96 and 1996/97. High dry matter accumulation was observed when there was high incidence of solar radiation during the period between emergence and flowering. However, as the mean air temperature exerts effect on the duration of that period, the growth rate during such period was more associated to temperature than to solar radiation. The effect of the temperature was inversely proportional to the number of grains per unit of growing rate in this period, possibly due to the longer time for solar radiation interception. As a result of the association between temperature and radiation, the photothermal coefficient was positively associated with the grain yield. (author) [pt

Experimental investigation of an indirect solar dryer integrated with phase change material for drying valeriana jatamansi (medicinal herb

Directory of Open Access Journals (Sweden)

A.K. Bhardwaj

2017-09-01

Full Text Available In this study, an experimental investigation of an indirect solar dryer integrated with phase change material has been carried out for drying Valeriana Jatamansi. The experimentation has been performed under the climatic conditions of Himalayan region, Solan (latitude − 30.91°N, longitude − 77.09°E, Himachal Pradesh (India in the month of October-November 2016. Paraffin RT-42 has been used as a phase change material in the dryer. Using this system, the moisture content of rhizomes reduced from 89% to 9% in 5 days as compared to heat pump drying and shade drying, which took 8 days and 14 days, respectively. Results of present study infer that the drying time using phase change material in this setup has reduced by 37.50% and 64.29% when compared to heat pump drying and shade drying, respectively. The dried rhizomes obtained are of superior quality in terms of colour, texture, aroma and bio-medical constituents. Analyses show that by using present setup, total valepotriates obtained were 3.47% as compared to traditional shade drying which yield 3.31%.

Crop Sequence Influences on Sustainable Spring Wheat Production in the Northern Great Plains

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Joseph M. Krupinsky

2010-11-01

Full Text Available Cropping systems in American agriculture are highly successful since World War II, but have become highly specialized, standardized, and simplified to meet the demands of an industrialized food system. Minimal attention has been given to the efficient exploitation of crop diversity and the synergistic and/or antagonistic relationships of crops in crop sequences. Objectives of our research were to determine if previous crop sequences have long-term benefits and/or drawbacks on spring wheat seed yield, seed N concentration, and seed precipitation-use efficiency in the semiarid northern Great Plains, USA. Research was conducted 6 km southwest of Mandan, ND using a 10 × 10 crop matrix technique as a research tool to evaluate multiple crop sequence effects on spring wheat (triticum aestivum L. production in 2004 and 2005. Spring wheat production risks can be mitigated when second year crop residue was dry pea (Pisium sativum L. averaged over all first year crop residues. When compared to spring wheat as second year crop residue in the dry year of 2004, dry pea as the second year residue crop resulted in a 30% spring wheat seed yield increase. Sustainable cropping systems need to use precipitation efficiently for crop production, especially during below average precipitation years like 2004. Precipitation use efficiency average over all treatments, during the below average precipitation year was 23% greater than the above average precipitation year of 2005. Diversifying crops in cropping systems improves production efficiencies and resilience of agricultural systems.

Fluctuation characteristics of solar radiation in crop cultivation

International Nuclear Information System (INIS)

Hayashi, S.; Suzuki, H.

1996-01-01

The objective of this study was to clarify the fluctuation of solar radiation for long and short periods, which is very crucial for plant growth. Data obtained from a meteorological observatory were used to investigate solar radiation and sunshine duration for a long period. For a short period, observation of global solar radiation and sky solar radiation were conducted in a glass house and at an open field. (1) Yearly average percentage of solar radiation at Kagawa from 1973 to 1994 was 44.3%, and its coefficient of variation was 3.9%. The percentage of possible sunshine and the coefficient were larger than those of solar radiation, 47.3% and 56% respectively. (2) Percentage of possible solar radiation and percentage of possible sunshine showed seasonal variation. Those coefficients of variation both increased exponentially with cloud amount. (3) Variations of global solar radiation and direct solar radiation were more remarkable in the glass house than those in the open field, while variations of sky solar radiation were small in the house and at the open field. (4) The fluctuation of solar radiation observed every 5 minutes was presented as the difference of radiation, present value minus the preceding value. The difference was positive in the morning, negative in the afternoon at the open field. In the house both positive and negative values were obtained the whole day. (5) Diurnal variation of ratio of direct solar radiation to sky solar radiation showed a parabolic effect, whereas it had irregular and large fluctuations at the open field

Energetic performance analysis of drying agricultural products ...

African Journals Online (AJOL)

Renewable energy sources such as solar energy for drying purposes in a more effective and efficient way is inevitable for preservation of agricultural products in developing nations with inadequate access to electricity. This study investigates the effects of using a solar tracking device on the energy performance of drying ...

Hydrogen-Rich Syngas Production from Gasification and Pyrolysis of Solar Dried Sewage Sludge: Experimental and Modeling Investigations

Directory of Open Access Journals (Sweden)

Aïda Ben Hassen Trabelsi

2017-01-01

Full Text Available Solar dried sewage sludge (SS conversion by pyrolysis and gasification processes has been performed, separately, using two laboratory-scale reactors, a fixed-bed pyrolyzer and a downdraft gasifier, to produce mainly hydrogen-rich syngas. Prior to SS conversion, solar drying has been conducted in order to reduce moisture content (up to 10%. SS characterization reveals that these biosolids could be appropriate materials for gaseous products production. The released gases from SS pyrolysis and gasification present relatively high heating values (up to 9.96 MJ/kg for pyrolysis and 8.02  9.96 MJ/kg for gasification due to their high contents of H2 (up to 11 and 7 wt%, resp. and CH4 (up to 17 and 5 wt%, resp.. The yields of combustible gases (H2 and CH4 show further increase with pyrolysis. Stoichiometric models of both pyrolysis and gasification reactions were determined based on the global biomass formula, CαHβOγNδSε, in order to assist in the products yields optimization.

Use of the solar and eolic energy in the drying of bean seed at rural level

International Nuclear Information System (INIS)

Grajales Avila, W.; Racines Sanchez, L.E.

1985-01-01

The drying is a camera through which is made pass air heated in a solar collector, by means of a rotational fan impelled by the wind. The dryer is wooden and the zinc consists of five levels where the trays are deposited that contain the product. In the end of the chimney placed above the drying camera this the fan that is a rotor of corrugate fins; when rotating under the action of the wind it extracts air of the ventilation chimney; in the periods that the wind doesn't blow the drying it happens for natural convention. In the collector the badge absorbent is zinc colored corrugate of black; the mark is wooden, isolated in its inferior part with icopor and the cover a sheet of plastic. To evaluate the dryer they were carried out four drying rehearsals with seed of bean variety Calima. One observes that the bean drying with this dryer type is feasible even with cloudy or partially cloudy sky. The drying was satisfactory with the two loads of 200 and 400 kg. With the flow of air through the trays and for the load of 210 kg with flow around them; being the drying uniform for this it finishes. The quality of the seeds was not affected in the drying coke superior temperatures they were presented to 43-centigrade degrees. The dryer can adapt to individual necessities and conditions you specify of operation. It is recommended to carry out rehearsals for other agricultural products that allow knowing the capacity and functionality from the dryer to property level

Possible causes of dry pea synergy to corn

Science.gov (United States)

Dry pea improves corn yield and tolerance to weed interference compared with soybean, spring wheat, or canola as preceding crops. To understand this synergy between dry pea and corn, we examined growth and nutrient concentration of corn following dry pea or soybean in sequence. Each corn plot was ...

Growth enhancement of soybean (Glycine max) upon exclusion of UV-B and UV-B/A components of solar radiation: characterization of photosynthetic parameters in leaves.

Science.gov (United States)

Guruprasad, Kadur; Kadur, Guruprasad; Bhattacharjee, Swapan; Swapan, Bhattacharjee; Kataria, Sunita; Sunita, Kataria; Yadav, Sanjeev; Sanjeev, Yadav; Tiwari, Arjun; Arjun, Tiwari; Baroniya, Sanjay; Sanjay, Baroniya; Rajiv, Abhinav; Abhinav, Rajiv; Mohanty, Prasanna

2007-01-01

Exclusion of UV (280-380 nm) radiation from the solar spectrum can be an important tool to assess the impact of ambient UV radiation on plant growth and performance of crop plants. The effect of exclusion of UV-B and UV-A from solar radiation on the growth and photosynthetic components in soybean (Glycine max) leaves were investigated. Exclusion of solar UV-B and UV-B/A radiation, enhanced the fresh weight, dry weight, leaf area as well as induced a dramatic increase in plant height, which reflected a net increase in biomass. Dry weight increase per unit leaf area was quite significant upon both UV-B and UV-B/A exclusion from the solar spectrum. However, no changes in chlorophyll a and b contents were observed by exclusion of solar UV radiation but the content of carotenoids was significantly (34-46%) lowered. Analysis of chlorophyll (Chl) fluorescence transient parameters of leaf segments suggested no change in the F v/F m value due to UV-B or UV-B/A exclusion. Only a small reduction in photo-oxidized signal I (P700+)/unit Chl was noted. Interestingly the total soluble protein content per unit leaf area increased by 18% in UV-B/A and 40% in UV-B excluded samples, suggesting a unique upregulation of biosynthesis and accumulation of biomass. Solar UV radiation thus seems to primarily affect the photomorphogenic regulatory system that leads to an enhanced growth of leaves and an enhanced rate of net photosynthesis in soybean, a crop plant of economic importance. The presence of ultra-violet components in sunlight seems to arrest carbon sequestration in plants.

Capture and utilization of solar radiation by the soybean and common bean crops and by weeds

International Nuclear Information System (INIS)

Santos, Jose Barbosa dos; Procopio, Sergio de Oliveira; Silva, Antonio Alberto da; Costa, Luiz Claudio

2003-01-01

Aiming to develop techniques for the establishment of a Weed Integrated Management Program, the performance of common bean (Phaseolus vulgaris L.) and soybean (Glycine max (L.) Merrill) and of weeds Bidens pilosa L., Euphorbia heterophylla L. (two biotypes), sensitive and resistant to ALS inhibitor - herbicides and [ Desmodium tortuosum (SW.) DC.], was evaluated in relation to their efficiency in capturing and utilizing solar radiation.The following indices were calculated: total dry biomass production rate (Ct), leaf dry biomass production rate (Cf), radiation efficient use (x), net assimilation rate (EA), specific leaf area (SA), leaf area index (L), leaf matter ratio (FW) and leaf area ratio (FA). No difference was observed for all characteristics evaluated among E. heterophylla biotypes. Soybean showed the highest rate of total dry biomass production along its cycle and also the highest leaf area index, indicating its greater capacity in capturing light and providing shade to competitive plants. Especially after flowering, common bean was the most efficient in draining its photoassimilates for leaf formation. Soybean showed greater efficiency in converting radiation intercepted in the biomass. (author)

Improvement of crop yield in dry environments: benchmarks, levels of organisation and the role of nitrogen.

Science.gov (United States)

Sadras, V O; Richards, R A

2014-05-01

Crop yield in dry environments can be improved with complementary approaches including selecting for yield in the target environments, selecting for yield potential, and using indirect, trait- or genomic-based methods. This paper (i) outlines the achievements of direct selection for yield in improving drought adaptation, (ii) discusses the limitations of indirect approaches in the context of levels of organization, and (iii) emphasizes trade-offs and synergies between nitrogen nutrition and drought adaptation. Selection for yield in the water- and nitrogen-scarce environments of Australia improved wheat yield per unit transpiration at a rate of 0.12kg ha(-1) mm(-1) yr(-1); for indirect methods to be justified, they must return superior rates of improvement, achieve the same rate at lower cost or provide other cost-effective benefits, such as expanding the genetic basis for selection. Slow improvement of crop adaptation to water stress using indirect methods is partially related to issues of scale. Traits are thus classified into three broad groups: those that generally scale up from low levels of organization to the crop level (e.g. herbicide resistance), those that do not (e.g. grain yield), and traits that might scale up provided they are considered in a integrated manner with scientifically sound scaling assumptions, appropriate growing conditions, and screening techniques (e.g. stay green). Predicting the scalability of traits may help to set priorities in the investment of research efforts. Primary productivity in arid and semi-arid environments is simultaneously limited by water and nitrogen, but few attempts are made to target adaptation to water and nitrogen stress simultaneously. Case studies in wheat and soybean highlight biological links between improved nitrogen nutrition and drought adaptation.

Geo-environmental model for the prediction of potential transmission risk of Dirofilaria in an area with dry climate and extensive irrigated crops. The case of Spain.

Science.gov (United States)

Simón, Luis; Afonin, Alexandr; López-Díez, Lucía Isabel; González-Miguel, Javier; Morchón, Rodrigo; Carretón, Elena; Montoya-Alonso, José Alberto; Kartashev, Vladimir; Simón, Fernando

2014-03-01

Zoonotic filarioses caused by Dirofilaria immitis and Dirofilaria repens are transmitted by culicid mosquitoes. Therefore Dirofilaria transmission depends on climatic factors like temperature and humidity. In spite of the dry climate of most of the Spanish territory, there are extensive irrigated crops areas providing moist habitats favourable for mosquito breeding. A GIS model to predict the risk of Dirofilaria transmission in Spain, based on temperatures and rainfall data as well as in the distribution of irrigated crops areas, is constructed. The model predicts that potential risk of Dirofilaria transmission exists in all the Spanish territory. Highest transmission risk exists in several areas of Andalucía, Extremadura, Castilla-La Mancha, Murcia, Valencia, Aragón and Cataluña, where moderate/high temperatures coincide with extensive irrigated crops. High risk in Balearic Islands and in some points of Canary Islands, is also predicted. The lowest risk is predicted in Northern cold and scarcely or non-irrigated dry Southeastern areas. The existence of irrigations locally increases transmission risk in low rainfall areas of the Spanish territory. The model can contribute to implement rational preventive therapy guidelines in accordance with the transmission characteristics of each local area. Moreover, the use of humidity-related factors could be of interest in future predictions to be performed in countries with similar environmental characteristics. Copyright © 2014 Elsevier B.V. All rights reserved.

Characteristics of Timbers Dried Using Kiln Drying and Radio Frequency-Vacuum Drying Systems

Directory of Open Access Journals (Sweden)

Rabidin Zairul Amin

2017-01-01

Full Text Available Heavy hardwoods are difficult-to-dry timbers as they are prone to checking and internal stresses when dried using a conventional kiln drying system. These timbers are usually dried naturally to reach 15% to 19% moisture content with an acceptable defects. Besides long drying time, timbers at these moisture contents are not suitable for indoor applications since they will further dry and causing, for example, jointing and lamination failures. Drying to a lower moisture content could only be achieved in artificial drying kilns such as conventional kiln, dehumidification kiln, solar kiln, radio frequency-vacuum, etc. The objective of this study was to evaluate the characteristics of 30 mm and 50 mm thick kekatong (Cynometra spp. timber dried using kiln drying (KD and radio frequency-vacuum drying (RFV system. The investigation involved drying time, moisture content (MC variations between and within boards, drying defects, shrinkage, and drying stress. Drying defects include checks (surface, end, and internal checks and warping (bowing, cuping, spring, and twisting. The results showed that RFV drying time was reduced to 50% compared to the KD. RFV dried boards demonstrated a more uniform MC between and within boards. Shrinkage in width and thickness, as well as tangential/radial and volumetric shrinkages were substantially less in RFV boards. The amount of cupping, bowing and spring were very low and negligible in all drying runs. There was no twisting observed in all drying methods. The number of stress-free RFV board was higher than KD. With proper procedure, the RFV technology could be used for drying heavy hardwoods which are difficult to dry in conventional kilns due to excessive drying times and degradation.

Design of Solar Heat Sheet for Air Heaters

Science.gov (United States)

Priya, S. Shanmuga; Premalatha, M.; Thirunavukkarasu, I.

2011-12-01

The technique of harnessing solar energy for drying offers significant potential to dry agricultural products such as food grains, fruits, vegetables and medicinal plants, thereby eliminating many of the problems experienced with open-sun drying and industrial drying, besides saving huge quantities of fossil fuels. 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 have been developed in the recent past, mainly for drying agricultural products. Major problems experienced with solar dryers are their non-reliability as their operation largely depends on local weather conditions. While back-up heaters and hybrid dryers partly solved this issue, difficulties in controlling the drying air temperature and flow rate remains a problem, and affects the quality of the dried product. This study is aimed at eliminating the fluctuations in the quality of hot air supplied by simple solar air heaters used for drying fruits, vegetables and other applications. It is an attempt to analyse the applicability of the combination of an glazed transpired solar collector (tank), thermal storage and a intake fan(suction fan) to achieve a steady supply of air at a different atmospheric temperature and flow rate for drying fruits and vegetables. Development of an efficient, low-cost and reliable air heating system for drying applications is done.

Nitrogen fertilizer fate after introducing maize into a continuous paddy rice cropping system

Science.gov (United States)

Thiemann, Irabella; He, Yao; Siemens, Jan; Brüggemann, Nicolas; Lehndorf, Eva; Amelung, Wulf

2017-04-01

After introducing upland crops into permanent flooded cropping systems, soil conditions temporally change from anaerobic to aerobic, which profoundly impacts nitrogen (N) dynamics. In the framework of the DFG research unit 1701 ICON we applied a single 15N-urea pulse in a field experiment in the Philippines with three different crop rotations: continuous paddy rice, paddy rice-dry rice, and paddy rice-maize. Subsequently, we traced the fate of the labelled urea in bulk soil, rhizosphere, roots, biomass and microbial residues (amino sugars) within the following two years. 15N recovery in the first 5 cm of bulk soil was highest in the first dry season of continuous paddy rice cropping (37.8 % of applied 15N) and lowest in the paddy rice-maize rotation (19.2 %). While an accumulation over time could be observed in bulk soil in 5-20 cm depth of the continuous paddy rice system, the recoveries decreased over time within the following two years in the other cropping systems. Highest 15N-recovery in shoots and roots were found in the continuous paddy rice system in the first dry season (27.3 % in shoots, 3.2 % in roots) as well as in the following wet season (4.2 % in shoots, 0.3 % in roots). Lowest recoveries in biomass were found for the paddy rice-dry rice rotation. Long-term fixation of 15N in microbial biomass residues was observed in all cropping systems (2-3 % in the 3rd dry season). The results indicate that the introduction of maize into a continuous paddy rice cropping system can reduce the fertilizer N use efficiency especially in the first year, most likely due to nitrate leaching and gaseous losses to the atmosphere.

Rodigo Uno (Italy) geothermal thermal energy for crop drying

International Nuclear Information System (INIS)

Facchini, U.; Sordelli, C.; Magnoni, S.; Cantadori, M.

1992-01-01

This paper outlines the chief design and performance features of a forage drying installation which makes use of locally available geothermal energy. The heat exchange is accomplished through a water-air exchanger directly fed by 59 degrees C geothermal springs. Two 80,000 cubic meter/hour ventilators, making use of this energy (58 to 38 degrees C heat exchange), raise the drying air temperature by 16 degrees C, while providing an overall drying capacity of 43,200 kg/day. The balance of available 38 degrees C geothermal energy is being employed by a local aquaculture farm. The paper comments on the economic and environmental benefits being derived from this direct utilization of geothermal energy

Liquid chromatographic analysis of the main pungent principles of solar dried West Indian ginger (Zingiber officinale Roscoe)

Energy Technology Data Exchange (ETDEWEB)

Balladin, D.A.; Headley, Oliver [University of the West Indies, Center for Resource Management and Environmental Studies, St. Michael (Barbados)

1999-10-01

The main pungent principles and essential oils of West Indian ginger (Zingiber officinale Roscoe) were identified and quantified by liquid chromatography. The stationary phase used was (5.0 g silica gel 70-230 mesh) and the mobile phase [petroleum ether (60-80degC) : diethyl ether (3:7 v/v)]. The first 15 ml contained the very volatile and least polar compounds present in the extracted oleoresin from the solar dried ginger rhizome. These compounds are the essential oils (R{sub f} = 0.90) and 25.63% (w/w) of the total oleoresin charge to the column. The next 5 ml aliquot was without any compounds. The following 25 ml contained the shogaol fraction (R{sub f} = 0.42) and 47.74% (w/w) of the total oleoresin charge to the column. The next 5 ml aliquot was without any compounds. The following 35 ml contained the gingerol fraction (R{sub f} = 0.20) and 27.13% (w/w) of the total oleoresin charge to the column. This simple liquid chromatography method can be used to investigate the essential oils and pungent principles of the extracted oleoresin from the solar dried ginger rhizomes. (Author)

Transpiration and crop yields

NARCIS (Netherlands)

Wit, de C.T.

1958-01-01

Theoretical and practical aspects of the transpiration of crops in the field are discussed and he concludes that the relationship between transpiration and total dry matter production is much less affected by growing conditions than has been supposed. In semi-arid and arid regions, this relationship

Potassium efficiency of different crops grown on a sandy soil under controlled conditions

International Nuclear Information System (INIS)

El Dessougi, H. I.; Claassen, N.; Steingrobe, B.

2010-01-01

The objective of this work was to study K efficiency of different crops and determine the plant parameters affecting it. The study was carried out using 14 different crops and cultivars grown on a sandy soil rich in humus, with two potassium fertilisation levels under controlled conditions. The studied crops showed different K efficiency reflected in different dry matter yield production in unfertilised relative to fertilised treatments. All crops had , at low K supply, less than optimum K concentration in dry matter, indicating that the soil K concentration did not meet the K requirement of the plants, Thus, the ability to produce high dry matter yield indicated superior adaptability to K deficiency. The efficiency mechanisms employed by the different crops were low shoot growth rate and/or high root length-shoot weigh ratio and a high uptake rate per unit root, i.e. the influx, or low internal K requirement. Crops with high influx had higher calculated concentration gradients, since they caused further decrease of the concentration at the root surface. As such, they were able to create steeper concentration gradients between bulk soil solution and root surface. This resulted in higher diffusive flux to the roots.(Author)

Weed infestation of spring barley (Hordeum vulgare L. depending on the cover crop and weed control method

Directory of Open Access Journals (Sweden)

Dorota Gawęda

2014-04-01

Full Text Available The aim of this 3-year field study was to evaluate the effect of some stubble crops and weed control methods on the species composition, number and air-dry weight of weeds in a spring barley crop grown in short-term monoculture. The study was conducted in the period 2009–2011 at the Uhrusk Experimental Farm, on mixed rendzina soil classified as very good rye soil complex. It included stubble crops which were ploughed under in each year (control treatment without cover crop, white mustard, lacy phacelia, a mixture of legumes – narrow-leaf lupin + field pea and 3 weed control methods used in spring barley crops (mechanical, mechanical and chemical, chemical weed control. Veronica persica was the weed species that occurred in greatest numbers in the spring barley crop sown after stubble crops. All cover crops reduced the numbers of Avena fatua which was the dominant species in the control treatment. Chemical as well as chemical and mechanical weed control significantly reduced the numbers of Avena fatua compared to the treatment where only double harrowing was used for weed control. The stubble crops did not reduce weed infestation of spring barley. Compared to the control treatment, the ploughing-in of white mustard and the mixture of legumes reduced the dry weight of weeds by 49.1 and 22.7%, respectively. Mechanical weed management proved to be less effective in reducing the number and dry weight of weeds compared to the other weed control methods. A significant negative correlation was found between the dry weight of weeds in the spring barley crop and the dry weight of the ploughed-in white mustard cover crop under the conditions of chemical weed control as well as in the case of the mixture of legumes when complete mechanical and chemical weed control was used.

Effect of solar drying on the composition of essential oil of Sacha culantro (Eryngium foetidum L.) grown in the Peruvian Amazon

Czech Academy of Sciences Publication Activity Database

Banout, J.; Havlík, J.; Kulik, M.; Klouček, P.; Lojka, B.; Valterová, Irena

2010-01-01

Roč. 33, č. 1 (2010), s. 83-103 ISSN 0145-8876 Institutional research plan: CEZ:AV0Z40550506 Keywords : Sacha culantro * essential oil * solar drying Subject RIV: CC - Organic Chemistry Impact factor: 0.875, year: 2010

(AJST) THIN- LAYER DRYING OF DICED CASSAVA ROOTS

African Journals Online (AJOL)

opiyo

effect of drying temperature on thin-layer drying was high, followed by initial moisture .... The moisture content was converted to moisture ratio (MR) using the non-exponential part .... The Potential of Cassava As a Cash. Crop For Small Holder ...

Radiometric relations of a sugarcane crop

International Nuclear Information System (INIS)

Machado, E.C.; Pereira, A.R.; Camargo, M.B.P. de; Fahl, J.I.

1985-01-01

The radiometric relations of a sugarcane crop, cv. NA56-79, are studied during the period of maximum leaf area index. The coefficients of reflection, transmission and absorption of the incoming solar radiation were function of solar elevation and the waveband considered. The photosynthetically active radiation was always less reflected and transmitted but more absorved than the near infrared radiation. (M.A.C.) [pt

Elimination of pathogenic bacteria in sewage sludge during the solar drying; Eliminacion de bacterias patogenas en lodos residuales durante el secado solar

Energy Technology Data Exchange (ETDEWEB)

Cota Espericueta, Alma Delia; Ponce Corral, Carlos [Instituto de Ciencias Biomedicas, Universidad Autonoma de Ciudad Juarez, Ciudad Juarez, Chihuahua, (Mexico)

2008-11-15

This paper describes the performance of a solar dryer capable of bacterial pathogen removal from the physicochemical sludge of the main wastewater treatment plant for Ciudad Juarez, Mexico. The solar setup was proposed as an alternative solution, technically feasible, for reducing the volume of the 135 tons of sludge produced per day in this plant. The experimental-greenhouse prototype has a 4.5 m{sup 2} collection area, a 1 m{sup 3}-drying bed, and automatic systems for ventilation, extraction, and data acquisition. The automatic operation was controlled by temperature and humidity differences between internal and external conditions. Global solar radiation, pH and water content of the sludge were monitored. The overall effectiveness of the solar dryer was determined by assessing thermal and microbiological performance. Water content in sludge during the process was used as an indicator of thermal effectiveness. The microbiological elimination was quantified at different residence times considering two contamination indicators: faecal coliforms and Salmonella spp. Quantification of the pathogenic microorganisms was carried out by the multiple-tube fermentation technique presented in the Mexican regulation NOM-004-SEMARNAT-2002. The thermal results related to the water content showed an exponential decay that achieved up to a 99 % reduction. Regarding microbiological removal effectiveness, there was a strong dependence between the number of bacteria present and the water content in the sludge. As a consequence, with the removal of 92 % of water, it was verified that the elimination of faecal coliforms fell from 3.8x10{sup 6} to 1.6 MPN per gram of dried sludge; and for Salmonella spp. the reduction was from 1.5x10{sup 1}3 to 1.9x10{sup 3} MPN per gram of dried sludge. [Spanish] La presente investigacion describe el desempeno de un secador solar con respecto a la eliminacion de bacterias patogenas contenidas en lodos fisicoquimicos provenientes de la principal

Use of solar distillation for olive mill wastewater drying and recovery of polyphenolic compounds.

Science.gov (United States)

Sklavos, Sotirios; Gatidou, Georgia; Stasinakis, Athanasios S; Haralambopoulos, Dias

2015-10-01

Olive mill wastewater (OMW) is characterized by its high organic load and the presence of phenolic compounds. For first time, a solar distillator was used to investigate the simultaneous solar drying of OMW and the recovery of phenolic compounds with antioxidant properties in the distillate. Two experiments were conducted and the role of thermal insulation on the performance of the distiller was studied. The use of insulation resulted to higher temperatures in the distillator (up to 84.3 °C and 78.5 °C at the air and sludge, respectively), shorter period for OMW dewatering (14 days), while it increased the performance of distillator by 26.1%. Chemical characterization of the distillate showed that pH and COD concentration gradually decreased during the experiments, whereas an opposite trend was noticed for conductivity and total phenols concentration. Almost 4% of the total phenols found initially in OMW were transferred to the distillate when an insulated solar distillator was used. Gas chromatographic analysis of collected distillates confirmed the presence of tyrosol in all samples; whereas hydroxytyrosol was found only in fresh collected distillate samples. Further experiments should be conducted to optimize the process and quantify the concentrations of recovered phenolic compounds. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of cover crops on citrus crops on arbuscular mycorrhizal fungi development in the Colombian piedmont Oxisols

Directory of Open Access Journals (Sweden)

Hernán Javier Monroy L.

2013-01-01

Full Text Available Native arbuscular mycorrhizal fungi associated with grassand legume cover crops established on Oxisol soils in the Colombian piedmont (Meta were identified morphologically and the ability to colonize was evaluated. The experimental area consisted of cover crops Arachispintoi (CIAT 18744, Brachiaria brizantha cv. Toledo, B. dictyoneura cv. Llanero, Desmodium ovalifolium c v. Maquenque, Panicum maximum (CIAT 36000, Paspalumnotatum, and a chemical control (Glyphosate and mechanical control established in the rows in a Valencia orange grove. The experiment followed a complete randomized block design (8 cover crops and three replications, evaluated during the wet and dry seasons. Rhizosphere soil and grass and legumes roots were sampled in order to identified AMF and quantify the number of spores and the percentage of colonization. A total of 26 species were identified, including Acaulosporascrobiculata, A. morrowiae and, Scutellospora heterogama, which accounted for over 65% of the population. Thepercentage of root colonization ranged between 47% and 94% with spore counts between 63 and 300/100 g of dry soil. Cover crops with the highest colonization percentage and AMF diversity were B. brizantha, B. dictyoneura and P. notatumin their respective order. Glyphosate and mechanical control had a negative influence on the sporulation and colonization of the arbuscular mycorrhizal fungi in the root system

Movable air solar collector and its efficiency

International Nuclear Information System (INIS)

Lauva, A.; Aboltinš, A.; Palabinskis, J.; Karpova Sadigova, N.

2008-01-01

Implementing the guidelines of the Latvian National Programme for Energy in the field of alternative energy, intensive research shall be carried on regarding the use of solar energy, as it can be successfully used not only for the purposes of water heating and production of electrical energy, but also for air warming. The amount of heat necessary for the drying of rough forage and grain drying by active aeration in June, July and August can be obtained using solar radiation. The Latvian Guidelines for the Energy Development 2006-2016 state that the solar radiance in Latvia is of quite low intensity. The total amount of solar energy is 1109 kWh m -2 per year. The period of usage of the solar thermal energy is beginning from the last decade of April, when the intensity of radiation is 120 kWh m -2 , until the first decade of September. Within this period (approximately 1800 hours), it is possible to use the solar thermal energy by placing solar collectors. The usage of solar collectors for in drying of agricultural production is topical from the viewpoint of decreasing the consumption of energy used for the drying, as electrical energy and fossil energy resources become more expensive and tend to run out. In the processes that concern drying of agricultural production, efficiently enough solar radiation energy can be used. Due to this reason researching continues and expands in the field of usage of solar energy for the processes of drying and heating. The efficiency factor of the existing solar collectors is not high, but they are of simple design and cheep for production and exploitation. By improving the design of the solar collectors and choosing modern materials that absorb the solar radiation energy, it is possible the decrease the efficiency factor of solar collectors and decrease the production costs. In the scientific laboratory of grain drying and storage of Latvia University of Agriculture, a pilot device movable folding solar collector pilot device

Photosynthetic energy conversion efficiency: setting a baseline for gauging future improvements in important food and biofuel crops.

Science.gov (United States)

Slattery, Rebecca A; Ort, Donald R

2015-06-01

The conversion efficiency (ε(c)) of absorbed radiation into biomass (MJ of dry matter per MJ of absorbed photosynthetically active radiation) is a component of yield potential that has been estimated at less than half the theoretical maximum. Various strategies have been proposed to improve ε(c), but a statistical analysis to establish baseline ε(c) levels across different crop functional types is lacking. Data from 164 published ε(c) studies conducted in relatively unstressed growth conditions were used to determine the means, greatest contributors to variation, and genetic trends in ε(c )across important food and biofuel crop species. ε(c) was greatest in biofuel crops (0.049-0.066), followed by C4 food crops (0.046-0.049), C3 nonlegumes (0.036-0.041), and finally C3 legumes (0.028-0.035). Despite confining our analysis to relatively unstressed growth conditions, total incident solar radiation and average growing season temperature most often accounted for the largest portion of ε(c) variability. Genetic improvements in ε(c), when present, were less than 0.7% per year, revealing the unrealized potential of improving ε(c) as a promising contributing strategy to meet projected future agricultural demand. © 2015 American Society of Plant Biologists. All Rights Reserved.

Studies on the radiation drying method for grain, 2: A good drying method of paddy rice from the viewpoint of the drying rate and the crack generation of rice

International Nuclear Information System (INIS)

Horibe, K.; Nakagawa, K.; Tohjo, T.

1990-01-01

A drying rate of paddy rice in a solar heat drying plant was studied. Solar-heated air at the upper part of a plastic house was blasted to the surface of the layer of paddy rice which was piled on the floor of the house. The drying rate increased with higher wind velocity, but it was found that the velocity was limited to 6m/s by the crack generation of the paddy rice. The effects of the layer thickness, the number of layer agitations and the heat supplied on the drying rate at a given wind velocity (6m/s) were expressed with a multiple regression equation. Then, the equation positively proposed appropriate conditions for effective operation of the plant in fine days

Nitrogen acquisition by pea and barley and the effect of their crop residues on available nitrogen for subsequent crops

DEFF Research Database (Denmark)

Jensen, E.S.

1996-01-01

Nitrogen acquisition by field pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.) grown on a sandy loam soil and availability of N in three subsequent sequences of a cropping system were studied in an outdoor pot experiment. The effect of crop residues on the N availability was evaluated....... The dry matter production and total N uptake of a spring barley crop following pea or barley, with a period of unplanted soil in the autumn/winter, were significantly higher after pea than after barley. The barley crop following pea and barley recovered 11% of the pea and 8% of the barley residue N...

Evaluation of a integral systems greenhouse - solar dryer for small growers; Evaluacion de un sistema integral invernadero - secadero solar para pequenos productores

Energy Technology Data Exchange (ETDEWEB)

Garcia, Victor O; Iriarte, Adolfo A [INENCO, Universidad Nacional de Catamarca, Catamarca (Argentina); Carabajal, Dante; Sabadzija, Gabriela; Tomalino, Luis [E.E.A. INTA, Catamarca, Catamarca (Argentina)

2000-07-01

Due to poor yielding capacity in the province of Catamarca, Argentina, it is necessary to improve solar drying systems in order to have a better quality final product. It is also essential to divide the costs of infrastructure with other complementary activities because of the need to make drying methods profitable. The system proposed in this work is a dryer-greenhouse with a double purposed macrotunnel greenhouse: during Winter it is used as a yielding system, and in Summer it is prepared to fulfill the functions of a solar dryer. The crops evaluated in winter were: small vegetable marrow (Curcubita maxima L), melon (Cucumis melo), ad cucumber (Cucuis sativus). Crop cycle, harvest time and tield in Kg/m were determined for each species. The assessment of the dryer was made using pepper for paprika observation of the thermal behavior of the product during drying and its final quality. The product obtained had a very good quality in color, taste and aroma with a classification of extra quality according to the Argentine Nutritional Code and the 7541 ISO Standard. Drying time decreased considerably compared to that observed in open air drying, 1995, 1996 and 1997 campaigns were economically assessed, and an evaluation of investments in five years was also conducted obtaining a positive VAN and a TIR above the cost of the best alternative for money expenditure. This integrated system is valid alternative in a sustainable production for small growers. [Spanish] Debido a las caracteristicas productivas de la Provincia de Catamarca Argentina, es necesario optimizar los procesos del secado solar teniendo en cuenta la calidad final del producto. Ademas, debido a la necesidad de rentabilizar los metodos de secado, imprescindible repartir los costos de infraestructura con otro tipo de actividad complementaria. El sistema propuesto en este trabajo es un invernadero secadero que utiliza un invernadero macrotunel que cumple una doble funcion, durante el invierno se usa como

An economic optimization of evaporator and air collector area in a solar assisted heat pump drying system

International Nuclear Information System (INIS)

Rahman, S.M.A.; Saidur, R.; Hawlader, M.N.A.

2013-01-01

Highlights: • The optimum combination will provide around 89% of the total load. • The system has a savings during the life cycle with least payback period of 4.37 year. • The optimal system is insensitive to the variation in fuel inflation and discount rate. - Abstract: This paper presents an economic optimization of evaporator and air collector area of a solar assisted heat pump drying system. Economic viability of solar heating systems is usually made by comparing the cost flows recurring throughout the lifetime of the solar and conventional alternative systems. Therefore, identification of optimum variables by using a simulation program and an economic analysis based on payback period of the system are presented in this paper. FORTRAN language is used to run the simulation. Effect of load and different economic variables on payback period is also investigated. Economic analysis reveals that system has sufficient amount of savings during the life cycle with a minimum payback period of about 4 years

Multi-shelf domestic solar dryer

International Nuclear Information System (INIS)

Singh, Parm Pal; Singh, Sukhmeet; Dhaliwal, S.S.

2006-01-01

The solar dryer described in this paper can be used for drying various products at home under hygienic conditions with the self guarantee of adulteration free product. This solar dryer is of multi-shelf design, consisting of three perforated trays arranged one above the other. The drying air flows through the product by natural circulation. One of its novel features is variable inclination to capture more solar energy in different seasons. Another novel feature is the option to dry product under shade or without shade as per requirement. The rate of drying is uniform in all the trays due to heating of the air by solar energy in between the trays. The maximum stagnation temperature of this solar dryer was found to be 100 deg. C in the month of November at Ludhiana (31 o N). The moisture evaporation on the 1st, 2nd and 3rd drying day for drying fenugreek leaves was 0.23, 0.18 and 0.038 kg/m 2 h. To overcome the problem of reduction in efficiency on the second and third drying day, a semi-continuous mode of loading has been investigated, in which the efficiency remains almost the same on all drying days. The drying rate in the dryer was more than double that in open shade drying. Moreover, the final moisture content of the product was low enough (7.3% wb) for grinding it to a powder form and for good shelf life (1 year). An uncertainty analysis was performed, and the uncertainty in the efficiency was found to be 1.35%. An economic analysis was performed by three methods. The cost of drying fenugreek leaves in the domestic solar dryer turned out to be about 60% of that in an electric dryer. The cumulative present worth of the savings are much higher (18,316 Rupees) than the capital cost of the dryer (1600 Rupees). The payback period is also very low (<2 years) as compared to the life of the dryer (20 years), so the dryer will dry product free of cost during almost its entire life period. The quality and shelf life of the dried products are comparable to those of

Modification of Indirect Solar Dryer for Simplicia Production

Science.gov (United States)

Purnomo, C. W.; Indarti, S.

2018-03-01

Simplicia is natural ingredient for herbal medicine that has been subjected to drying only. This study aims to develop an appropriate drying equipment to produce dried leaves of sambung nyawa (Gynura procumbens (Lour.) Merr.) or also called “longevity spinach”. Typical indirect solar drier was modified to be able to process more fresh leaves in order to speed up the production. The modification was done using double solar collector and wind powered ventilation. The double solar collector was applied in order to collect more solar energy for larger dimension of drying chamber, while the wind-ventilator was installed to provide forced convection of hot air flow inside the dryer. The drying kinetic including the drying constants were investigated using three common thin layer drying equations to model the drying behavior of the leaves. The moisture ratio (MR) depletion with respect to the drying time (t) of the leaves can be well represented by equation of MR=1.1732exp(-0.0993.t)-0.1732exp(-17.3871.t).

Sensitivity of APSIM/ORYZA model due to estimation errors in solar radiation

Directory of Open Access Journals (Sweden)

Alexandre Bryan Heinemann

2012-01-01

Full Text Available Crop models are ideally suited to quantify existing climatic risks. However, they require historic climate data as input. While daily temperature and rainfall data are often available, the lack of observed solar radiation (Rs data severely limits site-specific crop modelling. The objective of this study was to estimate Rs based on air temperature solar radiation models and to quantify the propagation of errors in simulated radiation on several APSIM/ORYZA crop model seasonal outputs, yield, biomass, leaf area (LAI and total accumulated solar radiation (SRA during the crop cycle. The accuracy of the 5 models for estimated daily solar radiation was similar, and it was not substantially different among sites. For water limited environments (no irrigation, crop model outputs yield, biomass and LAI was not sensitive for the uncertainties in radiation models studied here.

Design, development and performance testing of a new natural convection solar dryer

Energy Technology Data Exchange (ETDEWEB)

Pangavhane, D.R. [K.K. Wagh College of Engineering, Nashik (India). Department of Mechanical Engineering; Sawhney, R.L.; Sarsavadia, P.N. [Devi Ahilya Vishwa Vidhyalaya, Indore (India). School of Energy and Environmental Studies

2002-06-01

Mechanical drying of agricultural products is an energy consuming operation in the post-harvesting technology. Greater emphasis is given to using solar energy sources in this process due to the high prices and shortages of fossil fuels. For these purposes, a new natural convection solar dryer consisting of a solar air heater and a drying chamber was developed. This system can be used for drying various agricultural products like fruits and vegetables. In this study, grapes were successfully dried in the developed solar dryer. The qualitative analysis showed that the traditional drying, i.e. shade drying and open sun drying, dried the grapes in 15 and 7 days respectively, while the solar dryer took only 4 days and produced better quality raisins. (author)

Yields of crops on a rhodic ferralsol in southern Brazil in relation to ...

African Journals Online (AJOL)

Even though no-tillage, crop rotation management systems have been accepted as useful for sustaining crop production, there is the need to identify which crops can be used for such rotations. This study evaluated the dry matter and grain yields of eight winter and two summer crops (maize, Zea mays L. and soybean, ...

Natural radioactivity in Swedish agricultural soils and crops

International Nuclear Information System (INIS)

Eriksson, Ake; Rosen, K.

2000-01-01

In this work we report on investigations in Sweden of the natural radioactivity of 40 K, 226 Ra and 232 Th in the agricultural soils and of 226 Ra in the crops. In addition information is given on factors important for the plant availability of these nuclides to the crop plants. Also, from a number of works, background data on the transfer from soils to plants in different environments are presented. These works show that there is a large variation depending on local conditions and crop type in the accumulation of natural radioactive elements by the plants. Thus, concentration ratios (plant/soil) calculated for fresh crop weight and dry soil weight showed for 238 U in forage crops and in grain a range 0.001-0.005, for 226 Ra a range 0.001-0.03 and for 210 Pb a range 0.0004-0.2. The higher value was limit for vegetative plant parts and the lower value limit for generative parts, seeds and grain. In Swedish early studies, evidence was found that in field crops on the same soils the radium/calcium-ratio in grain was reduced according to the following order winter wheat>spring wheat> barley>oats. Variation among the crops on different soils showed ranges from 1-0.1 to 1-0.4. The radium/calcium-ratio in straw was 4 to 7 times higher than in grain. Also field experiments showed that proper liming on acid soils could reduce the radium/calcium ratio by 40 per cent. Our study shows that the average contents of the nuclides 226 Ra and 232 Th in Bq per kg dry weight is of the same size of order, 40, 50 and 80 Bq per kg in the southern, in the western and in the middle regions of Sweden, respectively. The difference between regions is not occasional. It depends on the type of the mother material and on the different clay contents of the soils, as is indicated also by the potassium content. Considering also the daughters of the nuclide series it is found that the total nuclide activity will reach a sum of 300-600 kBq per square meter of the plough layer. The total activity may

Sustainable Irrigation Allocation Model for Dry and Wet Periods using Reservoir Storage and Inflow

Science.gov (United States)

Surianarayanan, S.; Suribabu, C. R.; Ramakrishnan, K.

2017-07-01

The dry period agriculture is inevitable both for the farmers for their earning, and for the soil for its fertility by crop-rotation. In tropical countries like INDIA, dry period agriculture becomes difficult because of less (or) no rain fall. Hence a simple water balancing model for irrigation scheduling, using the measure “Volumetric Reliability” is prepared in this paper, with the storage and inflow of a reservoir both for the dry and wet periods. The case-study is done for a reservoir in INDIA with thirty one years of hydrological data(from 1982 to 2012). The objective of this paper is to prepare a simple water balance model taking 10 days periods of demand and supply for ID crop(Irrigated Dry crop, ground nut) with usage of volumetric reliability concept for the periods of deficiency and adoption of less water requirement crops to reduce the water-stress during critical periods of crop growth, and finally arrive at a feasible allocation schedule for the success of agriculture and the yield throughout the year both for wet and dry crops with the available storage on the start of irrigation for a particular year. The reservoir is divided for storages such as full, deficient and critical storages. The starting storage for the dry period from January is used after adequate allocation for wet crops, the quantity for riparian rights and for drinking water, for the sustainability. By the water-balancing, the time-series for thirty one years, it is found that for twenty two years the demand for the ID crops is satisfied with the storage in the reservoir, and in the remaining years of deficient inflows, for three years (1986,1996,2004)the demand is managed by using the safe reliability factor for demand which can nullify the deficit in demand for the whole supply period. But it is genuine to assure that the reduction in the amount of water for each 10 days periods should not exceed the survival limit of the crop. Necessary soil-moisture must be ensured in the crop

DryCardTM — A Low-Cost Dryness Indicator for Dried Products

Directory of Open Access Journals (Sweden)

James F. Thompson

2017-10-01

Full Text Available Mycotoxin contamination of food and feed is a significant health hazard in humid areas of the world. Fungal development can be halted if the water activity of dried products is kept below 0.65. This preliminary study evaluates the color response and response time of a low-cost humidity indicator that estimates water activity. The DryCardTM has a consistent color response to relative humidity and its response time is fast enough to be used in practical situations for estimating water activity. The card comes with use instructions and it can be reused many times. It is a crucial tool to assist smallholder farmers and traders in ensuring their crops have been adequately dried.

Engineering developments for small-scale harvest, storage and combustion of woody crops in Canada

Energy Technology Data Exchange (ETDEWEB)

Savoie, P.; Ouellet-Plamondon, C.; Morissette, R.; Preto, F. [Agriculture and Agri-Food Canada, Quebec City, PQ (Canada)

2010-07-01

Although wood remains an important source of energy for cooking and heating in developing countries, it has been largely replaced by fossil fuels, nuclear energy and hydroelectric power in developed countries. Given the need to diversify sources of energy, wood energy is being revitalized in developed countries. This paper reported on a current research program on woody crops at Agriculture and Agri-Food Canada. The research involves the development of a woody crop harvester to collect small size trees in plantations as well as in natural growth. The harvested package is a small round bale that enables natural drying from about 50 per cent moisture at harvest, down to 30 and 20 per cent after 4 to 6 months of storage outside and under shelter, respectively. The combustion value of woody crops averaged 19.4 GJ/t on a dry matter basis with little variation. The woody crops can be pulverized into fine particles, dried artificially to 10 per cent moisture content and processed into pellets for combustion. In a practical trial, more than 7.5 MJ/t DM were needed to produce pellets without providing more energy than coarse wood chips. The rural applications for this biomass include heating community and farm buildings and drying crops. These applications can use locally grown woody crops such as willow, or forest residues such as branches and bark in the form of chips to replace fossil energy sources.

Declining trends of water requirements of dry season Boro rice in the north-west Bangladesh

NARCIS (Netherlands)

Acharjee, Tapos Kumar; Halsema, van Gerardo; Ludwig, Fulco; Hellegers, Petra

2017-01-01

The drought prone North-West Bangladesh is vulnerable to the impacts of climate change, particularly because of less water availability in the dry period and high water requirement for crop production. Improved understanding of recent changes in crop water demand in the dry season is important

Weed Interference Effects on Leaves, Internode and Harvest Index of Dry Bean (Phaseolus vulgaris L.

Directory of Open Access Journals (Sweden)

Hossein GHAMARI

2015-03-01

Full Text Available The development of appropriate weed management strategies and efficient use of herbicides relies upon understanding weed-crop interactions. A field study was carried out to assess the effect of weed interference on leaves, internode and harvest index of dry bean (Phaseolus vulgaris L.. The experiment was established under a randomized complete block design with two types of weed interference treatments: plots with weeds and plots without weeds at different time intervals (0, 10, 20, 30, 40 and 50 days after crop emergence. The sigmoid Boltzmann model was used to quantify the crop traits as influenced by weed interference. Prolonged delays in weed removal reduced gradually the number of leaves of the crop. Weed interference decreased dry weight of leaves as well, so that the lowest value of it (33.49 g plant-1 was observed in full season during weed-infested treatment. Infestation of weeds affected the length of the crop internodes. While the weed interference duration increased, the length of the internodes decreased. Harvest index was also sensitive to weed competition. As the crop was kept weed-infested from the emergence for increasing periods of time, harvest index decreased to a value of 28.01%. A significant negative correlation between total biomass of weeds and dry bean traits (number of leaves, leaves dry weight, internode length and harvest index was observed. Therefore, weeds are able to adversely affect dry bean growth through constraining environmental resources and impairing leaves as the photosynthetic areas.

Development of reflectance-based crop coefficients for corn

International Nuclear Information System (INIS)

Neale, C.M.U.; Bausch, W.C.; Heermann, D.F.

1989-01-01

Concurrent measurements of reflected canopy radiation and the basal crop coefficient (K^b) for corn were conducted throughout a season in order to develop a reflectance-based crop coefficient model. Reflectance was measured in Landsat Thematic Mapper bands TM3 (0.63 - 0.69 um) and TM4 (0.76 - 0.90 um) and used in the calculation of a vegetation index called the normalized difference (ND). A linear transformation of the ND was used as the reflectance-based crop coefficient (Kcr). The transformation equates the ND for dry bare soil and the ND at effective cover, to the basal crop coefficient for dry soil evaporation and at effective cover, respectively. Basal crop coefficient values for com were obtained from daily evapotranspiration measurements of corn and alfalfa, using hydraulic weighing lysimeters. The Richards growth curve function was fitted to both sets of data. The K^b values were determined to be within -2.6% and 4.7% of the K^^ values. The date of effective cover obtained from the K^b data was within four days of the date on which the ND curve reached its maxima according to the Richards function. A comparison of the Kcr with basal crop curves from the literature for several years of data indicated good agreement. Reflectance-based crop coefficients are sensitive to periods of slow and fast growth induced by weather conditions, resulting in a real time coefficient, independent from the traditional time base parameters based on the day of planting and effective cover

Design and performance evaluation of a new hybrid solar dryer for banana

International Nuclear Information System (INIS)

Amer, B.M.A.; Hossain, M.A.; Gottschalk, K.

2010-01-01

A hybrid solar dryer was designed and constructed using direct solar energy and a heat exchanger. The dryer consists of solar collector, reflector, heat exchanger cum heat storage unit and drying chamber. The drying chamber was located under the collector. The dryer was operated during normal sunny days as a solar dryer, and during cloudy day as a hybrid solar dryer. Drying was also carried out at night with stored heat energy in water which was collected during the time of sun-shine and with electric heaters located at water tank. The efficiency of the solar dryer was raised by recycling about 65% of the drying air in the solar dryer and exhausting a small amount of it outside the dryer. Under Mid-European summer conditions it can raise up the air temperature from 30 to 40 deg. C above the ambient temperature. The solar dryer was tested for drying of ripe banana slices. The capacity of the dryer was to dry about 30 kg of banana slices in 8 h in sunny day from an initial moisture content of 82% to the final moisture content of 18% (wb). In the same time it reduced to only 62% (wb) moisture content in open sun drying method. The colour, aroma and texture of the solar dried products were better than the sun drying products.

Origin of the enhanced performance in poly(3-hexylthiophene) : [6,6]-phenyl C-61-butyric acid methyl ester solar cells upon slow drying of the active layer

NARCIS (Netherlands)

Mihailetchi, Valentin D.; Xie, Hangxing; Boer, Bert de; Popescu, Lacramioara M.; Hummelen, Jan C.; Blom, Paul W.M.; Koster, L. Jan Anton

2006-01-01

The origin of the enhanced performance of bulk heterojunction solar cells based on slowly dried films of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C-61-butyric acid methyl ester is investigated, combining charge transport measurements with numerical device simulations. Slow drying leads to a

Solar dryer with thermal storage and biomass-backup heater

Energy Technology Data Exchange (ETDEWEB)

Madhlopa, A. [Department of Physics and Biochemical Sciences, Malawi Polytechnic, P/Bag 303, Blantyre 3 (Malawi); Ngwalo, G. [Department of Mechanical Engineering, Malawi Polytechnic, P/Bag 303, Blantyre 3 (Malawi)

2007-04-15

An indirect type natural convection solar dryer with integrated collector-storage solar and biomass-backup heaters has been designed, constructed and evaluated. The major components of the dryer are biomass burner (with a rectangular duct and flue gas chimney), collector-storage thermal mass and drying chamber (with a conventional solar chimney). The thermal mass was placed in the top part of the biomass burner enclosure. The dryer was fabricated using simple materials, tools and skills, and it was tested in three modes of operation (solar, biomass and solar-biomass) by drying twelve batches of fresh pineapple (Ananas comosus), with each batch weighing about 20 kg. Meteorological conditions were monitored during the dehydration process. Moisture and vitamin C contents were determined in both fresh and dried samples. Results show that the thermal mass was capable of storing part of the absorbed solar energy and heat from the burner. It was possible to dry a batch of pineapples using solar energy only on clear days. Drying proceeded successfully even under unfavorable weather conditions in the solar-biomass mode of operation. In this operational mode, the dryer reduced the moisture content of pineapple slices from about 669 to 11% (db) and yielded a nutritious dried product. The average values of the final-day moisture-pickup efficiency were 15%, 11% and 13% in the solar, biomass and solar-biomass modes of operation respectively. It appears that the solar dryer is suitable for preservation of pineapples and other fresh foods. Further improvements to the system design are suggested. (author)

Evaluation of a fruit solar dryer; Avaliacao de um secador solar de frutas

Energy Technology Data Exchange (ETDEWEB)

Berthier, L.J.; Bittencourt, J.; Queiroz, M.R.

2000-07-01

A study of the Nanica banana drying was carried out in a solar dryer with six trays operating with direct exposure of the product to the solar radiation and internal convection. The solar drying was performed College of Agricultural Engineering of the UNICAMP, Campinas, S.Paulo state, Brazil. The study aimed a 20 to 25 per cent final humidity of the dry product, result obtained in the different trays during a maximum drying period of 147 hours (6 days), in a batch system. During the drying period, the average temperature of the environment air at daylight was of 26 degree Celsius with a maximum of 32 degree Celsius, and 18 degrees Celsius during nocturnal period, with a minimum of 12,6 degree Celsius. In the inward of the dryer reached average values near to 50 degree Celsius, measured at noon. The 29,540 kg initial net weight of peeled banana was reduced to yield of 10,815 kg after the drying process, obtaining an income of 36,61 percent of the total production. With the values of the product weight loss, the curves of the drying in each tray had been built, observing that, in the upper trays reached the desired humidity in a lesser period.

Consumer knowledge, preference, and perceived quality of dried tomato products in Ghana.

Science.gov (United States)

Owureku-Asare, Mavis; Ambrose, R P Kingsly; Oduro, Ibok; Tortoe, Charles; Saalia, Firibu K

2017-05-01

Postharvest losses (PHL) are incurred in the tomato value chain in Ghana and solar drying of tomato is a promising technology for reducing the loss. However, there are concerns on the usage, functionality and sensory appeal of the dried products to consumers, compounded with the lack of information and research on dried tomato processing in Ghana. A survey was carried out by administering semistructured questionnaires to 395 randomly selected and willing respondents in the Accra Metropolis. Information was obtained on the socioeconomic profile, consumption pattern, knowledge, and acceptance of tomato processing technologies and assessment of quality attributes important to consumers. Most consumers (74%) preferred tomato powder that is conveniently packaged to retain the characteristic intense taste and the flavor using Friedman's rank mean procedure. The study indicated that consumers were more concerned about good manufacturing practices during the production of solar-dried tomato (48.8%) rather than the quality attributes (8.6%). These findings indicate the need for safe solar drying procedures in order to increase consumer acceptability of solar-dried tomato products in Ghana.

Energy crops - where are they?

Energy Technology Data Exchange (ETDEWEB)

Coombs, Jim [CPL Scientific Ltd., Newbury (United Kingdom)

1999-07-01

The author examines briefly the factors controlling the growth of energy crops, particularly the relationship between dry matter yield and fuel costs and conversion efficiency and electricity price. The EU target is for 135 Mtoe from biomass by 2010 and consideration is given on how this can be met.

Mercury fluxes from air/surface interfaces in paddy field and dry land

Energy Technology Data Exchange (ETDEWEB)

Zhu Jinshan [Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), College of Resources and Environment, Southwest University, No. 216, Tiansheng Street, Beibei, Chongqing 400715 (China); Wang Dingyong, E-mail: dywang@swu.edu.cn [Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), College of Resources and Environment, Southwest University, No. 216, Tiansheng Street, Beibei, Chongqing 400715 (China)] [Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716 (China); Liu Xiao; Zhang Yutong [Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), College of Resources and Environment, Southwest University, No. 216, Tiansheng Street, Beibei, Chongqing 400715 (China)

2011-02-15

Research highlights: {yields} It was found that agricultural fields are important local atmospheric Hg sources in the region. {yields} The Hg emissions from dry cornfield were higher than those from the flooded rice paddy, higher mercury emissions in the warm season than the cold season, and during daytime than at night. {yields} Mercury evasion is strongly related to solar radiation which is important in the emission of Hg at both sites. - Abstract: In order to provide insight into the characteristics of Hg exchange in soil/water-air surface from cropland (including paddy field and dry land), Hg fluxes were measured in Chengjiang. Mercury fluxes were measured using the dynamic flux chamber method, coupled with a Lumex (registered) multifunctional Hg analyzer RA-915{sup +} (Lumex Ltd., Russia). The Hg fluxes from paddy field and dry land were alternatively measured every 30 min. Data were collected for 24-48 h once per month for 5 months. Mercury fluxes in both fields were synchronously measured under the same conditions to compare Hg emissions between paddy field and dry land over diurnal and seasonal periods and find out what factors affect Hg emission on each surface. These results indicated that air Hg concentrations at the monitoring site was double the value observed at the global background sites in Europe and North America. The Hg release fluxes were 46.5 {+-} 22.8 ng m{sup -2} h{sup -1} in the warm season, 15.5 {+-} 18.8 ng m{sup -2} h{sup -1} in the cold season for dry land, and 23.8 {+-} 15.6 ng m{sup -2} h{sup -1} in the warm season, 6.3 {+-} 11.9 ng m{sup -2} h{sup -1} in the cold season for paddy field. Solar radiation is important in the emission of Hg over both sites. Hg exchange at the soil/air and water/air interfaces showed temporal variations. The amount of Hg emission from dry land was higher than that from the paddy field, and the emission in daytime was higher than that at night. Moreover, Hg emissions from land covered by crops, was lower

A freeze-dried graphene counter electrode enhances the performance of dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Hung, Kai-Hsiang; Wang, Hong-Wen, E-mail: hongwen@cycu.edu.tw

2014-01-01

A flexible graphene/polyimide (PI) counter electrode without a fluorine-doped tin oxide (FTO) layer has been fabricated for dye-sensitized solar cell (DSSCs) applications. The flexible counter electrode consists of polyimide double-sided tape as a substrate beneath a graphene film acting as the conductive and catalytic layer. Chemically reduced graphene oxide (rGO) on the PI electrode (rGO-PI) shows comparable catalytic activity to that of the reference sputtered platinum/FTO counter electrodes (Sputter-Pt/FTO). A DSSC with a freeze-dried rGO-PI (FD-rGO-PI) counter electrode shows an overall conversion efficiency (η) of 5.45%, while that of the conventional Sputter-Pt/FTO electrode is 5.52%. The DSSC with a thermally dried rGO-PI (Gel-rGO-PI) counter electrode (not freeze-dried) exhibits a smooth morphology and much poorer performance (η = 1.61%). Field emission scanning electron microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry measurements demonstrate that the FD-rGO-PI electrode possesses a porous structure, numerous edges, minimum charge-transfer resistance and a higher electrocatalytic activity toward the I{sub 3}{sup −}/I{sup −} redox couple than that of the Gel-rGO-PI electrode. The high electrocatalytic activity, facile preparation procedure, absence of FTO, and material flexibility render the FD-rGO-PI electrode an ideal alternative to conventional DSSC counter electrodes. - Highlights: • Highly rough and conductive graphene-based counter electrode is synthesized. • The characteristics of graphene surface by freeze drying are different. • The graphene counter electrode exhibits comparable performance to that of sputtered Pt one.

Doses and application seasons of potassium on soybean crop in succession the cover crops

Directory of Open Access Journals (Sweden)

Amilton Ferreira Silva

2014-02-01

Full Text Available Potassium (K is the second nutrient that is required in larger amounts by soybean crop. With the use of high doses of that nutrient and increase of no-tillage areas in last years, some changes occurred in ways of this nutrient application, as well as the introduction of cover crops in the system for straw formation. Due those facts, the aim with this work was to study doses and times of potassium application for soybean sowed as succession for cover crops in no-tillage system, in a clayey Distrofic Red Latosol, in cerrado region. The experimental design was a randomized block with treatments arranged in 3x3x5 factorial scheme, with the following factors, cover crops: Pearl millet (Pennisetum glaucum and Proso millet (Panicum miliaceum and a control (fallow area, rates of K2O (0, 50 e 100 kg ha-1 and K2O application forms (100% in the cover crops; 100% at sowing of soybean; 100% in topdressing in soybean; 50% at sowing cover crops + 50% at soybean sowing; 50% at soybean sowing + 50% in topdressing in the soybean with four replicates. The Pennisetum glaucum as soybean predecessor crop yields higher dry matter content than the Panicum miliaceum in a short period of time. In clay soil with high content of potassium there was no response to the applied potassium levels. Full doses of potassium maintenance fertilization can be applied in the predecessor cover crop, at sowing or topdressing in soybean crop.

Biosolarization in garlic crop

Science.gov (United States)

Fabeiro, Concepcion; Andres, Manuela; Wic, Consuelo

2014-05-01

One of the most important limitations of garlic cultivation is the presence of various soil pathogens. Fusarium proliferatum and Sclerotinium cepivorum and nematode Ditilenchus dipsaci cause such problems that prevent the repetition of the crop in the same field for at least 5 -8 years or soil disinfection is necessary. Chemical disinfection treatments have an uncertain future, in the European Union are reviewing their use, due to the effect on the non-pathogenic soil fauna. This situation causes a itinerant cultivation to avoid the limitations imposed by soil diseases, thereby increasing production costs. The Santa Monica Cooperative (Albacete, Spain) requested advice on possible alternative techniques, solarization and biosolarization. For which a trial was conducted to evaluate the effectiveness on the riverside area of the municipality. This place has recently authorized irrigation, which would allow the repeated cultivation of garlic if the incidence of soil diseases and the consequent soil fatigue could be avoided. Additionally, this work will serve to promote the cultivation of organic garlic. Last, but not least, the biosolarization technique allows to use waste from wineries, oil mills and mushroom crops. (Bello et al. 2003). The essay should serve as demonstrative proof for farmers' cooperative members. The specific objective for this first year is to assess, the effect on the global soil biota, on the final garlic production and quality and the effect of biosolarization to control soil pathogens. The trial is set on a cooperative's plot previously cultivated with corn. 5 treatments were set, defined by different amounts of organic matter applied, 7.5, 5, 2.5 kg m -2, a solarized with no organic matter, and a control without any treatment. The plot has inground sprinkler for full coverage with four sprinkler lines demarcating the five bands of differential treatment, randomly arranged. Organic matter was incorporated the August 14, 2013, then thoroughly

Hydrological Responses of Weather Conditions and Crop Change of Agricultural Area in the Rincon Valley, New Mexico

Science.gov (United States)

Ahn, S.; Sheng, Z.; Abudu, S.

2017-12-01

Hydrologic cycle of agricultural area has been changing due to the impacts of climate and land use changes (crop coverage changes) in an arid region of Rincon Valley, New Mexico. This study is to evaluate the impacts of weather condition and crop coverage change on hydrologic behavior of agricultural area in Rincon Valley (2,466km2) for agricultural watershed management using a watershed-scale hydrologic model, SWAT (Soil and Water Assessment Tool). The SWAT model was developed to incorporate irrigation of different crops using auto irrigation function. For the weather condition and crop coverage change evaluation, three spatial crop coverages including a normal (2008), wet (2009), and dry (2011) years were prepared using USDA crop data layer (CDL) for fourteen different crops. The SWAT model was calibrated for the period of 2001-2003 and validated for the period of 2004-2006 using daily-observed streamflow data. Scenario analysis was performed for wet and dry years based on the unique combinations of crop coverages and releases from Caballo Reservoir. The SWAT model simulated the present vertical water budget and horizontal water transfer considering irrigation practices in the Rincon Valley. Simulation results indicated the temporal and spatial variability for irrigation and non-irrigation seasons of hydrologic cycle in agricultural area in terms of surface runoff, evapotranspiration, infiltration, percolation, baseflow, soil moisture, and groundwater recharge. The water supply of the dry year could not fully cover whole irrigation period due to dry weather conditions, resulting in reduction of crop acreage. For extreme weather conditions, the temporal variation of water budget became robust, which requires careful irrigation management of the agricultural area. The results could provide guidelines for farmers to decide crop patterns in response to different weather conditions and water availability.

The effect of species, planting date, and management of cover crops on weed community in hybrid sunflower (Helianthus annuus

Directory of Open Access Journals (Sweden)

M. Bolandi Amoughein

2016-02-01

Full Text Available Introduction: Studies showed that if mixed populations of annual weeds grow with the sunflower, for every 10% increase in weed biomass, seed yield would decrease by 13% (Van Gessel & Renner, 2000. In addition to control weeds using herbicides multi-stage spraying is required. In organic farming systems mulch is used to control weeds, protection, fertility and improve soil quality (Glab & Kulig, 2008; Kuchaki et al., 2001. Surface mulches from cover crops suppress weed growth by reducing light levels at the soil surface, thereby slowing photosynthesis. In return, these conditions reduce seed germination and act as a physical barrier to seedling emergence and growth (Teasdale et al., 2007. Materials and Methods: The experiment was carried out in Ardabil Agricultural Research Station, as a factorial experiment based on randomized complete block design with three replications during 1390-1391. The first factor was considered four types of cover crops including winter rye (Secale cereal, spring barley (Hordeum vulgare, winter wheat (Triticum aestivum and control (no cover crop, no weeding.The second factor was mulch management at two levels (living mulch and dead mulch and the third factor was two planting dates for cover crops (synchronous with sunflower planting and 45 days after sunflower planting. Sunflower seeding performed manually on 23 May on the ridges with 50 cm row distance and spacing between plants was 25 cm in depth of 5 cm. Cover crops seeds, rye, barley and wheat, were planted between rows of sunflower. Due to the low density of weeds in study field, complete weeding and sampling of weeds in one session was performed (60 days after planting date sunflower. Statistical analysis of data performed using SAS software and mean comparison performed using Duncan's test with probability level of 5% and 1%. Diagrams drawn using Excel (Version 8.2. Results and Discussion\t: Density and dry weight of Field bindweed (Convolvulus arvensis L

Heritability, combining ability and inheritance of storage root dry ...

African Journals Online (AJOL)

Storage root dry matter content (RDM) is central to the improvement of consumer and industrial attributes of root crops. Yam bean (Pachyrhizus species) is a legume root crop newly introduced in Uganda, but its adoption may be constrained by low RDM. The objective of this study was to investigate the magnitude of ...

Performance of indirect solar cabinet dryer

International Nuclear Information System (INIS)

Sreekumar, A.; Manikantan, P.E.; Vijayakumar, K.P.

2008-01-01

In this paper, the development and testing of a new type of efficient solar dryer, particularly meant for drying vegetables and fruit, is described. The dryer has two compartments: one for collecting solar radiation and producing thermal energy and the other for spreading the product to be dried. This arrangement was made to absorb maximum solar radiation by the absorber plate. In this dryer, the product was loaded beneath the absorber plate, which prevented the problem of discoloration due to irradiation by direct sunlight. Two axial flow fans, provided in the air inlet, can accelerate the drying rate. The dryer had six perforated trays for loading the material. The absorber plate of the dryer attained a temperature of 97.2 deg. C when it was studied under no load conditions. The maximum air temperature in the dryer, under this condition was 78.1 deg. C. The dryer was loaded with 4 kg of bitter gourd having an initial moisture content of 95%, and the final desired moisture content of 5% was achieved within 6 h without losing the product colour, while it was 11 h for open sun drying. The collector glazing was inclined at a particular angle, suitable to the location, for absorption of maximum solar radiation. A detailed performance analysis was done by three methods, namely 'annualized cost method', 'present worth of annual savings' and 'present worth of cumulative savings'. The drying cost for 1 kg of bitter gourd was calculated as Rs. 17.52, and it was Rs. 41.35, in the case of an electric dryer. The life span of the solar dryer was assumed to be 20 years. The cumulative present worth of annual savings over the life of the solar dryer was calculated for bitter gourd drying, and it turned out be Rs. 31659.26, which was much higher than the capital cost of the dryer (Rs. 6500). The payback period was calculated as 3.26 years, which was also very small considering the life of the system (20 years). So, the dryer would dry products free of cost during almost its

CFD analysis for greenhouse effect solar dryer

International Nuclear Information System (INIS)

Wulandani, D.; Abdullah, K.; Hartulistiyoso, E.; Siswantara, I.

2006-01-01

Greenhouse Effect (GHE) solar dryer is a transparent wall structure, consists of absorber plate as solar heat collector, product holders (tray or batch) and fans to discharge moisture from the product. GHE solar dryer is one of the alternative dryer for the farmer and merchants to improve the quality of dried products. Direct sun drying is still popular choice by farmers because it is cheap and simple. However, the method is greatly dependent on the existence of solar irradiation and the product is contaminated very easily by pollution and dirt. The general constraint in designing artificial dryer is the problem of non-uniformity of final moisture content of product, especially for the cabinet of rack type dryer. This condition can be solved by providing uniform distribution of temperature, relative humidity (RH) and airflow velocity of the drying air. Therefore, in this study, such problem was approached by conducting flow simulation within the drying structure by using computational fluid dynamics (CFD) technology to determine the proper position of drying air inlet and outlet, location and capacity of the heat exchanger unit, the position and the capacity of the fan, to produce uniform distribution of the drying air temperature, RH and airflow velocity within the drying chamber.(Author)

Symbiotic nitrogen fixation and nitrate uptake by the pea crop

International Nuclear Information System (INIS)

Jensen, E.S.

1986-08-01

Symbiotic nitrogen fixation and nitrate uptake by pea plants (Pisum sativum L.) were studied in field and pot experiments using the 15 N isotope dilution technique and spring barley as a non-fixing reference crop. Barley, although not ideal, seemed to be a suitable reference for pea in the 15 N-technique. Maximum N 2 fixation activity of 10 kg N fixed per ha per day was reached around the flat pod growth stage, and the activity decreased rapidly during pod-filling. The pea crop fixed between 100 and 250 kg N ha -1 , corresponding to from 45 to 80 per cent of total crop N. The amount of symbiotically fixed N 2 depended on the climatic conditions in the experimental year, the level of soil mineral N and the pea cultivar. Field-grown pea took up 60 to 70 per cent of the N-fertilizer supplied. The supply of 50 kg NO 3 -N ha -1 inhibited the N 2 fixation approximately 15 per cent. Small amounts of fertilizer N, supplied at sowing (starter-N), slightly stimulated the vegetative growth of pea, but the yields of seed dry matter and protein were not significantly influenced. In the present field experiments the environmental conditions, especially the distribution of rainfall during the growth season, seemed to be more important in determining the protein and dry matter yield of the dry pea crop, than the ability of pea to fix nitrogen symbiotically. However, fertilizer N supplied to pot-grown pea plants at the flat pod growth stage or as split applications significantly increased the yield of seed dry matter and protein. (author)

The utilization of ultisol soil for horticulture crops cultivation

Science.gov (United States)

Sumono; Parinduri, SM; Huda, N.; Ichwan, N.

2018-02-01

Ultisol soil is a marginal soil commonly used for palm oil cultivation in Indonesia, its very potential for cultivation of horticulture crops. The utilization of ultisol soil can be done with adding compost with certain proportions. The research aimed to know best proportion of ultisol soil and compost, and proportion of water concentration, and its relationship with fresh and dry weight of horticulture crops . The research was divided 3 steps. The first, mixed ultisol soil and compost with certain proportion and flooding until steady. The second, watering with different concentration to soil mixture. The last, studied its relationship with fresh and dry weight of crops. The result show that physical properties and nutrient content of ultisol soil was increasing with adding compost. SC4 (70% soil and 30% compost) is the best composition to soil mixture. Watering with different concentration show that trend decreased from reference and the bulk density and porosity decreased not significantly at the significant level ∝ = 0.05. Watering affect mass of pakcoynot significantly at the significant level ∝ = 0.05. Hence, ultisol soil was a potential marginal soil to utilizing as a media for cultivating horticulture crops.

Method of aeration disinfecting and drying grain in bulk and pretreating seeds and a transverse blow silo grain dryer therefor

Science.gov (United States)

Danchenko, Vitaliy G [Dnipropetrovsk, UA; Noyes, Ronald T [Stillwater, OK; Potapovych, Larysa P [Dnipropetrovsk, UA

2012-02-28

Aeration drying and disinfecting grain crops in bulk and pretreating seeds includes passing through a bulk of grain crops and seeds disinfecting and drying agents including an ozone and air mixture and surrounding air, subdividing the disinfecting and drying agents into a plurality of streams spaced from one another in a vertical direction, and passing the streams at different heights through levels located at corresponding heights of the bulk of grain crops and seeds transversely in a substantially horizontal direction.

Development of drying equipment for heat sensitive material : final report

Energy Technology Data Exchange (ETDEWEB)

Schoenau, G.J.; Sokhansanj, S. [Saskatchewan Univ., Saskatoon, SK (Canada)

2003-07-01

This paper described a project in which two types of prototype heat pump dryer systems were designed, constructed and field tested in 2000 to 2002. Performance testing was accomplished through a computer based simulation model for predicting dryer performance. The paper describes the procedures followed and the results obtained. The dryer is used for high value specialty crops such as ginseng, herbs and echinacea which require low temperature drying. The heat pump dryer operates under a closed loop and can dry these crops at low temperatures, independent of ambient conditions. The first prototype was a small fixed bed cabinet dryer suitable for small growers. The other was a full scale prototype moving bed cross flow system suitable for large scale commercial drying of sensitive agricultural crops. The heat pump system is faster and more energy efficient than conventional dryers. The average moisture content of ginseng roots was reduced by 10 per cent in 5 days using 190 kWh of energy. The heat pump dryer is 22 per cent more efficient than a conventional dryer due to its recirculating system. Drying time is reduced by 65 per cent. A computerized simulation validated experimental results. 30 refs., 10 tabs., 29 figs.

Greenhouse Gas Emissions and Global Warming Potential of Traditional and Diversified Tropical Rice Rotation Systems including Impacts of Upland Crop Management Practices i.e. Mulching and Inter-crop Cultivation

Science.gov (United States)

Janz, Baldur; Weller, Sebastian; Kraus, David; Wassmann, Reiner; Butterbach-Bahl, Klaus; Kiese, Ralf

2016-04-01

Paddy rice cultivation is increasingly challenged by irrigation water scarcity, while at the same time changes in demand (e.g. changes in diets or increasing demand for biofuels) will feed back on agricultural practices. These factors are changing traditional cropping patterns from flooded double-rice systems to the introduction of well-aerated upland crop systems in the dry season. Emissions of methane (CH4) are expected to decrease, while emissions of nitrous oxide (N2O) will increase and soil organic carbon (SOC) stocks will most likely be volatilized in the form of carbon dioxide (CO2). We measured greenhouse gas (GHG) emissions at the International Rice Research Institute (IRRI) in the Philippines to provide a comparative assessment of the global warming potentials (GWP) as well as yield scaled GWPs of different crop rotations and to evaluate mitigation potentials or risks of new management practices i.e. mulching and inter-crop cultivation. New management practices of mulching and intercrop cultivation will also have the potential to change SOC dynamics, thus can play the key role in contributing to the GWP of upland cropping systems. To present, more than three years of continuous measurement data of CH4 and N2O emissions in double-rice cropping (R-R) and paddy rice rotations diversified with either maize (R-M) or aerobic rice (R-A) in upland cultivation have been collected. Introduction of upland crops in the dry season reduced irrigation water use and CH4 emissions by 66-81% and 95-99%, respectively. Moreover, for practices including upland crops, CH4 emissions in the subsequent wet season with paddy rice were reduced by 54-60%. Although annual N2O emissions increased twice- to threefold in the diversified systems, the strong reduction of CH4 led to a significantly lower (pbalance but also with regard to soil fertility. New upland crop management practices where first implemented during land-preparation for dry season (July) 2015 where i) 6t/ha rice straw

Biomass supply from alternative cellulosic crops and crop residues: A spatially explicit bioeconomic modeling approach

International Nuclear Information System (INIS)

Egbendewe-Mondzozo, Aklesso; Swinton, Scott M.; Izaurralde, César R.; Manowitz, David H.; Zhang, Xuesong

2011-01-01

This paper introduces a spatially-explicit bioeconomic model for the study of potential cellulosic biomass supply. For biomass crops to begin to replace current crops, farmers must earn more from them than from current crops. Using weather, topographic and soil data, the terrestrial ecosystem model, EPIC, dynamically simulates multiple cropping systems that vary by crop rotation, tillage, fertilization and residue removal rate. EPIC generates predicted crop yield and environmental outcomes over multiple watersheds. These EPIC results are used to parameterize a regional profit-maximization mathematical programming model that identifies profitable cropping system choices. The bioeconomic model is calibrated to 2007–09 crop production in a 9-county region of southwest Michigan. A simulation of biomass supply in response to rising biomass prices shows that cellulosic residues from corn stover and wheat straw begin to be supplied at minimum delivered biomass:corn grain price ratios of 0.15 and 0.18, respectively. At the mean corn price of $162.6/Mg ($4.13 per bushel) at commercial moisture content during 2007–2009, these ratios correspond to stover and straw prices of $24 and $29 per dry Mg. Perennial bioenergy crops begin to be supplied at price levels 2–3 times higher. Average biomass transport costs to the biorefinery plant range from $6 to $20/Mg compared to conventional crop production practices in the area, biomass supply from annual crop residues increased greenhouse gas emissions and reduced water quality through increased nutrient loss. By contrast, perennial cellulosic biomass crop production reduced greenhouse gas emissions and improved water quality. -- Highlights: ► A new bioeconomic model predicts biomass supply and its environmental impacts. ► The model captures the opportunity cost of switching to new cellulosic crops. ► Biomass from crop residues is supplied at lower biomass price than cellulosic crops. ► Biomass from cellulosic crops has

A solar cooling system for greenhouse food production in hot climates

Energy Technology Data Exchange (ETDEWEB)

Davies, P.A. [School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom)

2005-12-01

This study is motivated by the difficulty of cultivating crops in very hot countries and by the tendency for some such countries to become dependent on imported food. Liquid desiccation with solar regeneration is considered as maintained at or above room temperature, and this was confirgreenhouses. Previous studies demonstrated the technical feasibility of the desiccation-evaporation process, but mainly in the context of human dwellings. In the proposed cycle, the air is dried prior to entering the evaporative cooler. This lowers the wet-bulb temperature of the air. The cooling is assisted by using the regenerator to partially shade the greenhouse. The heat of desiccation is transferred and rejected at the outlet of the greenhouse. The cycle is analysed and results given for the climate of the The Gulf, based on weather data from Abu Dhabi. Taking examples of a temperate crop (lettuce), a tropical crop (tomato) and a tropical crop resistant to high temperatures (cucumber) we estimate the extension in growing seasons relative to (i) a greenhouse with simple fan ventilation (ii) a greenhouse with conventional evaporative cooling. Compared to option (ii), the proposed system lowers summers maximum temperatures by 5{sup o}C. This will extend the optimum season for lettuce cultivation from 3 to 6 months of the year and, for tomato and cucumber, from 7 months to the whole year. (author)

Studies of a photovoltaic-thermal solar dryi system for rural applications

International Nuclear Information System (INIS)

Othman, Mohd Yusof; Yatim, Baharudin; Abu Bakar, Mohd Nazari; Sopian, Kamaruzzaman

2006-01-01

Importance of solar drying in increasing worldwide. especially in areas where the use of abundant, renewable and clean solar energy is essentially advantageous. In developing countries and in rural areas the traditional open-air drying methods should be substituted by the more effective and more economic solar drying technologies. In the present work, a new design of a photovoltaic-thermal (PV/T) solar drying system was fabricated. An experimental study of PV/T solar air collector has been performed towards achieving n efficient design of air collector suitable foe a solar dryer. A series of experiments were conducted based on the ASHRAE standard, under Malaysia Climatic conditions. The performance of the collector is examined over a wide range of operating conditions. Results of the test are presented and discussed.(Author)

Cover Crops in Hillside Agriculture

International Development Research Centre (IDRC) Digital Library (Canada)

Our study focuses on the wet tropical hillsides of northern Honduras (Figure 1). ..... The eastern extreme of the region (Jutiapa) is a dry spot, with less rainfall (2 000 mm a-1) as a result ...... Paper presented at the International Workshop on Green Manure–Cover Crops for Smallholders in ..... Lamaster, J.P.; Jones, I.R. 1923.

Large-area dry bean yield prediction modeling in Mexico

Science.gov (United States)

Given the importance of dry bean in Mexico, crop yield predictions before harvest are valuable for authorities of the agricultural sector, in order to define support for producers. The aim of this study was to develop an empirical model to estimate the yield of dry bean at the regional level prior t...

A novel solar energy integrated low-rank coal fired power generation using coal pre-drying and an absorption heat pump

International Nuclear Information System (INIS)

Xu, Cheng; Bai, Pu; Xin, Tuantuan; Hu, Yue; Xu, Gang; Yang, Yongping

2017-01-01

Highlights: •An improved solar energy integrated LRC fired power generation is proposed. •High efficient and economic feasible solar energy conversion is achieved. •Cold-end losses of the boiler and condenser are reduced. •The energy and exergy efficiencies of the overall system are improved. -- Abstract: A novel solar energy integrated low-rank coal (LRC) fired power generation using coal pre-drying and an absorption heat pump (AHP) was proposed. The proposed integrated system efficiently utilizes the solar energy collected from the parabolic trough to drive the AHP to absorb the low-grade waste heat of the steam cycle, achieving larger amount of heat with suitable temperature for coal’s moisture removal prior to the furnace. Through employing the proposed system, the solar energy could be partially converted into the high-grade coal’s heating value and the cold-end losses of the boiler and the steam cycle could be reduced simultaneously, leading to a high-efficient solar energy conversion together with a preferable overall thermal efficiency of the power generation. The results of the detailed thermodynamic and economic analyses showed that, using the proposed integrated concept in a typical 600 MW LRC-fired power plant could reduce the raw coal consumption by 4.6 kg/s with overall energy and exergy efficiencies improvement of 1.2 and 1.8 percentage points, respectively, as 73.0 MW th solar thermal energy was introduced. The cost of the solar generated electric power could be as low as $0.044/kW h. This work provides an improved concept to further advance the solar energy conversion and utilisation in solar-hybrid coal-fired power generation.

Studies of a photovoltaic-thermal solar during system for rural applications

Energy Technology Data Exchange (ETDEWEB)

Othman, Y.; Yatim, B.; Bakar, N.A. [Kebangsaan Malaysia Univ., Bangi, Selangor (Malaysia). Center for Applied Physics Studies; Sopian, K. [Kebangsaan Malaysia Univ., Bangi, Selangor (Malaysia). Dept. of Mechanical and Material Engineering

2007-07-01

The use of solar drying is increasing in areas where the use of abundant, renewable and clean solar energy is advantageous. Particularly in developing countries and in rural areas, the traditional open-air drying methods are being substituted by the more effective and more economic solar drying technologies. Since the air collector is the most important component of a solar food drying system, improvement of the design of collectors would lead to better performance of the system. This paper presented a new design of a photovoltaic-thermal (PVT) solar drying system. In order to achieve an efficient design of an air collector suitable for a solar dryer, the results of an experimental study of PVT solar air collector was conducted and presented. The paper presented the methodology and discussed a series of experiments that were conducted under Malaysian climatic conditions. The paper discussed the design of a double pass photovoltaic-thermal solar air collector with compound parabolic concentrator (CPC) and fins. The collector design concept and the collector array were demonstrated. The performance of the collector was examined over a wide range of operating conditions. Results of the test were then presented and discussed. It was concluded that the performance of the solar collector was satisfactory. The quality attributes such as colour, flavour, and taste were significantly improved since it was protected from rain, dust, and insects, in contrast to sun drying. 10 refs., 8 figs.

Performance of indirect solar cabinet dryer

Energy Technology Data Exchange (ETDEWEB)

Sreekumar, A.; Manikantan, P.E.; Vijayakumar, K.P. [Solar Thermal Energy Laboratory, Department of Physics, Cochin University of Science and Technology, Kochi 682 022 (India)

2008-06-15

In this paper, the development and testing of a new type of efficient solar dryer, particularly meant for drying vegetables and fruit, is described. The dryer has two compartments: one for collecting solar radiation and producing thermal energy and the other for spreading the product to be dried. This arrangement was made to absorb maximum solar radiation by the absorber plate. In this dryer, the product was loaded beneath the absorber plate, which prevented the problem of discoloration due to irradiation by direct sunlight. Two axial flow fans, provided in the air inlet, can accelerate the drying rate. The dryer had six perforated trays for loading the material. The absorber plate of the dryer attained a temperature of 97.2 C when it was studied under no load conditions. The maximum air temperature in the dryer, under this condition was 78.1 C. The dryer was loaded with 4 kg of bitter gourd having an initial moisture content of 95%, and the final desired moisture content of 5% was achieved within 6 h without losing the product colour, while it was 11 h for open sun drying. The collector glazing was inclined at a particular angle, suitable to the location, for absorption of maximum solar radiation. A detailed performance analysis was done by three methods, namely 'annualized cost method', 'present worth of annual savings' and 'present worth of cumulative savings'. The drying cost for 1 kg of bitter gourd was calculated as Rs. 17.52, and it was Rs. 41.35, in the case of an electric dryer. The life span of the solar dryer was assumed to be 20 years. The cumulative present worth of annual savings over the life of the solar dryer was calculated for bitter gourd drying, and it turned out be Rs. 31659.26, which was much higher than the capital cost of the dryer (Rs. 6500). The payback period was calculated as 3.26 years, which was also very small considering the life of the system (20 years). So, the dryer would dry products free of cost

N2O Emission from energy crop fields

International Nuclear Information System (INIS)

Joergensen, B.J.; Nyholm Joergensen, R.

1996-03-01

The interest in N 2 O emissions from soils with energy crops is a results of its properties as a greenhouse gas, since the global warming potential of N 2 O per unit mass is about 320 times greater than CO 2 . The contribution of N 2 O from the soil to the atmosphere may increase due to agricultural management. Consequently, large N 2 O emissions can lower the reduction of the greenhouse effect achieved by the substitution of fossil fuels by energy crops. For this reason it is crucial to find the crops for combustion with the lowest potential for emission of N 2 O from the soil per produced energy unit. The aims of this study were to assess the annual N 2 O flux from a Miscanthus 'Giganteus' (M. 'Giganteus') and winter rye (Secale cereale) field, and to investigate the factors affecting the N 2 O emission. To obtain these aims a method was developed for measurements in tall crops. The thesis contains a literature review on the N 2 O emission from the soils, a section with development of the technique for N 2 O flux measurements, and an experimental section. Finally, the thesis contains a section where the results are discussed in relation to the use of energy crops. In all the filed studies, the N 2 O emission was measured by using a new developed closed-chamber technique. The main advantages of the chamber method were the ability to contain growing plants up to a height of 3 m, and the relatively large area (2X2m) covered by each other. Soils with annual and perennial crops can be expected to emit less then 3 kg N 2 O ha -1 yr -1 . This amount corresponds to 960 kg CO 2 ha -1 yr -1 compared to a total CO 2 reduction of 10 to 19 tons CO 2 ha -1 yr -1 using the energy crops as substitution for fossil fuels. An efficient way to reduce the N 2 O emission is to exclude use of fertiliser but this also reduces the dry matter yield and consequently also the CO 2 reduction per unit dry matter. Following the guidelines for good agricultural practice concerning the

Conceptual design of pilot scale solar dryer for seaweeds

International Nuclear Information System (INIS)

Marta Abreu de Las Villas (Cuba))" data-affiliation=" (Departamento de Ingeniería Química, Facultad de Química y Farmacia, Universidad Central Marta Abreu de Las Villas (Cuba))" >Roche-Delgado, Liset; Marta Abreu de Las Villas (Cuba))" data-affiliation=" (Departamento de Ingeniería Química, Facultad de Química y Farmacia, Universidad Central Marta Abreu de Las Villas (Cuba))" >Hernández-Touset, Juan Pedro; Marta Abreu de Las Villas (Cuba))" data-affiliation=" (Departamento de Ingeniería Química, Facultad de Química y Farmacia, Universidad Central Marta Abreu de Las Villas (Cuba))" >García-Rodríguez, Agustín

2017-01-01

Drying algal biomass with the use of solar radiation is an economical and environmentally compatible option. The aim of this work was to design an indirect solar dryer with natural air circulation for seaweeds drying. The equipment supports discrete quantities of wet biomass and is protected from environmental situations that may damage the product; it does not need electricity to operate and the construction and operating costs are low. This comprises a collector made of copper plates for air circulation, heated by solar radiation, a glass cover and drying trays with a wooden structure. The dryer was designed to obtain 0, 3 kg / day of dry biomass. The methodology allows construction and operation of a flexible solar dryer in different operating conditions for research on seaweeds. Correspondingly with environmental and operating conditions the design included estimation of drying time, the determination of drying area, number of trays, air flow from the collector to the trays, collector sizing; heat transfer area, temperature reached by air and collector efficiency. (author)

Morphological responses of crop and weed species of different growth forms to ultraviolet-B radiation

International Nuclear Information System (INIS)

Barnes, P.W.; Flint, S.D.; Caldwell, M.M.

1990-01-01

The influence of ultraviolet-B (UV-B) radiation (280-320 nanometers) on the morphology of 12 common dicot and monocot crop or weed species was examined to determine whether any common responses could be found that might, in turn, be useful in predicting possible changes in competitive balance under solar UV-B enhancement. Under glasshouse conditions, UV-B exposure (simulating a 20% reduction in stratospheric ozone at Logan, Utah) was found to reduce leaf blade and internode lengths and increase leaf and axillary shoot production in several species. Overall, the directions of these trends were similar in the majority of species that exhibited a significant response. These morphological changes occurred without any significant reduction in total shoot dry matter production. There was no clear distinction in the response of crops and weeds, though monocots were found to be generally more responsive than dicots. Previous work in dense canopies has shown that the photomorphogenetic effects of UV-B alter leaf placement and thereby influence competition for light. Our results suggest that, under these conditions, changes in competitive balance resulting from increased UV-B might be expected more frequently when monocots are involved in mixtures, rather than mixtures of only dicots

The Instituto Nacional de Pesquisas da Amazonia-INPA solar dryer: an economical alternative for wood drying; O secador solar do INPA: uma alternativa economica para secar madeira

Energy Technology Data Exchange (ETDEWEB)

Moraes-Duzat, Rejane; Barbosa, Ana Paula; Vetter, Roland [Instituto Nacional de Pesquisas da Amazonia (INPA), Manaus, AM (Brazil)]. E-mail: duzat@inpa.gov.br; apaula@inpa.gov.br

2000-07-01

As an alternative to the expensive and high energy consuming conventional dryers available at the market, INPA developed a solar wood dryer technically adequate to the climatic conditions of the Amazon region, and economically suitable to an industrial segment that could not afford large investments to dry wood. The dryer has received great acceptance by the industry due to its low cost and good operating efficiency. The prototype was dimensioned with a capacity of 5 to 8 m{sup 3} of sawn wood, which is sufficient for the needs of small sawmills or furniture shops. A total of 20 units have been installed in Brazil and other countries. Research work is underway to improve the performance of the original model, and some modifications are conducted to adapt it to dry other natural products as seeds, nuts, fruits, and herbs. (author)

RELATIVE COMPETITIVENESS OF GOOSEGRASS BIOTYPES AND SOYBEAN CROPS

Directory of Open Access Journals (Sweden)

JADER JOB FRANCO

2017-01-01

Full Text Available he goosegrass ( Eleusine indica (L. Gaertn is an annual plant that has a low - level resistance to glyphosate (LLRG, resulting in control failure in genetically modified soybean crops for resistance to this herbicide. Alleles related to resistance may cause changes in the plant biotype, such as inferior competitive ability. Thus, the objective of this work was to evaluated the competitive ability of soybean crops and susceptible and resistant (LLRG goosegrass biotypes. Replacement series experiments were conducted with soybean crops and goosegrass biotypes. The ratios of soybean to susceptible or resistant (LLRG goosegrass plants were 100:0, 75:25, 50:50, 25:75 and 0:100, with a total population of 481 plants m - 2 . The leaf area, plant height and shoot dry weight were evaluated at 40 days after emergence of the soybean crops and weeds. The soybean crop had superior competitive ability to the susceptible and resistant (LLRG goosegrass biotypes. The soybean crop showed similar competitive ability in both competitions, either with the susceptible or resistant (LLRG goosegrass biotypes. The intraspecific competition was more harmful to the soybean crop, while the interspecific competition caused greater damage to the goosegrass biotypes competing with the soybean crop

Dry Matter Production, Nutrient Cycled and Removed, and Soil Fertility Changes in Yam-Based Cropping Systems with Herbaceous Legumes in the Guinea-Sudan Zone of Benin

Directory of Open Access Journals (Sweden)

Raphiou Maliki

2016-01-01

Full Text Available Traditional yam-based cropping systems (shifting cultivation, slash-and-burn, and short fallow often result in deforestation and soil nutrient depletion. The objective of this study was to determine the impact of yam-based systems with herbaceous legumes on dry matter (DM production (tubers, shoots, nutrients removed and recycled, and the soil fertility changes. We compared smallholders’ traditional systems (1-year fallow of Andropogon gayanus-yam rotation, maize-yam rotation with yam-based systems integrated herbaceous legumes (Aeschynomene histrix/maize intercropping-yam rotation, Mucuna pruriens/maize intercropping-yam rotation. The experiment was conducted during the 2002 and 2004 cropping seasons with 32 farmers, eight in each site. For each of them, a randomized complete block design with four treatments and four replicates was carried out using a partial nested model with five factors: Year, Replicate, Farmer, Site, and Treatment. Analysis of variance (ANOVA using the general linear model (GLM procedure was applied to the dry matter (DM production (tubers, shoots, nutrient contribution to the systems, and soil properties at depths 0–10 and 10–20 cm. DM removed and recycled, total N, P, and K recycled or removed, and soil chemical properties (SOM, N, P, K, and pH water were significantly improved on yam-based systems with legumes in comparison with traditional systems.

Peri-urban Dry Season Vegetable Production in Ibadan, Nigeria

Directory of Open Access Journals (Sweden)

Kintomo, AA.

1997-01-01

Full Text Available Peri-urban dry season vegetable production in Ibadan is increasingly becoming important, due to its relatively recent importance as a means of producing food in the city. Information on : (1 management practices ; (2 cropping systems ; and (3 economies of production, was hardly available. A diagnostic study organised in the dry season of 1994/95 addresses these issues. Its results indicate that the major crops in the system are Corchorus, Amaranthus and Celosia and are grown in intercropping systems. Farmers in the systems were constrained by poor drainage systems, weeds, dearth of improved seeds and marketing, inefficient input delivery system, high cost of input, pests and diseases and unavailability of labour at critical times. However, net benefits amounts to approximately N235650/ha/season ($ 2772. Significant and sustainable increases in productivity of the system could be achieved with the use of integrated water, crop, soil and pest management systems together with efficient input delivery systems.

Response of cactus pear genotypes to different crop densities

Directory of Open Access Journals (Sweden)

Lucas Aroaldo Dantas Cavalcante

2014-09-01

Full Text Available Considering the importance of cactus pear as an alimentary alternative for the herd of cattle of the Brazilian semiarid region and the effect of crop spacing among plants, this study aimed to evaluate the morphometry, yield and chemical-bromatological composition of cactus pear genotypes, under different cropping densities. The experimental design was completely randomized blocks, in a 3x4 factorial scheme. Treatments consisted of a combination of three cactus pear genotypes (Gigante, Redonda and Miúda and four cropping densities (10,000 plants ha-1; 20,000 plants ha-1; 40,000 plants ha-1; and 80,000 plants ha-1, with three replications. The cactus pear genotypes reacted differently, regarding morphometry, yield and chemical-bromatological composition, and, regardless of the species, the denser planting increased yield (tons ha-1. The Miúda palm presented the highest dry matter yield and consequently the greater accumulation of total digestible nutrients, raw protein and water per hectare, as well as the highest in vitro dry matter digestibility.

Agave as a model CAM crop system for a warming and drying world.

Science.gov (United States)

Stewart, J Ryan

2015-01-01

As climate change leads to drier and warmer conditions in semi-arid regions, growing resource-intensive C3 and C4 crops will become more challenging. Such crops will be subjected to increased frequency and intensity of drought and heat stress. However, agaves, even more than pineapple (Ananas comosus) and prickly pear (Opuntia ficus-indica and related species), typify highly productive plants that will respond favorably to global warming, both in natural and cultivated settings. With nearly 200 species spread throughout the U.S., Mexico, and Central America, agaves have evolved traits, including crassulacean acid metabolism (CAM), that allow them to survive extreme heat and drought. Agaves have been used as sources of food, beverage, and fiber by societies for hundreds of years. The varied uses of Agave, combined with its unique adaptations to environmental stress, warrant its consideration as a model CAM crop. Besides the damaging cycles of surplus and shortage that have long beset the tequila industry, the relatively long maturation cycle of Agave, its monocarpic flowering habit, and unique morphology comprise the biggest barriers to its widespread use as a crop suitable for mechanized production. Despite these challenges, agaves exhibit potential as crops since they can be grown on marginal lands, but with more resource input than is widely assumed. If these constraints can be reconciled, Agave shows considerable promise as an alternative source for food, alternative sweeteners, and even bioenergy. And despite the many unknowns regarding agaves, they provide a means to resolve disparities in resource availability and needs between natural and human systems in semi-arid regions.

Agave as a model CAM crop system for a warming and drying world

Directory of Open Access Journals (Sweden)

J. Ryan eStewart

2015-09-01

Full Text Available As climate change leads to drier and warmer conditions in semi-arid regions, growing resource-intensive C3 and C4 crops will become more challenging. Such crops will be subjected to increased frequency and intensity of drought and heat stress. However, agaves, even more than pineapple (Ananas comosus and prickly pear (Opuntia ficus-indica and related species, typify highly productive plants that will respond favorably to global warming, both in natural and cultivated settings. With nearly 200 species spread throughout the U.S., Mexico, and Central America, agaves have evolved traits, including crassulacean acid metabolism (CAM, that allow them to survive extreme heat and drought. Agaves have been used as sources of food, beverage, and fiber by societies for hundreds of years. The varied uses of Agave, combined with its unique adaptations to environmental stress, warrant its consideration as a model CAM crop. Besides the damaging cycles of surplus and shortage that have long beset the tequila industry, the relatively long maturation cycle of Agave, its monocarpic flowering habit, and unique morphology comprise the biggest barriers to its widespread use as a crop suitable for mechanized production. Despite these challenges, agaves exhibit potential as crops since they can be grown on marginal lands, but with more resource input than is widely assumed. If these constraints can be reconciled, Agave shows considerable promise as an alternative source for food, alternative sweeteners, and even bioenergy. And despite the many unknowns regarding agaves, they provide a means to resolve disparities between natural and human systems in semi-arid regions.

Experimental investigation of a Hybrid Solar Drier and Water Heater System

International Nuclear Information System (INIS)

Mohajer, Alireza; Nematollahi, Omid; Joybari, Mahmood Mastani; Hashemi, Seyed Ahmad; Assari, Mohammad Reza

2013-01-01

Highlights: • A Hybrid Solar Drier and Water Heater System experimentally investigated. • Using collected data, GIS maps were plotted for solar energy of Khuzestan Province. • System is presented which facilitates a dual-purpose solar collector. • The system includes a 100 l water storage tank, a solar dryer with 5 trays. • Experiments were carried out to dry vegetables (parsley, dill and coriander). - Abstract: Drying process is of great importance in food industries. One of the best methods of food drying is using solar dryers. For initial estimation of solar energy, calculations were made for statistical information measured by Renewable Energy Organization of Iran. Using collected data, GIS maps were plotted for solar energy of Khuzestan Province, Iran. In this study, a new hybrid system is presented which facilitates a dual-purpose solar collector to simultaneously support a dryer system and provide consumptive hot water. The system includes a 100 l water storage tank, a solar dryer with 5 trays, and a dual-purpose collector. Experiments were carried out to dry a mixture of vegetables (parsley, dill and coriander) at constant air and water flow rates. Besides, an electrical heater has been used as an auxiliary source for heating. The results indicated that the system optimally dried the vegetables and simultaneously provided the consumptive hot water

Agronomy of metal crops used in agromining

Science.gov (United States)

This review of the agronomy of metal crops used in agromining/phytomining summarizes the history of the development of phytomining and the experimental work to identify the agronomic practices most important to high annual nickel yield when hypernickelophore (accumulate over 1% Ni in dry shoots). Th...

Sensitivity of APSIM/ORYZA model due to estimation errors in solar radiation

OpenAIRE

Alexandre Bryan Heinemann; Pepijn A.J. van Oort; Diogo Simões Fernandes; Aline de Holanda Nunes Maia

2012-01-01

Crop models are ideally suited to quantify existing climatic risks. However, they require historic climate data as input. While daily temperature and rainfall data are often available, the lack of observed solar radiation (Rs) data severely limits site-specific crop modelling. The objective of this study was to estimate Rs based on air temperature solar radiation models and to quantify the propagation of errors in simulated radiation on several APSIM/ORYZA crop model seasonal outputs, yield, ...

Proportional relationship between intercepted solar radiation and dry matter production in a mulberry [Morus] field

International Nuclear Information System (INIS)

Aqueel, S.A.; Ito, D.; Naoi, T.

1999-01-01

In order to investigate the relationship between dry matter production (DMP) and the amount of intercepted solar radiation (S), and to analyze the fluctuations in the radiation conversion efficiency (DMP/S), summer-pruned mulberry (Morus alba L.) trees under a standard planting density were subjected to a shading treatment using a cheesecloth. Then, using a non-destructive method, DMP was examined for 5 plants from each plot every 15 days from July to September. DMP was also examined for mulberry trees under a high planting density. Rates of radiation that penetrated onto the ground and beneath the cheesecloth were measured to calculate S from the incoming solar radiation. In the shading plots, DMP decreased depending on the degree of shading throughout the experimental period. Compared with the control plot, 70 and 60 % DMP were produced finally under 71 and 53 % S. Therefore, DMP was considered to be almost proportional to S even in a broad-leaf population like mulberry. Radiation conversion efficiency gradually decreased with growth regardless of the planting density. At the late growth stage, radiation conversion efficiency was lower in the densely planted field than in the standard density field

Desenvolvimento da cultura do feijoeiro submetida a dois sistemas de manejo de irrigação e de cultivo = Growth of dry bean crop submitted to two water management and tillage systems

Directory of Open Access Journals (Sweden)

Luiz Carlos Pavani

2009-07-01

Full Text Available A cultura do feijoeiro apresenta elevada importância no contexto agrícola nacional. Além de ser uma cultura que atende às características da agricultura familiar, também é cultivada em áreas extensivas com alta tecnologia. Pesquisas relacionadas ao desenvolvimento do feijoeiro frente às variantes edafoclimáticas regionais vêm assumindo papel de destaque, principalmentepor se tratar de uma planta sensível tanto ao déficit quanto ao excesso hídrico. O objetivo deste trabalho foi avaliar a cultura do feijoeiro de ‘inverno’ submetida a dois métodos de manejo deirrigação, em pivô central, um via solo por meio de tensiômetros, outro via clima por meio do tanque Classe ‘A’, em dois sistemas de plantio, convencional e direto, no primeiro ano. Foram avaliados o índice de área foliar (IAF, massa seca total (MS de plantas e a variação do potencial mátrico de água no solo. Concluiu-se que os manejos de irrigação e os sistemas de plantio não resultaram em diferenças no IAF e nem no acúmulo de matéria seca total ao longo do ciclo da cultura; o manejo da irrigação por tensiometria acarretou maior variação no potencial mátrico de água no solo do que o método via clima por meio do tanque Classe ‘A’.The dry bean has great importance to Brazilian agriculture. In addition to being a crop that meets the characteristics of family agriculture, it is also cultivated in extensive areas using high technology. Research related to the behavior and development ofthe bean crop in relation to regional soil and climatic variants have assumed a prominent role, especially because it is a plant that is sensitive both to the lack and excess of water in the soil. The objective of this research was to compare two methods of management ofcenter pivot irrigation: a soil sensor (tensiometry and b simplified climatological water balance – Class A pan; in conventional and no-tillage systems of soil cultivate (first year, onthe irrigated

Comparisons of solar radiation interception, albedo and net radiation as influenced by row orientations of crops

International Nuclear Information System (INIS)

Baten, Md.A.; Kon, H.

1997-01-01

Field experiments were conducted on soybean (Glycin max L.) in summer and potato (Solanum tuberosum L.) in autumn to evaluate the effect of row orientations of crops on some selected micro meteorological factors during 1994 and 1995. The intercepted solar radiation was the largest in the plants growing in bidirection in summer and it exhibited intermediate trend in autumn as compared to E-W or N-S row orientations. In summer, penetrated solar radiation between two plants and near the stem base of a N-S row was larger than that of E-W row. While in autumn, the observed solar radiation between two plants and near the stem base of a E-W row was markedly larger than that of N-S row. The area weighted mean of penetrated solar radiation was larger in E-W soybean rows but lower in potato rows as compared to N-S row orientations. Soil surface temperature between N-S potato rows was larger than that of E-W potato rows and the upper canopy surface temperature of potato was larger in E-W rows as compared to N-S rows. Net radiation observed over E-W potato rows was larger as compared to N-S potato rows but net radiation measured under canopy of E-W potato rows was smaller than that of in N-S rows. Net radiation measured over N-S soybean rows was larger than that of E-W soybean rows and it was smaller between N-S soybean rows when measured under canopy as compared to E-W rows. The albedo observed over potato was larger over E-W rows as compared to N-S rows. Albedos over soybean canopy showed opposite trend with the albedos observed over potato canopy. It was larger over N-S rows as compared to E-W rows. High harvest index was associated with larger interception of radiation. (author)

太阳能热泵联合干燥技术在农副产品中应用与展望%Application and Prospect on the Technology of Combined Drying for Solar Energy and Heat Pump in Agricultural and Sideline Products

Institute of Scientific and Technical Information of China (English)

白旭升; 李保国; 朱传辉; 苏树强

2017-01-01

Drying was widely used in processing industries such as industry of agriculture, food and aquatic products. A wide range of solar energy can be taken full advantage of by the combined drying for solar energy and heat pump devices, meanwhile some problems of solar energy for the instability, easily affected by weather and other factors would be solved and it had broad application prospects. In addition, the combined drying for solar energy and heat pump devices were gradually promoted and applied because of its energy saving, improving the quality of the dried product and other factors in drying industry. The purpose of this paper is to comprehensively expound the drying mode of combined drying for solar energy and heat pump, and its application situation on the drying industries such as timber, agricultural products was reviewed. Besides, the research and development trend of combined drying for solar energy and heat pump were put forward. It can be used to direct the selection of drying technology.%干燥技术被广泛应用于农业、食品和水产品等加工领域.太阳能热泵联合干燥装置既能充分利用广泛的太阳能资源,同时又能解决太阳能不稳定、易受天气影响等因素,具有广阔的应用前景;又因其节能,改善干燥产品品质等因素,而逐渐被干燥行业所推广应用.阐述了太阳能热泵联合干燥的工作模式,综述了太阳能热泵联合干燥在木材、农副产品等行业的应用现状,并提出了太阳能热泵联合干燥技术的现存问题和发展展望,可为干燥技术的选择提供参考.

Development of greenhouse solar systems for bulk tobacco curing and plant production

Energy Technology Data Exchange (ETDEWEB)

Huang, B.K.; Bowers, C.G. Jr.

1986-12-01

Among many farm crops, bright leaf tobacco is the most energy- and labor-intensive crop. The greenhouse solar system (solar bulk-curing/greenhouse system, or solar barn) was developed to provide multiple-use facilities for year-round solar energy utilization to save fossil fuels in tobacco curing and plant production and to facilitate the total mechanization of tobacco culture. Two types of full-size greenhouse solar systems, the load-supporting wall design and the shell design, both utilizing the thermal envelope concept, were designed and constructed for solar bulk-curing of tobacco, growing transplants and horticultural crops under controlled environment, and aiding automation of transplanting operations. Full-scale field tests of solar bulk curing showed that the fuel savings were consistantly improved from 37% in 1975 to 51% in 1978 for this solar bulk-curing system as compared with a conventional bulk-curing barn as a control. The feasibility of the system to save energy by using solar energy as a first priority source was significantly demonstrated. Three-year greenhouse and field tests showed that high germination rate of 95-97% with excellent emergence frequency was obtained for tobacco seeds under the controlled environment provided by the greenhouse solar system. In general, the containerized transplants from greenhouse solar system significantly exceeded the conventional bare-root transplants in growth, leaf-quality and yield. 9 figs., 3 tabs., 10 refs.

Vicia narbonensis-Avena strigosa mixture, a viable alternative in rainfed cropping systems under Mediterranean conditions

Energy Technology Data Exchange (ETDEWEB)

Pedraza, V.; Perea, F.; Saavedra, M.; Fuentes, C.; Alcántara, C.

2017-07-01

The demand of vegetable protein for animal feed and the need to diversify the crop rotation in rainfed Mediterranean climates has led to study the viability as new forage crop of the Vicia narbonensis-Avena strigosa mixture. Therefore, a 3-year field trial was conducted at two different and representative locations of the area to evaluate the capacity of both species to form a balanced mixture and to define its potential for high yield and forage quality. Different seeding ratios (65:35, 50:50 and 35:65) were compared with their pure stands and the standard mixture Avena sativa-Vicia sativa (65:35). Forage mixtures establishment and growth varied according to the environmental conditions with a negative influence of a dry year 1 for legumes (<300 mm) and a wet year 2 for oats (>630 mm). However, competition ratio indicated that there were not significant differences between mixed treatments, displaying intermediate ground coverage values, dry matter yield and crude protein regarding pure stands. Higher dry matter yield than control mixture in addition to similar crude protein, acid-detergent fibre, neutral-detergent fibre and digestible dry matter values, were produced at 35:65 in dry years and 65:35 and 50:50 in rainy years with loamy and clay soils, respectively. The appropriate development of both species in the mixture at different soil and rainfall conditions, as well as a good yield often higher than control mixture and a great forage quality, confirm to the narbon bean-black oat mixture as a viable and profitable crop alternative in rainfed cropping systems under Mediterranean conditions.

Thermal Testing Methods for Solar Dryers

DEFF Research Database (Denmark)

Singh, Shobhana

2017-01-01

Solar food drying is a complex heat and mass transfer phenomena which depend on a number of drying process-dependent parameters such as operating conditions and characteristics of the food product to be dried. The variation in these parameters significantly affects the overall performance...... of the dryer system. Since commercial growth and acceptance of any solar dryer system momentously depend on its performance guarantee, the development of a standard methodology for their thermal testing has become necessary. The standard testing method not only provides better performance management...... of the dryer system but allows the manufacturers to achieve competitive efficiency and good product quality by comparing the available designs. In this chapter, an extensive review of solar dryer performance evaluation has been carried out. Furthermore, the chapter describes the existing testing procedures...

Bivariate return periods of temperature and precipitation explain a large fraction of European crop yields

Science.gov (United States)

Zscheischler, Jakob; Orth, Rene; Seneviratne, Sonia I.

2017-07-01

Crops are vital for human society. Crop yields vary with climate and it is important to understand how climate and crop yields are linked to ensure future food security. Temperature and precipitation are among the key driving factors of crop yield variability. Previous studies have investigated mostly linear relationships between temperature and precipitation and crop yield variability. Other research has highlighted the adverse impacts of climate extremes, such as drought and heat waves, on crop yields. Impacts are, however, often non-linearly related to multivariate climate conditions. Here we derive bivariate return periods of climate conditions as indicators for climate variability along different temperature-precipitation gradients. We show that in Europe, linear models based on bivariate return periods of specific climate conditions explain on average significantly more crop yield variability (42 %) than models relying directly on temperature and precipitation as predictors (36 %). Our results demonstrate that most often crop yields increase along a gradient from hot and dry to cold and wet conditions, with lower yields associated with hot and dry periods. The majority of crops are most sensitive to climate conditions in summer and to maximum temperatures. The use of bivariate return periods allows the integration of non-linear impacts into climate-crop yield analysis. This offers new avenues to study the link between climate and crop yield variability and suggests that they are possibly more strongly related than what is inferred from conventional linear models.

Tropical field performance of dual-pass PV tray dryer

Science.gov (United States)

Iskandar, A. Noor; Ya'acob, M. E.; Anuar, M. S.

2017-09-01

Solar Photovoltaic technology has become the preferable solution in many countries around the globe to solve the ever increasing energy demand of the consumers. In line with the consumer need, food processing technology has huge potentials of integration with the renewable energy resources especially in drying process which consumes the highest electricity loads. Traditionally, the solar dryer technology was applied in agriculture and food industries utilizing the sun's energy for drying process, but this is highly dependable on the weather condition and surrounding factors. This work shares some field performance of the new design of portable dual-pass PV tray dryer for drying crops in an enclosed system. The dual-pass PV tray dryer encompass a lightweight aluminium box structure with dimensions of 1.1m (L) x 0.6m (W) x 0.2m (H) and can hold a load capacity of 300g - 3kg of crop depending on the types of the crops. Experiments of field performance monitoring were conducted in October -November 2016 which justifies a considerable reduction in time and crops quality improvement when using the dual-pass PV tray dryer as compared to direct-sun drying.

Simulation of potato yield in temperate condition by the AquaCrop model

DEFF Research Database (Denmark)

Razzaghi, Fatemeh; Zhenjiang, Zhou; Andersen, Mathias Neumann

2017-01-01

Potato production ranks fourth in the world after rice, wheat, and maize and it is highly sensitive to water stress. It is thus very important to implement irrigation management strategies to minimize the effects of water stress under different climate conditions. The use of modelling tools...... to calculate the soil water balance on a daily basis has become widespread in the last decades. Therefore, this study was performed to simulate potato yield, dry matter and soil water content under different water stress condition using the AquaCrop model. Three levels of irrigation comprising full irrigated...... (If), deficit irrigated (Id) and not irrigated (I0) were investigated in three-years potato field experiment (2013–15) with four replicates in randomized complete block design. Tuber and total dry matter yield, canopy cover, dry matter production during the crop growth season, and soil water content...

Effects of Weather Variability on Crop Abandonment

Directory of Open Access Journals (Sweden)

Kelvin Mulungu

2015-03-01

Full Text Available In Zambia, every year some parts of the maize fields are abandoned post-planting. Reasons for this are not clearly known. In this paper, we examine the influence of soil and climatic factors on crop abandonment using a six-year (2007–2012 panel data by modeling the planted-to-harvested ratio (a good indicator of crop abandonment using a fractional and linear approach. Therefore, for the first time, our study appropriately (as supported by the model specification tests that favour fractional probit over linear models the fractional nature of crop abandonment. Regression results, which are not very different between the two specifications, indicate that, more than anything, high rainfall immediately after planting and inadequate fertilizer are the leading determinants of crop abandonment. In the agro-ecological region where dry planting takes place, low temperature during planting months negatively affects the harvested area. The results have implications on the sustainability of farming systems in the face of a changing climate.

The Design And Development Of Solar Maize Dryer With Subsidiary ...

African Journals Online (AJOL)

A solar Dryer with a subsidiary heating source for drying maize seed is designed and constructed. The dryer is made up a solar collector (heat source), the drying chamber (Product storage), and a subsidiary heating source (local oil). The plant when put in operation by expositing it to the solar rays, is capable of attaining a ...

The Evaluation of Science Learning Program, Technology and Society Application of Audio Bio Harmonic System with Solar Energy to Improve Crop Productivity

Directory of Open Access Journals (Sweden)

D. Rosana

2017-04-01

Full Text Available One of the greatest challenges in science learning is how to integrate a wide range of basic scientific concepts of physics, chemistry, and biology into an integrated learning material. Research-based teaching material in this area is still very poor and does not much involve students of science education in its implementation as part of the learning program science technology and society (STS. The purpose of this study is to get the result of evaluation of the teaching and learning of STS in the form of public service in Kulon Progo, Yogyakarta. The program to improve crop productivity through the application of Audio Bio Harmonic System (ABHS with solar energy have been selected for utilizing the natural animal sounds to open stomata of the leaves conducted during foliar fertilization, making it suitable for integrated science lessons. Component of evaluation model used is Stufflebeam model evaluation (CIPP. CIPP evaluation in these activities resulted in two aspects: The first aspect was improving the skills of students and farmers in using ABHS, and these two aspects, namely food crop productivity; (1 cayenne increased 76.4%, (2 increased red onions (56.3% and (3 of maize increased by 67.8%. Besides, it was also the effect of the application of ABHS on the rate of plant growth. The outcome of this study is the STS teaching materials and appropriate technology of ABHS with solar energy.

Crop scheduling improvements for rainfed agriculture in the high jungle of Peru

Directory of Open Access Journals (Sweden)

Enrique Meseth

2014-12-01

Full Text Available This work was aimed to improve the water management for agriculture by applying efficient crop schedules in Vilcabamba and similar areas of the high jungle, which can satisfy most of the water requirements with rainfed agriculture to maximize the crops yield. For this purpose, two field practices were carried out during the dry (September 2012 and wet season (February 2013 to measure rivers and canals flows with the velocity/area method; 19 soil samples were collected on-site and analyzed, presenting prevalent sandy loam and loam textures. Cropwat program was used to estimate crop water requirements and scheme irrigation requirements, resulting in a maximum flow capacity of 1.72 l s-1 in May, during the dry season. The flow capacity can be satisfied, since small ditches convey approximately 2 to 6 l s-1 on the same season. The research findings indicate that rainfed farming can be practised, yet an initial pre-irrigation needs to be applied, for crops should not be water stressed. However, if soil is not pre-irrigated the production can be affected, with vegetables and potato crop yields being reduced by 4.7% and 1.4% respectively. To minimize these effects, both crops are suggested to be sowed one month later, adapting their growth period to the rainy season.

Evapotranspiração e coeficiente de cultivo do algodoeiro BRS-200 Marrom, irrigado Evapotranspiration and crop coefficient of irrigated cotton crop, cultivar BRS-200 Marrom

Directory of Open Access Journals (Sweden)

José R. C. Bezerra

2010-01-01

Full Text Available Experimento conduzido na Embrapa, em Barbalha, CE, nos anos de 2003 e 2005, objetivou a estimativa da evapotranspiração da cultura e do coeficiente de cultivo do algodoeiro BRS-200 Marrom. Sensores de radiação solar global; saldo de radiação; temperatura do ar (bulbos seco e úmido e velocidade do vento nos níveis de 0,30 e 1,50 m acima da copa da cultura e fluxo de calor no solo foram instalados e os dados coletados por um sistema automático de aquisição de dados. A evapotranspiração da cultura (ETc e a evapotranspiração de referência (ETo foram estimadas pelos métodos da razão de Bowen e Penmam-Monteith, respectivamente, enquanto o coeficiente de cultivo (Kc foi determinado pela razão ETc/ETo. A ETc da cultura variou em função de sua fenologia, obtendo-se valores médios de 3,8 mm d-1 no período da emergência a 10% da cobertura de solo (Fase I; 5,0 mm d-1 no período do crescimento vegetativo (Fase II; 5,9 mm d-1 no período do desenvolvimento reprodutivo (Fase III e 5,4 mm d-1 no período de maturação (Fase IV. O Kc pode ser definido em função dos dias após a emergência, pela equação Kc = -0,00006 DAE² + 0,009 DAE + 0,632.Field experiments were carried out at the EMBRAPA, Barbalha, CE, during the growing seasons of 2003 and 2005 with the objective of estimating the evapotranspiration and crop coefficient of irrigated BRS-200 Marrom cotton cultivar. For this sensors of solar radiation, net radiation, dry and wet bulbs air temperature and wind speed at the 0.30 and 1.50 m levels above crop canopy and soil heat flux were installed and data were collected by a data acquisition system. Crop (ETc and reference (ETo evapotranspiration were estimated by the Bowen ratio and Penman-Monteith methods, respectively, while the crop coefficient (Kc was estimated by the ratio of ETc to ETo. The ETc changed throughout the phonological cycle of the cotton crop, with mean values of 3.8 mm d-1 in the period from emergence to 10% of

Assessing the Performance of Global Solar Radiation Empirical ...

African Journals Online (AJOL)

In the region where solar radiation data are scarce, the next alternative method is to use solar radiation models to estimate the data needed for some applications such as simulation of crop performance and the design of solar energy conversion devices. In this paper, the validations of fifteen models for estimating monthly ...

Best practices to hasten field drying of grasses and alfalfa

Science.gov (United States)

Rapid drying of hay and silage shortens the harvest window, enhances forage quality, and reduces the chance for rain damage. Forage generally has about 75% moisture when it is cut. This means the crop must lose 2.3 to 3 tons of water per acre (550 to 720 gal/acre) to dry to haylage at 60 to 65% mois...

Solar thermal drum drying performance of prune and tomato pomaces

Science.gov (United States)

Fruit and vegetable pomaces are co-products of the food processing industry; they are underutilized in part because their high water activity (aw) renders them unstable. Drum drying is one method that can dry/stabilize pomaces, but current drum drying methods utilize conventional, high-environmental...

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African Journals Online (AJOL)

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higher air temperature and consequently lowered the relative humidity which are both conducive to improve ... solar crop drying techniques, which provide heating at economically ... solar dryer and construction of a prototype of the dryer for ...

Sorghum - An alternative energy crop for marginal lands and reclamation sites

Science.gov (United States)

Lukas, Stefan; Theiß, Markus; Jäkel, Kerstin

2017-04-01

The production of biogas and the associated cultivation of energy crops are still of great importance. Considering increasing restrictions for the cultivation of standard biogas crop maize regarding an environmentally friendly production of biomass, a wider range of energy crops is needed. The cultivation of sorghum can contribute to this. As maize, sorghum is a C4-plant and offers a high biomass yield potential. Originated in the semi-arid tropics, sorghum is well adapted to warm and dry climate and particularly noted for its drought tolerance compared to maize. It also makes few demands on soil quality and shows a good capability of nutrient acquisition. Therefore, particularly on marginal areas and reclamation sites with low soil nutrient and water content sorghum can contribute to secure crop yield and income of farmers. The applied research project aims at and reflects on the establishment of sorghum as a profitable and ecological friendly cropping alternative to maize, especially in the face of probable climate change with increasing risks for agriculture. For this purpose, site differentiated growing and cultivar trials with a standardized planting design as well as several practical on-farm field experiments were conducted. The agronomical and economic results will lead to scientifically based procedures and standards for agricultural practice with respect to cultivation methods (drilling, pest-management, fertilization), cropping sequence and technique, cropping period or position in crop rotation. Even by now there is a promising feedback from the agricultural practice linked with an increasing demand for information. Moreover, the specific cropping area is increasing continuously. Therefore, the leading signs for the establishment of sorghum as profitable alternative to maize biogas production are positive. Sorghum cultures perform best as main crops in the warm D locations in the middle and East German dry areas. Here, the contribution margin

From the weather forecast to the prognostic moisture content of dry agricultural crops

NARCIS (Netherlands)

Atzema, A.J.

1994-01-01

Part 1

The aim of the study of grass is to forecast the drying of cut grass up to five days ahead, hourly. The first investigated problem is the response of the drying of cut grass to the weather elements. Next a simple model and an advanced model for the drying of cut

Importance of NDF digestibility of whole crop maize silage for dry matter intake and milk production in dairy cows

DEFF Research Database (Denmark)

Krämer, Monika; Lund, Peter; Weisbjerg, Martin Riis

2016-01-01

The importance of maize silage as a feed component in cattle rations and for biogas production has substantially increased. Whole crop maize silage is a forage with a high starch concentration, but also the cell wall fraction, commonly analysed as neutral detergent fibre (aNDFom) is a major energy...... source for use in ruminant nutrition. Even though ruminants require forage fibre to maintain rumen function and maximize productivity, excess fibre limits feed intake due to its contribution to physical fill in the rumen. As feed intake is the most important factor for milk production, both a......NDFom concentration and aNDFom digestibility are key determinants of the nutritive value of a diet. Therefore, the importance of maize silage aNDFom digestibility on nutritive value, dry matter (DM) intake (DMI) and milk production was investigated in a literature review across a wide range of studies varying...

Dynamics of Phenol Degrading-Iron ReducingBacteria{1mm in Intensive Rice Cropping System

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

Field and greenhouse experiments were conducted to investigate theeffects of cropping season, nitrogen fertilizer input and aeratedfallow on the dynamics of phenol degrading-iron reducingbacteria (PD-IRB) in tropical irrigated rice ({ Oryza sativa L.)systems. The PD-IRB population density was monitored at different stagesof rice growth in two cropping seasons (dry and early wet) in acontinuous annual triple rice cropping system under irrigated condition.In this system, the high nitrogen input (195 and 135 kg N ha-1 indry and wet seasons, respectively) plots and control plots receiving noN fertilizer were compared to investigate the effect of nitrogen rate onpopulation size. The phenol degrading-iron reducing bacteria (PD-IRB)were abundant in soils under cropping systems of tropical irrigatedrice. However, density of the bacterial populations varied with ricegrowth stages. Cropping seasons, rhizosphere, and aerated fallow couldaffect the dynamics of PD-IRB. In the field trial, viable counts ofPD-IRB in the topsoil layer (15 cm) ranged between 102 and 108cells per gram of dry soil. A steep increase in viable counts during thesecond half of the cropping season suggested that the population densityof PD-IRB increased at advanced crop-growth stages. Population growth ofPD-IRB was accelerated during the dry season compared to the wet season.In the greenhouse experiment, the adjacent aerated fallow revealed 1-2orders of magnitude higher in most probable number (MPN) of PD-IRB thanthe wet fallow treated plots. As a prominent group of Fe reducingbacteria, PD-IRB predominated in the rhizosphere of rice, since maximumMPN of PD-IRB (2.62108 g-1 soil) was found in rhizospheresoil. Mineral N fertilizer rates showed no significant effect on PD-IRBpopulation density.

Optimal Control Design for a Solar Greenhouse

NARCIS (Netherlands)

Ooteghem, van R.J.C.

2010-01-01

Abstract: An optimal climate control has been designed for a solar greenhouse to achieve optimal crop production with sustainable instead of fossil energy. The solar greenhouse extends a conventional greenhouse with an improved roof cover, ventilation with heat recovery, a heat pump, a heat

Review on advanced of solar assisted chemical heat pump dryer for agriculture produce

International Nuclear Information System (INIS)

Fadhel, M.I.; Sopian, K.; Daud, W.R.W.; Alghoul, M.A.

2011-01-01

Over the past three decades there has been nearly exponential growth in drying R and D on a global scale. Improving of the drying operation to save energy, improve product quality as well as reduce environmental effect remained as the main objectives of any development of drying system. A solar assisted chemical heat pump dryer is a new solar drying system, which have contributed to better cost-effectiveness and better quality dried products as well as saving energy. A solar collector is adapted to provide thermal energy in a reactor so a chemical reaction can take place. This reduces the dependency of the drying technology on fossil energy for heating. In this paper a review on advanced of solar assisted chemical heat pump dryer is presented (the system model and the results from experimental studies on the system performance are discussed). The review of heat pump dryers and solar assisted heat pump dryer is presented. Description of chemical heat pump types and the overview of chemical heat pump dryer are discussed. The combination of chemical heat pump and solar technology gives extra efficiency in utilizing energy. (author)

Growth and solar energy conversion of Azolla sp., cultivated under four solar irradiance flux density; Crescimento e conversao da energia solar de Azolla sp. cultivada em quatro densidades do fluxo radiante

Energy Technology Data Exchange (ETDEWEB)

Carvalho, E.F. de [Acre Univ., Rio Branco, AC (Brazil); Lopes, N.F. [Vicosa Univ., MG (Brazil). Dept. de Biologia Vegetal

1994-02-01

Growth and solar energy conversion were studied in three Azolla species grown under four levels (30, 50, 70 and 100%) of solar radiation incidence under outdoor conditions. Under full sunlight, the specie A. microphylla showed higher crop growth rate, relative growth rate, net assimilation rate and efficiency of solar energy conversion than the other ones. (author). 8 figs., 23 refs.

Standing crop dry matter accumulation and quality patterns of ...

African Journals Online (AJOL)

Nine-week production curves and quality values of eight subtropical pasture species were studied under supplemental spray irrigation to characterize their productive capacity, periodicity and quality.All species exhibited a slow dry matter regrowth rate for two to three weeks after defoliation to 7,5 or 10 cm height. Thereafter ...

Weed infestation of spring common wheat (Triticum aestivum L. grown in monoculture depending on the cover crop and weed control method

Directory of Open Access Journals (Sweden)

Dorota Gawęda

2012-10-01

Full Text Available The aim of this 3-year field study was to evaluate the effect of some stubble crops and in-crop weed control methods on the species composition, number and air-dry weight of weeds in a wheat crop grown in short-term monoculture. The study was conducted in the period 2009-2011 in the Uhrusk Experimental Farm on mixed rendzina soil classified as very good rye soil complex. It included various types of stubble crops ploughed in each year (control treatment without cover crop, white mustard, lacy phacelia, a mixture of legumes – narrow-leaf lupin + field pea and methods of weed control in spring wheat (mechanical, mechanical and chemical, chemical weed control. On average during the study period, all stubble crops used reduced the air-dry weight of weds in the treatments with mechanical weed management relative to the control treatment. Irrespective of the weed control method, the number of weeds in the wheat crop was significantly lower only after the ploughing in of white mustard. Mechanical weed management proved to be less effective in reducing the number and dry weight of weeds compared to other weed control methods. The white mustard and legume mixture cover crops had a reducing effect on the number of weed species in relation to the treatment without cover crops. The highest floristic diversity of weed communities was found in the spring wheat crop in which only mechanical weeding alone was used.

Techno-economic analysis of a roof-integrated solar air heating system for drying fruit and vegetables

Energy Technology Data Exchange (ETDEWEB)

Sreekumar, A. [Dept. of Physics, Cochin University of Science and Technology, Kochi 682 022 (India)

2010-11-15

The solar air heater was 46 m{sup 2} and recorded a maximum temperature of 76.6 C. The dryer was loaded with 200 kg of fresh pineapple slices 5 mm thick. The initial moisture content of 82% was reduced to the desired level (<10%) within 8 h. The performance of the dryer was analyzed in detail by three methods namely annualized cost, present worth of annual savings, and present worth of cumulative savings. The cost of drying 1 kg pineapple worked out to Rs. 11 which was roughly half of that of an electric dryer. The payback period worked out to 0.54 year, much less than the estimated life of the system (20 years). (author)

Techno-economic analysis of a roof-integrated solar air heating system for drying fruit and vegetables

International Nuclear Information System (INIS)

Sreekumar, A.

2010-01-01

The solar air heater was 46 m 2 and recorded a maximum temperature of 76.6 deg. C. The dryer was loaded with 200 kg of fresh pineapple slices 5 mm thick. The initial moisture content of 82% was reduced to the desired level (<10%) within 8 h. The performance of the dryer was analyzed in detail by three methods namely annualized cost, present worth of annual savings, and present worth of cumulative savings. The cost of drying 1 kg pineapple worked out to Rs. 11 which was roughly half of that of an electric dryer. The payback period worked out to 0.54 year, much less than the estimated life of the system (20 years).

Solar and Lighting Transmission through Complex Fenestration Systems of Office Buildings in a Warm and Dry Climate of Chile

Directory of Open Access Journals (Sweden)

Waldo Bustamante

2014-05-01

Full Text Available Overheating, glare, and high-energy demand are recurrent problems in office buildings in Santiago, Chile (33°27'S; 70°42'W during cooling periods. Santiago climate is warm and dry, with high solar radiation and temperature during most of the year. The objective of this paper is to evaluate the thermal and daylighting performance of office buildings transparent façades composed of three different complex fenestration systems (CFS. Each CFS contains a different external shading device (ESD: (1 external roller, (2 vertical undulated and perforated screens, and (3 tilted undulated and perforated screens. The study was carried out by in situ monitoring in three office buildings in Santiago, Chile. Buildings were selected from a database of 103 buildings, representing those constructed between 2005 and 2011 in the city. The monitoring consisted of measuring the short wave solar and daylighting transmission through fenestration systemsby means of pyranometers and luxometers, respectively. This paper shows measurements that were carried out during summer period. A good performance is observed in a building with the external roller system. This system—applied to a northwest façade—shows a regular and high solar and daylighting control of incoming solar radiation. The other two ESD systems evidence a general good performance. However, some deficiencies at certain times of the day were detected, suggesting a non-appropriated design.

7 CFR 457.150 - Dry bean crop insurance provisions.

Science.gov (United States)

2010-01-01

... Food and Drug Administration or other public health organizations of the United States as being... area to the extent feasible. We may obtain prices from any buyer of our choice. If we obtain prices... additional costs required to deliver the dry beans to those buyers. Discounts used to establish the net price...

Crop maize evapotranspiration; 2: ratios between the evapotranspiration to class A pan evaporation, to the reference evapotranspiration and to global solar radiation, at three sowing dates

International Nuclear Information System (INIS)

Matzenauer, R.; Bergamashi, H.; Berlato, M.A.

1998-01-01

Water availability is the most limiting factor for growth and grain yield of maize in the State of Rio Grande do Sul, Brazil, reducing frequently this production. Therefore, studies involving the determination of the water requirements are important for irrigation management to minimize the water availability problem. The main objective of this study was to calculate ratios between the maize crop evapotranspiration (ETm) to the class A pan evaporation (Eo), to the reference evapotranspiration (ETo) and to global solar radiation (Rs), in order to obtain ralations between ETm/Eo, ETm/ETo and ETm/Rs, at different crop stages for three different sowing dates. Field experiments were carried out at the Experimental Station of Taquari/RS, 29°48’ of south latitude, 51°49’of west longitude, and 76m of altitude, from 1976/77 to 1988/89. ETm was measured using drainage lysimeters (Thornthwaite-Mather type). The average ratio between ETm and Eo for whole crop cycle (from sowing to physiological maturity) was 0.66, 0.72, and 0.68, respectively, in crops sown on September, October, and November. The average ratio between ETm and ETo for whole crop cycle was 0.74, 0.81, and 0.8, in crops sown on September, October, and November, while the average ratio between ETm and Rs was 0.45, 0.51, and 0.49 for the same sowing dates. The higher average values of crop coefficients occured from tasseling to the milk grain stage, when ETm/Eo was 0.81, 0.92, and 0.81; ETm/ETo was 0.97, 1.05, and 0.96, whereas ETm/Rs was 0.6, 0.68, and 0.6 for crops sown on September, October, and November, respectively [pt

Effects of shading on dry matter partitioning and yield of field-grown sunflower

International Nuclear Information System (INIS)

Villalobos, F.J.; Soriano, A.; Fereres, E.

1992-01-01

Crop simulation models require quantitative descriptions of the effects of irradiance on dry matter partition and yield. The objective of this work was to quantify the effects of reduced radiation intensity during different phenological stages on the growth, dry matter partitioning and grain numbers of sunflower (Helianthus annuus, L.). A field experiment was carried out in 1990 with 50 per cent shading treatments. The earliest treatment began at crop emergence while the latest ended at first anthesis. Shading had little effect on plant leaf area growth but reduced biomass and yield. The dry matter: radiation quotient and specific leaf area increased with shading. Grain number per head was decreased by shading, with the greatest effect occurring when shading was applied prior to anthesis. All shading treatments increased dry matter partitioning to stems, decreased assimilate partitioning to the heads and had no effect on the partitioning to leaves. (author)

Solar tower enhanced natural draft dry cooling tower

Science.gov (United States)

Yang, Huiqiang; Xu, Yan; Acosta-Iborra, Alberto; Santana, Domingo

2017-06-01

Concentrating Solar Power (CSP) plants are located in desert areas where the Direct Normal Irradiance (DNI) value is very high. Since water resource is scarcely available, mechanical draft cooing technology is commonly used, with power consumption of mechanical fans being approximately 2% of the total power generated. Today, there is only one solar power plant (Khi Solar One in South Africa) uses a condenser installed in a Natural Draft Cooling (NDC) tower that avoids the windage loss of water occurring in wet cooling towers. Although, Khi Solar One is a cavity receiver power tower, the receivers can be hung onto the NDC tower. This paper looks at a novel integration of a NDC tower into an external molten salt receiver of a solar power plant, which is one of a largest commercial molten salt tower in China, with 100MWe power capacity. In this configuration study, the NDC tower surrounds the concrete tower of the receiver concentrically. In this way, the receiver concrete tower is the central support of the NDC tower, which consists of cable networks that are fixed to the concrete tower and suspended at a certain height over the floor. The cable networks support the shell of the NDC tower. To perform a preliminary analysis of the behavior of this novel configuration, two cases of numerical simulation in three dimensional (3D) models have been solved using the commercial Computational Fluid Dynamics (CFD) code, ANSYS Fluent 6.3. The results show that the integration of the NDC tower into an external central receiver tower is feasible. Additionally, the total heat transfer rate is not reduced but slightly increases when the molten salt receiver is in operation because of the additional natural draft induced by the high temperature of the receiver.

Bivariate return periods of temperature and precipitation explain a large fraction of European crop yields

Directory of Open Access Journals (Sweden)

J. Zscheischler

2017-07-01

Full Text Available Crops are vital for human society. Crop yields vary with climate and it is important to understand how climate and crop yields are linked to ensure future food security. Temperature and precipitation are among the key driving factors of crop yield variability. Previous studies have investigated mostly linear relationships between temperature and precipitation and crop yield variability. Other research has highlighted the adverse impacts of climate extremes, such as drought and heat waves, on crop yields. Impacts are, however, often non-linearly related to multivariate climate conditions. Here we derive bivariate return periods of climate conditions as indicators for climate variability along different temperature–precipitation gradients. We show that in Europe, linear models based on bivariate return periods of specific climate conditions explain on average significantly more crop yield variability (42 % than models relying directly on temperature and precipitation as predictors (36 %. Our results demonstrate that most often crop yields increase along a gradient from hot and dry to cold and wet conditions, with lower yields associated with hot and dry periods. The majority of crops are most sensitive to climate conditions in summer and to maximum temperatures. The use of bivariate return periods allows the integration of non-linear impacts into climate–crop yield analysis. This offers new avenues to study the link between climate and crop yield variability and suggests that they are possibly more strongly related than what is inferred from conventional linear models.

Performance Analysis of a Solar Dryer Equipped with a Recycling Air System and Desiccant Chamber

Directory of Open Access Journals (Sweden)

M.H Aghkhani

2013-09-01

Full Text Available Drying is a high energy consuming process. Solar drying is one of the most popular methods for dehydration of agricultural products. In the present study, the performance of a forced convection solar dryer equipped with recycling air system and desiccant chamber was investigated. The solar dryer is comprised of solar collector, drying chamber, silica jell desiccant chamber, air ducts, fan and measuring and controlling system. Drying rate and energy consumption in three levels of air temperature (40, 45 and 50 oC and two modes of drying (with recycling air and no-recycling with open duct system were measured and compared. The results showed that increasing the drying air temperature decreased the drying time and increased the energy consumption in the mode of non-recycling air system. The dryer efficiency and drying rate were better in the mode of recycling air system than open duct system. The highest dryer efficiency was obtained from drying air temperature of 50 oC and the mode of recycling air system. In general, the efficiency of solar collector and the highest efficiency of the dryer were 0.34 and 0.41, respectively.

Effect of dry land transformation and quality of water use for crop irrigation on the soil bacterial community in the Mezquital Valley, Mexico

Science.gov (United States)

Lüneberg, Kathia; Schneider, Dominik; Daniel, Rolf; Siebe, Christina

2017-04-01

Soil bacteria are important determinants of soil fertility and ecosystem services as they participate in all biogeochemical cycles. Until now the comprehension of compositional and functional response that bacterial communities have to land use change and management, specifically in dry land its limited. Dry lands cover 40% of the world's land surface and its crop production supports one third of the global population. In this regions soil moisture is limited constraining farming to the rainy season or oblige to irrigate, as fresh water resources become scarce, to maintain productivity, treated or untreated wastewater for field irrigation is used. In this study the transformation of semiarid shrubland to agriculture under different land systems regarding quantity and quality of water use for crop irrigation on bacterial communities was investigated. The land systems included maize rain-fed plantations and irrigation systems with freshwater, untreated wastewater stored in a dam and untreated wastewater during dry and rainy season. Bacterial community structure and function was heavily affected by land use system and soil properties, whereas seasonality had a slighter effect. A soil moisture, nutrient and contaminant-content increasing gradient among the land use systems, going from rain fed plantation over fresh water, dam wastewater to untreated wastewater irrigated plantations was detected, this gradient diminished the abundance of Actinobacteria and Cyanobacteria, but enhanced the one from Bacteroidetes and Proteobacteria. Discernible clustering of the dry land soil communities coincides with the moisture, nutrient and contaminant gradient, being shrubland soil communities closer to the rain-fed's system and farer to the one from untreated wastewater irrigated soil. Soil moisture together with sodium content and pH were the strongest drivers of the community structure. Seasonality promoted shifts in the composition of soil bacteria under irrigation with

Operational Augmentation of Forced Circulation Type Solar Dryer System Using CFD Analysis

OpenAIRE

Atul Patel; Gaurav Patel

2014-01-01

Solar drying is basically heat and mass transfer process in which the liquid water from the surface and the vapour removed by draft. The efficiency of a solar drying system is affected by the properties of drying materials.e.g. size, shape and geometry as well as ambient conditions. In this research article, the authors have done the CFD analysis of a Forced Circulation type Solar Dryer used conventionally for dehydrating vegetables and fruits. Using CFD analysis, the limiting...

Growth and energy yield when cultivating various energy crops on farming soil. Tillvaext och energiutbyte vid odling av olika energigroedor paa jordbruksmark

Energy Technology Data Exchange (ETDEWEB)

Thoerner, L.

1988-03-01

In four fields in the south of Sweden different energy crops were tested. In all trials sugar beet, barley, alfalfa, corn, sunflower and quickgrowing species of Salix (energy forest) were grown. In some of the trials broome-grass, potatoes and winter wheat were tested. One trial also included marrow-stem kale, Jerusalem artichoke and a hybride of J artichoke and sunflower. The purpose of the experiment was to illustrate the effect of increasing N-fertilizing and the effect of growing the crops in different climatic conditions. The yield varies between the crops. Some of the crops were harvested in different stages of development. The largest yields were noticed for sugar beet, corn, potatoes and energy forest. For these crops the yield was 11.5-14.5 tons of dry matter per hectare. The yield of potatoes was very large but it is figures for only one place with very good conditions. Barley, sunflower and alfalfa produced 8-10 tons of dry matter per hectare. The smaller yield depends on a short vegetation season for these crops. The year of establishment the energy forest produced about four tons of dry matter in the form of stem wood. When fully established the production has been 12-15 tons of dry matter per hectare and annum. The analysis of plant material indicates small divergences in the content of carbon and heat value.

Radiation balance in the sweet sorghum crop

International Nuclear Information System (INIS)

Assis, F.N. de; Mendez, M.E.G.; Martins, S.R.; Verona, L.A.

1987-01-01

The fluxes of incident solar radiation, reflected and net radiation were measured during the growing cicle of two fields of sweet sorghum (Sorghum bicolor L.), cus. BR-501 and BR-503, maintained under convenient irrigation level. Resultant data allowed to estimate the crop albedo as well as the estimates of Rn. (M.A.C.) [pt

Nutrient status of crop contents of rural scavenging local chickens in Tanzania.

Science.gov (United States)

Mwalusanya, N A; Katule, A M; Mutayoba, S K; Minga, U M; Mtambo, M M A; Olsen, J E

2002-03-01

1. A total of 144 chickens purchased from peasants in Morogoro, Tanzania were slaughtered, their crops dissected and the contents analysed. The birds consisted of 48 chickens from each of three climatic zones (warm and wet, warm and dry, cool and wet). Seventy-two chickens were slaughtered in each season, that is short rainy and long rainy season. 2. Cereal grains, bran, green forages, insects/worms and kitchen food wastes were the main crop contents and their composition varied significantly with season and climate. 3. The overall mean chemical compositions (g/kg) of the crop contents were: 430.8 +/- 107.78 dry matter (DM), 104.4 +/- 43.47 crude protein (CP), 61.2 +/- 36.48 ether extract (EE), 58.2 +/- 26.29 crude fibre (CF), 125.4 +/- 58-27 ash, 6.3 +/- 5.19 calcium (Ca) and 3.6 +/- 2.41 phosphorus (P). 4. CP, EE, ash and P contents varied significantly (Pnutritional requirements and varied with season, climate and age of birds.

Climate change impacts on maize and dry bean yields of smallholder farmers in Honduras

Directory of Open Access Journals (Sweden)

MENDOZA, Carlos O.

2013-06-01

Full Text Available The rotation maize and dry bean provides the main food supply of smallholder farmers in Honduras. Crop model assessment of climate change impacts (2070–2099 compared to a 1961–1990 baseline on a maize–dry bean rotation for several sites across a range of climatic zones and elevations in Honduras. Low productivity systems, together with an uncertain future climate, pose a high level of risk for food security. The cropping systems simulation dynamic model CropSyst was calibrated and validated upon field trail site at Zamorano, then run with baseline and future climate scenarios based upon general circulation models (GCM and the ClimGen synthetic daily weather generator. Results indicate large uncertainty in crop production from various GCM simulations and future emissions scenarios, but generally reduced yields at low elevations by 0 % to 22 % in suitable areas for crop production and increased yield at the cooler, on the hillsides, where farming needs to reduce soil erosion with conservation techniques. Further studies are needed to investigate strategies to reduce impacts and to explore adaptation tactics.

Recent advances in drying and dehydration of fruits and vegetables: a review

OpenAIRE

Sagar, V. R.; Suresh Kumar, P.

2010-01-01

Fruits and vegetables are dried to enhance storage stability, minimize packaging requirement and reduce transport weight. Preservation of fruits and vegetables through drying based on sun and solar drying techniques which cause poor quality and product contamination. Energy consumption and quality of dried products are critical parameters in the selection of drying process. An optimum drying system for the preparation of quality dehydrated products is cost effective as it shortens the drying ...

Increasing the total productivity of a land by combining mobile photovoltaic panels and food crops

International Nuclear Information System (INIS)

Valle, B.; Simonneau, T.; Sourd, F.; Pechier, P.; Hamard, P.; Frisson, T.; Ryckewaert, M.; Christophe, A.

2017-01-01

Highlights: •Combining solar panels and crops on the same land increases the total productivity. •Use of solar trackers permits to balance or promote food/energy production. •Controlling mode of trackers strongly affect the total production per unit area. •Dynamic agrivoltaic systems increases productivity without competing with food. -- Abstract: Agrivoltaic systems, consisting of the combination of photovoltaic panels (PVPs) with crops on the same land, recently emerged as an opportunity to resolve the competition for land use between food and energy production. Such systems have proved efficient when using stationary PVPs at half their usual density. Dynamic agrivoltaic systems improved the concept by using orientable PVPs derived from solar trackers. They offer the possibility to intercept the variable part of solar radiation, as well as new means to increase land productivity. The matter was analysed in this work by comparing fixed and dynamic systems with two different orientation policies. Performances of the resulting agrivoltaic systems were studied for two varieties of lettuce over three different seasons. Solar tracking systems placed all plants in a new microclimate where light and shade bands alternated several times a day at any plant position, while stationary systems split the land surface into more stable shaded and sunlit areas. In spite of these differences, transient shading conditions increased plant leaf area in all agrivoltaic systems compared to full-sun conditions, resulting in a higher conversion of the transmitted radiation by the crop. This benefit was lower during seasons with high radiation and under controlled tracking with more light transmitted to the crop. As expected, regular tracking largely increased electric production compared to stationary PVPs but also slightly increased the transmitted radiation, hence crop biomass. A large increase in transmitted radiation was achieved by restricting solar tracking around midday

Dry Bean Morpho-Physiological Responses to Gradual Weed Biomass Accumulation

Directory of Open Access Journals (Sweden)

Hossein GHAMARI

2013-02-01

Full Text Available Field study was carried out in 2011 in west of Iran to assess responses of dry bean (Phaseolus vulgaris L. morpho-physiological traits to gradual weed biomass accumulation. The treatments consisted of two different periods of weed interference, which weeds either infested the plots or removed for an increasing duration of time (0, 10, 20, 30, 40, 50 days after crop emergence. Relative dominance and relative importance of weed species fluctuated over the crop cycle. As the duration of weed interference was increased, a declining trend of crop growth rate (CGR was observed. When weeds were allowed to compete with crop throughout the crop cycle, maximum value of CGR was decreased from 25.57 g m-2 days in full season weed free treatment to 16.78 g m-2 days in full season weed infested treatment. Effect of treatments on leaf area index (LAI was significant. Weed removal increased LAI but it could not significantly affect this trait, at the early of growing season. Weed interference caused a significant reduction on number of branches. The minimum number of branches was registered in full season weed infested treatment (2.58 branches per plant, while the maximum one was observed in the full season weed free treatment (4.25 branches per plant. Weed competition severely reduced crop yield. At 10 and 20 days after crop emergence, weed infestation could not significantly affect the yield. A negative relationship between weeds’ dry matter accumulation and LAI as well as number of branches was observed which signify the vulnerability of these morpho-physiological traits to weed competition.

The role of catch crops in the ecological intensification of spring cereals in organic farming under Nordic climate

DEFF Research Database (Denmark)

Doltra, Jordi; Olesen, Jørgen E

2013-01-01

common practices in organic farming. Measurements of dry matter (DM) and N content of grain cereals at harvest, above-ground biomass in catch crops and green manure crops in autumn and of the green manure crop at the first cutting were performed. The effect of catch crops on grain yield varied...... the nitrate leaching and increasing N retention, but also by improving yields. Management practices in relation to catch crops must be adapted to the specific soil and cropping systems....

Farmer evaluation of dried banana based products | Pekke | African ...

African Journals Online (AJOL)

A farmer participatory evaluation of dried banana based products was conducted in various districts of Uganda. Bananas were dried using a tunnel solar dryer developed by Post Harvest Handling and Storage project (PHHS) of Kawanda Post-harvest Programme and improved by the National Banana Research ...

Water Productivity of Irrigated Rice under Transplanting, Wet Seeding and Dry Seeding Methods of Cultivation

Directory of Open Access Journals (Sweden)

Murali, NS.

1997-01-01

Full Text Available Water productivity (WP of irrigated lowland rice was determined during the 1994 dry (January to May and wet (August to December seasons on a heavy clay acid sulphate soil. Treatments consisted of three cultivation methods : transplanted rice, pregerminated seeds broadcasted on puddled soil (wet seeding and dry seeds broadcasted on unpuddled soil (dry seeding. In wet and dry seeded plots, continuous standing water condition was initiated 17 days after sowing. Total water requirement for rice production was highest in transplanted plots (755 mm in wet season and 1154 mm in dry season and was lowest in dry seeded plots (505 mm in wet season and 1040 mm in dry season. Dry seeding required no water for land preparation but transplanting and wet seeding methods required 18 - 20 % of total water requirement in dry season and 27 - 29 % in wet season. Total percolation was maximum (99 mm in wet season and 215 mm in dry season in dry seeding method and was minimum (62 mm in wet season and 94 mm in dry season in transplanting method. In dry and wet seeding methods, daily percolation gradually decreased with the age of the crop. Total seepage loss did not show any significant difference between the cultivation methods in the two seasons. Grain yield was not affected by the three cultivation methods in both seasons. Water productivity (the ratio between grain yield and total amount of water used in production was 3.5 - 4.1 kg ha-1 mm-1, 3.8 - 4.4 kg ha-1 mm-1 and 4.1 - 5.5 kg ha-1 mm-1 in transplanted, wet seeded and dry seeded rice, respectively. Labour requirement for land preparation and sowing was maximum in transplanted (219 - 226 man-hours ha-1 followed by wet (104 -112 man-hours ha-1 and dry seeded (94 - 99 man-hours ha-1 methods. However, in wet season extra labour (77 man-hours ha-1 was required for weeding after crop establishment in dry and wet seeding methods. Crop maturity was 20 days earlier in wet and dry seeding methods compared to

Comparing annual and perennial crops for bioenergy production - influence on nitrate leaching and energy balance

DEFF Research Database (Denmark)

Pugesgaard, Siri; Schelde, Kirsten; Ugilt Larsen, Søren

2015-01-01

Production of energy crops is promoted as a means to mitigate global warming by decreasing dependency on fossil energy. However, agricultural production of bioenergy can have various environmental effects depending on the crop and production system. In a field trial initiated in 2008, nitrate...... concentration in soil water was measured below winter wheat, grass-clover and willow during three growing seasons. Crop water balances were modelled to estimate the amount of nitrate leached per hectare. In addition, dry matter yields and nitrogen (N) yields were measured, and N balances and energy balances...... was also measured in an old willow crop established in 1996 from which N leaching ranged from 6 to 27 kg ha−1 yr−1. Dry matter yields ranged between 5.9 and 14.8 Mg yr−1 with lowest yield in the newly established willow and the highest yield harvested in grass-clover. Grass-clover gave the highest net...

Evaluation of usage and fuel savings of solar ovens in Nicaragua

International Nuclear Information System (INIS)

Bauer, Gordon

2016-01-01

Solar cooking technology has been promoted as a solution to both global poverty and environmental degradation, but relatively little research exists on the impact of solar oven usage on biomass fuel consumption. This study evaluates solar oven usage and wood consumption in northern Nicaragua during both the rainy and dry seasons, using surveys, temperature dataloggers, and direct measurements of fuelwood use. Solar oven owners reported usage on 79% of days during the dry season, and 41% of days during the rainy season. Comparison with oven temperature records confirmed usage on 50% of days during the dry season, and 16% of days during the rainy season. However, wood consumption measurements showed no statistically significant difference between days with solar oven usage and days without, suggesting that frequency of usage alone is not an appropriate proxy for fuel savings. Survey results suggest that a large part of solar oven usage came in addition to biomass cooking, as opposed to replacing it. These results suggest a need for further study of wood consumption in situ and more focus on the specific kinds of foods prepared in solar cookers, as well as local cultural and climatic conditions. - Highlights: • Solar oven usage reported on most days during dry season. • No statistically significant fuelwood savings can be attributed to solar oven use. • Usage reported on surveys differs substantially from solar oven temperature data. • Possible causes of lack of wood savings range from weather to diet and gender norms.

N{sub 2}O Emission from energy crop fields

Energy Technology Data Exchange (ETDEWEB)

Joergensen, B.J. [The Royal Veterinary and Agricultural Univ., Dept. of Agricultural Sciences, Section of Soil, Water and Plant Nutrition (Denmark); Nyholm Joergensen, R. [Research Centre Foulum, The Danish Inst. of Plant and Soil Science, Dept. of Soil Science (Denmark)

1996-03-01

The interest in N{sub 2}O emissions from soils with energy crops is a results of its properties as a greenhouse gas, since the global warming potential of N{sub 2}O per unit mass is about 320 times greater than CO{sub 2}. The contribution of N{sub 2}O from the soil to the atmosphere may increase due to agricultural management. Consequently, large N{sub 2}O emissions can lower the reduction of the greenhouse effect achieved by the substitution of fossil fuels by energy crops. For this reason it is crucial to find the crops for combustion with the lowest potential for emission of N{sub 2}O from the soil per produced energy unit. The aims of this study were to assess the annual N{sub 2}O flux from a Miscanthus 'Giganteus' (M. 'Giganteus') and winter rye (Secale cereale) field, and to investigate the factors affecting the N{sub 2}O emission. To obtain these aims a method was developed for measurements in tall crops. The thesis contains a literature review on the N{sub 2}O emission from the soils, a section with development of the technique for N{sub 2}O flux measurements, and an experimental section. Finally, the thesis contains a section where the results are discussed in relation to the use of energy crops. In all the filed studies, the N{sub 2}O emission was measured by using a new developed closed-chamber technique. The main advantages of the chamber method were the ability to contain growing plants up to a height of 3 m, and the relatively large area (2X2m) covered by each other. Soils with annual and perennial crops can be expected to emit less then 3 kg N{sub 2}O ha{sup -1} yr{sup -1}. This amount corresponds to 960 kg CO{sub 2} ha{sup -1} yr{sup -1} compared to a total CO{sub 2} reduction of 10 to 19 tons CO{sub 2} ha{sup -1} yr{sup -1} using the energy crops as substitution for fossil fuels. An efficient way to reduce the N{sub 2}O emission is to exclude use of fertiliser but this also reduces the dry matter yield and consequently also the

N{sub 2}O Emission from energy crop fields

Energy Technology Data Exchange (ETDEWEB)

Joergensen, B.J. [The Royal Veterinary and Agricultural Univ., Dept. of Agricultural Sciences, Section of Soil, Water and Plant Nutrition (Denmark); Nyholm Joergensen, R. [Research Centre Foulum, The Danish Inst. of Plant and Soil Science, Dept. of Soil Science (Denmark)

1996-03-01

The interest in N{sub 2}O emissions from soils with energy crops is a results of its properties as a greenhouse gas, since the global warming potential of N{sub 2}O per unit mass is about 320 times greater than CO{sub 2}. The contribution of N{sub 2}O from the soil to the atmosphere may increase due to agricultural management. Consequently, large N{sub 2}O emissions can lower the reduction of the greenhouse effect achieved by the substitution of fossil fuels by energy crops. For this reason it is crucial to find the crops for combustion with the lowest potential for emission of N{sub 2}O from the soil per produced energy unit. The aims of this study were to assess the annual N{sub 2}O flux from a Miscanthus `Giganteus` (M. `Giganteus`) and winter rye (Secale cereale) field, and to investigate the factors affecting the N{sub 2}O emission. To obtain these aims a method was developed for measurements in tall crops. The thesis contains a literature review on the N{sub 2}O emission from the soils, a section with development of the technique for N{sub 2}O flux measurements, and an experimental section. Finally, the thesis contains a section where the results are discussed in relation to the use of energy crops. In all the filed studies, the N{sub 2}O emission was measured by using a new developed closed-chamber technique. The main advantages of the chamber method were the ability to contain growing plants up to a height of 3 m, and the relatively large area (2X2m) covered by each other. Soils with annual and perennial crops can be expected to emit less then 3 kg N{sub 2}O ha{sup -1} yr{sup -1}. This amount corresponds to 960 kg CO{sub 2} ha{sup -1} yr{sup -1} compared to a total CO{sub 2} reduction of 10 to 19 tons CO{sub 2} ha{sup -1} yr{sup -1} using the energy crops as substituion for fossil fuels. An efficient way to reduce the N{sub 2}O emission is to exclude use of fertiliser but this also reduces the dry matter yield and consequently also the CO{sub 2} reduction

Effect of Varieties and Plant Population Densities on Dry Matter Production, Radiation Interception and Radiation Energy Conversion in Peanut

Directory of Open Access Journals (Sweden)

agus suprapto

2012-05-01

Full Text Available The solar radiation is one of the major criteria to obtaining advantages on peanuts (Arachishypogaea L.. Although various combinations of crops have been reported, but variety association and plant population densities (PPD during the periodically stage of growth on peanuts have yet to be analyzed. Dry matter production (DM, radiation energy interception, and radiation energy conversions were monitored over the growth period of two varieties of peanut. An experiment was conducted in Jambegede Research Farm, Indonesian Legume and Tuber Crops Research Institute, Malang, East Java, Indonesia, from July until October 2011. The experiment was arranged in a Split Plot Design with three replications. Peanut varieties, as the main plot consisted of two treatments: Kelinci andKancil variety. In addition, five PPD variations as sub plot consisted of 8.1, 11.1, 16.0, 25.0 and 44.4 plant m-2 were arranged in a square spacing. The results showed that DM production from high PPD increased gradually to lower PPD in all varieties. Interception efficiency (IE increased in all varieties from early sowing. A plant population density of 25.0 m-2 and 44.4 plants m-2 intercepted more radiation over 11.1 or 16.0 plants m-2. Conversion efficiency of radiation energy (CE to total dry matter production on Kelinci variety (1.52% indicated a slight higher percentage than on Kancil variety (1.41%. Moreover, the CE and IE values indicated a decrease as the PPD increased on maximum DM.

Some applications of solar energy in Thailand. Research report No. 61

Energy Technology Data Exchange (ETDEWEB)

Htun, M N; Aftab, M P; Ramachandran, P N

1976-06-01

Solar energy for process heat is identified as the application with potential for widescale use in rural areas rather than urban centres of Thailand. Three applications of solar energy, namely distillation, drying, and cooking are investigated. The units for the study are designed with low cost, flexibility and durability as the aim. The production efficiency of a conventional solar still is improved by the use of internal or external mirrors. To improve the production and efficiency of a solar still, a suspension of activated carbon particles is introduced into the still. However, the most significant improvement in efficiency and production occurs when the solar still is filled and operated with a static bed of burnt rice husk. The solar dryer, drying tapioca chips can reduce moisture content of around 71% down to 14% within 8 hours of operation. The solar dryer performs more efficiently and effectively than open floor drying. The solar cooker is inconvenient to use and operate and the potential for widescale use is concluded to be remote unless social habits change and the cooker made more comfortable to utilize.

Prospects of potential fodder-crops in hilly regions, especially northern areas of pakistan, their production and conservation

International Nuclear Information System (INIS)

Hussain, A.; Khan, S.

2005-01-01

The comparison of green-fodder and dry-matter yields in various winter cereal fodder crops showed that oat is a high fodder-yielding and more nutritive crop than barley, cereal rye wheat and triticale. Average of the three locations in northern areas of Pakistan (i.e. Gilgit, Chilas and Skardu) indicated that green-fodder yield obtained from oats was 54% higher than barley and 50% than cereal rye. It was also determined that oats and barley have greater re-growth potential than triticale. In oats, it was assessed that whole dose of N=75 kg/ha applied at the time of sowing and the split doses of N at the time of sowing and at vegetative stage of the crop increased green-fodder yield by 250% and 287% respectively than control. Improved varieties of oats viz. PD2L V65 and S-81 produced the highest total green-fodder yields of 87.34 and 86.10 t/ha under two cut system. Also re-growth potential of these varieties was the highest than the other cultivars. In winter legume fodder crops, berseem produced two times more green and dry matter yields as compared to shaftal at Gilgit and Chilas. Berseem harvested 6 cm above ground level and 45 days interval showed good results. Protein percentage decreased as cutting intervals increased in berseem crop. The improved lucerne variety Sundor was superior to local variety both in green-fodder and dry-matter yields. The yield of lucerne decreased with the increase in altitude which might be due to low temperattlre, variation in soil fertility and short growing seasons. Green forage and pasture crop species are dried enough to permit their safe storage, without spoilage or serious loss of nutrients. About 70-90% of water present in standing crop at mowing is reduced to 18-20% by sun and wind without adversely affecting nutritive value. (author)

Seasonal light interception, radiation use efficiency, growth and tuber production of the tuber crop Plectranthus edulis

NARCIS (Netherlands)

Taye, M.; Lommen, W.J.M.; Struik, P.C.

2013-01-01

Plectranthus edulis (Vatke) Agnew (Lamiaceae) is an ancient Ethiopian crop that produces below-ground, edible tubers on stolons. It is grown from seed tuber pieces. There is thus far little quantitative information on dry matter production of this crop and parameters determining growth and yield.

Leaf wetness distribution within a potato crop

Science.gov (United States)

Heusinkveld, B. G.

2010-07-01

The Netherlands has a mild maritime climate and therefore the major interest in leaf wetness is associated with foliar plant diseases. During moist micrometeorological conditions (i.e. dew, fog, rain), foliar fungal diseases may develop quickly and thereby destroy a crop quickly. Potato crop monocultures covering several hectares are especially vulnerable to such diseases. Therefore understanding and predicting leaf wetness in potato crops is crucial in crop disease control strategies. A field experiment was carried out in a large homogeneous potato crop in the Netherlands during the growing season of 2008. Two innovative sensor networks were installed as a 3 by 3 grid at 3 heights covering an area of about 2 hectares within two larger potato crops. One crop was located on a sandy soil and one crop on a sandy peat soil. In most cases leaf wetting starts in the top layer and then progresses downward. Leaf drying takes place in the same order after sunrise. A canopy dew simulation model was applied to simulate spatial leaf wetness distribution. The dew model is based on an energy balance model. The model can be run using information on the above-canopy wind speed, air temperature, humidity, net radiation and within canopy air temperature, humidity and soil moisture content and temperature conditions. Rainfall was accounted for by applying an interception model. The results of the dew model agreed well with the leaf wetness sensors if all local conditions were considered. The measurements show that the spatial correlation of leaf wetness decreases downward.

Soil hydrology of agroforestry systems: Competition for water or positive tree-crops interactions?

Science.gov (United States)

Gerjets, Rowena; Richter, Falk; Jansen, Martin; Carminati, Andrea

2017-04-01

In dry periods during the growing season crops may suffer from severe water stress. The question arises whether the alternation of crop and tree strips might enhance and sustain soil water resources available for crops during drought events. Trees reduce wind exposure, decreasing the potential evapotranspiration of crops and soils; additionally hydraulic lift from the deep roots of trees to the drier top soil might provide additional water for shallow-rooted crops. To understand the above and belowground water relations of agroforestry systems, we measured soil moisture and soil water potential in crop strips as a function of distance to the trees at varying depth as well as meteorological parameters. At the agroforestry site Reiffenhausen, Lower Saxony, Germany, two different tree species are planted, each in one separated tree strip: willow breed Tordis ((Salix viminalis x Salix Schwerinii) x Salix viminalis) and poplar clone Max 1 (Populus nigra x Populus maximowiczii). In between the tree strips a crop strip of 24 m width was established with annual crop rotation, managed the same way as the reference site. During a drought period in May 2016 with less than 2 mm rain in four weeks, an overall positive effect on hydrological conditions of the agroforestry system was observed. The results show that trees shaded the soil surface, lowering the air temperature and further increasing the soil moisture in the crop strips compared to the reference site, which was located far from the trees. At the reference site the crops took up water in the upper soil (sunlight. The two tree species behaved differently. The poplar strips showed more marked diurnal changes in soil water potential, with fast drying during daytime and rewetting during nighttime. We suppose that the rewetting during nighttime was caused by hydraulic lift, which supports passively the drier upper soil with water from the wetter, lower soil layers. This experimental study shows the importance of above- and

Charging-discharging characteristics of macro-encapsulated phase change materials in an active thermal energy storage system for a solar drying kiln

Directory of Open Access Journals (Sweden)

Kumar Shailendra

2017-01-01

Full Text Available The present study explores suitability of two phase change materials (PCM for development of an active thermal storage system for a solar drying kiln by studying their melting and solidification behaviors. A double glass glazing prototype solar kiln was used in the study. The storage system consisted of a water storage tank with PCM placed inside the water in high density polyethylene containers. The water in the tank was heated with help of solar energy using an evacuated tube collector array. The melting and solidification temperature curves of PCM were obtained by charging and discharging the water tank. The study illustrated the utility of the PCM in using the stored thermal energy during their discharge to enhance the temperature inside the kiln. The rate of temperature reduction was found to be higher for paraffin wax as compared to a fatty acid based PCM. The water temperature during the discharge of the PCM showed dependence on the discharge characteristics of each PCM suggesting their suitability in designing active thermal storage systems.

Evaluating shade effects on crop productivity in sorghum-legume intercropping systems using support vector machines

Science.gov (United States)

Sorghum-legume intercropping has the potential to improve forage productivity, resource use efficiency, and forage quality under irrigation in the Southern High Plains of the United States. Crop production is conversion of solar radiation into biomass and solar radiation is wasted early in the seaso...

Market potential of solar thermal system in Malaysia

International Nuclear Information System (INIS)

Othman, M.Y.H.; Sopian, K.; Dalimin, M.N.

1992-01-01

This paper reviews the market potential for solar thermal systems in Malaysia. Our study indicates that solar thermal systems such as solar drying, solar water heating and process heating have a good potential for commercialization. The primary obstacle facing the utilization of these technologies is the financial aspects. (author)

Phytotoxicity of water-soluble substances from alfalfa and barley soil extracts on four crop species.

Science.gov (United States)

Read, J J; Jensen, E H

1989-02-01

Problems associated with continuously planting alfalfa (Medicago saliva L.) or seeding to thicken depleted alfalfa stands may be due to autotoxicity, an intraspecific form of allelopathy. A bioassay approach was utilized to characterize the specificity and chemical nature of phytotoxins in extracts of alfalfa soils as compared to fallow soil or soil where a cereal was the previous crop. In germination chamber experiments, water-soluble substances present in methanol extracts of soil cropped to alfalfa or barley (Hordeum vulgare L.) decreased seedling root length of alfalfa L-720, winter wheat (Triticum aestivum L. Nugaines) and radish (Raphanus sativa L. Crimson Giant). Five days after germination, seedling dry weights of alfalfa and radish in alfalfa soil extracts were lower compared to wheat or red clover (Trifolium pralense L. Kenland). Growth of red clover was not significantly reduced by soil extracts from cropped soil. Extracts of crop residue screened from soil cropped to alfalfa or barley significantly reduced seedling root length; extracts of alfalfa residue caused a greater inhibition of seedling dry weight than extracts of barely residue. A phytotoxic, unidentified substance present in extracts of crop residue screened from alfalfa soil, which inhibited seedling root length of alfalfa, was isolated by thin-layer chromatography (TLC). Residues from a soil cropped continuously to alfalfa for 10 years had the greatest phytotoxic activity.

Evaluation for Multi Purpose Free Species for Inter Cropping with Maize

International Nuclear Information System (INIS)

Kimotho, L.M

2002-01-01

The continued increase in Kenya's population has forced people to move into the dry lands and hence increasing demand for food and tree products in these areas. This has forced farmers to clear the existing natural forests to pave way for agricultural activities. In order to address this problem an integrated approach of planting both trees and crops on farm has been adopted. A trial was established to compare the growth performance of some local and exotic timber tree species as well as examine their effect on maize (Zea mays) crop yield. the tree treatments included Acacia polyacantha, caesalpinia velutina, Grevillae robusta, melia azaderach, senna spectabilis and senna siamea, planted at 5m x 5m spacing, in a Randomized Complete Block Design with three (3) replicates. Maize crop (Dry Land Hybrid 1 -DH1) was used as inter-crop during November-January seasons. The maize was planted at a spacing of 90 cm by 40 cm. There was a control with no trees. Growth of the trees was based on increase in both height and girth while whilst the crop yield was asses d by estimating average plot yield under each species. Results indicated that, different tree species affected the maize grain yield differently: i.e. there was no tre effect on maize yield in the earlier stages but as the trees increased in age and hence size some species caused reduction in the maize grain yields while others did not cause any reduction as yet. However, depending on the individual needs various decisions could be made on whether to compromise the crop yields, which are minimal in order to attain some timber products in addition to food. The trial is continuing in order to establish how long each tree species would permit a maize crop

Introduction to solar cell production

International Nuclear Information System (INIS)

Kim, Gyeong Hae; Lee, Jun Sin

2009-08-01

This book introduces solar cell production. It is made up eight chapters, which are summary of solar cell with structure and prospect of the business, special variable of solar cell on light of the sun and factor causing variable of solar cell, production of solar cell with surface texturing, diffusion, metal printing dry and firing and edge isolation, process of solar cell on silicone wafer for solar cell, forming of electrodes, introduction of thin film solar cell on operating of solar cell, process of production and high efficiency of thin film solar cell, sorting of solar cell and production with background of silicone solar cell and thin film solar cell, structure and production of thin film solar cell and compound solar cell, introduction of solar cell module and the Industrial condition and prospect of solar cell.

Ensuring sustainable grain legume-cereal cropping systems

DEFF Research Database (Denmark)

Bedoussac, Laurent; Journet, E-P; Hauggaard-Nielsen, Henrik

2017-01-01

health makes them a key rotation crop in the sustainable intensification and diversification of smallholder farming. This makes grain legumes a key food security crop. However, yields in developing countries are low as a result of such factors as the need for improved varieties of seed, poor seed......Grain legumes are widely cultivated, particularly for their dry seeds (known as pulses). Grain legumes are an important crop for a number of reasons. They are a rich source of protein and fibre, minerals and vitamins. In addition, their rapid growth and ability to fix nitrogen and improve soil...... distribution, the impact of pests and diseases, as well as vulnerability to poor soils, drought and other effects of climate change. This chapter summarises data from over 50 field experiments undertaken since 2001 on cereal-grain legume intercropping in 13 sites in southern and western France as well...

PERFORMANCE ASSESSMENT OF SOLAR DRYER WITH INDIRECT HEATING

Directory of Open Access Journals (Sweden)

Boryana Brashlyanova

2014-03-01

Full Text Available The performed tests were designed to identify and analyze the parameters of drying in a authors model solar dryer. They to be the basis for constructing of an improved model. Drying was carried out in a pilot model solar dryer with prunes in two cycles. Both samples were run under steady sunshine in outdoor air temperature ranging between 20-22°C in the morning and 33-35°C in the early afternoon hours. Depending on the ambient conditions, the drying temperature was found in the range of 30 to 50°C. The dried samples had a water activity Aw> 0.9, due to which the storage is at -18°C. The duration of the drying process of prunes was inconstant and lasted from 2 to 3 days, depending on the final moisture content of the product and the external temperature, humidity, and intensity of solar radiation. The obtained two products intermediate moisture prunes, in addition to direct human consumption could be used as a base for incorporation into other products. Prunes with intermediate moisture content 40% could be consumed directly at ambient temperature or after freezing and tempering at -6 to -5ºC. Based on the established parameters we are to design and produce an improved solar dryer model that allows better utilization of heat and shortening the process duration.

Soil Moisture Anomaly as Predictor of Crop Yield Deviation in Germany

Science.gov (United States)

Peichl, Michael; Thober, Stephan; Schwarze, Reimund; Meyer, Volker; Samaniego, Luis

2016-04-01

indicate that wet and dry soil moisture anomalies have a causal effect on crop yields. However, the effects vary in magnitude and direction for each crop depending on the month. For instance dry soil moisture anomalies in July, August and September reduce silo maize yield more than ten percent with respect to average conditions. Extreme wetness, however, increases silo maize yield in the same time period. A negative effect is observed for winter wheat during this period for both wet and dry anomalies. The reduction due to dry anomalies is smaller for winter wheat than for silo maize. This study shows that the impact of soil moisture anomalies varies dependent on months and crops. These evolving patterns provide new insights to improve adaptation measures for extreme soil moisture conditions. References Auffhammer, M., and W. Schlenker. 2014. "Empirical studies on agricultural impacts and adaptation." Energy Economics 46:555-561. COPA-COGECA. 2003. "Assessment of the impact of the heat wave and drought of the summer 2003 on agriculture and forestry." In Committee of Agricultural Organisations in the European Union General Committee for Agricultural Cooperation in the European Union, Brussels. p. 15.

Design, Development and Performance Evaluation of a Small Scale Solar Assisted Paddy Dryer for on Farm Processing

Directory of Open Access Journals (Sweden)

Sidrah Ashfaq

2016-04-01

Full Text Available With the continued escalation in population growth and the expansion of international food trade and demand of high quality product for food security at low cost has created considerable interest in the development of new post-harvest technologies. This is particularly important for developing countries where post-harvest losses of cereals are between 10-20% and of fruits and vegetables as high as 20- 100% A new solar assisted paddy dryer with central air distribution model (along the length of drying chamber has been developed. Due to this distinct feature of the dryer high drying rate was achieved during the drying processes .Other components of the dryer are perforated drying chamber, blower and flat plat solar air collector. Dryer was evaluated using 100kg of freshly harvested paddy at 23.78% moisture content (wb. Performance evaluation results showed that the mean drying rate of the solar assisted paddy dryer was 0.87kg/hr per for every 100kg, whereas 0.46kg/hr was the sun drying rate comparatively. The faster drying rate of the dryer reveals its suability to dry the paddy for its safe storage moisture content rapidly. By using the solar assisted paddy dryer, approximately 50% saving in time was also achieved as compared with the traditional sun drying method. Solar assisted paddy dryer took 10hr for drying the 100kg paddy up to 14%, while sun drying method dried paddy up to 13.89% in 19 hours. Cost analysis also showed that, by using solar assisted paddy dryer we candry good quality paddy at low cost as compared with the open sun drying method. For development of agriculture in the rural areas, commercial size of the solar assisted paddy dryer can be amplified and produced at community level.