Energy interaction of sub processes in drying value chain using exergy waste. Study case: drying and greenhouse growing of tomato

In the drying value chain for fruits and vegetables, nine sub-processes have been identified. This work analyses the interaction between growing in greenhouses and drying sub processes for exergy and water flow reutilization. By thermodynamic model simulation, wet air from drying process is retrieved back to the crops within greenhouses. This interaction is an economic solution for the problem of high temperatures and low relative humidity within the greenhouses in hot dry environments. Humidity after the drying is quantified to estimate exergy profiles. Results are an average decrease of temperature of 12.8 °C and 8.7 °C and an increment of relative humidity of 7% and 9%, for different day conditions

Energy interaction of sub processes in drying value chain using exergy waste. Study case: drying and greenhouse growing of tomato

In the drying value chain for fruits and vegetables, nine sub-processes have been identified. This work analyses the interaction between growing in greenhouses and drying sub processes for exergy and water flow reutilization. By thermodynamic model simulation, wet air from drying process is retrieved back to the crops within greenhouses. This interaction is an economic solution for the problem of high temperatures and low relative humidity within the greenhouses in hot dry environments. Humidity after the drying is quantified to estimate exergy profiles. Results are an average decrease of temperature of 12.8 °C and 8.7 °C and an increment of relative humidity of 7% and 9%, for different day conditions

Mathematical model for a heat pump dryer for aromatic plant

A mathematical model was developed to evaluate the performance of heat pump dryer for drying of aromatic plants. The model consists of three sub-models; namely, drying model, heat pump model, and performance model. Drying model was developed based on mass balance, heat balance, heat transfer and drying rate equations. Heat pump sub-model consists of some theoretical and empirical equations for estimating the parameters of evaporator, compressor, condenser and expansion valve. The performance sub-model was the equations for prediction of drying efficiency, COP (coefficient of performance), MER (moisture evaporating rate) and SMER (specific moisture evaporating rate). The model was validated with the experimental data. The experiments was conducted in a fixed bed drying of valerian roots (Valeriana officinalis L.) in cooperation with a agricultural company (Agrargenossenschaft Nöbdenitz e.G., Thüringen) in Thüringen, Germany. Data logger was used to record the temperature, relative humidity, humidity ratio and enthalpy of air at different positions of the dryer equipped with different types of sensors. The average drying air temperature was 36.84°C and relative humidity was about 20%. About 89 hours were required to reduce the moisture content of valerian roots from 89 to 9% (wb). The simulated results (temperature, relative humidity and moisture content) agreed well with the experimental results. The average COP, MER and SMER and drying efficiency were 5.45, 140.03 kg/h, 0.038 kg/kWh, and 78.23%, respectively. This model may be used for design data for heat pump dryer for drying of aromatic plants as well as other heat sensitive crops

Euroland: New conditions for economic policy

The cyclical situation at the beginning of the European Monetary Union (EMU) is favorable: The upswing in Euroland has firmed, unemployment is going down, and inflation is low. However, economic growth outside the new currency area has weakened significantly during 1998, and fears are mounting that the crises in various regions of the world economy could endanger the current expansion in Euroland. Against this background, the significance of external conditions for the business cycle in Euroland — as well as the regional structure of exports — is analyzed. An important issue for an adequate design of economic policy is to what extent capacities in Euroland are currently utilized and whether cyclical unemployment is still significant. In addition, it is important to know whether the business cycles in the individual countries converge or not. In light of the findings from these analyses, the course of monetary, fiscal, and wage policy is evaluated in order to assess the outlook for Euroland until the end of 1999. --

FEM Analysis of Effects of Mechanical Impact Parameters on Fruit Characteristics

Mechanical impact on fresh agriculture commodities may be a criterial issue during mechanical processes such as grading, sorting, conveying, packing or transport. The applications of electronic measuring devices in form of artificial fruits like ‘Instrumented Spheres’ (IS) are an aid to quantify influences of mechanical impact on the value of fruit, vegetable and potato. Additionally, modelling and simulation of impact on fruits helps to identify those influencing parameters. In this study, modelling and simulation runs were performed based on the Finite Element Method (FEM). For dropping tests an ‘Acceleration Measuring Unit’ (AMU) was used which can be implemented into real or artificial fruits to measure the accelerations upon impact. The test stand was equipped with a force sensor. The relevant parameters Young moduli, density, mass, fruit dimensions, and dropping test heights were varied for the tests. FEM simulation results were compared with measured acceleration values of the AMU and force values of the test stand. On dropping potato tubers with mass of 100‑120 g from 25 cm height onto steel plates, the impact force ranged from 190 to 220 N. Simulations showed that the impact force in similar conditions (mass of 102‑113 g and Young moduli of 2.5‑3.5 MPa) ranged from 198 to 242 N, which is in good agreement with the experimental results. When the tuber mass was 190‑210 g, the measured impact force varied from 310 to 325 N. Simulations for masses of 199–221 g resulted in impact forces of 306‑325 N, again in good agreement with the experimental results. However, AMU acceleration values ranged from 922‑932 m s-2, for masses of 100‑200 g, to 765‑824 m s-2 for masses of 190‑210 g. Simulations, in similar conditions, provided acceleration values of 1934‑2314 m s-2 for masses of 102‑221 g (Young moduli 2.5‑3.5 MPa) and ranging from 1497 to 1843 m s-2 for masses of 199‑221 g, which are about twice as high than measured, probably due to effects from imperfect fit when implanted the AMU into the test fruit

Crop conceptual model for predicting productivity of bread wheat in semi-arid Kenya

 P. K. Kimurto1, K. Gottschalk2, M. G. Kinyua3, J. B. O. Ogola4, B. K. Towett 1(1. Department of Crops, Horticulture & Soil Sciences, Egerton University, P.O. Box 536, Njoro, Kenya;2. Leibniz-Institut für Agrartechnik Potsdam-Bornim e.V. ATB, Max-Eyth-Allee 100, 14469 Potsdam, Germany;3. Department of Plant Breeding and Biotechnology, Moi University, P.O. Box 39000, Eldoret, Kenya;4. Department of Plant Production, University of Venda, a, Private bag X5050, South Africa) Abstract: Carrying out field trial-research in dryland areas is usually expensive and costly for most national breeding programmes; hence development of simple crop simulation models for predicting crop performance in actual semi-arid and arid lands (ASALS) would reduce the number of field evaluation trials.  This is especially critical in developing countries like Kenya where dry areas is approximately 83% of total land area and annual rainfall in these area is low, unreliable and highly erratic, causing frequent crop failures, food insecurity and famine.  This paper used data generated from the rain shelter by measurement of evapotranspiration together with weather variables in Katumani to predict wheat yields in that site.  Maximum yield of the wheat genotype considered for genotype Chozi under ideal conditions was 5 t/ha.  Total above-ground biomass was obtained and grain yield was to be predicted by the model.  Transpiration was estimated from the relationship between total dry matter production and normalised TE (7.8 Pa).  The results presented are based on the assumption that all agronomic conditions were optimal and drought stress was the major limiting factor.  Predicted grain yield obtained from the conceptual model compares very well with realised yields from actual field experiments with variances of 14% – 43% depending on watering regime.  This study showed that it is possible to develop simple conceptual model to predict productivity in wheat in semi-arid areas of Kenya to supplement complicated and more sophisticated models like CERES-maize and ECHAM models earlier used in Kenya.  The presence of uncontrolled factors in the simulation not accounted for in the estimation and could have contributed to decrease in observed yield need to be included in the model, hence modulation of the equations by introducing these factors may be necessary to reduce variances; thus need to be quantified.  To improve the accuracy of prediction and increase wheat production in these areas measures that conserve water and/or make more water available to the crop such as prevention or minimisation of run-off, and rain water harvesting for supplemental irrigation are necessary.Keywords: wheat, conceptual model, drought, evapotranspiration, yield response Citation: Kimurto P. K., K. Gottschalk, M. G. Kinyua, J. B. O. Ogola, and B. K. Towett.  Crop conceptual model for predicting productivity of bread wheat in semi-arid Kenya.  Agric Eng Int: CIGR Journal, 2010, 12(3): 25-37.&nbsp