Open Cycle Regenerator Gas Turbine Power Plant Engineering Essay

Open Cycle Regenerator Gas Turbine Power Plant Engineering Essay A performance analysis and optimization of an open cycle regenerator gas turbine power-plant is to be performed. The analysis is performed by considering the eight pressure-drop losses within the open cycle during the calculation of the power output which is not considered in classical thermodynamic analysis. The power output can be optimized by adjust the mass flow rate and the distribution of pressure losses along the flow path. The power output also can be optimize by having the optimum fuel flow rate or any of the overall pressure drops as well as the overall pressure ratio. A computer program is to be produced to allow user to obtain the performance analysis based on the parameter entered by the user. Keywords Open cycle regenerator gas turbine power plant, pressure drop, pressure ratio. 1. Introduction The gas turbine is unquestionably one of the most important inventions of the 20th century, and it has changed our lives in many ways. Early gas turbines for power generation applications were of low power and their thermal efficiency was too low to be competitive. By the end of the 20th century, however, gas turbines were capable of output up to 300MW with thermal efficiencies of 40 per cent and the gas turbine became widely used in power generation. The power plant usually consists of an air compressor, a heat exchanger, a combustion chamber and a gas turbine. First, the air is being compressed by the air compressor and then being raised its temperature by the heat exchanger before being combusted in the combustion chamber. The air then undergoes expansion in the gas turbine and finally being channel back to the heat exchanger before being released to ambient environment. The gas turbine is used in a wide range of applications. Common uses include power generation plants and military and commercial aircraft. In Jet Engine applications, the power output of the turbine is used to provide thrust for the aircraft. Gas turbines operate on the principal of the Brayton Cycle, which is defined as a constant pressure cycle, with four basic operations which it accomplishes simultaneously and continuously for an uninterrupted flow of power. The Brayton cycle is a thermodynamic cycle that describes the workings of the gas turbine engine that can be used in both internal combustion engines (such as jet engines) and for external combustion engines. It usually consists of a compressor, a combustion chamber and a turbine. The four steps of the cycle are: (1-2) Isentropic Compression-Ambient air compressed in the compressor (2-3) Isobaric Heat Addition-Pressurized air heated in the combustion chamber (3-4) Isentropic Expansion-Expansion of heated pressurized air in the turbine (4-1) Isobaric Heat Rejection-Heat rejection to the atmosphere Pressure ratio Thermal efficiency of a Brayton cycle Isentropic relation 2. Literature review Every gas turbine has three fundamental elements in common, an axial compressor, a combustor and a turbine. These elements work together to produce usable energy. First it converts fuel energy into heat energy and then it harness as much of that heat as possible and converts it into mechanical energy. The more heat it produces, the more energy it can extract. However, basic cycle gas turbine can only achieve maximum efficiency of less than 50%. Thus element such as regenerator, intercooler or reheater can be added to increase its thermal efficiency and the power output. 2.1 Open Cycle Gas Turbine Gas turbines usually operate on an open cycle, as shown in Figure 1. Fresh air at ambient conditions is drawn into the compressor, where its temperature and pressure are raised. The high-pressure air proceeds into the combustion chamber, where the fuel is burned at constant pressure. The resulting high-temperature gases then enter the turbine, where they expand to the atmospheric pressure through a row of nozzle vanes. This expansion causes the turbine blade to spin, which then turns a shaft inside a magnetic coil. When the shaft is rotating inside the magnetic coil, electrical current is produced. The exhaust gases leaving the turbine in the open cycle are not re-circulated. 2.2 Closed Cycle Gas Turbine The open gas-turbne cycle can be modeled as a closed cycle as shown in Figure 2 by utilizing the air-standard assumptions Here the compression and expansion processes remain the same, but the combustion process is replaced by a constant-pressure heat-addition process from an external source, and the exhaust process is replaced by a constant pressure heat-rejection process to the ambient air. 2.3Principal irreversibilities and Losses In real gas turbine, the T-S diagram deviates from an actual gas turbine as a result of irreversibility. There are pressure losses due to fluid friction during compression and expansion. There are also pressure losses during heat addition and heat rejection due to fluid flow. Efficiency of compressor Efficiency of turbine 2.4 Open Cycle Regenerator Gas Turbine Regeneration involves the installation of a regenerative heat exchanger through which the turbine exhaust gases pass. In gas-turbine engines, the temperature of the exhaust gas leaving the turbine is often considerably higher than the temperature of the air leaving the compressor. Therefore, the high-pressure air leaving the compressor can be heated by transferring heat to it from the hot exhaust gases in a counter-flow heat exchanger, which is known as a regenerator. The highest temperature occurring within the regenerator is T4, the temperature of the exhaust gases leaving the turbine and entering the regenerator. Under no conditions can the air be preheated in the regenerator to a temperature above this value. Air normally leaves the regenerator at a lower temperature, T5. In the limiting (ideal) case, the air exits the regenerator at the inlet temperature of the exhaust gases T4. The thermal efficiency of the Brayton cycle increases as a result of regeneration since the portion of energy of the exhaust gases that is normally rejected to the surroundings is now used to preheat the air entering the combustion chamber. 2.5 Brayton cycle with regeneration Thermal efficiency of a Brayton cycle with regeneration: Degree of regeneration 3. Methodologies 3.1 Open regenerated Brayton-cycle for a gas-turbine power-plant Performance analysis will be based on the open cycle regeneration gas turbine power plant model shown above. The cycle consists of a compressor, a regenerator, a combustion chamber, and a gas turbine. 3.2 The temperature-entropy diagram and the flow resistances of the power-plant model The performance analysis will include the with considerations of the eight pressure-drop losses in the intake, compression, regeneration, combustion, expansion and discharge processes and flow process in the piping, the heat-transfer loss to the ambient environment, the irreversible compression and expansion losses in the compressor and the turbine, and the irreversible combustion-loss in the combustion chamber. 3.3 Procedure Perform theoretical analysis on the performance of an open cycle regenerator gas turbine power plant by considering the pressure losses. Write a computer program to analyze the performance of an open cycle regenerator gas turbine power plant with and without pressure losses. Compare the performance of the open cycle regenerator gas turbine power plant with and without pressure losses. 3.4 Expected results 4. Progress report based on Gantt chart Table 1 à ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬ Progress Report Task done July August September October Information research Preparing proposal Study on thermodynamic Study on related journal paper Study on Matlab Study on related mathematical formulae Attempt to plot desired graph Preparation of progress report 4.1 Current progress The above are some of the sample graph plotted that are similar to the expected results. However, the similarities are limited as the degree of regeneration of the regenerator in the expected results remains unknown. The remaining graphs are still in the progress as there are so difficulties encountered with the mathematical formulae. 5. Conclusion The project is going according to the timeline given. Further analysis on the turbineà ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬Ãƒ ¢Ã¢â‚¬Å¾Ã‚ ¢s temperature ratio and the regeneratorà ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬Ãƒ ¢Ã¢â‚¬Å¾Ã‚ ¢s temperature ratio will help to create the program desired. 6. Recommendation Further study into thermodynamic will ease the progress of this project. There are one particular journal related to the project that is yet to be purchased. Purchasing this journal will solve most of the problem encountered.

The Great Pyramid of Giza :: Ancient Egypt Egyptian History

The Great Pyramid of Giza The pyramids of Ancient Egypt are as fascinating and intriguing, as they are breathtaking. Egyptologists and historians have long debated the question of who built the pyramids, and for what reason. There are many different and often conflicting theories in regard to the construction of the Great Pyramid of Giza. When turning back the pages of history, it is discovered that a number of theories have been developed to explain the presence of such a significant historical landmark. "Theories vary from a tomb for a king, to a special chemical factory, a beacon for extraterrestrial aircraft's, a stone form of the Bible, a possible way to contact a Higher Being and a stone announcement of the second coming of Christ..." (Schillings, M. : 1999 : Sheet 1). Such examples of varying controversial theories have sparked a number of speculations to the mystery of the Great Pyramid of Giza. According to traditional Egyptology, the Great Pyramid of Giza was built by Egyptian pharaoh Khufu during the Fourth Dynasty around "...the year 2560 BCE..." (Schillings, M. : 1999 : Sheet 1). It has been suggested that the Egyptian civilisation succeeded in establishing a complex and organised work force of people to create and build an astonishing burial tomb for the pharaoh in aid of his journey to the afterlife. However, contrary to this suggestion, one must ask why the modern Egyptians continue to rely on traditional beliefs and attitudes to explain the presence of the Great Pyramid of Giza. Could this be the prefect example of nationalistic views? It could be argued that as a result of the continual spread of Egyptian hearsay, the Egyptians obtained the understanding that the entire civilisation - past and present - is somehow superior in status to that of the average mortal man. Undoubtedly, in modern times, the world has gained an increased awareness of the uncertainties that surround investigations into such a distant past. Despite several emerging historical puzzles and conclusions, modern Egyptians continue to adhere to the theory presented by traditional Egyptology. The sheer size, the huge proportions and the amazing geographical positioning of the pyramid have greatly contributed to the rise of uncertainty as to it's origin and purpose. The construction of the pyramid was no mean feat, regardless of the creator. Considering the fact that the pyramid is "...thirty times larger than the Empire State Building.

The Impact of Human Resource and Operational Management Practices on Company Productivity: a Longitudinal Study

Article 1: The Impact of Human Resource and Operational Management Practices on Company Productivity: A Longitudinal Study Dana Cuffee BSA 523 Operations Management and Analysis August 31, 2009 Dr. Woo This article talks about human resource and the operational management practices on a company productivity. This paper reports on the study that evaluates the individual and collective impact on manufacturing performance of the seven managerial practices most associated with these theoretical perspectives: empowerment, training, teamwork, total quality management, just in time, advanced manufacturing, technology, and supply chain partnering. There was little or no evidence related to a company performance in longitudinal practices to show companies that adopted specific practices to improve their performances. A study was conducted by Birdi, Clegg, Patterson, Robinson, Stride, Wall and Woo (2008), to determine the importance of psychology-based practice on a company’s productivity. They studied 308 companies over 22 years and implemented the 7 practices. As a result of the study, it was concluded that none of the operational practices were directly related to productivity. Empowerment focuses on giving individual or teams’ responsibility rather than management. Extensive training is providing employees with a wide range of skills. Teamwork is a group of employees working together on a common task. Total quality management is based on the principle that quality control should be a part of the production process. Just in time is a system for making products in direct response to internal and external demand from customers. Advanced manufacturing technology includes a range of computer based machinery, such as computer numerically controlled machines, robots, and computers aided design and process planning. Supply chain partnering is trategic alliances through long term relationships with suppliers to guarantee that the right materials and components are provided at minimum cost. The case study has three hypotheses. The first hypotheses included empowerment, extensive power and teamwork would independently enhance company performance. This is based on the theory that empowerment required extensive skills in order for it to work, thus both of t hese practices underscore the effectiveness of teams. Also, learning from extensive training requires teamwork and problem solving skills, which provides the competencies on which team performance depends. The second hypothesis was that having total quality management, just in time, advanced manufacturing technology, and supply chain partnering will independently enhances company performance. The combined practices worked as a synergy, affecting each other. Lean production adds supply chain partnering in the mix, which in turns, bolster the other practices by helping to ensure all the other components. The third hypothesis was that empowerment, extensive training, and teamwork will positively interact with total quality management, just in time, advanced manufacturing technology, and supply chain partnering to predict company performance. Stevenson (2007) also uses the seven practices in his book. Total quality management (p. 427) involves everyone in the organization in a continual effort to improve quality and achieve customer satisfaction. The just in time (p. 694) concept believes in a processing system in which goods move through the system and services are performed just as they are needed. Empowerment (p. 428) believes in giving employees the responsibility and the authority to make changes to accomplish their task. Cross training workers (p. 07) to perform different parts of a process and to operate a variety of machines adds flexibility and value to the worker. Some organizations use self directed teams (p. 329) to achieve a higher level of teamwork and employee involvement. They are empowered to make certain changes in their work processes. Stevenson has several advanced manufacturing technologies described in his book. To name a few are computer aided manufacturing, numerically controlled machine (p. 246) a nd robots (p. 247). All of them depend on the level of automation a company need. Every job wants to improve and get better over time (even the military). The military also focuses on the 7 practices of empowerment, training, teamwork, total quality management, just in time, advanced manufacturing, technology, and supply chain partnering. With the budget cuts, shortage of personnel and the concept â€Å"do more with less†; the military has to strategize just like civilian company. Normal every day function that were usually a soldier’s unit responsibility, but now the soldier is required to maintain and perform himself. In conclusion, this article, focuses on the importance of psychology based practices; empowerment, extensive training, and teamwork to sustain competitive advantages within human resource management. Once the companies fully implemented the seven practices, their overall performance did improved. References Stevenson, W. J. , (2007) Operation Management (10-ed) New York. McGraw- Hill/Irwin Birdi, k. Clegg, C. , Patterson, M. , Roberson, A. , Stride, C. , Wall, T. , & Woods, S. (2008). The Impact of Human Resource and Operational Management Practices on Company Productivity: A Longitudinal Study. Personnel Psychology, 61(3), 467-501.

Essay on Conscription

Essay on Conscription The reason why the system of conscription (or â€Å"draft†, as it is commonly referred to in the United States) is inferior to that of volunteer or professional army is simply an economical one. It is the old and irrevocable law of economics, stating that the less you have to pay for something, the less you tend to try and use this resource wisely, irrespectively of its objective value. For you only its subjective value – what you have paid for it – is important, all the rest is the matter of little consequence. The army using conscription is one of the most picturesque examples of a system that gets a certain resource (people) for free and is most unlikely to be interested in sparing it in any way. It doesn’t only mean that human lives will be wasted for no reason; it means also that people’s time will be wasted. A perspective nuclear physicist, who could have used this time to work for a scientific institution, carries out a project of his own and finally makes a discovery, which, when drafted, will be sent to clean the toilets for the army officials, who got his time for free and have no reasons whatsoever to try and find an application for him that would suit his abilities and the objective value of his time. Whatever democratic policies are carried out by a country and whatever democratic ideals are considered to be prevalent in its society, the conscription is a titanic step towards the lawlessness and tyranny of a totalitarian state. It leaves its imprint on everything, whatever other details are. That’s why no society can practice conscription and consider itself to be a free nation. These two concepts are incompatible and nothing may justify bringing them together.