scholarly journals Performance Enhancement of Microturbine Engines Topped With Wave Rotors

2004 ◽  
Vol 128 (1) ◽  
pp. 190-202 ◽  
Author(s):  
Pezhman Akbari ◽  
Razi Nalim ◽  
Norbert Müller
Keyword(s):  
Gas Turbines ◽  
Design Space ◽  
Performance Enhancement ◽  
Weather Conditions ◽  
Wave Rotor ◽  
Advantages And Disadvantages ◽  
Wave Rotors ◽  
Significant Performance ◽  
Hot Weather ◽  
The Impact

Significant performance enhancement of microturbines is predicted by implementing various wave-rotor-topping cycles. Five different advantageous cases are considered for implementation of a four-port wave rotor into two given baseline engines. In these thermodynamic analyses, the compressor and turbine pressure ratios and the turbine inlet temperatures are varied, according to the anticipated design objectives of the cases. Advantages and disadvantages are discussed. Comparison between the theoretic performance of wave-rotor-topped and baseline engines shows a performance enhancement up to 34%. General design maps are generated for the small gas turbines, showing the design space and optima for baseline and topped engines. Also, the impact of ambient temperature on the performance of both baseline and topped engines is investigated. It is shown that the wave-rotor-topped engines are less prone to performance degradation under hot-weather conditions than the baseline engines.

Performance Improvement of Small Gas Turbines Through Use of Wave Rotor Topping Cycles

2003 ◽  
Author(s):  
Pezhman Akbari ◽  
Norbert Mu¨ller
Keyword(s):  
Gas Turbines ◽  
Performance Enhancement ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Wave Rotor ◽  
Advantages And Disadvantages ◽  
Turbine Inlet ◽  
Compressor Pressure Ratio ◽  
Significant Performance ◽  
Almost All

Results are presented predicting the significant performance enhancement of two small gas turbines (30 kW and 60 kW) by implementing various wave rotor topping cycles. Five different advantageous implementation cases for a four-port wave rotor into given baseline engines are considered. The compressor and turbine pressure ratios, and the turbine inlet temperatures vary in the thermodynamic calculations, according to the anticipated design objectives of the five cases. Advantages and disadvantages are outlined. Comparison between the theoretic performance (expressed by specific cycle work and overall thermal efficiency) of wave-rotor-topped and baseline engines shows a performance enhancement by up to 33%. The results obtained show that almost all the cases studied benefit from the wave-rotor-topping, but the highest gain is obtained for the case in which the topped engine operates with the same turbine inlet temperature and compressor pressure ratio as the baseline engine. General design maps are generated for the small gas turbines, showing the design space and optima for baseline and topped engines.

Performance Enhancement of One and Two-Shaft Industrial Turboshaft Engines Topped With Wave Rotors

2018 ◽  
Vol 35 (2) ◽  
pp. 137-147 ◽  
Author(s):  
Antonios Fatsis
Keyword(s):  
Gas Turbines ◽  
Performance Enhancement ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Specific Work ◽  
Wave Rotor ◽  
Wave Rotors ◽  
Compressor Pressure Ratio ◽  
Industrial Gas Turbines ◽  
The One

Abstract Wave rotors are rotating equipment designed to exchange energy between high and low enthalpy fluids by means of unsteady pressure waves. In turbomachinery, they can be used as topping devices to gas turbines aiming to improve performance. The integration of a wave rotor into a ground power unit is far more attractive than into an aeronautical application, since it is not accompanied by any inconvenience concerning the over-weight and extra dimensioning. Two are the most common types of ground industrial gas turbines: The one-shaft and the two-shaft engines. Cycle analysis for both types of gas turbine engines topped with a four-port wave rotor is calculated and their performance is compared to the performance of the baseline engine accordingly. It is concluded that important benefits are obtained in terms of specific work and specific fuel consumption, especially compared to baseline engines with low compressor pressure ratio and low turbine inlet temperature.

Performance Benefits of R718 Turbo-Compression Cycle Using 3-Port Condensing Wave Rotors

2004 ◽  
Author(s):  
Amir A. Kharazi ◽  
Pezhman Akbari ◽  
Norbert Mu¨ller
Keyword(s):  
Performance Enhancement ◽  
The Novel ◽  
Wave Rotor ◽  
Flash Evaporation ◽  
Pressurized Water ◽  
Wave Rotors ◽  
Compression Cycle ◽  
Performance Map ◽  
Wave Compression ◽  
Novel Concept

A number of technical challenges have often hindered the economical application of refrigeration cycles using water (R718) as refrigerant. The novel concept of condensing wave rotor provides a solution for performance improvement of R718 refrigeration cycles. The wave rotor implementation can increase efficiency and reduce the size and cost of R718 units. The condensing wave rotor employs pressurized water to pressurize, desuperheat, and condense the refrigerant vapor — all in one dynamic process. In this study, the underlying phenomena of flash evaporation, shock wave compression, desuperheating, and condensation inside the wave rotor channels are described in a wave and phase-change diagram. A computer program based on a thermodynamic model is generated to evaluate the performance of R718 baseline and wave-rotor-enhanced cycles. The detailed thermodynamic approach for the baseline and the modified cycles is described. The effect of some key parameters on the performance enhancement is demonstrated as an aid for optimization. A generated performance map summarizes the findings.

scholarly journals A Numerical Investigation of Premixed Combustion in Wave Rotors

1996 ◽  
Author(s):  
M. Razi Nalim ◽  
Daniel E. Paxson
Keyword(s):  
Premixed Combustion ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Wave Rotor ◽  
Governing Equations ◽  
Simulation Methodology ◽  
Advantages And Disadvantages ◽  
Wave Rotors ◽  
Rotor Wall ◽  
Combustion Processes

Wave rotor cycles which utilize premixed combustion processes within the passages are examined numerically using a one-dimensional CFD-based simulation. Internal-combustion wave rotors are envisioned for use as pressure-gain combustors in gas turbine engines. The simulation methodology is described, including a presentation of the assumed governing equations for the flow and reaction in the channels, the numerical integration method used, and the modeling of external components such as recirculation ducts. A number of cycle simulations are then presented which illustrate both turbulent-deflagration and detonation modes of combustion. Estimates of performance and rotor wall temperatures for the various cycles are made, and the advantages and disadvantages of each are discussed.

scholarly journals A Numerical Investigation of Premixed Combustion in Wave Rotors

1997 ◽  
Vol 119 (3) ◽  
pp. 668-675 ◽  
Author(s):  
M. R. Nalim ◽  
D. E. Paxson
Keyword(s):  
Premixed Combustion ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Wave Rotor ◽  
Governing Equations ◽  
Simulation Methodology ◽  
Advantages And Disadvantages ◽  
Wave Rotors ◽  
Rotor Wall ◽  
Combustion Processes

Wave rotor cycles that utilize premixed combustion processes within the passages are examined numerically using a one-dimensional CFD-based simulation. Internal-combustion wave rotors are envisioned for use as pressure-gain combustors in gas turbine engines. The simulation methodology is described, including a presentation of the assumed governing equations for the flow and reaction in the channels, the numerical integration method used, and the modeling of external components such as recirculation ducts. A number of cycle simulations are then presented that illustrate both turbulent-deflagration and detonation modes of combustion. Estimates of performance and rotor wall temperatures for the various cycles are made, and the advantages and disadvantages of each are discussed.

scholarly journals Toward efficient energy consumption in middle income housing buildings in Egypt

2020 ◽  
Vol 15 (2) ◽  
pp. 180-189
Author(s):  
Ibrahim Rizk Hegazy
Keyword(s):  
Energy Efficiency ◽  
Energy Efficient ◽  
Energy Use ◽  
Energy Analysis ◽  
Weather Conditions ◽  
Energy Performance ◽  
Middle Income ◽  
Efficient Energy ◽  
Hot Weather ◽  
The Impact

Abstract Current research pays special attention to the application of approaches that promote sustainable design in a built environment and ensure energy efficiency. In this context, the form of housing buildings is an important parameter that has a meaningful impact on the use of energy in housing buildings. Hence, this research attempts to study the impact of the form of housing buildings on energy efficiency taking into account the mid-hot weather conditions in one of the middle-income housing buildings in new communities in Egypt. To achieve the research aim, a comparative analysis is carried out using parametric numerical analysis—DesignBuilder energy analysis—to compare the various hypothetical proposals for different building configurations. The study determines that the efficiency of energy use in buildings depends to a large extent on their forms that will help urban designers and planners to propose the best energy performance in the form of housing buildings in the stage of conceptual design suitable for other environmental, social and economic urban planning issues. These results should be incorporated into the building codes adopted in Egypt’s new cities in order to reach more energy-efficient housing buildings in Egypt.

scholarly journals A Review of Wave Rotor Technology and Its Applications

2004 ◽  
Author(s):  
Pezhman Akbari ◽  
Razi Nalim ◽  
Norbert Mu¨ller
Keyword(s):  
Gas Turbines ◽  
Experimental Studies ◽  
Operating Characteristics ◽  
Wave Rotor ◽  
Thermodynamic Cycles ◽  
The Past ◽  
Wave Rotors ◽  
Wide Range ◽  
Novel Concept ◽  
Analytical Approaches

The objective of this paper is to provide a succinct review of past and current research in developing wave rotor technology. This technology has shown unique capabilities to enhance the performance and operating characteristics of a variety of engines and machinery utilizing thermodynamic cycles. Although there have been numerous efforts in the past dealing with this novel concept, this technology is not yet widely used and barely known to engineers. Here, an attempt is made to summarize both the previously reported work in the literature and ongoing efforts around the world. The paper covers a wide range of wave rotor applications including the early attempts to use wave rotors, its successful commercialization as supercharges for car engines, research and development for gas turbine topping, and other developments. The review also pays close attention to more recent efforts: utilization of such devices in pressure-gain combustors, ultra-micro gas turbines, and water refrigeration systems, highlighting possible further efforts on this topic. Observations and lessons learnt from experimental studies, numerical simulations, analytical approaches, and other design and analysis tools are presented.

scholarly journals A Study Protocol to Determine Heat-Related Health Impacts among Primary Schoolchildren in South Africa

2020 ◽  
Vol 17 (15) ◽  
pp. 5531
Author(s):  
Shalin Bidassey-Manilal ◽  
Caradee Yael Wright ◽  
Thandi Kapwata ◽  
Joyce Shirinde
Keyword(s):  
South Africa ◽  
Primary Schools ◽  
Climate Models ◽  
Neuropsychological Test ◽  
Panel Study ◽  
Weather Conditions ◽  
Well Being ◽  
Mitigation Measures ◽  
Hot Weather ◽  
The Impact

Climate models predict that the global average temperature of Earth will rise in the future. Studies show that high classroom temperatures can affect the ability of the student to learn and function. It is important to understand the impact that heat will have on the health, wellbeing, and academic performance of learners, as they spend a significant amount of time in classrooms compared to any other environment. A follow-up panel study among 20 public primary schools in the Gauteng province (South Africa) will be carried out, in which Grade 4 learners will be selected to complete an hourly heat-health symptom questionnaire. A Cambridge Neuropsychological Test Automated Battery (CANTAB) test will be used to determine their memory and attention span. A nursing practitioner will measure body weight, height, and temperature. Lascar data loggers will be used to measure indoor classroom temperature. School principals will complete a questionnaire on existing school coping mechanisms and policies in place that help deal with hot weather conditions. This is the first study to quantitatively assess the effects of heat on learners’ health, well-being and school performance in South Africa. The outcomes of this study will enable policymakers and public officials to develop appropriate school heat adaptation and mitigation measures and will assist in channeling their resources where it is most needed.

Architectural traits of fruiting shoots in Juglans regia (Juglandaceae) related to fruiting habit and environmental conditions

2010 ◽  
Vol 58 (2) ◽  
pp. 141 ◽  
Author(s):  
Damijan Kelc ◽  
Franci Stampar ◽  
Anita Solar
Keyword(s):  
Juglans Regia ◽  
Weather Conditions ◽  
Basal Diameter ◽  
Shoot Morphology ◽  
Vegetative Buds ◽  
Shoot Architecture ◽  
The Mean ◽  
Hot Weather ◽  
The Impact ◽  
Architectural Traits

The objective of the present study was to compare some basic architectural traits of annual shoots (1YS) in common walnut (Juglans regia L.), and to evaluate the impact of extreme drought and heat on the fruiting and growing response of the annual shoots. Measurements were conducted on three cultivars that have a terminal-bearing fruiting habit (Franquette), intermediate fruiting behaviour (Zdole-59) and a lateral-bearing fruiting habit (Fernor). Across 3 years, the mean 1YS of Franquette were one-third longer than those of the other two cultivars and their mean basal diameter was larger than that in Fernor and almost equal to that in Zdole-59. For Franquette, the length : diameter ratio showed a slender shoot morphology, whereas the shoot morphology was more compact in Fernor and Zdole-59. The 1YS of Franquette and Fernor had equal fruiting potential, with 2.8 and 2.7 fruits per shoot, respectively. Short but thick 1YS with the highest number of vegetative buds indicated dense branching and the good growing capacity of Zdole-59. The number of vegetative buds per 1YS changed during the 3 years in all cultivars, whereas the number of flowering buds per 1YS did not change in Franquette. Extreme dry and hot weather during the spring and summer of 2003 caused a reduction of 35–58% in length and a reduction of 2–16% in the basal diameter of the 1YS, regardless of fruiting behaviour. In the less vigorous, but highly productive lateral-bearer Fernor, unsuitable weather conditions in 2003 affected flower differentiation and resulted in significantly fewer fruits in 2004. The mean daily temperature in the period March–August was negatively correlated with the 1YS diameter and the number of vegetative buds per 1YS, whereas the mean precipitation during the same period showed a positive relationship with the length and diameter of the 1YS. Information obtained through shoot-architecture analysis could be useful in cultivar choice for new orchards, especially at a time of great climatic changes. Simple predictions for further development of the annual shoots could also be made.

scholarly journals Exploring Owner Perceptions of the Impacts of Seasonal Weather Variations on Canine Activity and Potential Consequences for Human–Canine Relationships

Animals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3302
Author(s):  
Emily J. Hall ◽  
Anne J. Carter ◽  
Mark J. Farnworth
Keyword(s):  
Online Survey ◽  
Weather Conditions ◽  
Exercise Duration ◽  
Activity Levels ◽  
Winter Weather ◽  
Cooling Strategies ◽  
Baseline Activity ◽  
Hot Weather ◽  
The Impact ◽  
Seasonal Weather

Climate change is leading to more instances of seasonal weather variation. Studies have explored the impact of adverse winter weather on dog walking, but the impact on the dog’s overall activity levels have not been previously considered. This study explored dog owner perceptions of the effects of both summer and winter weather on their dog’s activity levels. An international online survey recruited 3153 respondents between May and December 2018, to explore the impact of summer and winter weather conditions on baseline activity levels. Owners reported their dogs were more impacted by cold (48.2% less likely to exercise their dog in the cold) and ice (64.0% less likely), than rain (25.3% were less likely). In hot weather, over 80% of owners reported reduced exercise duration and vigour for their dogs. Carrying water or walking near water to facilitate activity in the summer was the most popular mitigation strategy (90.8%). Participation in dog sports appeared to reduce the impact of winter weather on canine activity and increase owner awareness of cooling strategies to facilitate summer activity. Strategies to promote safe activity participation are needed to maintain canine activity levels amidst rising global temperatures, including better understanding of cooling strategies for exercising dogs.

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