Spraying pesticides are important to protect crops from insects consequently to obtain the highest production yield. The manual or battery knapsack sprayers are dominant in the Egyptian market. However, the first type depends on the operator skill and for the second type; the battery charge is not constant throughout the operating period. Therefore, the research aimed to develop a knapsack sprayer powered by solar energy that operates throughout the day at constant flow rate pressure. This was achieved by manufacturing the developed sprayer from local materials, and by providing it with a solar pump powered by a battery, the photovoltaic panel and an electronic circuit in which the spray pressure can be controlled from 0 to 4 bars. The amount of pesticide can be controlled according to the age of the plant, as well as, the uniformity of pesticide distribution identified using constant pressure throughout the spray period and thus ensuring the fairness of pesticide distribution and not relying on lobar experience. The results indicated that the number of operating hours for the developed sprayer reaches more than 8 hours per day with constant pressure compared to using the battery-powered sprayer only, which operates from 1.5 to 3 hours only with no pressure stability at a flow rate 600 to 1000 ml/min. On the economic side, the cost of spraying from the developed sprayer is 54.37 L.E/fed compared with (102.50 and 79.70 LE /fed) for manually sprayer and battery sprayer, respectively. Therefore, a developed sprayer is high economic and practical value in the agricultural sector.
The presented study aims to investigate the effect of using two effective irrigation techniques; the pulse-deficit drip irrigation and the deficit irrigation powered by solar energy in a greenhouse. This work studied impact of these factors a tomato soilless productivity, water productivity and of these techniques solar energy productivity. The experimental study was carried out at Tractors and Farm Machinery Research and Test Station, Alexandria Governorate. The results showed that, the pulsed-full drip irrigation at 100% of ETc (FP100) gave the highest yield of 35.8 ton/fed., but the continuous-deficit drip irrigation at 50% of ETc (DC50) gave the lowest yield of 20.4 ton/feddan. The highest water productivity (WP) was 37.1 kg/m 3 when using the treatment of (DP50), on the other hand the Continuous-Full drip irrigation at 100% of ETc (FC100) (control treatment) represents the lowest WP of 27.9 kg/m 3 . Application of pulse-deficit irrigation (DP50) saved 50% of the water irrigation requirements and decreased the total tomato yield per feddan by 34%, but the water productivity increased by 33% compared with continuous-full irrigation (FC100) as control. Treatment of pulse-deficit irrigation (DP50) saved 50% of solar energy consumption and increase energy productivity (908 kg/kWh) by 33% compared to continuous-full irrigation (FC100) as control. The results showed that pulse-deficit drip irrigation technique, decrease tomato yield but increase WP in all treatments. This study recommend apply, pulse-deficit irrigation (DP75) technique results in reducing tomato yield by 3% and increasing water and energy productivity by 29.3 and 29.4% respectively.
Egypt has one of the best weather conditions for producing renewable energy in the world. As a result, there has been a proven market pull for solar energy in the region in a growing clean energy export market as clean energy. Solar energy maintenance is relatively low comparing to other power generation sources. Although, less maintenance is required, the important factor that reduces its generation according to accumulate dust on solar PV modules. Dust accumulation effectively reduces the energy yield of solar panels. So, the current paper deals with the locally designed automatic cleaning mechanism for solar PV modules. The designed mechanism consists of an electronic solar module that automatically cleans the solar module at the required rate. without requiring water to clean the solar module. This cleaning mechanism is also suitable for pole mounted street lighting systems where daily manual cleaning is not possible and could be more costly. Six months later from start experiments, the obtained results of PV panel recorded maximum value of volts, current and power were 18.1 V, 0.85 Amp 15.39 Watts respectively for cleaned one while it was decreased up to 8.87 V, 0.425 Amp and 3.77 Watt for the uncleaned respectively. The use of the developed cleaning unit improves the energy produced from PV panel by 42.32% compared to the control.
A photovoltaic panel (PV) is a practical method to produce electrical energy from solar light. The solar conversion efficiency of PV panels is still low, improving it wills makes great differs of PV panels used. However, the efficiency of PV panels can be improved in many ways. One of them is to connect reflectors with PV panel. So, the aim of this research is to study the effect of three types flat reflectors (Nickel Chrome reflector; NCR, Aluminum sheet reflector; ASR and reflective glass reflector, RGR) connected with both sides of PV panels at four different tilts angles (30, 45, 60 and 90 o) on the intensity of solar radiation falling per different periods of times and to determine the impact and performance of the PV panels output. Generally, the maximum daily average of solar radiation flux incident on the PV panel (from 8:00 to 17:30) was 828.93 W.h/m 2 for NCR at a reflector angle of 30 o (RA 30) and the corresponded percentage increment compared to the control panel was 24.98 %. Also, at zero shade periods (ZSP) from 10:30 to 13:30, the maximum daily average value of total power was 0.758 kW, which represents 74.61 % of the daily total power for NCR at RA 90. The highest PV panel temperature was recorded for PV panel with NCR at RA 90. The rate of increase in the power resulting from the reflectors is much greater than the amount of loss of power resulting from the rise in temperature.
The aim of this research was study the effect of dust deposition on solar radiation and solar photovoltaic panel. A theoretical calculation was done and experiments were carried out at Mariout Research Station, El-Amria-Alexandria-Desert Research Center. To study the effect of dust deposition two square plates of glass (20x20 cm) and three pyrnometers were used, the first plate (the control) was cleaned daily and the other was used to determine the solar radiation. The period of the experiment is 175 days from 14 th march to 26 th August 2017. From the experiments; the dust deposition reduces the amount of solar radiation which is falling on the solar panel and creates shadow effect. With the passage of time the density of dust on the panel increases. And this reduces the electric power of the solar panel,. From the data, there was power reduction up to 51.12 %. The efficiency of the solar photovoltaic panel system was reduced from 15.9 to 7.88 % for clean and unclean modules respectively. The total correction solar radiations for the experimental period are 37.4 and 18.28 (kW.h/m 2) for clean and unclean modules respectively. The unclean module with dust deposition, showed total output power (24.88%) less than the clean module for the period of 25 weeks.
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