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Methods of Heat Transfer Analysis of Buried Pipes in District Heating and Cooling Systems
Issue:
Volume 2, Issue 2, December 2018
Pages:
33-38
Received:
28 September 2018
Accepted:
17 October 2018
Published:
21 November 2018
DOI:
10.11648/j.ae.20180202.12
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Abstract: District heating and cooling system is an energy-efficient and environment-friendly way of energy supply. Transmission and distribution pipeline system is an essential part of district heating and cooling system. Underground buried laying is the prevailing way of transmission and distribution pipeline system in district heating and cooling systems. Heat transfer calculation of pipeline is very important to determine the thickness of the insulation layer, accessory load of central plant, and the possibility of thermal damage. There are some factors that influence the heat transfer calculation of underground buried pipeline, including: temperature difference between fluid and soil, pipe insulation properties, burial depth, soil thermal conductivity and distance between adjacent pipes. Numerical methods to compute transient heat gains or losses in underground piping systems, is complicated and time consuming. To simplify the calculations, this paper introduces the steady-state thermal calculation method based on thermal resistance formulations that, that avoids the complex calculation process, and greatly simplifies the computational effort, and the calculated results can meet project needs. This method is suitable for the majority types of buried pipeline, so it can be used as reference for engineering design.
Abstract: District heating and cooling system is an energy-efficient and environment-friendly way of energy supply. Transmission and distribution pipeline system is an essential part of district heating and cooling system. Underground buried laying is the prevailing way of transmission and distribution pipeline system in district heating and cooling systems....
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Performance Improvement of a Dry Mode Natural Gas Fired Turbine Plant for Combined Cycle Operation
Anthony Kpegele Le-ol,
Duabari Silas Aziaka
Issue:
Volume 2, Issue 2, December 2018
Pages:
39-53
Received:
17 September 2018
Accepted:
5 November 2018
Published:
3 December 2018
DOI:
10.11648/j.ae.20180202.13
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Abstract: This research considers the design of combined cycle (CC) operation for a dry mode natural gas fired turbine plant in southern Nigeria. It entails evaluation and utilization of the amount of waste heat energy exhausted by the Omoku gas turbine (GT) power plant by integrating a steam Rankine cycle retrofitted with a heat recovery steam generator (HRSG) for CC operation, with the focus to improving its performance and reducing waste heat intensity to the environment. Gathered data from the human machine interface (HMI) and log sheets were used for the analysis. Thermodynamic sensitivity analysis was implemented for the combined cycle system (CCS) using a developed model in the MATLAB platform. The outcome of energy balance of the HRSG having a heat load of 38.49 MW showed that for every kg of exhaust gas, 0.1164 kg of steam is generated at an optimum pressure of 40 bar and mass flow of 14.45 kg, with acceptable steam turbine exhaust moisture content of 10%. These revealed a quantified amount of 45.28 MW heat energy contained in the usually wasted exhaust gas of the dry mode GT which was thus recovered in the HRSG, producing additional 16.32 MW as the steam turbine (ST) power output with a feed pump heat load of 0.06 MW and a condenser heat load of 28.96 MW. Further analysis in terms of power outputs, energy efficiencies, and environmental impacts showed that the CCS achieved 41.32 MW, 49.26% and HRSG stack temperature of 170.25oC compared to the previously 25 MW, 26.60% and exhaust gas temperature (EGT) of 487°C respectively of the dry mode GT. These indicate that the CCS generates about 65.30% boost in the net power output, 85.20% improvement in overall efficiency and 65.10% reduction in waste heat intensity to the environment when compared with the dry mode GT operating in isolation. Thus, the work showed that for the design of a CCS with a single pressure level HRSG without supplementary firing, a recommended range for the power output of the steam bottoming plant falls within 34 – 40% of the total power output of the CCS while that of the gas topping plant falls within the range of 60 – 66% of the total power output of the CCS. This study therefore confirms the viability as well as demonstrates the application, of the combined cycle concept for the Omoku gas turbine and recommends for further research, the introduction of a multiple pressure level HRSG with supplementary firing to the combined cycle system for an improved efficiency and output.
Abstract: This research considers the design of combined cycle (CC) operation for a dry mode natural gas fired turbine plant in southern Nigeria. It entails evaluation and utilization of the amount of waste heat energy exhausted by the Omoku gas turbine (GT) power plant by integrating a steam Rankine cycle retrofitted with a heat recovery steam generator (HR...
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Behavior of Two-Way Post Tension Flat Slab
Hanaa E. Abd-El-Mottaleb,
Heba A. Mohamed
Issue:
Volume 2, Issue 2, December 2018
Pages:
54-59
Received:
8 December 2018
Accepted:
25 December 2018
Published:
22 January 2019
DOI:
10.11648/j.ae.20180202.14
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Abstract: Post tension floors (PT) are one of the most widely used system which are very effective method regarding ultimate and serviceability limit states. A numerical model for discretized the two-way reinforced concrete flat slab with different system is investigated by using RAM software. The effects of different parameters are investigated in this study. Parameters investigated include concrete strength, thickness of the flat slab, different values of jacking (force (P) / area of strand (A)) and also, study the flat slab with opening by changing the values of P/A. Results indicated significant effect of PT system in the flat slab by decreasing the deflection. Also, the magnitude of the bending moment is reversed at one internal column by increasing the value of P/A for large thickness.
Abstract: Post tension floors (PT) are one of the most widely used system which are very effective method regarding ultimate and serviceability limit states. A numerical model for discretized the two-way reinforced concrete flat slab with different system is investigated by using RAM software. The effects of different parameters are investigated in this stud...
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Improving Operational Procedures in Riyadh’s (Saudi Arabia) Water Treatment Plants Using Quality Tools
Yasser Alshammari,
Djamel Ghernaout,
Mohamed Aichouni,
Mabrouk Touahmia
Issue:
Volume 2, Issue 2, December 2018
Pages:
60-71
Received:
10 December 2018
Accepted:
22 December 2018
Published:
22 January 2019
DOI:
10.11648/j.ae.20180202.15
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Abstract: In Saudi Arabia, as population growth increases, the need for safe drinking water is more and more increasing for both human use and industrial applications. These requires highly efficient processing plants that meet the growing needs of customers and their expectations of providing more service to all segments of the society at the lowest possible cost. On the other hand, these stations consume high amounts of energy in addition to the high maintenance and operating costs due to emergency breakdowns, which in turn result in lower production and the exit of some units from operation. This research aims to enhance the operational procedures of the stations and to study the possibility of reducing the high consumption of electric power and work to increase the performance of the plants by reducing the costs of maintenance and operation through the application of Quality Tools (QTs). This work focused on: (1) collecting data, equipment inventory, maintenance and operation costs and energy consumption rate of the equipment; (2) analyzing these data using the Seven QTs and the New QTs for Management and Planning; (3) finding solutions and presenting the results using the Minitab software; and, (4) the obtained results will be then generalized to the other stations in other Saudi Arabia regions.
Abstract: In Saudi Arabia, as population growth increases, the need for safe drinking water is more and more increasing for both human use and industrial applications. These requires highly efficient processing plants that meet the growing needs of customers and their expectations of providing more service to all segments of the society at the lowest possibl...
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