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The purpose of this paper is to reveal the effect of working oil temperature, load and starting time on hydro‐viscous drive speed‐regulating start.
Abstract
Purpose
The purpose of this paper is to reveal the effect of working oil temperature, load and starting time on hydro‐viscous drive speed‐regulating start.
Design/methodology/approach
The authors developed an experimental equipment and carried out a number of experiments under different temperatures, load and starting time.
Findings
The results show that both the temperature rise of working oil and the increase of load can induce fluctuations in output speed, but the effect of the working oil temperature rise is more serious; also the longer the starting time is, the more perfectly the output speed can trace the given speed.
Practical implications
It indicates that the working oil temperature should be kept in a certain range by using a cooling device in practical application; and that under this experimental condition, kinematics viscosity of the working oil should be greater than 45 mm2/s under rated working temperature, and the relatively suitable starting time should range from 90 to 120 s.
Originality/value
The paper explains the effect of various factors on speed‐regulating start, and provides the basis for the design and the application of hydro‐viscous drives.
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Lubomir Livovsky and Alena Pietrikova
This paper aims to present a new method of real-time monitoring of thermal profiles applied in vapour phase soldering (VPS) reflow processes. The thermal profile setting is a…
Abstract
Purpose
This paper aims to present a new method of real-time monitoring of thermal profiles applied in vapour phase soldering (VPS) reflow processes. The thermal profile setting is a significant variable that affects the quality of joints. The method allows rapid achievement of a required thermal profile based on software control that brings new efficiency to the reflow process and enhanced joint quality, especially for power electronics.
Design/methodology/approach
A real-time monitoring system based on computerized heat control was realized in a newly developed laboratory VPS chamber using a proportional integral derivation controller within the soldering process. The principle lies in the strictly accurate monitoring of the real defined reflow profile as a reference.
Findings
Very accurate maintenance of the required reflow profile temperature was achieved with high accuracy (± 2°C). The new method of monitoring and control of the reflow real-time profiling was verified at various maximal reflow temperatures (230°C, 240°C and 260°C). The method is feasible for reflowing three-dimensional (3D) power modules that use various types of solders. The real-time monitoring system based on computerised heat control helped to achieve various heights of vapour zone.
Originality/value
The paper describes construction of a newly developed laboratory-scale VPS chamber, including novel real-time profiling of the reflow process based on intelligent continuously measured temperatures at various horizontal positions. Real-time profiling in the laboratory VPS chamber allowed reflow soldering on 3D power modules (of greater dimensions) by applying various flux-less solder materials.
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Electric motor heating during biomass recovery and its handling on conveyor is a serious concern for the motor performance. Thus, the purpose of this paper is to design and…
Abstract
Purpose
Electric motor heating during biomass recovery and its handling on conveyor is a serious concern for the motor performance. Thus, the purpose of this paper is to design and develop a hardware prototype of master–slave electric motors based biomass conveyor system to use the motors under normal operating conditions without overheating.
Design/methodology/approach
The hardware prototype of the system used master–slave electric motors for embedded controller operated robotic arm to automatically replace conveyor motors by one another. A mixed signal based embedded controller (C8051F226DK), fully compliant with IEEE 1149.1 specifications, was used to operate the entire system. A precise temperature measurement of motor with the help of negative temperature coefficient sensor was possible due to the utilization of industry standard temperature controller (N76E003AT20). Also, a pulse width modulation based speed control was achieved for master–slave motors of biomass conveyor.
Findings
As compared to conventional energy based mains supply, the system is self-sufficient to extract more energy from solar supply with an energy increase of 11.38%. With respect to conventional energy based \ of 47.31%, solar energy based higher energy saving of 52.69% was reported. Also, the work achieved higher temperature reduction of 34.26% of the motor as compared to previous cooling options.
Originality/value
The proposed technique is free from air, liquid and phase-changing material based cooling materials. As a consequence, the work prevents the wastage of these materials and does not cause the risk of health hazards. Also, the motors are used with their original dimensions without facing any leakage problems.
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ITSURO SAKAI and YOSHIHIRO KAWAGUCHI
The purpose of this study is to analyse dynamic response of rotary regenerator for dynamic simulation of automotive gas turbine using a simplified method. Exit temperatures of…
Abstract
The purpose of this study is to analyse dynamic response of rotary regenerator for dynamic simulation of automotive gas turbine using a simplified method. Exit temperatures of working fluids in rotary regenerator depend on time, position of core, inlet temperature of working fluid and initial temperature of core. We tried to simplify the calculation model of rotary regenerator, as a counter flow heat exchanger and show that they give good results compared to the available analytical solution.
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Varinder Kumar and Santosh Bopche
This paper aims to present the numerical models and experimental outcomes pertain to the performance of the parabolic dish concentrator system with a modified cavity-type receiver…
Abstract
Purpose
This paper aims to present the numerical models and experimental outcomes pertain to the performance of the parabolic dish concentrator system with a modified cavity-type receiver (hemispherical-shaped).
Design/methodology/approach
The numerical models were evolved based on two types of boundary conditions; isothermal receiver surface and non-isothermal receiver surface. For validation of the numerical models with experimental results, three statistical terms were used: mean of absolute deviation, R2 and root mean square error.
Findings
The thermal efficiency of the receiver values obtained using the numerical model with a non-isothermal receiver surface found agreeing well with experimental results. The numerical model with non-isothermal surface boundary condition exhibited more accurate results as compared to that with isothermal surface boundary condition. The receiver heat loss analysis based on the experimental outcomes is also carried out to estimate the contributions of various modes of heat transfer. The losses by radiation, convection and conduction contribute about 27.47%, 70.89% and 1.83%, in the total receiver loss, respectively.
Practical implications
An empirical correlation based on experimental data is also presented to anticipate the effect of studied parameters on the receiver collection efficiency. The anticipations may help to adopt the technology for practical use.
Social implications
The developed models would help to design and anticipating the performance of the dish concentrator system with a modified cavity receiver that may be used for applications e.g. power generation, water heating, air-conditioning, solar cooking, solar drying, energy storage, etc.
Originality/value
The originality of this manuscript comprising presenting a differential-mathematical analysis/modeling of hemispherical shaped modified cavity receiver with non-uniform surface temperature boundary condition. It can estimate the variation of temperature of heat transfer fluid (water) along with the receiver height, by taking into account the receiver cavity losses by means of radiation and convection modes. The model also considers the radiative heat exchange among the internal ring-surface elements of the cavity.
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Sheri Kurgin, Jean M. Dasch, Daniel L. Simon, Gary C. Barber and Qian Zou
The purpose of this paper is to evaluate the cooling ability of minimum quantity lubrication (MQL) cutting fluid.
Abstract
Purpose
The purpose of this paper is to evaluate the cooling ability of minimum quantity lubrication (MQL) cutting fluid.
Design/methodology/approach
An experimental system is devised to find the heat transfer coefficient of MQL under simulated reaming conditions. Cooling rate of the specimen is measured with an infrared camera. The effect of air pressure and oil volume on cooling rate is tested. Metal cutting tests are performed to evaluate the effect of heat transfer coefficient on workpiece temperature.
Findings
Convective heat transfer coefficient for MQL increases with increasing air pressure. Oil volume has an indeterminate effect on the heat transfer coefficient; however, it is a dominant factor for controlling temperature during reaming.
Practical implications
The results of the study can provide guidance to optimize the temperature controlling ability of MQL for production.
Originality/value
There is limited information available in literature regarding the heat transfer coefficient of metal working fluids, particularly for MQL. In particular, experiments designed to investigate the effect of air pressure and oil volume on the heat transfer coefficient of the mist have not been previously documented. This information may be used to improve the overall cooling ability of MQL mist, thus increasing its effectiveness at controlling tool wear and maintaining part quality. The other major contribution of this work is to separate the role of the cooling and lubrication for controlling temperature while reaming aluminum. Prior to this study, there has been relatively little research performed for the reaming metal cutting operation, and still less for reaming with MQL. The nature of how metal working fluids control temperature is not fully understood, and this work provides insight as to whether cooling or lubrication plays the dominant role for reaming.
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Wenjie Cheng, Boqin Gu and Chunlei Shao
This paper aims to figure out the steady flow status in the molten salt pump under various temperatures and blade number conditions, and give good insight on the structure and…
Abstract
Purpose
This paper aims to figure out the steady flow status in the molten salt pump under various temperatures and blade number conditions, and give good insight on the structure and temperature-dependent efficiencies of all pump cases. Finally, the main objective of present work is to get best working condition and blade numbers for optimized hydraulic performance.
Design/methodology/approach
The steady flow in the molten salt pump was studied numerically based on the three-dimensional Reynolds-Averaged Navier–Stokes equations and the standard k-ε turbulence model. Under different temperature conditions, the internal flow fields in the pumps with different blade number were systematically simulated. Besides, a quantitative backflow analysis method was proposed for further investigation.
Findings
With the molten salt fluid temperature, sharply increasing from 160°C to 480°C, the static pressure decreases gently in all pump cases, and seven-blades pump has the least backflow under low flow rate condition. The efficiencies of all pump cases increase slowly at low temperature (about 160 to 320°C), but there is almost no variation at high temperature, and obviously seven-blades pump has the best efficiency and head in all pump cases over the wide range of temperatures. The seven-blades pump has the best performance in all selected pump cases.
Originality/value
The steady flow in molten salt pumps was systematically studied under various temperature and blade number conditions for the first time. A quantitative backflow analysis method was proposed first for further investigation on the local flow status in the molten salt pump. A definition about the low velocity region in molten salt pumps was built up to account for whether the studied pump gains most energy. This method can help us to know how to improve the efficiencies of molten salt pumps.
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Tan Chen, Wei-jun Zhang, Jian-jun Yuan, Liang Du and Ze-yu Zhou
This paper aims to present a different cooling method (water cooling) to protect all the mechanical/electrical components for Tokamak in-vessel inspection manipulator. The method…
Abstract
Purpose
This paper aims to present a different cooling method (water cooling) to protect all the mechanical/electrical components for Tokamak in-vessel inspection manipulator. The method is demonstrated effective through high temperature experiment, which provides an economical and robust approach for manipulators to work normally under high temperature.
Design/methodology/approach
The design of cooling system uses spiral copper tube structure, which is versatile for all types of key components of manipulator, including motors, encoders, drives and vision systems. Besides, temperature sensors are set at different positions of the manipulator to display temperature data to construct a close-loop feedback control system with cooling components.
Findings
The cooling system for the whole inspection manipulator working under high temperature is effective. Using insulation material such as rubber foam as component coating can significantly reduce the environmental heat transferred to cooling system.
Originality/value
Compared with nitrogen gas cooling applied in robotic protection design, although it is of less interest in prior research, water cooling method proves to be effective and economical through our high temperature experiment. This paper also presents an energetic analysis method to probe into the global process of water cooling and to evaluate the cooling system.
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The purpose of this paper is to present results of laboratory testing work on causes of a service failure/damage to an aircraft turbojet's gas‐turbine blade made of the EI 867‐WD…
Abstract
Purpose
The purpose of this paper is to present results of laboratory testing work on causes of a service failure/damage to an aircraft turbojet's gas‐turbine blade made of the EI 867‐WD alloy.
Design/methodology/approach
The tests comprised comparing the microstructure of a service‐damaged blade with microstructures of specimens drawn from a similar all‐new blade, both subjected to temperatures of different values for different annealing times.
Findings
Findings based on the comparison of experimentally gained results of microstructure examination of both the gas‐turbine blades were: the change in the microstructure of a damaged blade results from the growth and cuboidal‐to‐lamellar change of shape of the reinforcing phase γ′ (Ni3Al); and the size and shape of this phase are comparable to those of the phase γ′ of a new blade subjected to annealing at temperature exceeding 1,223 K for 1 h. The results gained allowed for drawing the conclusion that the damaged turbine blade was operated in the exhaust‐gas temperature exceeding the maximum permissible value of 1,013 K for approximately 1 h in the course of an air mission.
Research limitations/implications
The comparison‐oriented experimental testing work was carried out on a new blade manufactured in the way and from material identical to those of the damaged blade. The applied methodology enables us to gain qualitative results of investigating into the causes of a failure/damage to a gas‐turbine blade.
Practical implications
The presented methodology of identifying (origin‐finding of) a service‐induced damage to a gas‐turbine blade proves helpful in the case of an engine failure, when information on the operating conditions thereof is insufficient.
Originality/value
The paper is an original work by the authors. To the best of their knowledge, the issue has not been found in the literature, approached in this particular way. It has been based on research work on air accidents due to the service‐induced failures/damages to gas‐turbine blades in aircraft turbojet engines.
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Yunsong Shi, Wei Zhu, Chunze Yan, Jinsong Yang and Zhidao Xia
This study aims to report the preparation, selective laser sintering (SLS) processing and properties of a new nylon elastomer powder. The effects of solvent, dissolution…
Abstract
Purpose
This study aims to report the preparation, selective laser sintering (SLS) processing and properties of a new nylon elastomer powder. The effects of solvent, dissolution temperature and time and cooling method and speed on the particle size and morphologies of the prepared nylon elastomer powder are investigated.
Design/methodology/approach
The prepared nylon elastomer power possesses the particle size of around 50 mm and is spherical in shape, indicating that this study provides the feasible dissolution-precipitation process, a distillation cooling method and a suitable solvent to prepare nylon elastomer powders.
Findings
Compared to pure nylon 12, the nylon elastomer has a lower part bed temperature and a wider sintering window for the SLS process. The wider sintering window indicates the better SLS processibility. The lower part bed temperature is beneficial to the recycling of material and the decrease in the requirement of SLS equipment.
Originality/value
The nylon elastomer in this study has a lower part bed temperature and a wider sintering window for the SLS process. The wider sintering window indicates better SLS processibility. The lower part bed temperature is beneficial to the recycling of material and the decrease in the requirement of SLS equipment.
Details