Test Bench System Research Articles

Research on cooling-temperature control strategy of fuel-cell engine test bench

AbstractAs one of the important ways to utilize hydrogen energy, fuel cells are receiving more and more attention and research from countries and institutions. To meet the practical needs of testing the performance of high-power fuel-cell systems and simulate the actual application environment as much as possible, a fuel-cell system test bench is usually used to test the system performance, in which the cooling-temperature control of the test bench has a great impact on the results of the performance of the fuel-cell system. This paper studies the cooling-temperature control strategy of a 150-kW-class fuel-cell engine test platform, proposes a new test-bench cooling-system structure with a thermostat and heat exchanger as the main heat-dissipation components, and compares and analyzes the impact of coordinated thermostat and heat-exchanger control on the fuel-cell system test performance. The test results show that the control strategy of the coordinated operation of a thermostat and heat exchanger can maintain the steady-state error to within ±0.3℃ and maintain the temperature variation to within ±1.5℃ during the loading-condition test, so as to avoid the limitation of system output performance due to excessive cooling-temperature fluctuation and ensure that the fuel-cell engine performance-test process is carried out smoothly and efficiently.

Experimental Research on Photovoltaic-Temperature Difference Hybrid Power Generation System

With the increasingly prominent environmental problems, more and more attention has been paid to new energy power generation. A photovoltaic power generation is currently a well-developed form of new energy power generation. However, in the process of photovoltaic power generation, only part of the wavelength of light can be used to generate power. The rest will be converted to heat, which increases the temperature of the photovoltaic panels, resulting in lower power generation efficiency. In order to improve the efficiency of photovoltaic panels, a photovoltaic-temperature difference (PV-TE) hybrid power generation system can be formed by combining photovoltaic power generation with the thermoelectric generation, which is based on the Seebeck effect. Based on this, we set up the photovoltaic-temperature hybrid power system test bench for testing. The results show that when the working circuit of the TE device is closed, the residual heat of the photovoltaic panel can be used to generate power. It can also cool down the photovoltaic panel at the same time. Thus, the output power increase by about 0.68%.

Performance Improvement of a Geared Five-Bar Transplanting Mechanism for Salvia miltiorrhiza by Orthogonal Design Based on an Interactive Human–Computer Auxiliary Interface

A geared five-bar transplanting mechanism can meet the agronomic requirements for the vertical planting of Salvia miltiorrhiza. In order to improve the planting quality, this paper analyzed the structural composition and working principle of a transplanting mechanism and established an interactive human–computer auxiliary interface through a kinematic model. With the aid of an auxiliary interface, by taking the parameters of the transplanting mechanism as the factors and the parameters of the absolute trajectory and posture for the planter as the index, an orthogonal experimental design with five factors and five levels was carried out, and the optimal combination of the parameters of the mechanism was obtained. According to the optimal combination of the parameters of the mechanism, the structure of the transplanting mechanism was designed, a geared five-bar transplanting mechanism for Salvia miltiorrhiza prototype was developed, and a test bench system was built. The actual trajectory of the endpoint for the transplanting mechanism’s prototype was obtained using high-speed photographic technology. The bench test results showed that according to a comparison of the actual trajectory, the posture for the planter and the theoretical analysis results were basically consistent, which verified the correctness, rationality, and consistency of the optimal design for the mechanism.

Experimental Research on the Effect of Oil Charge Ratio on the Cooling Performance of CO2 Air Conditioning System for Electric Vehicles

From the perspective of the engineering application, the influence of the oil charge ratio on the cooling performance of the electric vehicle CO2 air conditioning system is experimentally studied in this paper. An online test device for oil circulation rate is set up on the built CO2 air conditioning system test bench. The experiment is conducted under different ambient temperatures and compressor speeds in the fresh air mode. As the oil charge ratio increases, the oil circulation rate increases as well as the oil mass flow rate, while the refrigerant mass flow rate decreases slightly. Under the refrigerant charge amount of 550 g and ambient temperature of 35 °C and 40 °C, this system reaches its best cooling performance when the oil charge ratio is in the range of 20% and 25%. And the maximum COPs are 2.46 and 2.36, respectively. The increase in the oil charge ratio is beneficial to the improvement of the isentropic efficiency and the volumetric efficiency of the compressor. The change in oil circulation rate has less effect on the pressure drop in the gas cooler than that in the evaporator.

Battery-Free and Real-Time Wireless Sensor System on Marine Propulsion Shaft Using a Wireless Power Transfer Module

In this paper, we present a wireless sensor system (WSS) that integrated an inductive wireless power transfer (I-WPT) module for battery-free real-time monitoring of the status of rotating shaft in ships. Firstly, an optimized I-WPT module for seamless power supply was implemented using multiple Tx and Rx coils, and its power capability of 1.75 W with an efficiency of 75% was achieved. Secondly, as a result of the high-power transfer performance of the implemented I-WPT module, an entire WSS that integrated four sensors was designed on the rotary shaft. Finally, the designed WSS was installed on a small-scale test bench system with a shaft diameter of 200 mm; it was demonstrated that the status of a propulsion shaft could be monitored in real time without a battery.

Mathematical modelling of the hydromechanical drive of the test bench for plunger hydraulic cylinders with energy recovery

Reliability is a significant parameter of machines, mechanisms, drives, technological equipment and its component parts, including hydraulic motors. Reliability is checked and confirmed by carrying out resource tests, the results of which reveal the characteristics and properties of materials, components and working fluids that are used in the production of hydraulic cylinders and during operation. One of the practical ways to determine reliability is testing. The aim of the work is to improve the theory and methods of calculation and design of the hydromechanical drive system of the service life test bench of plunger hydraulic cylinders through the use of an energy recovery scheme that provides an increase in the energy efficiency of the testing process. Developed on the basis of the application of the theory of volumetric rigidity, a mathematical model of the hydromechanical drive system of the plunger hydraulic cylinder service life test bench made it possible to compare the influence of various design and functional parameters of the elements of the hydromechanical system of the stand on the dynamic performance and energy efficiency of its drive.

Design and development of mechanical test bench for testing and calibration of multiple blood pressure measuring devices.

Blood pressure (BP) measurement is an important physiological parameter for human health monitoring, which plays a significant role in the diagnosis of many incurable diseases. However, due to inaccuracies in the different types of BP measuring devices, the calibration of these BP measuring instruments is a major concern for a medical practitioner. Currently, these devices' calibration, testing, and validation are performed using rigorous methods with complex clinical trials and following the available documentary standards. This article describes the design and development of an indigenous mechanical test bench (MTB) system for the testing and calibration of multiple BP devices, as per International Organization of Legal Metrology (OIML) recommended documents e.g., OIML R 16-1 and OIML R 16-2. The developed system can test and calibrate 20 BP devices, simultaneously. The traceability of the developed MTB is established by performing its calibration against the Air Piston Gauge, a national primary vacuum standard. The estimated expanded measurement uncertainty evaluated is found to be ±0.11mmHg, which is almost one order better than the measurement uncertainty required for the test and calibration of BP measuring instruments as per standard. The MTB has successfully been used to test and calibrate several BP measuring instruments. The data of one such device is reported herein as an indicator of the performance process. The calibration of these BP measuring instruments was performed in the static mode, and the estimated expanded measurement uncertainty was found to be ±1.25mmHg. The developed MTB system would prove to be an excellent instrument for calibration laboratories, hospitals, regulatory agencies, and other users to test and calibrate 20 BP measuring devices simultaneously and cost-effectively.

Effects of the air volume on cooling performance of a refrigeration system

In order to solve the problem of poor refrigeration performance during operation of the refrigeration system under low temperature conditions, this paper designs a refrigeration system test bench to study the effect of different air volumes on the cooling capacity of the refrigeration system under the conditions of 32?C outside the warehouse and -10?C inside the warehouse. The results show that when the air volume of condenser is set to 65% of the unit air volume and the air volume of evaporator is set to 100%, the cooling capacity of the system is 8.62 kW, the compressor power is 1.88 kW, the COP is 4.55 and the energy efficiency ratio is 1.64. In comprehensive consideration, this can not only ensure the best refrigeration performance but also can save considerable energy consumption.

Analysis of the Sound Field Characteristics of a Muffler at Different Flow Conditions

To reduce the noise in a pump piping system and increase the usage time of equipment, a new type of porous muffler is proposed in this paper. A water guide cone is incorporated into the muffler structure, which may help to redirect the fluid media in the piping system. The porous structure is adapted from a muffler shell, water cone wall and round bottom plate. According to this structure, the muffler sample is made, and a pump pipeline system test bench is set up. The outlet noise of the pump pipeline system is measured after installing the muffler. At the same time, the muffler is numerically simulated by combining computational fluid mechanics and Lighthill acoustic theory. The characteristics of the flow field and external sound field under three different flow conditions of 200 m3/h, 400 m3/h and 600 m3/h are assessed. The numerical simulation results show the same dominant frequency and trend as the experimental results. The rationality of the numerical simulation is verified. Research shows that: the level of sound pressure at the muffler's outlet is lower than at the inlet, causing muffling, and the characteristics of a quadrupole sound source appear at the outlet. The proposed muffler has a certain effect in reducing noise in the pump pipeline system.

Simulation of energy recovery system of high speed transmission shaft dynamic torque test bench

A hydraulic energy recovery and control system is proposed to solve the energy loss problem of the current vehicle transmission shaft torque test bench. On the basis of the original system, power recovery is realized by parallel hydraulic compensation. PID module is used to control the displacement of piston variable pump and motor respectively to adjust the speed and torque to achieve the established working conditions. The feasibility of the hydraulic system and control scheme is verified by AMEsim-MATLAB software and experiments. The results show that the proposed system can not only adjust the set speed and torque dynamically, but also achieve high power recovery.

Research on the Control Method of Force Servo System of Liquid Hydrostatic Guide Oil Film Thickness Test Bench for Machine Tools

The test bench was designed to solve the problem of measuring the oil film thickness of the liquid hydrostatic guideway of machine tools. And based on the fast overshoot of the classical PID control, introducing the self-antidisturbance control algorithm, this study established a mathematical model of the test bench electro-hydraulic servo control system. At the same time, this paper also designed a specific structure of the self-turbulence controller, which adopts optimal quadratic control, pole configuration, PID control, and self-turbulence control to study the control methods of the test bench electro-hydraulic servo system, respectively, and uses the SIMULINK module to establish the system simulation model of the above-mentioned four control methods of the test bench. Simulation results of the test bench control system show that the response speed of the self-turbulence control is 0.4 seconds, 0.2 seconds, and 4.4 seconds faster than PID control, pole configuration, and optimal quadratic control, respectively, and the overshoot is significantly reduced. Finally, the test bench was built to complete the experiments, and the experimental results showed that the followability of the loading force and thickness detection accuracy of the test bench were better after adding the self-turbulence control algorithm and the stability of the oil film thickness was significantly improved by the test bench electro-hydraulic servo control system.

Development of ZnO-coated bearings with the preferred crystal orientation for micro gas turbines

One approach to solving the energy shortage problem is to use low-friction components in order to reduce energy consumption and increase component life. In this study, low-friction ball bearings were fabricated using silicon nitride balls coated with zinc oxide (ZnO) while optimizing the preferred crystal orientation of the coating using a combinatorial sputter-coating system. The crystal structure of the ZnO coating formed on the balls was analyzed by X-ray diffraction measurements. The frictional properties of the ball bearings were measured in kerosene using a wide-range load friction and wear tester and a laboratory-developed bearing analysis tool. The friction coefficient of the ball bearings was lowered by more than 50% with the optimization of the low-friction ZnO coating. Furthermore, two of the thus-fabricated low-friction ball bearings were installed in a micro gas turbine bench test system, resulting in a decrease in the fuel consumption of more than 2.3%. Finally, we used the micro gas turbine with the low-friction ZnO-coated bearings to produce a light and compact power generator for disaster use. Thus, the proposed ZnO coating is suitable for use with a range of components.

Intelligent Vehicle Engine Dynamic Test System Based on Internet of Things

In the context of technological modernization in the field of automotive engine testing, the development of an intelligent automotive engine testing system based on IQ has become an important trend in the future. This paper mainly studies the development of engine test software platform, the technical control of test process conditions, and the intelligent conversion of important components such as temporary fuel flow meters. By comparing the traditional bench test system and the dynamic test system based on the Internet of Things, the efficiency of data information transmission, information security, perception ability, and response speed between them are compared, and the intelligent dynamic engine detection based on the Internet of Things is found. The system is more secure and more efficient in information transmission, with a 12% increase in perception performance and a 48% increase in system response time. This also fully shows that the intelligent dynamic engine detection system based on the Internet of Things will be more suitable for current equipment and can also be detected more accurately, which can realize effective supervision of the running status of the test prototype and remote online feedback of the analysis results, and solve the engine test process. It solves the problem of efficient, reliable, and safe transmission and transmission of data and information between all levels and layers, and improves the ability of rapid perception and response in the process of engine testing.

Study on axial force characteristics of coiled tubing rotating operation in marine riser under helical post-buckling

When using offshore rotating platforms for deep-sea operation, coiled tubing (CT) is affected by both the ocean load and torque. Moreover, the variation law of axial force complexity increases when the CT is in a helical post-buckling state. Therefore, in this paper, a “pipe-in-pipe” system test bench was built to simulate the effects of ocean loads and torques on the CT. A helical post-buckling state was reached and the axial force variation law was analyzed. The results have shown that both the ocean load amplitude and the initial torque increased the axial force fluctuation of CT. The torsion direction of helical post-buckling was determined by the direction of applied torque. Additionally, given the equal injection force, the greater the torque, the greater the helical post-buckling degree of CT and the lower the axial force transmission efficiency. Obtained results supplement the theoretical system of pipe mechanics and improve the operation efficiency of offshore rotating platforms.

Adjustable testbench system to stretch optical fiber

Actually, the use of optical fiber has been extended to several applications, not only its use for telecommunications; nowadays, optical fiber is used for sensor construction and instrumentation. For that reason, modifications and deformations in optical fiber sections are required and in order to observe how light transition is performed through to the fiber. The construction of this platform has the main objective to accomplish stretching test with different tensions on the fiber, different exposition terms to the electric arc and finally the gap between electrical electrodes to modify the affectations on the fiber, that are applied on the fiber. The different parts this system is conformed with, are presented in this work and the main features of each stage.

Prediction and experimental study of radiated noise of rotating vane compressor under compound effects of multiple sources excitations

Aiming at the problem that it is difficult to accurately predict the radiated noise of rotary vane compressor under multi-source excitation, in this paper, the rigid body dynamics model and the dynamics model of airflow pulse excitation of the suction-compression-exhaust process of the rotary vane compressor were established, and the mechanism of multi-body contact excitation and airflow pulsation excitation for rotating vane compressor is expounded. Meanwhile, a flexible multibody finite element mesh model including a rotor, blades, cylinder, end cover and shell was established, and mechanical excitation and airflow pulse excitation were taken as mechanical boundary conditions to calculate the vibration response characteristics of the rotary vane compressor. To estimate the radiated noise of the rotary vane compressor, a compressor acoustic boundary element model was established, and a noise test bench system was built in a semi-anechoic chamber to compare and analyze the calculated noise value. At constant speed and acceleration, the rear sound pressure value is larger, followed by the right part, which is close to the exhaust port, and the front sound pressure is obviously lower than other points. The maximum relative error of sound pressure levels at four field points is 4.8%, and the average relative error of all measured points is 2.4%. The measured values are in good agreement with the calculated values, which verifies the accuracy of the radiated noise prediction model of rotary vane compressor.

In-wheel motor control system used by four-wheel drive electric vehicle based on whale optimization algorithm-proportional–integral–derivative control

Aiming to more accurately control the wheel speed of an electric vehicle (EV) driven by four in-wheel motors, a developed whale optimization algorithm-proportional–integral–derivative (KW-WOA-PID) control algorithm is proposed herein. In this study, mathematical and simulation models are built for EVs by analyzing the mechanical structures of EVs driven by four in-wheel motors. Simulations are conducted, and the driving and control requirements for the in-wheel motors are obtained. Then, mathematical and simulation models are built for a specific in-wheel motor. The whale optimization algorithm (WOA) is optimized by kent mapping and the adaptive weight coefficient to improve the ability of the algorithm to jump out of the local optimum and the convergence speed and convergence accuracy of WOA. Then the further simulations are conducted. The simulation results display that the maximum overshoot and adjustment time of the motor under KW-WOA-PID control are significantly optimized. Then, a speed-control bench test system is built for the in-wheel motor, and real-life experiments were conducted. The experimental results verify that KW-WOA-PID has higher control accuracy and a better response performance; accordingly, the developed control algorithm can meet driving requirements. The handling stability of EVs is effectively improved by controlling the motor speed.

Experimental analysis of the performance of the air supply system in a 120 kW polymer electrolyte membrane fuel cell system

For analyzing the performance of 120 kW polymer electrolyte membrane fuel cell (PEMFC) system and its air supply system, an air system test bench was built, then applied on a 120 kW PEMFC system test bench composed of air supply subsystem, hydrogen supply subsystem, stack, cooling subsystem and electronic control subsystem. The strategy composed of feedforward table and Piecewise proportional integral (PI) feedback control strategy is employed to regulate the flow rate and pressure of air supply system. Firstly, the air compressor map and the mapping relationship between the speed of air compressor, opening of back-pressure valve and stack current are obtained by carrying out experiments on the PEMFC air system bench. Then, the max output performance, steady-state performance, the startup performance, the dynamic response abilities of PEMFC system are tested, respectively. During the experiments, performances under different test conditions were analyzed by comparing parameters such as voltage inconsistency, average voltage, minimum voltage, voltage range, net power of the PEMFC system, and stack power. The test results show that the air supply system can provide qualified flow rate and pressure for the PEMFC stack. The peak power of the stack is 120 kW and net power of the system is 97 kW when the current is 538 A. The response time from rated net power to idle net power is 12 s and from idle net power to rated net power is 23 s. The overshoot of average voltage and minimum voltage in the process of increasing load is both 0.01 V, which are 0.015 V and 0.02 V lower than that when the load is decreased, respectively. The dynamic response speed and stability of the PEMFC system in the process of decreasing the load are better than those in the process of increasing the load.

New Method to Determine the Dynamic Fluid Flow Rate at the Gear Pump Outlet

External gear pumps are among the most popular fluid power positive displacement pumps; however, they often suffer from excessive flow pulsation transmitted to the downstream circuit. To meet the increasing demand of quiet operation for modern fluid power systems, it is necessary to give a physically sound method of analyzing the operation of a volumetric pump. The analysis of the basic approach used by the majority of researchers for calculating the flow rate of a gear pump by E.M. Yudin is presented. The article presents a new method for analyzing the operation of volumetric pumps. The method is suitable for the pumps whose dynamic characteristics should be considered according to the model of an equivalent source of flow fluctuations by V.P. Shorin. The method is based on wave theory, the method of hydrodynamic analogies and the impedance method, where the pump is considered according to the model in lumped parameters. The method consists in determining the pressure pulsations at the pump output in bench systems with known dynamic characteristics and recalculating the pump flow rate in pulsations. Computational dynamic models of bench systems in lumped parameters are proposed for subsequent use in dynamic tests of pumps in the form of equivalent sources of fluid flow fluctuations. We give recommendations for the formation of test bench systems with a throttle, a cavity and a pipeline at the pump output. Using the example of an external gear pump with a working volume of 14 cm3/rev, the implementation of the proposed method is considered. The pump’s own pulsation characteristic of the flow rate in a bench system with an “infinitely long” pipeline along two harmonic components of the spectrum is determined, and a test of the method based on the method of determining the instantaneous flow rate by R.N. Starobinskiy is proposed. It is shown that, according to the proposed method and the method of R.N. Starobinskiy, the divergence of the amplitudes of flow pulsations does not exceed (5–10)%. The high degree of coincidence of the results confirms that the external gear pump in question should be considered according to the equivalent source of flow fluctuations model.

Research on Influence of Switching Angle on the Vibration of Switched Reluctance Motor

Switched Reluctance Motors (SRMs) have emerged as a viable competitor to other established electrical machines. Although SRMs have many advantages, such as a rare earth free nature, simple structure, high fault tolerance capability and low cost, vibration problems due to radial force variations is still a major issue faced by SRMs. Hence, aimed at the problem of vibration suppression for SRMs, this paper proposes a method that focuses on the influence of the change of the turn-on angle and turn-off angle on the vibration of the SRM under the switching angle control (SAC) strategy. Firstly, the influence of the turn-on and turn-off angles on the harmonic components of the current is analyzed in detail. Then, the vibration caused by the frequency of the harmonic components of the current and the natural frequency of the motor is mainly studied. The results show that the harmonic order affecting vibration is related to the rotational speed, and by analyzing the value of this harmonic order, the variation law of vibration with the switching angle can be obtained. When the turn-off angle is constant, the amplitudes of the current harmonic component and vibration first decrease and then increase with the increase of the turn-on angle. Additionally, when the turn-on angle is constant, the current harmonic and vibration show the tendency of periodic oscillation with the variation of the turn-off angle, and the oscillation period is related to the harmonic order. The combination of switching angles that minimizes the certain current harmonic component also minimizes vibration. The effectiveness of the variation law was verified on a 12/8 poles and 1.5 KW SRM drive system test bench, which provide a new perspective on vibration suppression of SRMs.