The Liquid Ring Pump

The Liquid Ring Pump The performance of a two-stage liquid ring pump with water as the sealant liquid was investigated under stand-alone conditions. The parameters varied in this experiment were the cooling water flowrate and inlet air volumetric flowrate which affects the sealant water temperature and pumping speed respectively. Pressure and temperature readings were taken to calculate the compression work and efficiency across the liquid ring pump. It was found that efficiency improved at higher cooling water flowrates and lower sealant water flowrates. As the inlet air mass flowrate was increased, it was also observed that the suction pressure, pumping speed, and compression work increased. These trends compare well to similar investigations done in literature. Assumptions made to describe the performance of the LRP were isothermal compression, ideal gas, dry air as inlet gas, and no loss of energy to the surroundings. Energy balance done across the liquid ring pump showed an agreement to literature ( 1) that isothermal compression was found to be more thermodynamically efficient compared to an adiabatic process. Further work can be done by investigating he pumps performance using different sealant liquids, inlet gas moisture content, and in conjunction with reflux/reboiler and reflux/condenser. Problem Statement Morton Labs Inc. has commissioned an independent evaluation of their liquid ring pump rig. They would like a report on the performance of the pump under a wide set of conditions and its suitability to operate with the Reboiler/Condenser and Reflux/Condenser rigs in their plant. Group A3 was required to plan and carry out experiments that can provide data for such evaluation. The evaluation should include mass and energy balance calculations, performance data and an analysis and description of the behaviour of the pump as well as any suitable model. You will have access to their facility and will be shown how to operate the equipment. Introduction The concept of vacuum has long been the subject of interest of philosophers since the times of the Ancient Greeks due to its profound uniqueness and was recreated by physical means with the creation of what can now be described as the first vacuum pump by Otto von Guericke in 1650. (2) Vacuum pumps have been steadily improved and advanced since then but it was not until huge advances in the late 19th and early 20th century paved the path to what would become a vital organ in several industries such as chemical, pharmaceutical and food industries. (2) In a typical paper mill for example, vacuum is mainly used to assist the removal of water in wire drainage and pressing sections in addition to several other purposes. (3) For such an industry, liquid ring vacuum pumps are utilized in order to create the vacuum needed for the mentioned processes. (4) In order to produce vacuums in the most efficient manner, the behaviour and performance of liquid ring pumps needs to be studied in order to reduce costs of operation and reduce energy consumption. Several investigations such as those by Powle and Kar (4) and Chilvers and Love (5) on measuring the behaviour of liquid ring pumps have been conducted due to the importance of determining performance. The objective of this set of experiments is to determine the performance of the 2 phase Hicks Hargreaves SLR type liquid ring pump the located on the B-floor of the Morton Laboratory. Performance can be described by varying flow conditions of the sealant water and cooling water supplied to the liquid ring pump and taking pressure and temperature measurements accordingly. This report will start by describing the operation of liquid ring pumps and the technical theory used to describe their performance, followed by the experimental plan and the methodology. The data collected will then be analysed in order to create trends describing the compression work and the isothermal efficiency of the pump in question. The report will be concluded by suggesting possible areas to be further studied in addition to answering the objective of the experiment. Background Liquid Ring Pump (LRP) The liquid ring pump operates as a vacuum pump using liquid as a compressing agent. It consists of a metal cylindrical body containing an impeller and blades set off centre with respect to the central line of the pump. The liquid ring pump must then be partially filled with a liquid which will act as the sealant and results in forming a vacuum. This is illustrated in figure 1A. The sealant liquid can be either water, oil or a solvent, depending on the application of the pump. When the impeller starts to rotate it throws the liquid in the pump against the walls by centrifugal force. This will cause the impeller blades closest to the wall to be completely submerged in the liquid sealant and the impeller blades furthest away from the wall create a void space with the liquid ring. This is because the impeller is set off centre. This void space sealed off by the liquid and the impeller can be seen by looking at figure 1B. As the impeller rotates anti-clockwise from the top to the bottom, the area of void between the impeller and liquid sealant expands. This creates a suction force which draws gaseous fluid into the pump inlet, as the impeller carries on rotating anti-clockwise from the bottom to the top the liquid is forced closer to the impeller compressing the void space and creating a compression force which pushes the gaseous fluid out of the pump outlet along with a little bit of the liquid sealant, this is because the liquid is highly turbulent inside the pump. (6) A two stage liquid ring pump is the same as described above but with two cycles in series; so that the outlet from the first stage is the inlet of the second stage. Typical values of the vacuum pressure in a two stage pump decreases to 25 mmHg from 35mmHg in a single stage pump. This shows it is much more efficient at creating the desired low vacuum which ranges from 22.5mmHg to 750mmHg. (B) (A)Figure 1: Illustration of liquid ring pump operation (7) Liquid ring pumps are commonly used on reflux / condenser and reboiler / condenser systems. One such system is the removal of air from steam surface condensers and other industrial processes. The liquid ring pump would be employed to evacuate air and any non-condensable gases from a condenser; the gas removal is done to eliminate the insulating effect of the gases present which affects the heat transfer between the steam and cooling medium. This greatly improves the efficiency of the heat transfer system and results in a smaller condenser surface area required, therefore saving space and costs of running a larger condenser. Typically for running such systems a two-stage liquid ring pump would be favoured to create a hogging operation. The first stage of the pump is used to evacuate the air from the condenser at very high pressures and then the second stage is used to optimize the efficiency of the pump and reduce the amount of peak power required. (8) Vacuum pumps are important units in plants that are involved in many applications like processing food, plastic processes, medical process that requires, etc. There are three types of vacuum pumps which can be concluded as molecular pumps which use very high speed jet of fluid, positive displacement pumps that enlarge the cavity and seal it off in frequent and entrapment pumps that traps fluid in solids. A liquid ring pump falls under the displacement pumps category, however there difference that distinguishes it from other displacement pumps. This is due to a liquid ring being formed, it creates a high convective heat and mass transfer phenomenon which dissipates the thermal effect of compression and achieves near isothermal behaviour. The effect of instantaneous convective heat and mass transfer is so rapid that the gas outlet temperature is noted to be close to the sealant inlet temperature almost instantaneously. Because of this effect the discharge temperature remains roughly co nstant, and since the volumetric flowrate also remains nearly constant then with high suction pressure the mass discharge can be enhanced. This causes the liquid ring pump to have faster evacuation during start up and faster turnaround during cycling. (1) Liquid ring pumps can use a variety of liquids, water is the most common, and the choice is generally related to the pressure you wish to be operating at. Oil is also commonly used as a liquid sealant, since oil has a very low vapour pressure; it is typically used in air-cooled systems. The liquid ring pump is also ideally suited for solvent recovery such as toluene provided the cooling water keeps the vapour pressure of the sealant down to produce the required vacuum. Ionic fluids also can be used to reduce the pressure from about 70mbar to below 1mbar. (9) Cavitation is considered a major issue that is associated with liquid ring pumps due to the fluid environment creating low pressures. At very low pressure, 35 mmHg, water boils at 31.7 CËÅ ¡. Therefore, it is essential to keep the sealant at low temperatures by supplying a cooling water flowrate to the system. Inertial cavitation is caused when the pressure falls below the vapour pressure and cause bubbles to form. These bubbles then start to collapse due to the high pressure of the surrounding medium as the pump starts to compress. As the bubble is collapsing the pressure and temperature inside rapidly start to increase, the bubble will eventually collapse, and this releases the gas into the surrounding liquid with a violent mechanism where the energy is released in a shock-wave. This can cause a series of craters and holes along the impeller this can reduce efficiency of the pump and can be seen in figure [2]. Figure [2]: Cavitation We can see the region of cavitation caused by the outlet water temperature, absolute suction pressure and air flowrate illustrated in figure [3] below. Figure [3] Figure [3] shows how a pump can operate within a safe region and then be carried into the cavitation region with only an increase in temperature. The graph also shows how the liquid in the pump vaporizes under certain conditions. For our experiment it makes sense to control the safe operation of the pump by supplying a cooling water stream. This will keep the temperature down and out of the cavitation region. It is also easier to control as the air flowrate depends on the rig that the liquid ring pump may be connected up to. And the suction pressure will have local variation within the pump. (10) Orifice meter for determining air flowrates The flowmeter used by the DeltaV software in the control room, was used to provide data on inlet air flowrates into the liquid ring pump and was unfortunately faulty. This meant the real time recordings of air flowrates could not be supplied. Thus, calibration of the orifice meter was necessary to determine the inlet air flowrates. Figure ?: Orifice meterA square-edged orifice with radius taps was used to calibrate the inlet air flowrate into the Liquid ring pump. Pressure tappings attached to mercury manometers were located one pipe diameter upstream and one-half pipe diameter downstream from the orifice plate as shown in Figure ?. Bernoullis equation for incompressible, inviscid flow along a streamline (11) without shaft work: Where is the inlet pressure (upstream pressure in this case), Pa is the outlet pressure (downstream pressure in this case), Pa are the inlet and outlet velocity respectively, m s-1 is the density of the fluid, kg m-3 is the gravity acceleration, m s-2 , are the inlet and outlet elevation respectively, m The continuity equation gives (11) Where and are the inlet and outlet cross-sectional area respectively, m2 The volumetric air flowrate across the orifice plate can be expressed by substituting Eq. (2.2.2) into Eq. (2.2.1) to give Where is the volumetric air flowrate across the orifice plate, m3 s-1 is the coefficient of discharge is the orifice cross-sectional area, m2 is the pipe cross-sectional area, m2 A typical equation relating the discharge coefficient, as a function of ÃŽÂ ² and Reynolds number, Re, was adapted to calibrate the orifice meter With the conditions of and Where is the viscosity of the fluid, Pa.s To calibrate the air flowrate across the orifice plate, the cooling water flowrate was kept constant and the pressure drop across the manometers were taken for 10-70 number of turns on Valve 11.6 for varying cooling water flowrates. From typical values of 0.61-0.65 (12), was used as the initial guess for iterations to take place. After three iterations, the values of between the corresponding iterations differ within an order of 10-6 and at the third iteration were used for calculations in this report. Where did the valve come from? Relate to diagram? 2,5,8,11 what? Figure 2: Calibration of inlet air mass flowrates across orifice plate give similar trend and magnitude for varying cooling water flowrates Figure 2 indicates that the varying cooling water flowrates do not affect the air mass flowrates across the orifice plate. Thus, the inlet air mass flowrates depends only on the number of turns on Valve 11.6. Average inlet air mass flowrates for cooling water at 2, 5, 8, and 11 kg h-1 were used to produce the following equation in Figure 3 which will be the calibration used in this experiment. Figure 3: Calibration of averaged inlet mass air flowrate across orifice plate Assumptions Temperature Factor Figure 4: Double Stage Pump (13) The suction pressure created falls within the range of approximately 106 to 531 torr while the temperature of sealant water used entered the pump at approximately 55 °F. These conditions fall within a region where the gradient of the graph is very gentle and the value of the temperature factor is around 1.0. Therefore, the temperature factor to be applied to the flowrate of sealant water is approximately the same even as inlet pressure changes. Also, even as the cooling water flowrate was changed, the sealant water temperature was observed to remain around 55 °F. The temperature factor to be applied would not be greatly affected by either of the two operating variables, namely the cooling water flowrate and the inlet air mass flowrate which affects the suction pressure. Since the temperature factor is approximately 1.0, it can be assumed that the mass flowrate of sealant water entering the pump and leaving the pump to be the same, making the vaporisation of air negligible. This a ssumption is investigated by performing a mass balance across the pump taking into account vaporisation of air during the compression process. Inlet air It is assumed that the inlet air into the Liquid ring pump contains no moisture, thus we refer to the inlet air as dry air. The heat exchanger is assumed to have 100% efficiency in heat transfer between the pump, sealant water, and cooling water streams. Assuming no heat loss to the surroundings, the compression work done by the pump is equal to the heat gained by the cooling water in the heat exchanger. For the purpose of calculating efficiency of the Liquid ring pump for this experiment, it is found to be more to calculate compression work from the cooling water heat gain. Steady State Vapour pressure Vapour pressure refers to the pressure in the gas phase when the liquid and gas phase of a system are in equilibrium. The vapour pressure of the sealant liquid into the Liquid ring pump plays an important role in determining the pump capacity. At higher temperatures of sealant liquid, the vapour pressure increases and more vaporisation occurs, causing a lower flowrate of air into the pump which results in low pump capacity. Although it might seem that maximum cooling of the sealant water might be a good idea, care must be taken that the sealant water temperature do not fall so low that cavitation might occur in the Liquid ring pump. [more on cavitation in limitations section] In this experiment, the temperature of the sealant liquid is varied by changing the cooling water flowrates. The relationship between vapour pressure and pump capacity is investigated. From Antoines equation, the vapour pressure of a liquid within a range of temperature can be determined (14) Where T is the temperature, K is the saturation vapour pressure, mmHg are constants for specific materials. For an air-water system, the standard Antoine coefficients are A=8.05573, B=1723.64, C=233.076  °C, valid between temperatures of 0.01  °C and 373.98  °C. (15) A relationship between the vapour pressure and temperature can be obtained from the Clausius-Clapeyron equation (16) Where T1 and T2 are temperatures at condition state 1 and state 2 respectively, K and are vapour pressures at T1 and T2 respectively, Pa is the heat of vaporisation, kJ/kg Isothermal System work done across T2 to T4 equals T7 to T6 T4,6,7? The compression process of a liquid ring pump can be approximated to an isothermal operation at inlet sealant water temperatures. (1) During compression, mechanical energy is converted to compression work and dissipated as thermal energy. The liquid ring formed in the pump provides high heat convection and mass transfer which dissipates the thermal energy, creating a near-isothermal operation. This phenomenon occurs in such a short time scale that the system reaches equilibrium rapidly, and the outlet gas temperature approximates the inlet sealant liquid temperature. Mallick (1) describes this as an achievement of highest degree of thermodynamic efficiency of compression. [Need temperatures to prove this] Compression work From the First Law of Thermodynamics, isothermal compression work of an ideal gas can be expressed by (16) Where W is work, J P is absolute pressure, Pa V is total volume of the system, m3 Assuming ideal gas behaviour applies (verify this!), Where m is mass, kg V1 is the inlet volume, m3 V2 is the outlet volume, m3 R is the gas constant, Pa m3 kg-1 K-1 T is the temperature, K For an isothermal system (17) PV = constant Where Wc is the compression work, J Equation ? is divided by time t, to express the compression work, Substituting = m/t = à Ã‚  Where is the mass flowrate, kg s-1 t is time, s And equation ? in equation ?, the compression work of a vacuum pump at any pressure P, for an isothermal system can be derived to be (4): Where is the pumping speed of the liquid ring pump is the theoretical power consumed for an isothermal process, kW Pump efficiency The efficiency of the liquid ring pump is a vital factor in deciding the suitability of the pump for its purpose. Through experimental investigation, we varied cooling water flow rate and air mass flow rate to determine the condition where the liquid ring pump is the most efficient. From theory, we have assumed an isothermal operating condition which leads us to calculating the efficiency, of the pump as: Where Wiso,c is defined as the compression work done under isothermal conditions Wactual,c is defined as the enthalpy gain and Wactual,c = m Cp ΆT. Units? m is the sealant water mass flowrate, units? Cp is the specific heat capacity of the sealant water (4.912 KJ/Kg.K) ΆT is the measured difference in discharge and suction temperatures in which our case will be (T6 -T7) (18) Where have they come from? Figure 5: Title (19) 3.0 Mass and energy balance 3.1 Mass balance During compression in the liquid ring pump, mechanical work is converted to thermal energy and dissipated, potentially vaporising the sealant water used for compression. Assuming the inlet air is dry air with no water content, the mass balance across the LRP is: Mass balance on the gas component Assuming This can be rearranged to give Where is the humidity ratio obtained from the psychometric chart for the air-water system at standard atmospheric pressure (20). By determining the relative humidity, RH, the value of HR at any temperature can be determined from the psychometric chart. Where is the vapour pressure which can be determined by Eq. ? (Antoine), Pa is the saturation vapour pressure, Pa Mass balance on the liquid component 3.2 Energy balance Total energy balance of a unit mass of fluid is given by (14) Where are internal energy at the inlet and outlet respectively, J is the gravitational acceleration, m s-2 z1 and z2 are the elevation at inlet and outlet respectively, m and are the velocities at inlet and outlet respectively, m s-1 q Heat absorbed from the surroundings units? Ws work done by the fluid on the surroundings units? Assumptions made for the energy balance across the pump: since the system is operating horizontally with no elevation between inlet and outlet Kinetic energy is assumed to be negligible since it is insignificant compared to enthalpy change. Negligible heat loss from the system, . This assumes an adiabatic process. Substituting the relation And Where h is the specific enthalpy, kJ kg-1 The energy balance equation reduces to Which is Where and are the inlet and outlet mass flowrates respectively, kg s-1 and are inlet and outlet specific enthalpy respectively, kJ kg-1 Methodology Apparatus Figure 6: Process Flow Diagram of Experimental Set-up Liquid Ring Pump Sealant Water Tank Scrubber Thermocouples Mercury Manometers Rotameter Orifice Plate DeltaV system Experimental design Firstly, we identified two operating variables that could be varied to investigate the performance of the pump. The two variables are the inlet air flowrate and the storage tank cooling water flowrate. The inlet air flowrate could be manipulated by a flow control valve over a range of 8 to 70 turns. By calculating the pressure drop across an orifice plate and plotting a calibration curve, we were able to get the mass flowrate associated with the number of turns on the valve. The storage tank cooling water could be manipulated over a range of 0.5 to 12.5 m3h-1. The adjacent flowmeter gives a measurement of the cooling water flowrate into the heat exchanger around the sealant water storage tank. A full set of measurements were taken to obtain pressure, flowrate and temperature data as we changed the operating variables. Pressure data was obtained for the pressure drop across the orifice plate, and the suction, interstage and outlet pressures for the pump through mercury manometers. Flowrate data was taken from a rotameter that measured the volumetric flowrate of the sealant water. Temperature data was extracted by the DeltaV logging software in the control room. Experimental Procedure The following procedure was conducted over two experimental runs. Through repeating the procedure, we were able to test the reproducibility of our results and reduce the effect of random errors on our results. Set and maintain cooling water flowrate at 2m3hr-1. Starting with the maximum air flowrate at 70 turns we waited for steady state to be achieved before taking the manometer readings for suction, interstage, outlet, orifice plate and rotameter readings for the sealant water flowrate. The air flowrate was then decreased to 60 turns followed by 50, 40, 30, 20 and 10 turns, all the while ensuring that steady state is reached before taking the readings. The full range of measurements from 70 to 10 turns for the inlet air flowrate was similarly taken at cooling water flowrates of 5, 8 and 11m3hr-1. Limitations In determining if the system is at steady state, the flowrate readings that can be monitored from the control room will provide good indication once the rate stabilises. However, the range of the flowmeter is limited beyond 119m3/hr (between 40 and 50 turns on V11.6). Therefore, the mercury manometer that reads the pressure drop across the orifice plate should be used to determine steady state after 40 turns on V11.6. A calibration curve will be plotted to relate the inlet air flowrate and the pressure drop across the orifice plate for mass flow calculations. Also, the flowmeter was faulty on our second run which meant that we would have to solely depend on our calibration curve to determine the inlet air mass flowrate at any number of turns. Analysis of results In the investigation of the performance of the two stage liquid ring pump, we ran the pump under different operating conditions by varying two variables; the air mass flowrates into the pump and cooling water flowrates. Pressures of the suction, interstage and outlet of the pump were measured and used to evaluate the pumps performance at different conditions, hence determining the efficiency of the pump. As the behaviour of inlet air mass flowrate, sealant water flowrate, suction pressure, compression work and pumping speed showed almost identical trends for different cooling water flowrates, an average of the four measurements were used. Sealant Liquid The sealant liquid used in the experiment is water and the compressed fluid is air. Before starting the run, the pump is filled with a specific level of water to ensure that there is sufficient sealant liquid to create vacuum. As the sealant fluid shares the same space in the pump as the fluid to be compressed, it would be expected that as the flowrate of the latter is increased, the flowrate of the sealant liquid decreases. Figure 7: Average Sealant Water Flowrate vs Inlet Air Mass Flowrate From figure 7, it can be seen that as the inlet air mass flowrate increases, the sealant water flowrate into the pump decreases. This is in line with the expected trend since the compressed air occupies a much greater volume in the pump at higher air mass flowrates. Suction Pressure Vacuum is created by the liquid ring pump due to the pressure difference between the source and the pump inlet. In the experiment, the source is air at atmospheric pressure and the inlet pressure is the suction pressure created by the pump. A low suction pressure would translate to a big pressure difference, creating vacuum. (21) Figure 8: The average inlet air mass flowrate for varying cooling water flowrates was plotted against suction pressure Figure 8: shows the trend we obtained where suction pressure increases as inlet air flowrate is increased. This shows that at lower air flowrates, more vacuum is created at a low suction pressure. As the air flowrate is increased, the ability to create vacuum decreases resulting in a higher vacuum pressure. Figure 9: The relationship between dry air capacity and suction pressure at a temperature of 20  °C obtained from literature. (22) As it is assumed that dry air is used and that its density remains constant throughout, the experimental results in Figure 8 can be compared to results obtained from literature in Figure 9. A similar trend is observed where there is the suction pressure is greater as the dry air capacity increases. Figure 10: Table categorising the degree of vacuum according to the absolute pressure of operation. (23) This experiment operates within a range of suction pressures which averages to approximately (1.41-6.00) x104 Pa abs. From figure 10, the range categorises the liquid ring pump as one that creates low vacuum. Low vacuum is sufficient in many industrial applications such as distillation in the petrochemical industry which keeps the liquid ring pump as a relevant piece of plant equipment. Compression Work (Sample calculations for a cooling water flowrate of 11 m3h-1 at 30 numbers of turns) shifted to appendix To calculate compression work under isothermal conditions, we can use Equation 3.7.11 Figure 12: shows that greater compression work is done by the pump with increasing suction pressure. From figure 12(above), it can be seen that greater compression work is done with increasing suction pressure. Based on the inlet air mass flowrate that we used, the suction pressure we created with the pump ranges from ~106 to 531 torr. The graph of the suction pressure against compression work shows a similar trend to literature values shown below in figure 11(below) for the same range. Figure 11: Effect of suction pressure compression work (4) Removed figure 13 Effect of Inlet Pressure on Pumping Speed Figure 15: Pumping Speed at different temperatures of sealant liquid (4) It can be seen from the graph Figure 15 that the change in pumping speed gradually becomes smaller. The inlet pressure (suction pressure) that we obtained from varying the inlet air mass flowrate falls within the range of around 106 to 531 torr. Therefore, we should obtain the same trend of pumping speed with increasing inlet pressure. Figure 16: Pumping speed changes with increasing suction pressure Replaced the graph with a newer one showing the right denotation for units on the y axis Figure 16 shows that the experimental results obtained agree with results obtained from literature. With increasing inlet pressure, the pumping speed increases while the gradient of the graph decreases. 5.5 Efficiency Figure 17: Plot of Isothermal Efficiency Vs Sealant Water Mass Flowrate Figure 17 shows that isothermal efficiency decreases with increasing sealent water flowrate. This result agrees with theory as we know from theory, the efficiency of the pump is affected by the vacuum capacity, and with an increase in sealent water flowrate, more vapour will be formed from the increased amount of sealent water forming the ring-liquid when the vacuum pressure approaches the vapour pressure of the sealent liquid. The increase in vapour volume released from the increase in sealent water will decrease the vacuum capacity and therefore reducing efficiency. Figure18: Plot of Efficiency Vs Cooling Water Flowrate Figure 18 shows that a higher cooling water flowrate will result in higher efficiency. The above trend is derived from the isothermal efficiency of the system at a fixed sealant water flowrate of 0.27 kg s-1. The cooling water flowrate is related to the enthalpy gain of the sealant water and consequently the isothermal efficiency. A higher flowrate would mean that the enthalpy gain is lower and that isothermal efficiency is higher which can be seen from equation 2.8.1. From the above results we can therefore conclude that the liquid ring pump is most efficient at the highest cooling water flowrate and a sealant water flowrate of 0.27 kg s-1 which translates to air flowrate at 60 turns flowing into the pump. Remove

Education in Nigeria Essay

Education in Nigeria is overseen by the Ministry of Education. And the local authorities take responsibility for implementing policy for state-controlled public education and state schools at a regional level. The education system is divided into Kindergarten, primary education, secondary education and tertiary education. Primary education Primary education, Yoruba, and Igbo. Private schools would also offer Computer science, French, and Fine Arts. Primary school students are required to take a Common Entrance Examination to qualify for admission into the Federal and State Government Secondary schools, as well as private ones. The Universal Basic Education, UBE, came as a replacement for Nigeria’s Universal Primary Education scheme of the 6-3-3-4 system of primary education. The 9-3-4 system of education was designed in conformity with the MDGs and Education For All, EFA (Kayode, 2006). The UBE involves 6 years of Primary School education and 3 years of Junior Secondary School education, culminating in 9 years of uninterrupted schooling, and transition from one class to another is automatic but determined through continuous assessment. This scheme is monitored by the Universal Basic Education Commission, UBEC, and has made it â€Å"free†, â€Å"compulsory† and a right of every child. [1] Therefore, the UBEC law section 15 defines UBE as early childhood care and education. The law stipulates a 9-year formal schooling, adult literacy and non-formal education, skill acquisition programs and the education of special groups such as nomads and migrants, girl child and women, Al-majiri, street children and disabled people (Aderinoye, 2007). [2] Secondary education. Students spend six years in Secondary School, that is 3 years of JSS (Junior Secondary School), and 3 years of SSS (Senior Secondary School). By Senior Secondary School Class 2 (SS2), students are taking the GCE O’Levels exam, which is not mandatory, but most students take it to prepare for the Senior Secondary Certificate Examination. The Senior Secondary School Exam is taken in the last year of secondary school (SS3). Private organizations, the State government or the Federal government manage secondary schools in Nigeria. The Federal Republic of Nigeria is made up of thirty-six States and the Federal Capital Territory. There are about two Federal Government Colleges in each state. These schools are funded and managed directly by the Federal Government through the Ministry of Education. Teachers and staff are Federal Government employees. Teachers at the Federal Government schools possess a Bachelors degree in Education or in a particular subject area, such as, Mathematics, Physics etc. These schools are supposed to be model schools carrying and maintaining the ideals of secondary education for Nigerian students. Admission is based on merit, determined by the National Common Entrance Examination taken by all final year elementary school pupils. Tuition and fees are very low, approximately sixteen thousand naira ($100), because funding comes from the Federal Government. [2] State-owned secondary schools are funded by each state government and are not comparable to the Federal government colleges. Although education is supposed to be free in the majority of the state owned institutions, students are required to purchase books, uniforms and pay for miscellaneous things costing them an average of thirty thousand naira ($200) in an academic year. Teachers in State-owned institutions usually have a National Certificate of Education or a Bachelors Degree, but this is not always the case as many secondary schools in Nigeria are filled with unqualified teachers who end up not being able to motivate the students. Often these schools are understaffed due to low state budgets, lack of incentives and irregularities in payment of staff salaries. [2] Some state-owned secondary schools are regarded as elite colleges because of the historically high educational standard and producing alumni who have prominent citizens in the various careers. These included King’s College, Lagos and Queen’s College, Lagos. However, the college ranking of these institutions have since dropped because of the arrival of some private institutions. Private secondary schools in Nigeria tend to be quite expensive with average annual fees averaging from one hundred and sixty to three hundred and twenty thousand naira($1000. 00 – $2000. 00). These schools have smaller classes (approximately twenty to thirty students per class), modern equipment and a better environment. Most teachers in these institutions possess at least a Bachelors Degree in a specific course area and are sent for workshops or short term programs on a regular basis. [2] Promotional examinations With the introduction of 6-3-3-4 system of education in Nigeria, the recipient of the education would spend six years in primary school, three years in junior secondary school,three years in senior secondary school, and four years in tertiary institution. The six years spent in primary school and the three years spent in junior secondary school are merged to form the nine in the 9-3-4 system. Altogether, the students must spend a minimum period of six years in Secondary School. During this period, students are expected to spend three years in Junior Secondary School and three years in Senior Secondary School. [2] The General Certificate of Education Examination (GCE) was replaced by the Senior Secondary Certificate Examination (SSCE). The SSCE is conducted at the end of the Secondary School studies in May/June. The GCE is conducted in October/November as a supplement for those students who did not get the required credits from their SSCE results. The standards of the two examinations are basically the same. A body called West African Examination Council (WAEC) conducts both the SSCE and GCE. A maximum of nine and a minimum of seven subjects are registered for the examination by each student with Mathematics and English Language taking as compulsory. [2] A maximum of nine grades are assigned to each subject from: A1, B2, B3 (Equivalent to Distinctions Grade); C4, C5, C6 (Equivalent to Credit Grade); D7, E8 (Just Pass Grade); F9 (Fail Grade). Credit grades and above is considered academically adequate for entry into any University in Nigeria. In some study programs, many of the universities may require higher grades to get admission. [2] The Federal Government policy on education is adhered to by all secondary schools in Nigeria. Six years of elementary school is followed by six years of secondary school. Senior Secondary school consists of the SS I, SS 2, and SS 3 which is equivalent to the 10th, 11th and 12th Grade. The Senior Secondary School Examination (SSCE) is taken at the end of the SS 3. The West African Examination Council (WAEC) administers both exams. Three to six months after a student has taken the SSCE examination, they are issued an official transcript from their institution. This transcript is valid for one year, after which an Official transcript from the West African Examination Council is issued. National Examination Council is another examination body in Nigeria Senior Secondary School Examination (SSCE)in June/July. The body also administer General Certificate of Education Examination (GCE)in December/January. The students often take both WAEC and NECO examinations in SSS 3. [2] Tertiary education The government has majority control of university education. The country has a total number of 128 universities registered by NUC among which federal and state government own 40 and 38 respectively while 50 universities are privately owned. First year entry requirements into most universities in Nigeria include: Minimum of SSCE/GCE Ordinary Level Credits at maximum of two sittings; Minimum cut-off marks in Joint Admission and Matriculation Board Entrance Examination (JAMB) of 180 and above out of a maximum of 400 marks are required. Candidates with minimum of Merit Pass in National Certificate of Education (NCE), National Diploma (ND) and other Advanced Level Certificates minimum qualifications with minimum of 5 O/L Credits are given direct entry admission into the appropriate undergraduate degree programs. [2] Students normally enter university from age 18 onwards, and study for an academic degree. Historically, universities are divided into several tiers: First Generation Universities Five of these Universities were established between 1948 and 1965, following the recommendation of the Ashby Commission set up by the British Colonial Government to study the necessity of university education for Nigeria. These universities are fully funded by the federal government. They were established primarily to meet a need for qualified personnel in Nigeria and to set basic standards for university education. These universities have continued to play their roles for the production of qualified personnel and the provision of standards, which have helped to guide the subsequent establishments of other generations of universities in Nigeria. Universities in this tier include the University of Nigeria, Nsukka and the University of Ibadan. [2] Second Generation Universities With the increasing population of qualified students for university education in Nigeria and the growing needs for scientific and technological developments, setting up more universities became imperative. Between 1970 and 1985, 12 additional universities were established and located in various parts of the country. [2] Third Generation Universities The need to establish Universities to address special areas of Technological and Agricultural demand prompted the setting up of 10 additional Universities between 1985 and 1999. [2] State Universities. Pressures from qualified students from each state who could not readily get admissions to any of the Federal Universities continued to mount on States Governments. It became imperative and urgent for some State Governments to invest in the establishment of Universities. [2] Private Universities In recognition of the need to encourage private participation in the provision of university education, the Federal Government established a law in 1993, allowing private sectors to establish universities following guidelines prescribed by the Government. [2] The typical duration of undergraduate programs in Nigerian universities depends largely on the program of study. For example, Social Sciences/Humanity related courses are 4 Years, Engineering/Technology related courses are 5 Years, Pharmacy courses are 5 Years, and Law courses are 5 Years, each with two semester sessions per year. Medicine (Vet/Human) degrees take 6 Years and have longer sessions during the year. [2] Women in education Education has been recognized as a basic human right since the 1948 adoption of the Universal Declaration of Human Rights. A positive correlation exists between the enrollment of girls in priary school and the gross national product and life expectancy. [3] Because of this correlation, enrollment in schools represents the largest component of societal investment into human capital. [4] Rapid socioeconomic development of a nation has been observed to depend on the calibre of women and their education in that country. [5] Education bestows on women a disposition for a lifelong acquisition of knowledge, values, attitudes, competence and skills. [6].

The Impact of Path-Goal Leadership Styles on Work Group

The Impact of Path-Goal Leadership Styles on Work Group Effectiveness and Turnover Intention Marva L Dixon, Laura Kozloski Hart. Journal of Managerial Issues. Pittsburg:Spring 2010. Vol. 22, Iss. 1, p. 52-69,6-7 (20 pp.) | Abstract (Summary) Leaders continuously seek to improve organizational performance and enhance work group effectiveness to drive competitiveness and curtail the cost of employee turnover. The diversity of many work groups in the U.S. creates potential benefits and challenges for their leaders. Using data gathered from a manufacturing facility in southeastern U.S., this study examines how Path-Goal leadership styles, diversity, work group effectiveness, and work group members turnover intention are related.†¦show more content†¦When individuals interact with people whom they perceive as different, they tend to classify themselves and those people into social categories (Cox and Nkomo, 1990). Research has found that, early in the life of a work group, members focus on the visible aspects of diversity such as gender, race/ethnicity, and age. As group members interact, they redirect their attention to other members non-visible features such as personality, education, expertise, values, and communi cation styles (Cunningham and Sagas, 2004; Hobman et al., 2004, 2003; Salomon and Schork, 2003; Richard et al, 2002; Caudron, 1994). Employees with more perceived value/informational dissimilarity with their leaders tend to be less satisfied with them and have weaker organizational attachment that those with high perceived similarity (Lankau et al., 2007). Diverse work groups present their leaders with challenges and benefits. Among the challenges are potentially unfavorable interpersonal relationships, impeded intra-group communication, low group cohesiveness, and high employee turnover (Joplin and Daus, 1997; Schneider, 1987; Pfeffer, 1983). If not managed correctly, diversity can negatively affect work group members retention, organizational commitment, and productivity, harming theShow MoreRelatedWhat Are The Four Leadership Styles Of Path Goal Theory Of Leadership1519 Words   |  7 Pagesled. Define leadership and explain what the path-goal theory of leadership is. Identify the four leadership styles of path-goal theory and explain when they are most appropriately used. Managers and leaders are both important individuals to have in an organisation, but it is important that the balance of management and leadership are at the right levels to ensure the business is running at its finest (Williams, McWilliams Lawrence 2017). Managers and leaders along with leadership and managementRead MoreThe Path Goal Theory Of Leadership Skills1318 Words   |  6 Pagesreasons may be due to lack of leadership skills. 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Essay on The Role and the Importance of Supply Chain...

1. Introduction The report highlights in detail the role and the importance of Supply Chain Management (SCM) in an organization with respect to Radio Frequency Identification (RFID) and its growing impact in the industry and talks about the changing SCM trends keeping RFID as the focal point. Over the past few years, the increasing dynamism and competition in the business operating environment has led to a lot of changes in how the companies conduct themselves with respect to its customers. Customers being the focal point of revenue; manufacturers are increasingly taking interest in being focused on customer satisfaction by delivering the products and services on time. RFID has taken strides from being a far off solution to becoming a†¦show more content†¦2. Radio Frequency Identification (RFID) As stated above, RFID is an identification and tracking tool for a product using radio waves. 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