Compressor

AbstractÐThe electrochemical compression of hydrogen is well known since years. But new developments of the polymer electrolyte membrane (PEM) fuel cells make it possible to realize the electrochemical compression in a PEM-cell with high eciency. A new cell design of PEM-cells for operation with a high pressure dierence between anode side and cathode side was developed. The puri®cation of hydrogen from carbon monoxide of the reformer gas can be integrated in the hydrogen compressor cell. Operation parameters are presented. #

Significant progress has been made in the application of low plasticity burnishing (LPB) technology to military engine components, leading to orders of magnitude improvement in damage tolerance. Improved damage tolerance can facilitate inspection, reduce inspection frequency, and improve engine operating margins, all leading to improved military readiness at significantly reduced total costs. Basic understanding of the effects of the different LPB process parameters has evolved, and finite element based compressive residual stress distribution design methodologies have been developed. By incorporating accurate measurement of residual stresses to verify and validate processing, this combined technology leads to a total solutions approach to solve damage problems in engine components. An example of the total solution approach

The low frequency rf linacs and bunch compressors in the NLC are heavily loaded by beam currents up to 0.9 A. Beam loading generates bunch-to-bunch energy deviations, which need to be compensated to operate with long bunch trains in the linear collider. There are two basic compensation techniques, namely T and F schemes. The F scheme is operationally straightforward but requires additional rf systems which are powered at slightly different frequencies. In contrast, the T scheme does not require any additional rf and is thus expected to be less expensive. Here, the loading compensation is realized by early injection combined with rf phase and amplitude modulation. The phase/amplitude modulation is performed with fast phase shifters at low rf power before amplification by the klystrons. With combined phase and amplitude modulation, the T scheme can be applied to both the accelerator and compressor linacs. In this paper, we present simulations of the T compensation scheme for the NLC low rf accelerator and compressor linacs. We discuss different rf configurations using the T scheme as well as some issues related to phase/amplitude modulations in such layouts.

The purpose of the work was to critically re-examine and investigate the evaluation of refrigerant compressors and to determine and discriminate between the factors which influence their characteristics. The objectives also included the investigation of techniques by which the characteristics can be established and the suggestion of ways in which compressor performance can be described and quantified. The particular compressor

The purpose of this work is to develop and evaluate an inverse optimization algorithm, which designs two-dimensional compressor-blade shapes based on a prescribed pressure or velocity distribution. Thus, the design meets prescribed constraints imposed by the aerodynamic performance requirements that are suggested by the designer/stakeholder. The algorithm is coded using "Visual Basic". Its three main components are: (i) Surface-panel-method flow solver, (ii) Bezier curve-surface-definition routine, (iii) Optimization method. The procedure starts with a given compressor-blade shape C4 as a base-profile. Interesting findings and beneficial conclusions are presented.

Theoretical analyses of subcritical/transcritical heat pumps using four natural refrigerants, carbon dioxide, ammonia, propane and isobutane have been carried out for high temperature heating applications at different heating outlet temperatures and heat sources using computer models. The compressor discharge pressures have been optimized for transcritical and subcritical (with near critical operation of condenser) cycles. Results show that for subcritical heat pumps, use of subcooling is efficient for heating applications with a gliding temperature. Results also show that although propane yields better coefficient of performance (COP) in low temperature heating applications, ammonia performs the best in high temperature heating applications. Finally, design aspects of major components of all the four heat pumps for high temperature heating have been discussed, particularly with reference to suitability of available lubricants to the newly evolved operating conditions.

Radial clearance OileR134a mixture Refrigerant leakage a b s t r a c t In this paper a non-isothermal two-phase model for oileR134a refrigerant mixture flow is presented to predict the R134a leakage through the radial clearance of rolling piston compressors. The flow is divided in a liquid single-phase region and in a two-phase region, in which the homogeneous model is used to simulate the flow. The refrigerant leakage is determined using the mixture mass flow rate and the refrigerant mass fraction variation along the flow. The results are obtained for inlet pressures varying from 200 to 700 kPa, inlet temperatures ranging from 40 to 60 C, and minimal clearances between 10 and 60 mm. The results are firstly compared to existing isothermal model data, showing that there is a significant difference between the leakage flow rates predicted by isothermal and non-isothermal models. Finally, a useful general equation for compressor designers is proposed to calculate the refrigerant leakage for a large range of operation conditions. ª 2012 Elsevier Ltd and IIR. All rights reserved.

Flare gas recovery is one of the most attractive methods to improve energy efficiency in oil refineries to decrease greenhouse gas emissions. The recovered gas is used to feed refinery processes, granting advantages in terms of fuel economy and flare stress. This paper presents the results obtained by a feasibility study of a flare gas recovery system in a real refinery; the work focused on: i) the choice and the design of the flare gas recovery system; ii) the gas treatment and reuse; iii) the economic feasibility, and the payback period. An experimental campaign has been performed to evaluate both the composition and the flow rate of the flare gas. Results showed that the flare gas had a strongly variable flow rate and composition due to the different gas species processed in refinery. A methodology for the system selection is presented: a 400 kg/h liquid ring compression device is chosen; its basic design is described as well as the chemical treatments of inert gases and hydrogen sulphide (H 2 S). The yearly energy recovery was estimated to be 2900 TOE, corresponding to 6600 tons of CDE (Carbon Dioxide Equivalent). Finally, an economic evaluation was carried out, showing a payback period of about 2.5 years.

Máy nén khí piston-Chất lượng, giá thành rẻ cạnh tranh Máy nén khí piston là thiết bị sở hữu kích thước gọn nhẹ, nên việc di chuyển khá đơn giản. Bên cạnh đó, đây còn là sản phẩm có công suất lớn đáp ứng đầy đủ nhu cầu sử dụng và nhiều ưu điểm nổi trội khác; được đông đảo người tiêu dùng lựa chọn sử dụng. Bạn đang tìm kiếm máy nén khí để có thể phục vụ mục đích sử dụng của gia đình cũng như trong các tiệm rửa, sửa chữa bảo dưỡng xe. Máy nén khí Piston đang là sản phẩm được sử dụng rộng rãi ở các cửa hàng sửa xe, hoặc các đơn vị nhỏ cho hiệu suất cao nhất. Một trong những thiết bị chất lượng được người tiêu dùng ưa chuộng sử dụng mà bạn không thể bỏ qua.
https://dienmayhoanglien.vn/may-nen-khi-piston.html

The present work includes the stress analysis of centrifugal compressor radial impeller blade designed for small 20kW gas turbine application using solver I-DEAS 10NX, which is powerful Finite element software. Effect of different material INCONAL, SS 310, aluminum and the rotational speed on stress generated on impeller blade is studied.

The aim of this research is to appraise the performance of a gas turbine engine through the use of compressor online and off-line water washing optimization maintenance technique. Data were collected from the power generation station, Sapele, Delta State over a period of twenty four months (two yrs) from two gas turbine engines "GT1 & GT2", of the same capacity, and at the same location, commissioned the same time. GT1 uses both compressor online and off-line water washing optimization technique, while GT2 uses only offline water washing optimization technique. The data collected were analyzed. It shows that before the offline water washing exercise, GT2 were operating at 8.47 bar, as depicted in trend for GT2. The compressor outlet pressure is an indication of fouling, as this menace causes a reduction of the pressure. The application of online water washing to GT1 increases the pressure to 9.99 bar. The trend shows that the use of online water washing improved the firing temperature of GT1 by 6.96%. The trend shows that the use of online water washing improved the Network output of GT1 by 6.42%. The network output momentarily decreases due to redeposition of foulants in the later stages of the compressor indicating inappropriate application of washing procedure. GT1 yielded compressor efficiency of 81.6% as a result of online water washing against the 78.5% of GT2. It also implies that the air pumping capacity of the GT1 compressor has increased. It is observed that a small change of the compressor efficiency have a significant effect on the overall GT performance and efficiency. GT1 has compressor efficiency of 81.6% which resulted to overall GT efficiency of 28.3% against 27.7% of GT2. GT1 fuel consumption was less by 2.14kg/kwh as a result of online water washing against the 18.55kg/kwh of GT2.

This paper proposes a multivariable model predictive control scheme for discharge pressure regulation in centrifugal compressors. The main novelty of the proposed approach is that three control inputs are considered: the rotational speed of the compressor, an anti-surge valve for gas recycle and the inlet guide vane, whose variations allow one to significantly enlarge the operating region of the compressor and hence to enhance the authority of the control system. Surge prevention is achieved by including in the model an output variable accounting for the distance of the operating point from the surge limit. Such distance is defined on a compressor performance map which is invariant to changes in the inlet conditions, and thus its computation requires only standard pressure measurements available from the plant. Numerical simulations show that the proposed control system is able to meet the desired specifications, in the presence of different types of disturbances occurring along the pipeline.

Independently of the choice of refrigerant, environmental and or safety issues can be minimised by reducing the amount of refrigerant charge per heat pump or refrigeration system. In the investigation reported here, a laboratory test rig was built, simulating a water-to-water heat pump with a heating capacity of 5 kW. The system was designed to minimize the charge of refrigerant mainly by use of mini-channel aluminium heat exchangers. It was shown that the system could be run with 200 g of propane at typical Swedish operating conditions without reduction of the COP compared to a traditional design. Additional charge reduction is possible by selecting proper compressor lubrication oils or by using a compressor with less lubrication oil. q Pompe à chaleur à propane et à faible charge: conception et essais en laboratoire

Design Compressor Simulation Performance a b s t r a c t The presence of oil in domestic heat pumps is an obstacle toward higher efficiency, particularly for enhanced surface evaporators and for advanced concepts based on twostage cycles. Very compact direct driven radial compressors supported on oil-free bearings represent a promising alternative. This paper presents the derivation of the specifications, the choice for an appropriate refrigerant fluid and the design of a proof of concept prototype with the various tradeoffs between the impeller characteristics to follow the seasonal heat demand, the bearing and rotordynamics for a stable operation. Heat pump simulation results, the design of the impeller as well as the layout of the experimental facility and first experimental results are presented. An impeller with a tip diameter of 20 mm has been tested at rotational speeds of up to 210 krpm reaching pressure ratios in excess of 3.3 and efficiencies above 78%. The refrigerant chosen for this first experimental approach is HFC 134a. 1. * Corresponding author. Tel.: þ41 (0) 62 956 88 50; fax: þ41 (0) 62 956 22 00. E-mail address: [email protected] (J. Schiffmann). w w w. i i fi ir . o r g a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / i j r e f r i g 0140-7007/$ -see front matter ª

Reciprocating and piston air compressors are interchangeable terms, and this type of air compressor is the most common on the market today. They take advantage of the principle of positive displacement. When the piston moves down inside the cylinder, the air enters the space above thanks to the difference between the atmospheric pressure and the pressure inside the cylinder. The air is then compressed as the piston moves upwards. These are known as single-stage compressors. Two-stage compressors take the air in from the atmosphere just like single-stage units, but they have two cylinders instead of one. During the first stage, the air is compressed to an intermediate pressure. After that the majority of heat is removed, and the air is passed on to another cylinder where it is compressed to a specified value. 2. Rotary Screw Air Compressors This type of compressor has two mated helical screws located inside a chamber. As each of the two screws rotates, the air pressure inside the chamber is increased which effectively reduces the volume of air. However there is a drawback to this mechanism.This type of functionality creates a lot of friction and heat which means you have to cool the whole system down in an efficient manner in order to keep operation smooth. For this purpose lubrication is used however, do bear in mind that oil has to be separated from the compressed air before it can be used. 3. Rotary Scroll Air Compressors This solution features fewer moving parts than the rotary screw approach. Basically, with rotary scroll compressors the compression within a scroll is carried out via the interaction of a fixed and an orbiting helical element which gradually compresses the air that's drawn in. As a result of this continuously repeated process you get pulsation-free compressed air. This type of design may feature either splash lubrication, or an oil free design. 4. Rotary Sliding Vane Air Compressors This type of compressor has a motor that consists of a rotor, stator, and blades. On one end there is an intake port, and on the other an exhaust port. The stator is located between the two and also contains the rotor. The turning of the rotor increases the volume on the intake end, and decreases it on the exhaust end. The blades or vanes move outward and remain in place against the walls of the stator thanks to rotational acceleration. Lubricant is also used to reduce friction as well as to plug up any potential leaks. As is the case with rotational screw compressors, the air and oil need to be separated first.

Reaction is the fundamental parameter by which the asymmetry of the velocity triangle of a stage is set. Little is understood about the effect that reaction has on either the efficiency or the operating range of a compressor. A particular difficulty in understanding the effect of reaction is that the rotor and stator have a natural asymmetry caused by the centrifugal effects in the rotor boundary layer being much larger than that in the stator boundary layer. In this paper a novel approach has been taken: McKenzie's 'linear repeating stage' concept is used to remove the centrifugal effects. The centrifugal effects are then reintroduced as a body force. This allows the velocity triangle effect and centrifugal force effect to be decoupled. The paper shows the surprising result that, depending on how the solidity is set, a 50% reaction stage can either result in the maximum, or the minimum, profile loss. When the centrifugal effects are removed, 50% reaction is shown to minimise endwall loss, maximise stage efficiency and maximise operating range. When the centrifugal effects are reintroduced, the compressor with the maximum design efficiency is found to rise in reaction by 5% (from 50% reaction to 55% reaction) and the compressor with the maximum operating range is found to rise in reaction by 15% (from 50% reaction to 65% reaction).

" Electro-Pneumatic braking system " uses laws of pneumatics to apply the brakes. When any hurdle is sensed in the path by the sensors, it will apply the instant brake in seconds, So that it will reduce the accidents which are caused by human unawareness's. So basically whenever the Bike senses any object ahead, it will apply automatic brakes by determining the distance, which we put in sensors. We have used Pneumatic breaking circuit and IR sensors to perform these operations. The circuit can break the vehicle within seconds running at a high speed. Automatic brake with the electro-pneumatic system will provide extra safety to the two-wheelers. This project has been made to perform the required task in shortest time and to add some innovation in the automobile industry.

Turbin gas adalah suatu penggerak mula yang memanfaatkan gas sebagai fluida kerja. Didalam turbin gas energi kinetik dikonversikan menjadi energi mekanik berupa putaran yang  menggerakkan  roda  turbin  sehingga  menghasilkan  daya.  Bagian  turbin  yang berputar disebut rotor atau roda turbin dan bagian turbin yang diam disebut stator atau rumah turbin. Rotor memutar poros daya yang menggerakkan beban (generator listrik, pompa, kompresor atau yang lainnya)

This technical report aims to design an axial flow compressor based on mean-line analysis at sea level static conditions. We are willing to a design leading to the highest stage pressure ratio and meanwhile maintaining
high stage efficiency. There are two problems to be considered, the first one is a subsonic axial flow compressor with maximum relative inlet Mach number 0.75, and the other one is supersonic axial flow compressor with maximum relative inlet Mach number 1.35. We are going to use the optimization method to handle the design of these two axial flow compressors using a built-in function in MATLAB software called fmincon which is a gradient-based method, used to find a minimum of constrained non-linear multivariable function.

In this article, working principle of compressor are reported. In addition to discussing the types of compressors, this course work includes information on circuit breakers and protectors that should be used in the process.
At the same time, detailed information on the safety system used in compressor systems and their controlled parameters is provided. This assignment lists the individual names and functions of the
Compressor parts and provides an example of a report of the energy consumed by the compressor.

This paper presents recent developments and state of the art for transcritical CO 2 cycle technology in various refrigeration, air-conditioning and heat pump applications. The focus will be on fundamental process and system design issues, including discussions of properties and characteristics of CO 2 , cycle fundamentals, methods of high-side pressure control, thermodynamic losses, cycle modifications, component/system design, safety factors, and promising application areas. The article provides a critical review of literature, and discusses important trends and characteristics in the development of CO 2 technology in refrigeration, air-conditioning and heat pump applications. Advanced cycle design options are also introduced suggesting possible performance improvements of the basic cycle. q

The noise level of refrigerating units is one of the very important factors to determine the quality of product. This paper reviews literature based on cavity resonance phenomenon in compressor, experimental setup designed to find out cavity resonance as well as effect of various parameters on cavity resonance has given.

Mechanical drive steam turbines are major prime movers for compressor, blower, and pump applications. Steam turbines are available for a wide range of steam conditions, power ratings and speeds. In this work, a simple predictive tool, which is easier than existing approaches, less complicated with fewer computations, is presented for rapid prediction of steam rate, turbine efficiency, and the inlet and exhaust nozzle diameters to determine the actual steam rate (ASR) and total steam requirements for both multi-stage and single-stage turbines. The proposed method predicts the above mentioned parameters for inlet steam pressures up to 12,000 kPa, turbine ratings up to 10,000 kW as well as the exhaust air over inlet air ratios of up to 0.55. The predictions from the proposed predictive tool have been compared with reported data and found good agreement with average absolute deviation hovering around 1.4%.

Theoretical analyses of subcritical/transcritical heat pumps using four natural refrigerants, carbon dioxide, ammonia, propane and isobutane have been carried out for high temperature heating applications at different heating outlet temperatures and heat sources using computer models. The compressor discharge pressures have been optimized for transcritical and subcritical (with near critical operation of condenser) cycles. Results show that for subcritical heat pumps, use of subcooling is efficient for heating applications with a gliding temperature. Results also show that although propane yields better coefficient of performance (COP) in low temperature heating applications, ammonia performs the best in high temperature heating applications. Finally, design aspects of major components of all the four heat pumps for high temperature heating have been discussed, particularly with reference to suitability of available lubricants to the newly evolved operating conditions.

The application of a valve positioning controller (VPC) on top of a basic regulatory plant-wide control structure for maximizing the process through-put to increase plant profitability is demonstrated. The input to the VPC is a measurement of the bottleneck constraint and its output is the set-point of the through-put manipulator. The hydrodealkylation (HDA) of toluene to benzene process is used as an example case study with the feed hydrogen compressor and the furnace considered as bottleneck constraints that limit production. Results show that the automatic adjustment of the through-put manipulator allows the process to be operated close to (or at) the bottleneck constraint. De-rating of the plant through-put due to the possibility of disturbances is then avoided resulting in enhanced through-puts and plant operating profit. The increase in the through-put and plant profit over the de-rated operation is quantified with respect to variation in the magnitude of the principal disturbance that causes the bottleneck constraint to be hit. Results show that significant enhancement of more than 10% increase operating profit can be achieved. VPC is thus demonstrated to be a simple and effective means for increasing plant profitability by maximizing through-put.

J.R. Barbosa Jr.). w w w. i i fi ir . o r g a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / i j r e f r i g i n t e r n a t i o n a l j o u r n a l o f r e f r i g e r a t i o n 3 3 ( 2 0 1 0 ) 1 4 0 2 e1 4 1 2 0140-7007/$ e see front matter ª

Supervisory control Ultra-capacitor a b s t r a c t Depending on growing concerns on energy crises and environmental issues, fuel cell (FC) powered electrical vehicles are favored for possible substitute to conventional internal combustion engine (ICE) based vehicular systems. However, the typical power profile of an automobile motor consisting of transients is not suitable for the use of a sole FC system for vehicle propulsion. This shortcoming could be partly overcome by hybridization. Two potential benefits of combining an FC system with an energy storage unit, ultra-capacitor (UC) has been presented in this study. Firstly, the durability of the FC system could be improved because the additional energy source can fulfill the transient power demand fluctuations. Secondly, the ability of the energy storage source to recover braking energy enhances the fuel economy greatly. An important aspect in designing a hybrid power structure is to find a suitable control strategy that can manage the active power sharing and take advantage of the inherent scalability and robustness benefits of the hybrid system. An integrated procedure for mathematical modeling and power control strategy design for an FC/UC hybrid vehicle is presented in this paper. A fuzzy logic supervisory controller based power management strategy that secures the power balance in hybrid structure, enhances the FC performance and minimizes the power losses is proposed. The main contribution of this paper apart from the previous studies of the authors is the modeling of the complete FC power system with air supply compressor and the integration of the control of the FC system internal dynamics (especially the oxygen excess ratio) into the overall supervisory control structure to maximize the efficiency and durability. To demonstrate the effectiveness of the proposed power management scheme, simulation studies were performed using MATLAB Ò , Simulink Ò and SimPowerSystems Ò environments by integrating the detailed mathematical and electrical models of the hybrid vehicular system.

Design of Turbo machinery is complex and efficiency is directly related to material performance, material selection is of prime importance. Temperature limitations are the most crucial limiting factors to gas turbine efficiencies. The problems at various components are of different magnitudes. As a result, the materials selection for individual components is based on varying criteria in gas turbines. Also materials and alloys for high temperatures application are very costly. This paper is focused on the study of various materials for their applicability for different components of gas turbine for increasing the performance, reliability and emissions in gas turbines. This paper presents a critical review of the existing literature of gas turbine materials. The paper will focus light on above issues and each plays an important role within the Gas Turbine Material literature and ultimately influences on planning and development practices. It is expected that this comprehensive contribution will be very beneficial to everyone involved or interested in Gas Turbines.

Courtesy of David W. Garside 2018

10 pages

When the Wankel principles were first published in the early 1950s most of the initial work was aimed at developing a compressor. At that time many of the characteristics appeared to promise a superior machine than hitherto known. However, all the early designs resulted in a high value for the minimum clearance volume (CV) and this problem was never overcome. Knowledge now gained from the development and manufacture of the Wankel engine has enabled the evolution of a new compressor concept where the rotor flank, radially very close-fitting over its central area, provides gas sealing with the housing bore. The rotor has an increased radial clearance towards the apices which makes the machine practical to manufacture. The 'nesting' of the rotor flank with the housing bore at the end of the exhaust stroke results in an extremely small CV. This machine promises to possess an exceptional combination of all the attributes which are important in achieving high energy efficiency in positive-displacement compressors and vacuum pumps:-near-zero CV-low mechanical friction losses-low internal gas leakage (assisted via oil flooding)-high volumetric efficiency. In addition it is compact, lightweight, vibration-free, consists of few components, and can be built in any chamber size. The Paper discusses the features and characteristics of the design.

The Regulation CE-1005/2009 has banned the use of virgin HCFC-22 in Europe from the 31st December 2009, because it contains chlorine, although its use is allowed up to the 31st December 2014 if it is recycled. Now, manufacturers are developing different free-chlorine drop-in solutions to replace the HCFC-22 in the existing equipment by non-ozone depleting substances in order to exhaust its remaining life. This work focuses on the experimental evaluation of two HCFC-22 drop-in solutions for low temperature applications, the HFC-422A and the HFC-417B, in a double-stage vapour compression plant driven by a compound compressor in an evaporating temperature range between À31 and À17 C and in a condensing temperature range between 30 and 48 C. The experimental results show that there is a reduction in cooling capacity and in COP with regard to the HCFC-22 operation, which is analysed and discussed in the paper.

The methods used today for the calculation of screw compressor thermodynamic and fluid flow processes, from quasi one-dimensional thermodynamic models to three-dimensional computational fluid dynamics (CFD) procedures, require accurate identification and quantification of geometric parameters, such as volume, gradient and cross-section, leakage flow and blow-hole areas. Historically, some of the geometric characteristics have been neglected, or approximated when calculation accuracy was not essential. However, more sophisticated models may lose some of their advantages if accurate geometric characteristics are not included in them. The work presented in this paper is aimed to enhance the accuracy of geometric calculations. The usual geometric calculation procedures are given and modified where necessary. The results are compared with models generated by 3D Computer Aided Design (CAD), software packages, from which improvements in the accuracy of predictions can be demonstrated.

The performance of a gas turbine is significantly affected by the environmental conditions. Net power output of a gas turbine can be increased by reducing the compressor inlet air temperature. There are different techniques used for inlet air cooling of the gas turbines. These techniques are evaporative coolers, spray inlet coolers or fogging systems, and mechanical refrigeration or chillers where a heat exchanger cools the inlet air. To improve the efficiency of gas turbine power plants, Ice Thermal Energy Storage (ITES) systems can be used as inlet cooling system. The aim of this study is to determine the use of an ITES system for a 239 MW powered gas turbine cycle, which is located in Bursa / Turkey. The performance of the system was investigated for full load conditions. Energy and exergy analysis were done by using last decade’s meteorological weather data. The results showed that utilizing the ITES system boosted the net power up to 12.60 %.

Thesis by Bo Yuan, 1994, Karlsruhe
117 pages
related to rotary compressors

> Content ...
> Vorwort  4
> Inhaltsverzeichnis  5
> Formelzeichen + Abkuerzungen  7
> 1 Einleitung  10
> 2 Grundlage der Randelementmethode  19
  » 2.1 Darstellung der Randintegralgleichungen  19
  » 2.2 Die Randelementmethode  25
      » 2.2.1 Diskretisierungsverfahren  25
      » 2.2.2 Quadratische Elemente  32
        » 2.2.2.1 Formfunktionen  33
        » 2.2.2.2 Singulaere Integrale  35
      » 2.2.3 B-Spline Elemente  37
        » 2.2.3.1 Eigenschaft der B-Splines  38
        » 2.2.3.2 Elemente  41
        » 2.2.3.3 Singulaere Integrale  46
      » 2.2.4 Spannungen in den inneren Punkten  46
      » 2.2.5 Spannungen auf dem Rand  48
      » 2.2.6 Volumenkraefte  53
  » 2.3 Kopplung des BE-Programms mit Pre- + Postprozessoren eines FE-Programms  55
  » 2.4 Nummerische Testergebnisse  58
      » 2.4.1 Beispiel 1  58
      » 2.4.2 Beispiel 2  61
      » 2.4.3 Beispiel 3  63

> 3 Optimierung eines Aussenlaeufersegments unter Beruecksichtigung verschiedener Randbedingungen  66
  » 3.1 Einfluss der Stuetzarten  66
  » 3.2 Profiloptimierung  72
> 4 Berechnung eines Aussenlaeufersegments unter Beruecksichtigung der Kontaktbedingungen am Rand  77
  » 4.1 Befestigung des Aussenlaeufersegments mit zwei Passtiften + einer Schraube an einer duennen Seitenscheibe  77
  » 4.2 Befestigung des Aussenlaeufersegments mit nur 2 Passtiften an einer duennen Seitenscheibe  86
  » 4.3 Aussenlaeufersegment mit dicker Seitenscheibe  88
> 5 Berechnung der Verformungen eines Aussenlaeufers mit vereinfachtem Innenprofil der Segmente + einer Seitenscheibe  96
  » 5.1 Boundary-Element-Modell des Aussenlaeufersegments  96
  » 5.2 Verformung des Laeufers  98
  » 5.3 Boundary-Element-Modell der Seitenscheibe  101
  » 5.4 Verformungen der Seitenscheibe  102
> 6 Modalanalyse des Aussenlaeufersegments  105
  » 6.1 Einsatz der Balkenelemente mit verschiedenen Randbedingungen  105
  » 6.2 Modalanalyse  107
> 7 Zusammenfassung  109
> 8 Literatur  112

german keywords: Wankelmotor / Kreiskolbenmotor
English Keywords: Wankel Engine / Wankel Rotary Engine / Rotary Piston Engine / Rotary Combustion Engine

Approximate computing is an attractive technique to gain substantial improvement in the area, speed, and power in applications where exact computation is not required. This paper proposes two improved multiplier designs based on a new 4:2 approximate compressor circuit to simplify the hardware at the partial product reduction stage. The proposed multiplier designs are targeted towards error-tolerant applications. Exhaustive error and hardware analysis has been carried out on the existing and proposed multiplier designs. The results prove that the proposed approximate multiplier architecture performs better than the existing architectures without significant compromise on quality metrics. Experimental results show that die-area and power consumed are reduced up to 28%, and 25.29% respectively in comparison with the existing designs without significant compromise on accuracy.