Search

Experiments were conducted to evaluate the performance of a flat plate solar collector in terms of its energy, exergy, and efficiency. The data were analyzed using three factors in a Completely Randomized Design. The first factor was tilt angle with three levels, the second was air mass flow rates with four levels, and the third was heat storage fluid with four levels, making a 4 x 3 x 4 factorial experiment. The least significant difference between means was calculated with Alfa (α) < 0.01. The results showed that the maximum energy of 1509.74 kJ hr-1 was gained by the flat plate solar collector when a polyethylene glycol solution was used in head raised pipes at 11.76 kg min-1 air flow rates with a 30o collector tilt. The maximum exergy of 46.0 % was gained by the flat plate solar collector when air was used in head raised pipes at 4.67 kg min- 1 air flow rates, with 30o collector tilt angle, while the minimum exergy gain of 32.67 % was recorded for a polyethylene glycol solution in the solar collector at 1.78 kg min-1air fl ow rates with collector tilting at 30o. The maximum efficiency of 39.71 % was gained by the fl at plate solar collector when a polyethylene glycol solution was used in head raised pipes at 9.69 kg min-1 air flow rates with 40o collector tilt angle. The storage medium showed that the maximum energy of 40,207 kJ day-1was stored in the energy storage unit per day, followed by 33,291 kJ day-1 stored in salt solution while minimum energy of 29,640 kJ day-1 was stored with water. [ABSTRACT FROM AUTHOR]

The objective of the study was to compare drying processes (open sun, Hot Air of Solar Collector and Micro wave) and preservatives (potassium meta bisulphate, Sodium benzoate and control) on drying kinetics, texture and antioxidants retention of three species (Morus alba, Morus nigra and Morus. Morus laevigata) in the mulberries. Mulberries were pretreated with preservatives and subject to selected drying processes. Drying kinetics, texture and antioxidant retention were determined before and after each drying process. The results were analyzed using three factorial completely randomized design and means were compared at p = 0.05. The statistical analysis of the data showed that different drying process showed a significant (p < 0.05) Effect on drying kinetics, texture and antioxidant retention in mulberry fruits. Preservatives showed a significant effect on drying kinetics while it showed a nonsignificant effect on the texture and antioxidant retention. High moisture lost hr-1 (5.4%) was recorded in the microwave while minimum (1.8%) was recorded in open sun drying. Good textured dried mulberries with optimum hardness (313g) and stiffness (141g.mm-1) were found in hot air dried samples. Similarly, more antioxidants (52%) retained in samples dried with hot air followed by microwave (47%) while the minimum (41%) was recorded in open sun drying. It was concluded that hot air drying is the best drying process to get valuable dried quality mulberries with good texture and more antioxidants. [ABSTRACT FROM AUTHOR]

Soil degradation is the major threat to agricultural sustainability because it affects the soil productivity. Present study was conducted in 2008 to evaluate physico-chemical properties and fertility status of some eroded soil series of Sharkul area district Manshera, Hazara division, Khyber Pakhtunkhwa, Pakistan. Six soil series including slightly eroded (Dosera and Girari), moderately eroded (Nakholi and Sharkul) and severely eroded (Ahl and Banser) were selected. Soil samples were collected from surface (0-15 cm), subsurface (30-45 cm) and substrata soil (60-75cm) depths and were analyzed for various soil properties. Due to severity of erosion, bulk density increased, while total porosity, saturation percentage and organic matter decreased significantly. AB-DTPA extractable P, K, Fe, Cu, Zn, and Mn concentrations were decreased due to the severity of erosion in surface and sub surface soils, whereas in the substrata soils (60-75 cm depth), the effect of erosion was almost non significant. Sub-surface and sub-strata soils were found deficient in available P (< 3 mg kg-1) while available K was in medium range (50-120 mg kg-1). Seventeen percent surface and 33% subsurface samples were deficient in available K. Organic matter (0.42-1.82%) was deficient only in severely eroded soils while satisfactory in moderately and slightly eroded soils All the soils were non saline (EC < 4 dS m-1), pH (7.0-8.6) and slightly calcareous (lime content 0.25-5.20%). Zinc, Fe and Mn contents were low in 44, 39 and 28% samples in surface soils, respectively. The extent of nutrient deficiency was in the order of P > Zn > Fe > Mn. The physical and chemical properties of eroded soils varied significantly and the increasing severity of erosion resulted in corresponding deterioration of soil quality. [ABSTRACT FROM AUTHOR]