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This paper presents results of strain gauge measurements, which have been carried out on a full-scale turbocharger test rig. Rotational speed of the turbocharger was ramped up and down through four preliminary anticipated rotor-blade resonances, with a known combination of main order of excitation and corresponding nodal diameter. An analysis of the transient data is presented. An investigation of spectra with high frequency resolutions, centered on individual blade resonance points in time, is presented. In contrast to former research, all blades resonate at the same point in time and thus at the same resonance frequency, if the excitation corresponds to a nodal diameter of zero. Strain data from the shaft is used to support findings, which, in other publications, often solely rely on strain data from individual blades. [ABSTRACT FROM AUTHOR]

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Abstract The study focuses on control optimization of linear compressor during the start-up process. An alternate method of voltage adjustment and frequency tracking is proposed to get higher performance. The algorithm of frequency adjustment is improved by taking the average of the measured inherent frequency and the operation frequency as the power frequency set value is proposed so that the stability of linear compressor during start-up process can be enhanced. An experimental bench is setup with the presented control program based on LabView. The experimental results prove that comparing with fixed frequency start-up mode frequency tracking can improve the efficiency of linear compressor. However, there exists unstable fluctuation on the critical state of gas pumping and the condition of piston bumping into the discharge valve. The unstable fluctuation can be dissolved by extending the delay of frequency tracking time from 1 s to 5 s. [ABSTRACT FROM AUTHOR]

Highlights • Three-stage scroll compressor was developed for double vapor injection cycle. • The effect of vapor injection model on heating performance was investigated. • Experimental investigation on double vapor injection heat pump. • Enlarged COP and heating capacity than conventional single vapor injection. Abstract Heat pumps with a vapor injection cycle are currently used to compensate for heating capacity degradation at lower outdoor temperatures. A double vapor injection system with a scroll compressor was developed in order to enhance the vapor injection technique. The heating performance of the variable refrigerant flow heat pump systems employing non-vapor injection, single vapor injection, and double vapor injection was experimentally investigated. At the compressor frequencies of 90, 110, and 150 Hz, the heating capacities of the double vapor injection system were improved by 8.9, 12.1, and 18.9%, respectively, compared to those of the single-vapor injection system; and the coefficient of performances (COPs) were improved by 5.8, 8.6, and 9.8%, respectively. The double vapor injection system appeared to be superior to the single vapor injection system in terms of heating capacity and COP. [ABSTRACT FROM AUTHOR]

Highlights • A method is proposed to improve the input power of the linear compressor. • Electrical analyses show the requirements of achieving a high input power. • Mechanical analyses show the methods to meet the demands of a high input power. • Changing the compression volume is adopted to improve the input power. Abstract Working characteristics of a linear compressor affected the performance of a pulse tube cryocooler significantly. However, its input power and efficiency need to be analyzed together in the optimization of a cryocooler. In this study, the electrical and mechanical characteristics of a linear compressor have been investigated to show how to achieve a high input power and a high efficiency. The electrical analyses show that a high input power requires the current and the displacement reaches the maximum simultaneously at the mechanical resonant point. The mechanical analyses show how to adjust the mechanical resonant point to meet these requirements. Changing the compression volume is adopted and verified by experiments. While it changes from 19 L to 17 L, the input power increases from 6.8 kW to 9.6 kW and the efficiency decreases a little from 59% to 57%. The study is helpful to take advantage of a linear compressor. [ABSTRACT FROM AUTHOR]

In high temperature reactor pebble-bed modules (HTR-PM), the helium blower is the key equipment which is in the primary loop and drives the helium to exchange the energy. The usage of active magnetic bearing (AMB) is to avoid the lubricating oil leaked and keep the environment of helium pure. However, helium blower test needs to proceed under the condition of helium loop, which is difficult in early construction stage and will result in much more time and money cost. In this paper, we propose and produce a new device to simulate the dynamic force to build a force environment similar to the helium loop. The device called aerodynamic force simulator (AFS) derives from the idea of active magnetic bearing and utilizes electromagnetic force replacing aerodynamic force when helium blower works. Active magnetic bearing commissioning and dropping load test of helium proceed successfully with the utilization of aerodynamic force simulator. Through a series of tests, it is proved that the aerodynamic force simulator is effective and economic, and the design of helium blower and its components is reasonable and reliable. [ABSTRACT FROM AUTHOR]

The design of the inter-stage seal in an axial compressor is an important topic because the leakage flow across the stator well would lead to aerodynamic mixing losses with the main flow, which will consequently impact the efficiency of the compressor. In this region, the leakage flow is normally controlled by a labyrinth seal with upstream and downstream rotating cavities. In addition, the long rotating wall results in substantial temperature rise and swirl flow development. In particular, the swirl flow in the compressor stator well has a great influence on the leakage behavior of the labyrinth seal. Therefore, it is essential to understand the leakage characteristic, windage heating characteristic and swirl flow characteristic of the stator well. A test rig capable of running at rotational speed 8100 rpm and pressure ratio 1.3 was built according to the simplified model of the labyrinth seal in a compressor stator well (one stage). Labyrinth rings with different rotor tip radii were manufactured to investigate the effect of tip clearance. Leakage flow rate, windage heating and swirl ratios in the outlet cavity were measured at different rotating speeds and different labyrinth rings. As the working tip clearance was very important for the analysis of the leakage behavior, the set up tip clearance was measured with plug gauges, while the radial displacements of rotating disc and stator casing were measured separately with two laser distance sensors. Since the tip clearance was varying with rotating speed and airflow temperature, the data interpolation method was used to find the pure influences of rotation and tip clearance. Numerical simulations were performed to analyze the flow characteristic, variation of total temperature and development of swirl flow in the stator well. Besides, CFD results could provide more detailed insight into the flow mechanisms that are responsible for the influences of rotation and tip clearance. [ABSTRACT FROM AUTHOR]

One of the main purposes of an SOFC-GT hybrid system is for distributed power generation applications. This study investigates the possible use of an SOFC-GT hybrid system to power multi-MW dynamic loads. Based upon the integration of commercially available gas turbine technology, control strategies for the SOFC-GT hybrid system are investigated for different stationary power applications. Risk analysis of compressor stall/surge in the hybrid SOFC-GT power system as it is dynamically dispatched to meet demand is assessed in transient pre-load and post-load modes. Optimal control algorithm is proposed and applied to mitigate stall/surge in compressor as a response to sudden power demand change. This study aims to study compressor stall/surge mitigation assuming a connecting pipe that reduces the back pressure on the compressor in order to maintain the compressor mass flow rate at a specific setpoint. [ABSTRACT FROM AUTHOR]

The multi-fractal spectrum algorithm is a simple, rapid and effective characteristic parameters extracting method for reciprocating machinery with non-stationary and nonlinear time-varying vibration signals. Whereas, its noise sensitivity makes the spectrum fluctuate and gives poor characteristic separability for partial fault. We demonstrate in this paper the optimized Local Mean Decomposition (LMD) algorithm to extract the main information vector of the vibration signal. Combined with Multi-fractal Generalized Spectrum (MGS) taking order q as the scaling factor, we constructed the generalized dimensional matrix and extracted the characteristic vector based on the maximum average distance between different states. Through training and recognizing the samples with K neighbor (IKNN Model) statistical algorithm, the proposed method can improve the fault characteristic separability and recognition accuracy. [ABSTRACT FROM AUTHOR]

In the last few years, the effect of diabatic test conditions on compressor performance maps has been widely investigated leading some Authors to propose different correction models. The aim of the paper is to investigate the effect of heat transfer phenomena on the experimental definition of turbocharger maps, focusing on compressor performance. This work was developed within a collaboration between the Polytechnic School of the University of Genoa (Italy) and the testing center CRITT M2A (France). In particular, an original model for the correction of compressor steady flow maps is presented and discussed. The major benefit of this method is represented by the easiness of data post-processing, the data base economy, the reduced number of geometrical and physical input parameters required and the accuracy of the solution. Besides, this model does not need an out-of-standard test bench to obtain the compressor maps. In the paper, experimental tests under quasi-adiabatic conditions developed to validate the proposed model are reported. A satisfactory agreement between measured and calculated compressor maps is highlighted. [ABSTRACT FROM AUTHOR]

This research paper focuses on the performance prediction and its validation via experimental investigation of a Stirling-type pulse tube refrigerator (PTR) equipped with a cold linear compressor. When the working gas is compressed at cryogenic temperature, the acoustic power (PV power) can be directly transmitted through the regenerator to the pulsating tube without experiencing unnecessary precooling process. The required PV power generated by the linear compressor, furthermore, can be significantly diminished due to the relatively small specific volume of the working gas at low temperature. The PTR can reach lower temperature efficiently with higher heat lift at the corresponding temperature than other typical single-stage Stirling-type PTRs. Utilizing a cryogenic reservoir as a warm end and regulating the entire operating temperature range of the PTR will enable a PTR to operate efficiently under space environment. In this research, the experimental validation as a proof of concept was carried out to demonstrate the capability of PTR operating between 80 K and 40 K. The linear compressor was submerged in a liquid nitrogen bath and the lowest temperature was measured as 38.5 K. The test results were analyzed to identify loss mechanisms with the simple numerical computation (linear model) which considers the dynamic characteristics of the cold linear compressor with thermo-hydraulic governing equations for each of sub components of the PTR. All the mass flows and pressure waves were assumed to be sinusoidal. [ABSTRACT FROM AUTHOR]

Abstract: Pierre (1982) developed general correlations of compressor performance for a wide range of open piston compressors based on a vast amount of data provided by the most important open compressors manufacturers at that time. Based on a wide experimental test campaign with 6 different hermetic and semihermetic compressors, this paper assesses the potential of Pierre's correlations to describe the performance of modern compressors. A full review of the functionals proposed by Pierre in order to improve their accuracy was then performed and as a result the authors found that it is possible to improve the characterization by employing a nondimensional definition of the compressor performance instead of using the efficiencies. These new parameters provide a much more consistent estimation at the borders of the correlation range than the usual correlation obtained following the ARI standard, and could be even employed to extrapolate the performance of the compressor to non-tested conditions with reasonable accuracy. [Copyright &y& Elsevier]

To improve the existing turbocharger compressor technologies (surge margin increase, improving compression abilities, etc.), compressor tests require accurate determination of efficiency, pressure, and exact surge line emplacement. Moreover, due to nonideal measurement conditions typically encountered during turbocharger compressor performance testing, it is imperative to define measurement uncertainties to the experiments. This article deals with how reliable the results of the turbocharger compressor tests for a given test facility are. This article begins with a general introduction to measurement uncertainties, and a description of the turbocharger test facility together with sources of error of the different transducers is then presented. Uncertainty equations are derived from compressor performance relations; transducer errors were introduced to uncertainty equations so that the efficiency, pressure, and mass flow uncertainties of compressor at different functioning points can be predicted before compressor testing. Uncertainty analysis of nine different compressor functioning points was carried out. Finally, parameters that mostly affect the compressor performance results were identified. [ABSTRACT FROM AUTHOR]

PowerCell Sweden has appointed Bumhan Industries Co Ltd as its new distributor and service provider for the South Korean market. Bumhan Industries will also start integrating PowerCell's PEM fuel cell stacks into its combined heat and power (CHP) products for building applications. Bumhan Industries specialises in manufacturing high-pressure compressors for ships and power generation applications. [ABSTRACT FROM AUTHOR]