EVALUATION OF THE TEMPERATURE EFFECT OF A THERMOSYPHON SOLAR WATER HEATER

This study investigated the effect of system temperature on the performance of thermosyphon solar water heater. Solar collector was designed and developed with galvanized steel, wood and copper pipes for the experiment. While the copper pipes serves as the tube through which the cold water flows, the wood was employed for the frame and stand, and the galvanized steel for the collector material. Also employed were two hot and cold water tanks of 60 and 110 litre capacities respectively. The period of experiment were taken to be 3 days each for sunshine, sun-off and moderate sunshine days, with the average data employed for the analysis. The results showed that temperature has a domineering effect on the performance of the thermosyphon system. The maximum outlet temperature obtained for sunshine, moderate sunshine and sun-off days were 94.6, 73.5 and 51oC respectively. Also the system efficiency was found to be 61.04%, demonstrating good performance. However, considering the fact that the experiment was carried out in rainy season (between April and September), it was concluded that if it is repeated during the dry periods (October to March), the efficiency of performance will be more as these period is characterized by low cloud cover, high temperature and high radiation intensities. The outcome of the study was compared with published results and it clearly demonstrates that the designed system can suitably be employed for both domestic and industrial uses

Linear Programming Approach to Sustainable Management of Gmelina Arborea Plantations in a Nigerian Lowland Rainforest

A linear programming (LP) model was used to prescribe timber harvest in the management of even-aged Gmelina arborea plantations in Omo Forest Reserve, Southwestern, Nigeria. The plantations now being managed for timber production are to be exploited within fifteen years based on a 5-year harvesting period. Data was generated from eight compartments which were established between 1991 and 2000, and covering an area of 9489 hectares with a total volume of 9,716,726.0m3. Sample plots (20m X 20m) were randomly laid out in each compartment. In each sample plot, tree diameters and heights were measured and tree volumes estimated. The maximization problem of wood volume on compartmental level was formulated and solved. The solution of the LP showed that about 12.5m3 million of wood was maximized. The optimal solution prescribed 3500ha (4,703,426.0m3) to be cut in period I (2008 –2012); 3000ha (3,400,946.0m3) is to be cut in period II (2013 – 2017) while 2989ha (4,402,982.0m3) will be cut in period 2018 – 2022). Sensitivity analysis and opportunity costs were used to highlight the effects of changing some of the model parameters on the prescribed optimal solution. Key words: Linear programming, timber harvest, Gmelina arborea, Omo forest reserve, optimal solution, sensitivity analysi

Thermodynamics Characterization of Density models for an Effective Solar Water Heater Sizing

The problem faced in Sizing of an effective Solar Water Heater (SWH) by engineers to meet certain design requirement is highly enormous. Using the thermodynamic characterization relation and the knowledge of Solar Water Heater (SWH) density’s model; various design were evaluated. The result shows that density model actually predicts adequately and providing alternative means of estimating these design parameters. Also, the properties of the system, such as entropy and enthalpy (specific heat capacities), which cannot be determined directly from experimental axiom, were evaluated. These evaluations therefore, give room to express the thermodynamics properties of the system and consequently improve the design performance. Further comparisons with experimental results reveal a better outfit. Therefore through the knowledge of thermodynamic relation an efficient Solar Water Heater is operated and empirical data is expanded

Construction and Testing of A Single and Double Ring Infiltrometers in Auchi Polytechnic, Edo State

This paper presents the results of the construction of an improvised double and single ring infiltrometers. The study was carried in Auchi Polytechnic campus, after the construction, the double ring and single ring infiltrometer were used to carryout infiltration tests at four different locations. The t-test was used to test check the performance of the double and single ring infiltrometers. The results of the soil properties showed that the soil texture was predominantly sandy loam and loam respectively. The result presented herein showed a high significant difference between the performance of the single and double ring infiltrometer at Plot A and no significant other plots. The total cumulative infiltration depth of the single-ring infiltrometer for the A, B, and C and D fields were 188.30 cm, 59.70 cm, 77.00 cm and 97.00 cm, respectively.  The total cumulative infiltration depth of the Double-ring infiltrometer for the A, B, and C and D fields were 123.30 cm, 75.60 cm, 70.50 cm and 95.20 cm, respectively. Generally, Philip’s model performed better than Kostiakov’s model Keywords: Single and Double ring infiltrometer, infiltration models DOI: 10.7176/JNSR/12-3-04 Publication date: February 28th 202

Design, procurement and construction strategies for minimizing waste in construction projects

The construction industry contributes the largest portion of waste to landfill, and it consumes a significant proportion of mineral resources excavated from nature. Due to adverse environmental impacts of waste generation, as well as financial gains associated with its minimization, waste intensiveness of the industry has remained a major concern across nations. This study investigates the design, procurement and construction strategies for waste minimization, using a dynamic approach. Apart from an investigation of the key and underlying measures for construction waste mitigation, the study considers the interrelationship between stages of projects' lifecycle. This is as activities carried out at an earlier stage are capable of engendering occurrences at later stages of the dynamic project delivery processes. Following the tenets of critical realism philosophy and exploratory sequential mixed method, the study combined qualitative and quantitative approaches at intensive and extensive stages respectively. At the early stage of the study, data were collected through literature review and focus group discussions with industry experts. Results of the qualitative study were used to develop a questionnaire, which was analysed using statistical approach and structural equation modelling. As a means of investigating the key drivers of waste minimization at a holistic level, a system dynamic model was developed to simulate the interplay and effects of different strategies that were confirmed through the previous process. The study suggests that design stage has the most decisive impacts on construction waste minimization. At this stage, the key dimensions for designing out waste include design for modern methods of construction, collaborative design process, design for standardisation and waste-efficient design documentation. Error-free design and involvement of contractors at early design stage are part of the critical success factors for designing out waste. With design being much important for waste minimization, competencies of design in terms of waste behavioural competency, design task proficiency, construction-related knowledge and inter-professional collaborative competency are essential for designing out waste. Materials procurement process could enhance waste minimization by considering its key dimensions for driving waste-efficient projects, which includes waste-efficient materials purchase management, suppliers' alliance and waste-efficient bill of quantity. Efficient materials take-off and take back scheme are confirmed as critical success factors for driving waste minimization through materials procurement processes. During construction activities, waste could be reduced through prefabrication and offsite technology, contractual requirements, maximisation of materials reuse and improved collaboration, among others. Prefabrication, supply chain alliance and collaborative procurement routes are confirmed as the critical success factors for reducing waste during construction process. Dynamic interplay among these sets of strategies suggests that notwithstanding the significance of the different measures during design, procurement and construction processes, prefabrication technology and collaborative procurement route are the holistic drivers of construction waste minimisation. The study implies that designers could effectively drive waste minimization through dimensional coordination and standardisation of design in line with standard materials supplies. In addition to the need for prefabrication and offsite technologies, increasing collaboration among project team is requisite to reducing waste generated by construction activities. By implementing the strategies suggested in the study, substantial proportion of construction waste would be diverted from landfill

Suitability of local binder compositional variation on silica sand for foundry core-making

The use of local oils, namely groundnut oil, cotton seed oil and palm oil with Nigeria local clay and silica sand for the production of foundry cores has been investigated on varying composition. Addition of cassava starch, local clay, oil and moisture to sand are used to produce strong and efficient core. These oils were tested and it was found that the three could be used to produce foundry cores. The best composition was found to be core comprising 2.5% starch, 2.5% clay, 8% oil, 8% moisture and 68% sand and baked at 150oC for 1 h 30min. The tensile strength of the core were as high as 600 KN/m2