ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY AND ENVIRONMENT

26-36

Authors: M K Othman, S Z Abubakar, X Litrico, G Belaud

Laboratory evaluation of three free overfall equations for predicting water profile over hydraulic structure – weir was conducted in Irrigation laboratory of Higher National College of Agriculture of Montpellier (ENSAM) , France. A broad-crested weir was constructed as a reduced physical model to simulate the gated-structure (Begemann gate) for upstream water control in the Main Canal of Hadejia Valley Irrigation Project (HVIP),Northern Nigeria. Instrumentation in the ENSAM laboratory allows precise variation of channel flows with incremental changes of 5 l/s. Three recently developed models in a progressive succession were used for comparison between measured and predicted data to establish degree of accuracy in the prediction of water profile passing over weir in open channel. Results of the evaluation show that the three equations performed differently in predicting water profile over weir at the selected channel flows of 60 l/s, 30 l/s and 10 l/s respectively. These stream sizes were chosen because they were the maximum, medium and minimum for the canal capacity. Although the stream size directly influenced the water profile as a result of internal pressure due to convergence of stream filaments between upper and lower laminar flow. Longer velocity jumps were recorded at the higher stream size (60 l/s) of 35 cm from weir crest end while less than 25 cm distance was covered by the least stream size of 10 l/s. Generally, based on the R2 values and percentage errors for the three models at all the three selected stream sizes, Cavailhé model predicted the water profile with high degree of accuracy followed by that ofDavis and lastly the Hager model. The same order was observed on ease of manipulation and user friendliness. The choice of water profile prediction model with high degree of accuracy is important in the design of hydraulic structures for water conveyance, diversion and measurements in irrigation canal network.

45-53

Authors: V I O Ndirika, S A Ademoye

A kerosene-heated chicken egg incubator of 160 eggs capacity was developed and its performance evaluated based on incubation temperatures, relative humidity, period of incubation and percentage of eggs hatched. The results revealed that the average incubation temperature and relative humidity obtained were 38.68 0C and 58.16% respectively at average ambient conditions of 27.20C temperature and 84.68% relative humidity. Also, the incubation temperature and incubation relative humidity at different levels of tray varied between 36.8-40.90C and 46.5 – 67% respectively, but the differences in their mean values at different egg tray levels were not statistically significant at 5% level. Up to 80% of the eggs were hatched over a period of 22 days at hatching temperature of 37.50C within ambient conditions of 270C temperature and 68.5% relative humidity. The results obtained were found to conform with the results obtained from already established research works on natural incubation method for chicken.

60-65

Authors: I S Aji, A A Balami, A T Abdulrahim

The harsh weather condition experienced in Maiduguribetween the months of February and June of most years has been a problem to the populace. Buying conventional air-conditioners to ameliorate this problem is difficult for the ordinary people in Maiduguri. In an attempt to lower the temperature of an average 16m2 room, an electrically operated water supply cooling system was designed, constructed and tested and was found to make the room conducive for human comfort. Guard sponge was selected and used out of the existing sponges because it has been found to reduce the ambient temperature better than others. Weather conditions of Maiduguri for the past fifteen years and the unreliability of electricity supply were put into consideration in the design of the water air conditioner. The machine was able to reduce the temperature of an average room (16 m2) by 28% over a period of 42 minutes. The efficiency of the water air-conditioner with respect to the conventional unit is 60%. Seventy five per cent the machine parts were sourced locally, this is to make its production cheap and more affordable to low income earners.

76-84

Authors: A U Dzivama, J C igbeka

The performance efficiency of an evaporative cooling system (fan and pad) under varied levels of parameters (water flow rate, pad thickness and air velocity) was evaluated using a 3-factor statistical design. A response equation was developed and was used to obtain the optimum levels of the parameters required for optimal operation of the evaporative cooling system. Simulation result of the response equation indicated that for optimum operation of the evaporative cooling system, a water flow rate of 4.4L/min, pad thickness of 47mm and air velocity of 1.6m/s was required. Simulated saturation efficiency of 70.4 % was obtained with these values while the measured was 84.6 % at water flow rate of 4.5L/min, pad thickness of 60mm and air velocity of 2.3m/s .