bluuebunny/crossref_metadata_2025_split huggingface dataset:
Incorporating Cogeneration Into a Geothermal Power Plant to Enhance Utilization and Profitability
Authors: Kanoğlu Mehmet , Çengel Yunus A. 
Published: January 2022

Abstract
An existing binary geothermal power plant in Nevada with a rated power of 1.2 MW is investigated. The current performance of the plant is assessed, and it is found that the power output of the plant could be increased by about 12% by simply upgrading one of the two turbines of the plant. There also appears to be a great potential for better utilization of this geothermal resource by incorporating cogeneration into the power plant. Using the geothermal brine after being used for power generation to preheat fresh water needs of a nearby plastics plant appears to be feasible and financially attractive. Selling thermal energy of the geothermal brine for preheating water has an annual revenue potential of about $18,000. This is about 5% of the revenue currently generated by the sale of electricity. The payback period for the initial cost of this project is determined to be less than 6 years. The preheating process could be met by only a small fraction of geothermal brine available. The region where the geothermal plant is located is expected to develop by new industrial facilities, and therefore, the potential of selling thermal energy of geothermal brine for preheating water could greatly improve in the future. Utilization of the entire brine available after being used for power generation for preheating water and possibly for space heating has an annual revenue potential of up to $5 million, which corresponds to 10 times increase in the revenue from this geothermal site.
The Maximum Power Cycle: A Model for New Cycles and New Working Fluids
Authors: Ibrahim Osama M. , Arnold Douglas G. 
Published: January 2022

Abstract
The objective of this paper is to extend a previously presented finite-time thermodynamic framework that explains the conceptual differences between power and efficiency optimization and defines the Maximum Power cycle. The shape and the performance of the Maximum-Power cycle are used as criteria to study and evaluate alternative working fluids that can improve the performance of the power cycle for low temperature heat sources, such as solar energy and waste heat. In this study, pure fluids, non-azeotropic and azeotropic mixtures in a single or multi-stage Rankine cycle are considered. The results show that pressure-dependent azeotropic mixtures have the potential to improve the performance of the Rankine cycle. The results also show that the Maximum Power cycle provides a useful tool for studying power cycles and forms the basis for making design improvements.
Thermoeconomic Analysis of Combined Cycle Units With Intercooled Gas Turbine, Derived From Existing Steam Power Plants
Authors: Negri di Montenegro G. , Peretto A. , Mantino E. 
Published: January 2022

Abstract
The paper presents a thermoeconomic analysis of three pressure level reheat combined cycles derived from existing steam power plants. The gas turbine employed is an intercooled gas turbine, proposed and investigated in the Collaborative Advanced Gas Turbine program by the major aero-engine manufacturers and international electric and natural gas industry sponsors.
The steam power plants to repower are conventional steam power plants of three different sizes, 320 MW, 160 MW and 70 MW, easily found in Italy.
Firstly, a thermodynamic analysis is performed for the different repowered plants, also in the presence of supplementary firing at the gas turbine outlet.
Subsequently, the economic analysis of the repowered plants is carried out determining the cost per kWh, the payback period and the internal rate of return. These economic variables, for each combined cycle derived from existing steam power plants, are discussed and compared with those relating to a new combined cycle power plant also equipped with intercooled gas turbine.
Finally, a sensitivity analysis is developed by using a sensitivity parameter. In this way, the influence of some economic parameters on the cost per kWh, pay back and internal rate of return is numerically evaluated.
On the basis of a plausible cost per kW for the intercooled gas turbine, the study reveals that the transformation of old conventional fossil fuel power plants, performed with intercooled gas turbine, supplies a cost per kWh lower than that of a new combined cycle power plant, also equipped with intercooled gas turbine. It occurs for all the repowered plants analyzed with or without supplementary firing.
Comparison of the costs per kWh for the repowered plants, employing either an intercooled gas turbine or a Brayton cycle gas turbine available on the market, indicated that the solution with an intercooled gas turbine may be worthy of consideration only for the combined cycles derived from the smallest size steam power plant. This remains valid also in the hypothesis of decreasing the cost of the intercooled gas turbine.
Some Simple and Economical Ways of Saving Energy in Industrial Facilities
Authors: Çengel Yunus A. , Çerci Yunus , Turner Robert H. 
Published: January 2022

Abstract
About 37% of the energy consumed in the United States is used by industrial facilities, and a considerable fraction of this energy can be saved by practicing simple energy conservation measures. In this paper we give an overview of such conservation measures complete with the analysis, the potential energy and cost savings, the implementation costs, and simple payback periods. The proposed measures are intended as a retrofit for existing facilities, and most of them can be implemented by the maintenance personnel of the facilities. The recommendations are based on our observations and measurements during energy audits of numerous manufacturing facilities in Nevada and California during the last three years. In a recent paper (Cerci et al, 1995) we discussed energy conservation opportunities related to compressors. In this paper we extend the discussions to other areas, and present economically attractive common sense measures such as (1) insulating hot and cold surfaces, (2) adjusting the air-fuel ratio in the furnaces, (3) installing programmable thermostats, (4) installing high efficiency fluorescent lamps, (5) installing occupancy sensors, (6) using reflective film on glazing, (7) improving the power factor, and (8) installing high efficiency motors. These measures are described in sufficient detail, and the energy and cost savings are analyzed and quantified. The typical potential savings from these measures are illustrated with examples taken from real-life applications. Our goal in this paper is not to present something new, but rather, to raise awareness and to show the tremendous energy and cost saving opportunities missed as a result of overlooking some simple and obvious conservation measures.
Thermoeconomic Evaluation of a Gas Turbine Cogeneration System
Authors: Guarinello Flávio , Cerqueira Sérgio A. A. G. , Nebra Silvia A. 
Published: January 2022

Abstract
The main purpose of this work is to apply the Thermoeconomics concepts to a projected steam injected gas turbine cogeneration system which aims at providing the thermal and electrical demands of an industrial district, sited in Cabo (Pernambuco-Brazil). The power plant is evaluated on the basis of the First and Second Laws of Thermodynamics. A Thermoeconomic analysis, using the Theory of Exergetic Cost, was performed, in order to determine the production costs of electricity and steam. Two hypothetical operational conditions, as regards to the level of electric power generation, were considered.
Design Improvements to Waste-to-Energy Plants Using Exergetic Analysis as a Project for the Second Course in Thermodynamics
Authors: Wong Kau-Fui Vincent , Witmer M. , Crowder B. , Han S. Y. , Serretti D. P. 
Published: January 2022

Abstract
It has been a concern that mechanical engineering graduates may not have enough exposure to real world engineering situations. A design project was assigned in conjunction with the second thermodynamics course in mechanical engineering to help alleviate this problem. The objective of the design project was to take an existing operating waste-to-energy plant, and modify it so that both its first and second law efficiencies are improved. The project indeed helped the students understand and use the second law effectively. The project exposed the students to real world situations, provided them with a chance to visit plants in operation, and gave them the confidence to apply theories and methods taught in the classroom. Student response was favorable and it gave them another opportunity to work in teams on design, as emphasized by ABET. This paper selects for presentation the analyses of the performance of two waste-to-energy plants.
Two-Shift Operation Economic Benefits for Conventional and Advanced Fossil Fueled Power Plants
Authors: Bianchi M. , Gadda E. , Peretto A. 
Published: January 2022

Abstract
In the context of cycling duty, two main operating schedules are prevalent: load following, in which the unit remains in service but changes load to match the system requirements, and two-shift operation, in which some units are shutdown during the night and the weekend/holiday.
The present paper analyses the economic benefits obtainable from the two-shift operation of fossil fuel power units with respect to load following. In particular, two different types of thermoelectric power units are considered:
• conventional steam power units;
• advanced fossil fuel power units (i.e. gas-steam combined cycle units).
Firstly, a thermodynamic analysis is carried out evaluating the off-design heat rate of the power units during the part load operation.
Subsequently, the economic hourly and annual savings, obtained by shutting down one unit, are performed.
Appreciable benefits are found for a large range of the system load requirements, thus indicating the two-shift operation as a strategy that can be pursued.
Performance of a Residential Sized GAX Absorption Chiller
Authors: Priedeman Douglas K. , Garrabrant Michael A. , Mathias James A. , Stout Roger E. , Christensen Richard N. 
Published: January 2022

Abstract
This research effort involved experimentally testing an advanced-cycle, ammonia-water absorption chiller with a cooling capacity of 17.6 kW (5 refrigeration tons (RT)). The system was a Generator-Absorber Heat Exchange (GAX) cycle and was sized for residential and light commercial use, where very little absorption equipment is currently used. The components of the cycle were assembled with instrumentation, including flow meters, pressure transducers, and thermocouples. The findings of the research were cycle cooling load and Coefficient of Performance (COP), as well as many component heat duties and working fluid state points throughout the cycle. The COP of the chiller at essentially full load was 0.68.
Existing market research shows that significant business opportunities exist for a GAX heat pump or chiller with a cooling COP of 0.70 or greater. The work performed in this study provides a breadboard cycle with performance approaching the target value and identifies improvements that must be made to achieve a packaged unit operating with a cooling COP of 0.70.
Piston Lubrication Model for Reciprocating Compressors
Authors: Prata A. T. , Fernandes J. R. S. , Fagotti F. 
Published: January 2022

Abstract
Piston dynamics plays a fundamental role in two critical processes related to fluid flow in reciprocating compressors. The first is the refrigerant leakage through the radial clearance, which may cause considerable loss in the pumping efficiency of the compressor. The second process is the viscous friction associated with the lubricant film in the radial clearance; certainly a significant factor in the compressor energy consumption. In the present contribution a numerical simulation of the piston movement inside the cylinder of a reciprocating compressor is performed. The compressor considered here is a small hermetic compressor employed in domestic refrigerators. For the problem formulation both the axial and the radial piston motion is considered. In operation, the piston moves up and down along the axis of the cylinder, but the radial oscillatory motion in the cylinder bore, despite being usually small, plays a very important role on the compressor performance and reliability. The compromise between sealing of the gas leakage through the piston-cylinder clearance and the friction losses requires a detailed analysis of the oscillatory motion for a good design. The forces acting on the piston are the hydrodynamic force due to the pressure build up in the oil film (lubrication effects), the force due to the connecting rod, the viscous force associated with the relative motion between the piston and oil, and the force exerted by the gas on the top of the piston. All corresponding moments are also included in the problem formulation of the piston dynamics, in order to determine the piston trajectory, velocity and acceleration at each time step. The hydrodynamic force is obtained from the integration of the pressure distribution on the piston skirt, which, in turn, is determined from a finite volume solution of the time dependent equation that governs the oil flow. A Newton-Raphson procedure was employed in solving the equations of the piston dynamics. The results explored the effects of some design parameters and operating conditions on the stability of the piston, its sealing performance and friction losses. Emphasis was placed on investigating the influence of the pin location, radial clearance and oil viscosity on the piston dynamics. The complexity of the piston movement in reciprocating compressors was demonstrated and the detailed model presented can be employed as an useful tool for engineering design.
A Mathematical Analysis of Accumulator Heat Exchangers to Achieve Liquid Overfeeding Effects in Small Air Conditioning Systems
Authors: Wood Craig W. , Meyer Josua P. 
Published: January 2022

Abstract
This paper derives a calculation procedure for sizing a heat exchange accumulator according to the required heat transfer. The model determines all the required diameters and pipe lengths according to the inner coil diameter (which is determined by physical pipe dimensions). The model ensures that refrigerant velocity through the accumulator is the same as the refrigerant velocity maintained in the original system.
Performance of a Series Air-to-Air Heat Pump for Continuous and Intermittent Drying
Authors: Fatouh M. , Abou-Ziyan H. Z. , Metwally M. N. , Abdel-Hameed H. M. 
Published: January 2022

Abstract
A series air to air heat pump assisted-dryer has been designed and tested under various operating conditions. Air flow rates of 500 to 1400 m3/hr at supply air temperatures of about 25 to 50 °C are used. This temperature range covers ambient air and warm air heated by either solar collector or waste heat recovery device. R22 is used as the working fluid in the heat pump circuit. The results showed that average refrigerant temperature lift of 33°C and Rankine coefficients of performance (COPR) up to 4.6 are obtained. This (COPR) proved that the heat pump is an efficient device that saves energy and money. Also, exergetic efficiency of the heat pump up to 0.35 and outlet air temperatures of 55°C are achieved. This air temperature level is adequate for drying of many products.
The heat pump assisted-dryer is tested with continuous and intermittent drying techniques. The continuous drying is used to dry onion, carrot, potato and sweet potato in which specific energy consumption lower than the conventional dryers by 18 to 32% are achieved. The intermittent and continuous drying techniques are compared for onion drying. The results showed that the use of intermittent drying saves about 30% of the energy consumed by the continuous drying when the appropriate heating and resting periods are used.
Heat Transfer Enhancement of Direct Contact Melting Process by Vibration
Authors: Oka Mineo 
Published: January 2022

Abstract
Direct contact melting process takes place in many natural and technological processes. One of the important application of this process is thermal storage system. Phase change material (PCM) is stored in a small capsule that is melted by heating peripherally. In this melting process, melting rate is important factor for the efficiency of the system. In this paper, utilization of vibrating motion of heating wall is proposed to enhance the melting rate. Effect of vibrating motion of the heating wall is studied. Non-steady heat transfer phenomena of direct contact melting process is studied theoretically while only steady state is studied in recent analytical researches. In this paper, it is clarified that the vibrating motion of heating wall enhances the heat transfer and melting rate.
Temperature Effect on Power MOSFET Devices
Authors: Lu W. , Chow L. C. , Sundaram K. B. 
Published: January 2022

Abstract
The development of the power MOSFET allows an electronic circuit designer greater flexibility in high power applications. Over the last several years, it has been demonstrated that there are marketable advantages of operating the power MOSFET devices at cryogenic temperature. This paper demonstrates by experiment and theoretical derivation that the on-resistance decreases significantly when the operating temperature decreases. Such a decrease leads to a considerable reduction in heat generation inside the MOSFET device. In other words, it becomes possible to push higher current through the MOSFET device with the same heat generation. It makes higher integration of MOSFET devices possible. This paper shows an experimental measurement of on-resistances at 77 K, 173 K, 243 K and 295 K by applying cryogenic cooling techniques. The results have been confirmed by comparing them with the threshold voltage calculations. Another important advantage of operating MOSFET devices under cryogenic temperature is that the thermal resistance of the device decreases. The thermal conductivity of silicon material increases about nine times when the temperature decreases from 295 K to 77 K (148 W/mK to 1340 W/mK). This will significantly decrease the internal thermal resistance of a MOSFET device. The junction temperature is the parameter under which all the characteristics of MOSFET should be evaluated. When the MOSFET is operating under an extremely high power condition, although there are several effective cooling techniques to maintain the heat sink temperature within a certain range, the junction temperature can be kept at a reasonable temperature only if the internal thermal resistance is small. By knowing the internal thermal resistance, heat generation rate and the sink temperature, the junction temperature can be calculated. This paper proposes a simple method to determine the internal thermal resistance under any power and any operating temperature. The experiment found that at liquid nitrogen temperature (77 K), the internal thermal resistance drops to 1/5 of that at room temperature (295 K). These results indicate that at cryogenic operating temperature, it is possible to obtain high power application while still maintain relatively low temperature at the junction.
A Study of Residual Stress and Property Mismatch on SIF Distributions for Cracks Parallel to and Within Bondlines
Authors: Smith C. W. , Finlayson E. F. , Liu C. T. 
Published: January 2022

Abstract
As a result of the need to extend the storage life of rocket motors, new emphasis has been placed upon the effect of cracks developed during storage and transport on the integrity of motor performance. In addressing this need, the authors have developed a three specimen test procedure for evaluating the stress intensity factor (SIF) distribution for cracks through the thickness of rubberlike materials near to and within simulated bond lines between the motor grain and its liner. A refined frozen stress method is employed for making measurements, and preliminary studies have shown that, for cracks in the bond line under both Mode I and Mixed Mode loads, the stress intensity factors are elevated primarily due to bond line residual stresses and may not be affected by modulus mismatch.
Damage Characteristics Near Crack Tip for a Particulate Composite
Authors: Liu C. T. , Ho H. 
Published: January 2022

Abstract
Nondestructive acoustic imaging experiments and three dimensional finite element analyses were performed to study the crack-damage interaction phenomenon of a particle reinforced polymeric composite. Effects of damage size and degree of damage on the mode I stress intensity factor and the local stress fields near the crack tip were evaluated and the damage and crack growth behavior were discussed.
Buckling Characteristics of Regular and Irregular Asymmetric Laminated Composites
Authors: Vinogradov Aleksandra M. 
Published: January 2022

Abstract
The paper examines the effects of composite material properties on the nonlinear buckling response of irregular asymmetric composite structures through the analysis of asymmetric laminated beam-columns composed of an arbitrary number of different material layers. The nonlinear buckling behavior of the structures subjected to combined compression and bending is examined as a function of the number, orientation and stacking sequence of the layers that make up the laminate. The analysis demonstrates that, typically, buckling of asymmetric composites is initiated immediately at the load application, however, under certain conditions, the structures exhibit bifurcation. In such cases, the critical load can be optimized through tailoring the material properties of the laminates.
Study of Effectiveness of Countermine Boots
Authors: Kwon Young W. , Muschek Richard C. 
Published: January 2022

Abstract
The goal of this study was to conduct a qualitative analysis to determine the effectiveness of countermine boots. This was done by determining their ability to dissipate a blast force equivalent to a typical anti-personnel landmine. This was followed by a parametric study that which involved altering the component materials in an effort to determine if the effectiveness of the boots varied as the materials changed. A finite element analysis was conducted to evaluate the effectiveness of the countermine boot based upon accepted tolerance levels of the lower extremity of the body. The materials and their dimensions were modified in the finite element model to determine how these modifications would impact the boots’ effectiveness.
Fatigue Analysis of 5-1/2 F.H. Threaded Connection
Authors: Hommel Mark 
Published: January 2022

Abstract
This paper examines the fatigue behavior of the 5-1/2 F.H. threaded connection. The finite element method was used to calculate the static and bending stresses in the pin and box for the purpose of estimating fatigue life of the connection. These stresses were compared with the material properties of the steel and a fatigue life was thereby predicted for a given dogleg.
The Gerber criterion was selected as the theoretical basis for combining mean and fluctuating stresses. Mean stress was linearized from the static case associated with the preload from make-up torque. Alternating stress was obtained from applying a bending moment associated with a prescribed dogleg. The last engaged thread in the pin, closest to the shoulder, and the last engaged thread in the box, farthest from the shoulder, were seen to be the sites of maximum stress. The pin stresses govern fatigue life because mean stress is higher than for the box.
In a parallel effort, a roll test was set up to examine fatigue life experimentally. A BHA was made up and installed horizontally in the roll machine. The deflection at the threaded connection was measured, and the assembly was rotated at a measured speed until the pin part of the threaded connection failed.
Next, the finite element results were compared with roll test data and good agreement was obtained. The data was then extrapolated to generate a graph showing expected life as a function of dogleg severity for the 5-1/2 F.H. connection. Finally, the maximum dogleg for which the connection has a 10 million cycle life was predicted.