Improving Refrigeration Performance by Using Pressure Exchange Characteristic of Wave Rotor

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Dapeng Hu ◽  
Yang Yu ◽  
Peiqi Liu ◽  
Xiaolin Wu ◽  
Yiming Zhao
Keyword(s):  
Effective Means ◽  
Expansion Ratio ◽  
Coefficient Of Performance ◽  
The Novel ◽  
Performance Curve ◽  
Wave Rotor ◽  
Exchange Characteristic ◽  
Pressure Exchange ◽  
Exchange Function ◽  
Isentropic Efficiency

Wave rotor with pressure exchange function can be attempted to improve refrigeration performance. The objective of this paper is to verify the feasibility of the method by thermodynamic and experimental analysis. First, a refrigeration process which contains wave rotor pressurization was established. Then, a thermodynamic model which reflects the refrigeration process was designed. The thermal performance was researched under various key parameters. Finally, based on the novel wave rotor refrigeration platform, the experimental work was carried out, and the effects of main parameters of the device were systematically studied. The results showed that it was feasible to enhance the coefficient of performance (COP) by using pressure exchange characteristic of wave rotor. The COP could be improved substantially at relatively small expansion ratio. Under the design point, more than half of the pressure energy could be restored. The performance curve of the novel equipment was also obtained. Enhancing the isentropic efficiency of expansion is the effective means to improve the COP and σ of the system. This paper was designed in a way that contained a novel equipment to enhance the COP of wave rotor refrigeration.

scholarly journals Becoming a Crorepati: From Glocal TV Game to Grobal Fiction

2020 ◽  
Vol 73 (3) ◽  
pp. 497-520
Author(s):  
Nicola Pozza
Keyword(s):  
Effective Means ◽  
The Novel ◽  
Cultural Products ◽  
Slumdog Millionaire ◽  
Interactive Nature ◽  
Tv Show ◽  
Shed Light ◽  
The Way

AbstractNumerous studies have dealt with the process of globalization and its various cultural products. Three such cultural products illustrate this process: Vikas Swarup’s novel Q and A (2005), the TV quiz show Kaun banega crorepati? (Who Wants to Be a Millionaire?), and Danny Boyle’s film Slumdog Millionaire (2008). The novel, the TV show and the film have so far been studied separately. Juxtaposing and comparing Q and A, Kaun banega crorepati, and Slumdog Millionaire provides an effective means to shed light on the dialogic and interactive nature of the process of globalization. It is argued through this case study that an analysis of their place of production, language and content, helps clarify the derivative concepts of “glocalization” and “grobalization” with regard to the way(s) contemporary cultural products respond to globalization.

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.

Axis-Asymmetric Profiled Endwall Design by Using Multiobjective Optimisation Linked With 3D RANS-Flow-Simulations

2007 ◽  
Author(s):  
Christian Dorfner ◽  
Eberhard Nicke ◽  
Christian Voss
Keyword(s):  
The Novel ◽  
3D Flow ◽  
Flow Solver ◽  
Axial Compressors ◽  
Flow Simulations ◽  
Flow Loss ◽  
Engine Components ◽  
Operating Points ◽  
Isentropic Efficiency ◽  
Wide Operating

Secondary flow loss in modern axial compressors is considered to be the prime reason for the reduction of overall isentropic efficiency in these engine components. This paper presents a new methodology to diminish blade secondary loss and endwall loss by an axis-asymmetric modification of endwalls using an automated multiobjective optimizer in conjunction with 3D-RANS-flow-simulations. In order to obtain a favorable design for a wide operating range, the most important operating-points are considered in the optimization process. The existing multiobjective optimization package is enhanced by implementation of DLR’s in-house 3D-flow-solver TRACE. A straightforward stator optimization was performed for a 3D-process-chain test run. Finally, the novel endwall design technique is introduced and the first optimization results and further studies are discussed.

scholarly journals Ode in Onia: Reading the Use of Myth and Twinhood in Diana Evans’ 26a

2017 ◽  
Vol 8 (1) ◽  
pp. 571-574
Author(s):  
Douglas E. Kaze
Keyword(s):  
Magical Realism ◽  
Effective Means ◽  
The Novel ◽  
Personal Experiences ◽  
And Migration ◽  
Postcolonial Writers ◽  
Over Time

Postcolonial writers have over time engaged in the use of folklore preserved from their precolonial heritage in their works that try to understand the complexities of their postcolonial existence. Such writers have used ancient stories, songs, proverbs and other ideas from their vernacular cosmologies in intertextual conversation with their fiction. In this article, I discuss this kind of practice in the novel 26a by Nigerian-British novelist, Diana Evans. The novel explores personal experiences of twinhood which also raises questions about identity, transnationalism and migration. This paper’s focus is on the ways in which Evans fetches material from her Nigerian background – the myth about twinhood – and merges it with her fiction, allowing both to engage and transform each other. Through this she has not only created a work of magical realism, but finds an effective means to represent trauma, psychic and existential struggles along with what it means to exist between categories.

Novel Endoscope Control Assessment System Using Video and Magnetic Tracking

2020 ◽  
Author(s):  
Alexandra Ferri ◽  
Saira Hussain ◽  
Eric Pauli ◽  
Randy Haluck ◽  
Barry Fell ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Full Range ◽  
Effective Means ◽  
Assessment System ◽  
The Novel ◽  
Training Performance ◽  
Magnetic Tracking ◽  
Endoscopic Control ◽  
Extensive Training ◽  
Magnetic Tracker

Abstract Colonoscopy procedures are commonly performed to diagnose and prevent colorectal cancer. These procedures require highly trained practitioners to perform complex maneuvers with an endoscope. Extensive training is necessary to become proficient. To improve assessment during endoscope training the novel endoscopic control assessment system (ECAS) is proposed. This device uses a magnetic tracker to track the end of the endoscope in manikin training. In addition, camera imaging is used to track the angle of the control knobs during the training. Experiment 1 demonstrated that the magnetic tracker could sense the full range of motion of the endoscope. Experiment 2 showed that the control knob angle could be accurately tracked through 4 positions to within 0.6° accuracy. The feasibility of the ECAS system was shown and in the future, this can be employed as an effective means of assessing endoscopic training performance.

Investigation of Temperature Separation Inside Various Models of Ranque–Hilsch Vortex Tube: Convergent, Straight, and Divergent With the Help of Computational Fluid Dynamic Approach

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
Adib Bazgir ◽  
Nader Nabhani
Keyword(s):  
Computational Fluid Dynamic ◽  
Vortex Tube ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Numerical Data ◽  
Coefficient Of Performance ◽  
Tube Length ◽  
Operational Parameters ◽  
Temperature Separation ◽  
Isentropic Efficiency

In this paper, a Ranque–Hilsch vortex tube (RHVT) has been optimized utilizing convergent (φ), straight, and divergent (θ) axial angles for hot-tube. Effects of divergent (θ) and convergent (φ) angles on the flow behavior have been investigated by computational fluid dynamic (CFD) techniques. By using a renormalization group (RNG) k–ε turbulence model based on finite volume method, all the computations have been carried out. The isentropic efficiency (ηis) and coefficient of performance (COP) of machine was studied under five different divergent angles (θ), namely 1 deg, 2 deg, 3 deg, 4 deg, and 6 deg, two different convergent (φ) angles (φ) namely 1 deg and 2 deg adjusted to the hot-tube. Furthermore, some geometrical and operational parameters including cold outlet diameter, hot-tube length, and different inlet pressures and mass flow rates have been analyzed in detail (spanwisely) in order to optimize the cooling efficiency of vortex tube (straight). The results show that utilizing the divergent hot-tubes increases the isentropic efficiency (ηis) and COP of device for most values of inlet pressures, and helps to become more efficient than the other shape of vortex tubes (straight and convergent). Finally, some results of the CFD models have been validated by the available experimental and numerical data, which show reasonable agreement, and others are compared qualitatively.

Wave Cycle Design for NOx-Limited Wave Rotor Core Engines for High Speed Propulsion

1993 ◽  
Author(s):  
M. Razi Nalim ◽  
Jeffrey C. Mocsari ◽  
Edwin L. Resler
Keyword(s):  
High Speed ◽  
Pressure Ratio ◽  
Aircraft Engine ◽  
Specific Power ◽  
Wave Rotor ◽  
Design And Optimization ◽  
Wave Channel ◽  
High Specific Power ◽  
Wave Cycle ◽  
Pressure Exchange

Direct work and pressure exchange between gases can be accomplished by cyclic wave processes in the channels of a wave-rotor, circumventing the limitations of turbo-compressors. A wave-rotor cycle is presented for use as the high-pressure core in a high speed aircraft engine with turbine bypass. The products of a “low-NOx” combustor undergo a large immediate wave-expansion to reach a permissible turbine blade temperature. The wave rotor provides a substantial increase in pressure ratio and peak cycle temperature resulting in high specific power and efficiency. Approximate analytical methods are employed for initial design and optimization of the cycle. The method of characteristics is then used to compute the detailed time evolution of the flow-field in a wave channel.

scholarly journals Characteristic of a multistage reheating radial inflow in supercritical compressed air energy storage with variable operating parameters

2018 ◽  
Vol 233 (3) ◽  
pp. 397-412
Author(s):  
Hui Li ◽  
Wen Li ◽  
Xuehui Zhang ◽  
Yangli Zhu ◽  
Zhitao Zuo ◽  
...  
Keyword(s):  
Energy Storage ◽  
Mass Flow ◽  
Total Pressure ◽  
Guide Vane ◽  
Expansion Ratio ◽  
Compressed Air ◽  
Total Power ◽  
Speed Ratio ◽  
Compressed Air Energy Storage ◽  
Isentropic Efficiency

In the present study, aerodynamic performance of a four-stage reheating radial inflow turbine, which is adopted in the 1.5 MW supercritical compressed air energy storage system, is analyzed by using the method of integral numerical calculation. Results illustrate that when the inlet total pressure of the first stage is decreased, the expansion ratio of the fourth stage decreases the most. System isentropic efficiency decreases about 1% when the inlet total pressure of the first stage is changed from 7 MPa to 3 MPa, and the fourth stage’s isentropic efficiency decreases about 7%. When the rotational speed is decreased, isentropic efficiency and total power decrease gradually and isentropic efficiency changes from 90.5% at 110% speed ratio to 71.1% at 60% speed ratio. Increasing reheating temperature results to the decrease of mass flow rate and isentropic efficiency and the increase of total power. Total power increases by about 105% when the reheating temperature is changed from 60 ℃ to 520 ℃. When the guide vane opening of the first stage is increased, the expansion ratio of the first stage shows different trends compared to other stages and mass flow rates, and total power are proportional to the guide vane opening. System isentropic efficiency decreases by about 4% when the guide vane opening is adjusted from 80% to 30%.

scholarly journals Mechanism of Power

2018 ◽  
Vol 8 (2) ◽  
pp. 92
Author(s):  
Mohamad Haj Mohamad
Keyword(s):  
Effective Means ◽  
The Novel ◽  
Hunger Games ◽  
Authoritarian State ◽  
The Social ◽  
The Hunger Games ◽  
Body And Soul ◽  
Democratic Rule ◽  
Divide And Rule ◽  
Definition Of

This paper attempts an examination of the concept of the mechanism of power in Suzanne Collins’ trilogy The Hunger Games. The author conducts an analytical approach to the way power is practiced, the measure that helps establish a clandestine of power relations affecting people’s life, mentality of thinking, politics and even economy.The introduction delves to present a definition of power and its concept and how it gets activated and why. Power, according to Collins is the backbone and even the elixir of life upon which the very survival of the authoritarian state headed by President Snow depends. The paper goes on to explicate the need for keeping power in place to secure the government’s grip on power. Mechanism of power as shown in the novel works on so many levels. Divide and rule marks the first and most necessary and effective means as a divisive policy aiming at preventing any potential unity among people who might employ this unity to rise up against the totalitarian government. Media and sport and economic factors are used effectively to ensure government’s control on man’s mind, body and soul and intimidate them whenever needed. Collins presents power and its mechanism as the sole relation between people and government in the novel. Absence of democratic rule in Panem, or, American states, leaves power as the only means to describe the social bond between man and state, a bond that is unilaterally respected and practiced.

scholarly journals AN EVAPORATION HEAT ENGINE AND CONDENSATION HEAT PUMP

2008 ◽  
Vol 49 (4) ◽  
pp. 503-524 ◽  
Author(s):  
N. G. BARTON
Keyword(s):  
Water Vapour ◽  
Heat Pump ◽  
Evaporative Cooling ◽  
Heat Engine ◽  
Expansion Ratio ◽  
Ideal Gas ◽  
Coefficient Of Performance ◽  
Specific Work ◽  
Reduced Pressure ◽  
Evaporation Heat

AbstractThis paper presents a thermodynamic model for a heat engine based on evaporative cooling of unsaturated air at reduced pressure. Also analysed is a related heat pump based on condensation of water vapour in moist air at reduced pressure. These devices operate as two-stroke reciprocating engines, which are their simplest possible embodiments. The mathematical models for the two devices are based on conservation of mass for both air and water vapour, ideal gas laws, constant specific heats, and, as appropriate, either constant entropy processes or cooling/heating by evaporation/condensation. Both models take the form of coupled algebraic systems in six variables, which require numerical solution for certain stages of the cycle. The specific work output of the heat engine increases as the inlet air becomes hotter and as the expansion ratio of the engine increases. The engine provides evaporative cooling of air from inlet to outlet. The heat pump has a good coefficient of performance, which decreases as the expansion ratio increases. The heat pump also has the effect of drying the air from inlet to outlet, producing distilled water as a by-product.

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