SUMMARY

The concept of thermoelectricity was employed in the investigation of thermoelectric potential of a multi-junction thermocouple embedded in an asphalt bonded solar panel. The system consists of asphalt embedded thermocouples; placed at a convenient angle and provided with transparent cover for applications requiring energy delivery at temperatures up to 100^oc, storage for electric potentials and load output.

INTRODUCTION

The development and use of new and renewable sources of energy has to be accelerated (Oladiran, 1999; Akarakiri 2003) as petroleum resources are being rapidly depleted, it is essential to diversify power production techniques so as to conserve these fuels for premium applications. In this era of energy shortages, the sun has become an unfailing source of energy because of its abundant and environmentally attractive potential with enormous economic promise. It is free, the only cost being to harness it.

APPLICATIONS

Solar energy has been limited mainly to low grade thermal applications in the Sub Saharan African region. For instance over 10,000 units of solar water heaters have been installed in Botswana, Zimbabwe, and South Africa Akarakiri (2003). A project funded by the Agency for International Development (AID) in Tangaye, Africa provides fresh water and runs a grain mill to make flour for sale (Maycock, 1981).

Specific areas of application of solar technology in Nigeria have been identified to include electricity supply during power outages and drying of agricultural and forestry products like cocoa, timber etc (Akarakiri and Ilori, 2003). In 1992, Nitel powered Ugonoba and the Gewadabawa repeater stations for electricity generating station in Nigeria. By 1997, more than 50 repeater stations in the Nigerian Network were powered by PV systems Coker (2004). Iheakpu-Awka village electrification project facilities were installed in 1998.

Several researches have been undertaken concerning the direct thermoelectric generation of electricity using the heat produced by nuclear reactors, kerosene lamps and firewood. Radioactive resources especially Strontium-90, have equally provided heat to activate small, rugged thermoelectric batteries for use in lighthouses, navigation buoys, isolated weather stations or oil platforms, in spaceships etc. Development of improved materials, use of multi-junction devices and novel cell designs to capture a higher proportion of the solar spectrum and use of concentration (Fresnel) lenses to focus the sunlight to high efficiency cells are areas of rapid development. For a given combination of materials (composite materials), the voltage difference varies in direct proportion to the temperature difference.

MECHANISM

Thermoelectric phenomenon can be utilized for the accurate measurement of temperature by means of a thermocouple in which a junction of two dissimilar wires is maintained at a known reference temperature (0^o, in an ice bath) and the other junction at the location where the temperature is to be measured. Thermocouples can be made very small, and also provide a means for the accurate measurement of local spot temperatures. The current can be increased by using semiconductors instead of metals, and a few watts of power can be produced at efficiencies of up to 6%.

The concept of thermoelectric power generator, a device that converts heat energy into electric by using the Seebeck effect was employed intended to generate power for poultry house lighting programme. Since natural light does not provide the desired day lengths for various poultry management systems, artificial lighting is used almost exclusively in modern poultry housing. Duration of light (photo period) is an important factor in poultry production and its variation is used to stimulate egg production in pullet flocks for both breeding and commercial layers (Winchell, 2001).

Therefore, the objective of this work is to investigate the use of solar thermal energy and thermoelectric potentials of asphalt-embedded thermocouple for electricity generation for poultry house lighting using asphalt as heat source.

RESULTS

The peak sun-hour value monitored at the site during raining season and dry season were found to be 4hrs and 5hrs respectively, a value agreeing with Onojo et al., (2004). According to measured temperature data, the average daily surface temperature increases with increase in sun-hour and reaching its peak between 1300hr and 1400hr (Figure 1) and then decline. There are on average, 10hrs of sunshine per day, but for useful solar harvest, 8hrs of sunshine is suggested because of difference in temperature between the collector surface and the ambient.

There appeared to be no significant difference in spot temperatures measured in each of the surfaces per hour, hence the surface temperature is independent of surface area. The Collector compaction test shows that a densely packed material retains more heat than a loosely packed material and hence increased surface temperature and higher electric potential.

The measured average daily current required within the mapped area is 5.14Ah. An average of 4 hrs of full sun hours per day round the years is taken for a non-critical system. When a peak sun-hour of 4.5 hours/day is required, the thermocouple array is capable of generating a measured 1.14A continuously to satisfy the load demand of 5.14Ah. At increased sun-hour period above 4 hours, more current generation is possible whereby the battery could be recharged. The daily load requirement determines the necessary battery bank capacity. The measured total useable capacity (TUC) of the battery in the system is 22.84Ah.

CONCLUSION

The research work showed the possibility of the utilization of asphalt bonded thermocouples to generate enough current for lighting programme in a small scale poultry house. The output voltage across the thermocouple generator can be increased to higher value enough to provide energy for other low thermal processes. Further work is on-going to develop a unit to supply light to a small poultry project.

REFERENCE

Akarakiri J.B. and Ilori M.O. (2003). Application of photovoltaic technology in developing countries. Nig. Jour. of Industrial & Systems Studies (NJISS) vol.2 No.2

Madueme T.C. (2002). Independent power producers and the power sector in Nigeria. Nig.J. Ind & Sys. Studies (NJISS) vol.1 no2. P.38-45.

Maycock D. Paul, Edward N. Stirewait (1981). A guide to the Photovoltaic revolution. Rodale Press, Emmans, Pa.

Oladiran M. T. (1999). New and renewable Energy Education in Sub. Saharan Africa. Proc. of renewable Energy Conf. Perth, Austria-energy 16.

Winchell W. (2001). Lighting For Poultry Housing. The Canada Plan Service 5602 2001:04

1.0 Farm Safety

The term farm safety seems like what only farmers who lives and work on farms should know about. The truth is that everyone stand to benefit from learning about farm safety, even people who are merely visiting farms or those who keep backyard gardens. Farming is a common form of employment, providing jobs for lots of people all over the country; however, farm machinery, animals, chemicals, and storage areas can pose a serious risk to people who don't know how to protect themselves.

1.1 Agricultural Safety in Nigeria

One of the most important tasks for any developing economy like Nigeria is to develop the agricultural sector. A strong agricultural sector can increase and generate employment, promote self-sufficiency in food, improve the standard of living, increase the gross domestic product and contribute to general development.

Agricultural safety is still in its infant stages of development in Nigeria compare to most industrialized countries and some developing nations like Asia. The barriers that impede the growth and sustainability of farm safety in Nigeria include; unsafe use or practices; unsafe conditions, and lack of training in safe handling of machine and resources to increase safety to their own health and the environment. Capacity building through regular workshops and training for operators on safe machinery use and awareness programme on the effects of agricultural hazards on the public will reduce the incidence of accident in the agricultural production in Nigeria.

1.2 Farmstead

Farm workersincluding farm families, visitors and paid workerslives in a community where safety also remains an issue. Such environment is referred to as farmstead. The farm is both a work and a home environment for these families. Without a separation between these two environments, inhabitants can be exposed to tremendous risks. For instance, young children could interact with livestock, which are unpredictable and can harm children. However, care and guidance from adults can reduce the risks.

1.2.1 Farmstead Safety

Farm injuries are not limited to the field alone but it also occurs at the farmstead. The following precautions should be taken to avoid accidents in farmsteads:

Step 1:Have proper equipment: Use appropriate instrument in carrying out particular task within the farmstead. For instance use good quality extension cords for electrical devices. Use only double-insulated power tools.

Step 2:Preserve your equipment with good maintenance: Keep tools such as chain saws, oiled and sharpened.

Step 3: Use protective devices and preventive measures: Use appropriate masks when welding. Have guards or shields on all moving parts, such as shop equipment, grain fans, buzz saws, and augers. Use underground feeder lines around the farmstead instead of aboveground lines, especially around grain bins.

Step 4: Follow correct procedures: Always read the operators manual before operating any piece of equipment. Block equipment before working on it, dont rely on hydraulics or jacks! Always check around, under and inside vehicles, grain trucks, mowers, etc., before operating, to make sure the vehicle or machinery and the area around it are clear of people, especially children.

Step 5: Take special precautions for children: Fence off ponds, manure pits and stock tanks. Lock up chemicals, firearms, and your shop.

Step 6: Keep the premises Safe and orderly: Demolish buildings that are in danger of collapsing. Store chemicals and fuel in proper containers; keep toxic substances in original containers only.

Step 7: Be prepared for emergencies: What to do in case of natural disaster.

1.2 How to Improve Safety on the Farm

Safety on the farm starts by increasing your awareness of farm hazards and making a conscious effort to prepare for emergency situations including fires, vehicle accidents, electrical shocks from equipment and wires, and chemical exposures. Be especially alert to hazards that may affect children and the elderly. Minimize hazards by carefully selecting the products you buy to ensure that you provide good tools and equipment. It is expedient that you always use seat belts when operating tractors, establish and maintain good farm/housekeeping practices. Below are other steps you can take to reduce illnesses and injuries on the farm:

1. Inspect equipment routinely for problems that may cause accidents.
2. Install approved rollover protective structures, protective enclosures, or protective frames on tractors.
3. Make sure that guards on farm equipment are replaced after maintenance.
4. Take precautions to prevent entrapment and suffocation caused by unstable surfaces of grain storage bins, silos, or hoppers. Never walk on the grain.

Be aware that methane gas, carbon dioxide, ammonia, and hydrogen sulphide can form in poorly ventilated grain silos and manure pits. This can suffocate or poison workers or even causes explosion.

1.3 Farmers Safety Responsibility

The most important responsibility of any farm owner or manager is to ensure the safety and health of his or her employees and family members. Not only is it the right thing to do, but a safe farm protects the farm owner or manager by limiting the likelihood of costly accidents. Safe farms protect co-workers, children, other family members, and animals from accidental injuries that can destroy a livelihood and devastate a family. Most farm accidents are completely preventable. The smart farm owner or manager takes a proactive approach to farm safety by conducting regularly scheduled and thorough inspections of the entire farmstead.

1.3.1 Checks Around Agricultural Facilities

Farming is an inherently dangerous occupation primarily because of the number and variety of hazards that exist. Tractor-related accidents account for over half of farm fatalities. Other dangers include farm machinery, equipment, and grain handling facilities, animals, chemicals, and environmental factors. Young children, family members, and farm visitors are injured and killed each year from poisoning, drowning, electrocution, and falling from farm structures and equipment. Consequently, it is essential that farm owners and managers assess the entire farm for hazards. At the minimum, the following facilities should be inspected:

1. Barns and buildings
2. Animal facilities
3. Grain storage and handling facilities
4. Workshops
5. Chemical storage and handling facilities
6. Farm machinery
7. Fuel storage and handling facilities and
8. General farmstead

All operators of machinery need to be trained on operation and safety precaution in working with machinery. Before operating any machinery, a safety check/inspection should be performed to identify and eliminate any machine defects and safety hazards. Before operating equipment, you should ensure the following procedures are carried out:

1. Inspect all safety guards, including chain guards. If any guards are missing or broken, notify your supervisor immediately so they can be replaced or repaired.
2. Keep machine parts clean and free of accumulation of crop material, dirt or debris.
3. Check all of the hydraulic lines and fuel lines to make sure they are securely fastened and in good condition.
4. Notify your supervisor if you notice any leaks and bad connections so they can be repaired or replaced. Check hydraulic lines for pinhole leaks using cardboard paper only, not bare hand.
5. Make sure that all stops and starts are set correctly.
6. Check to make sure that the tension belts and chain drives are adjusted properly.
7. Never operate any equipment that is not in safe working condition.

1.3.2 Look Around Before Starting the Equipment

Error of oversight on hazard points and haste in getting work done could lead to serious injury. To prevent avoidable risks, the following precautions and checks should be taken:

1. Adjust your seat so you easily reach all controls and see all gauges and indicator lights.
2. After you have completed the initial safety inspection, you can turn on the power.
3. Make sure that everyone is at a safe distance away from the machine before starting.
4. Keep your mind on your work. Most agricultural machines require your concentration in order for the process to run safely and efficiently. Do your best to avoid distractions from your job.
5. Never jump start any equipment. If the machine does not start the way it was designed, inform your supervisor.

1.4 Consequences of Unsafe Practices and Neglects

Within the context of Nigeria organizational plan, the issues of safety are mostly considered non-essential in operational plans because management viewed it as inconsequential to their profit margin. Labour is considered cheap and thus overhead cost resulting from provisions for safety is grossly cut down. Every stakeholder has an obligation to safety in workplaces, but when not regarded, it results in hazards and injury. However, cost of safety is not only in monetary terms but it cuts across all the stakeholders (the employer, the employee and the environment) in job delivery in the following ways:

The Employer: Safety has the following consequences on the employer:

1. Loss of valuable production time due to unnecessary machine down time
2. Economic loss due to payment of accident claims
3. Litigation cost from organised labour (workers Union) and families on accident cases, etc.
4. Loss of valuable worker to injury or death due to lack of safework and safework procedure

The Employee: Consequences of unsafe practices on the worker or employee include:

1. Pain, scars, bruises, cut, and lacerations etc., resulting from shear, cut, wrap and pinch points
2. Bone fractures, mangled flesh and other complications that could lead to amputation, skin grafting etc., as a result of entanglement with rotating parts, etc.
3. Burns to body parts due to exposure to hot surfaces, chemical and other harmful liquids
4. Hydraulic fluid injection into the body, spray to the eye, face or blood contamination etc.
5. Injury due to rollover, fall, and trips from tractors, transport vehicles, ATV bikes and horticultural machines.

The Environment: Consequences of unsafe practices on the environment includes:

1. Noise pollution
2. Air pollution resulting from discharge of harmful particulate materials to the atmosphere
3. Consequences of fire outbreak due to charging of the atmosphere with flammable gases
4. Depletion of ozone layer due to poor handling of depleting substances such as refrigerants
5. Accident from poor visibility as a result of dust pollution

References

Farm safe, 2005. Safe operation of All-terrain Vehicles and All-terrain Utilities on Australian Farms: An Industry Strategy 2004-2009

Farm Safety Association fact sheet, 2002. Agricultural machinery hazards 22-340 Woodlawn Road West, Guelph, Ontario (519) 823-5600.

Engineering Concept

Engineering as a concept is known to have been part of human practice since ancient times as fundamental and basic inventions were progressivelymade. These inventions form the basis on which hand-tool and other contrivanceshave emerged. These inventions included the lever mechanism, wheel and thepulley.

Engineering as documented by Wikipedia is expressed as having a much more recent etymology (definition), derived from the wordengineer, which itself dates back to 1325, when an engine or (literally, onewho operates an engine) originally referred to a constructor of militaryengines.
In this context, now obsolete, an engine referred to a military machine,i.e., a mechanical contraption used in wars (for example, a catapult). The wordengine itself is of even older origin, ultimately derived from the Latin wordingenium (1250). Meaning clever at inventing (an innate quality), especiallymental power, hence a clever invention.

Engineering Technology

Engineering technology was the basis for the industrial revolution which has transformed man. According to Dyson (1989): Next to thegift of life is technology, for it is the greatest of Gods gifts as it offersthe poor of the earth, a short cut to greatness and wealth, a way of gettingrich by cleverness rather than a back-breaking labour. Many engineeringproblems are as closely associated to social problems as they are to purescience.

Phases in Engineering Technological Development

The overlapping four phases of engineering and technological development are:

• Pre-scientific Revolution: The pre - history of modernengineering features ancient master builders and Renaissance engineerssuch as Leonardo da Vinci. The Acrioiucs in Greece, Roman aqueducts, theGreat Wall of China, etc. these are examples of works of ancient Civil andMilitary Engineers.
• Industrial Revolution: This period spans from 1800 - 1930. From the eighteenth century throughearly nineteenth century, the civil and mechanical engineers changed from practicalartists to scientific professionals.
• Second Industrial Revolution: In the century before World WarII, chemical, electrical, and other science-based engineering branchesdeveloped electricity, telecommunications, cars, airplanes, and massproduction.
• Information Revolution: As engineering science maturedafter the war, micro electronics, computers, and telecommunications,jointly produced information technology. Some of the very first projectswere simply based on trial and error. Imaginative and creative individualswith good technical skills would try and design and put things together.

REFERENCE

Fola Lasisi, 2010. Agricultural engineering and society - the challenges and sustainability. Paperpresented at the 1^st departmental lecture organized by thedepartment of agricultural and biosystems engineering, University of Ilorin,Ilorin, Nigeria on 1^st June, 2010.

Segun R. Bello (2007). Fundamental Principles of Agricultural Engineering Practice. Pub. Climax Printers #26/30 College Rd. Ogui New Layout,Enugu. ISBN: 978-080-015-8

Wikipedia, the Free Encyclopedia.