bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation and Prediction of Thermodynamic Performance of Reciprocating Compressor utilizing Physical Models Combining with Generalized Regression Neural Network
Authors: Qian Lv , Xiaoling Yu , Kun Wang , Junchao Ye , Shiyi Fan , Wang Xiaolin 
Published: September 2019

Abstract
Thermodynamic performance of a reciprocating compressor is generally evaluated or predicted by its physical models (PM). However in conventional PM, some key parameters are not easy to be determined and most time they can only be set values empirically. This article presented and experimentally verified physical models combining with generalized regression neural network (PMCGRNN) for the simulation and prediction of reciprocating compressor thermodynamic performance including the discharge temperature, and the volume flow rate. In PMCGRNN model of the compressor, firstly, the key parameters of compression polytropic exponent and the volume efficiency were obtained by generalized regression neural network (GRNN) with the input variables of suction temperature, suction pressure, discharge pressure, compressor rotate speed. Then the discharge temperature and the volume flow rate of the compressor were simulated respectively by their physical models (PM). The simulation results of discharge temperature and the volume flow rate by PMCGRNN were validated by a test bench of an air compressor. It was found that PMCGRNN has reliable prediction accuracy, and the relative errors of two PMCGRNN models are between −3.5% and +1.5%. and between −5% and 4%, respectively.
Modelling the Cylinder Cooling in an Oil-free Reciprocating Air Compressor
Authors: Tang Zhou , Wang Ting , Zhao Bin , Wang Mingfeng , Peng Xueyuan 
Published: September 2019

Abstract
Oil-free air compressors are widely applied in new energy vehicles, pharmaceutical, textile, food and the chemical industry for providing clean air. However, high temperature inside the cylinder due to compression heat and oil-less lubrication may lead to premature failure of the self-lubricating sealing rings and the grease-lubricating bearings. This paper presents the simulation of the cylinder cooling in an oil-free reciprocating air compressor for new energy vehicles. Based on the modelling, the cooling channel outside the cylinder was optimized to enable more effective cooling with limited air flow, obtaining lower temperature level of the cylinder, and therefore higher reliability of the sealing rings and bearings. The results show that the heat transfer model of the cylinder with numerical simulation is effective in predicting the cylinder temperature level as well as the cooling capacity of the air flow. The heat exchange efficiency of the compressor can be improved significantly by applying the optimized cooling duct structure. Compared with the model A, the maximum cylinder temperature was decreased by 13.1°C in the model B, and it also was decreased by 6.3°C in the model C.
A theoretical simulation model for optimization of fins on the shell of a hermetic reciprocating compressor
Authors: Dutra T , Moratelli S 
Published: September 2019

Abstract
The cost of a hermetic reciprocating compressor is quite dependent on the electric motor employed to drive it. Usually, the higher the motor efficiency, the higher the costs. Therefore, some compressors are designed to operate with low-efficiency electric motors. The main difficulty in such a case is to ensure that the motor operates at a temperature below the upper threshold. This paper presents a simulation model for optimization of fins on the shell of a hermetic reciprocating compressor which operates with a low-efficiency motor. The objective of the simulation is to obtain a set of fins with minimum volume that allows the compressor to operate under a critical operating condition without overheating the electric motor. The simulation model is implemented by coupling a lumped-parameter thermal simulation model of the reciprocating compressor with an optimization algorithm. The results of the thermal simulation are validated with experimental data. Different fin profiles are considered in the analysis. It is concluded that the optimum heat sink solution is conditioned to the minimum fin thickness or to the minimum fin diameter allowed, which are dependent on other compressor design constraints.
Opening up the lubricant toolbox
Authors: Karnaz J 
Published: September 2019

Abstract
Frequently, we fall back to concepts or ideas that we are comfortable with or have more understanding of. In these cases, we don’t always utilize all the resources available to us in make advancement or just try something new. This is sometimes true when it comes to using or evaluating lubricants for various refrigerants or refrigerant related applications. Too often we try to fit what is currently being used in existing applications into new applications instead of expanding our thinking and overall understanding. Usually these efforts are not put forward because we are not taking advantage of all the resources available to us to make good technical decisions. This paper will focus on the various types of lubricant chemistries available for use in the refrigeration and air conditioning industry and markets. Why some lubricants are used, while others are not used and while some lubricants are impractical. Various tools, techniques and computer assisted programs will be outlined that are useful when evaluating lubricant and refrigerant interaction properties.
A few key examples of refrigerants particular to current lower global warming potential reduction efforts will be investigated and what systematic approach can be used to make sure we don’t exclude potential lubricant candidates as viable options.
Understanding and improving the 9-coefficient pressure viscosity temperature (PVT) model
Authors: Barthel Anthony J , Majurin Julie 
Published: September 2019

Abstract
Data describing the physical properties of a mixed refrigerant-lubricant blend is necessary for compressor and system design and is measured using a pressure, viscosity, temperature (PVT) instrument setup. Measurements are taken at discrete conditions and refrigerant concentrations and a model is regressed which can describe pressure (refrigerant solubility), working viscosity, and density across the range of interest. Understanding the applicability of the model is crucial in choosing a suitable lubricant, since the tested conditions are unlikely to exactly match all operating conditions of interest.
This paper describes how the PVT model is created, and how choices in input data can affect the resulting model. Emphasis is placed on the range over which PVT models are valid and what can be done to increase model accuracy.
Performance optimization of two-stage compressor system using transcritical R744
Authors: Elbel S , Hrnjak P 
Published: September 2019

Abstract
The use of transcritical R744 systems has become increasingly popular in recent years in a variety of different applications. For applications that span a wide temperature range between the heat source and heat sink, the use of two-stage compressor results in numerous advantages in terms of efficiency and compressor discharge temperature. This paper presents experimental data for a transcritical R744 compressor system operating at high heat rejection temperatures. A comprehensive system model was developed and validated with the experimental results. Based on this, the simulation tool was used to further optimize the system design specifically to accommodate the two-stage compression process. The optimum heat transfer area distribution has been determined to simultaneously ensure efficient intercooling at intermediate pressure and gas cooling at the high-pressure level. Simultaneously, the system was also optimized with respect to optimal intermediate pressure and the results show that for this particular system, the optimum intercooler pressure deviated substantially from the standard design approach that uses the geometric mean between suction and discharge pressures.
Analysis of the thermodynamic disequilibrium loss of the two-phase expansion process and its influence on the performance of a reciprocating expander
Authors: Wang Qi , Huang Hao , Xu Liangcong , Yang Xiaotian , He Zhilong , Wu Weifeng 
Published: September 2019

Abstract
The screw expander and the reciprocating expander were considered as the suitable technologies to be employed as two-phase expanders of the Trilateral Flash Cycle (TFC) systems. The two-phase expansion process in the screw expander could be approximately viewed as the thermodynamic equilibrium process due to the strong disturbing and mixing between the two-phase working fluids in the chamber volume. However, for the reciprocating expander, the situation was different. The flashed vapor in the reciprocating expander cylinder was separated from liquid in the flash chamber, which would result in a significant thermodynamic disequilibrium loss. To assess this loss, the thermodynamic equilibrium model (TEM) and the flash vaporization model (FVM) were simultaneously proposed in this paper. Water was used as the two-phase working fluid. The two-phase expansion processes, the isentropic efficiencies and the output expansion works of the two models were obtained. Predicted results were analyzed and compared under different rotation speeds and injection temperatures. The results showed that when rotation speed of the expander was increased from 50 r/min to 1000 r/min, the thermodynamic disequilibrium loss was approximately increased from 5.3% to 6.3%, and when injection temperature was decreased from 523.15 K to 473.15 K, the thermodynamic disequilibrium loss was approximately increased from 4.5% to 6.2%.
Two-Phase Flow Analysis and Design of Geothermal Energy Turbine
Authors: Rane S , He L 
Published: September 2019

Abstract
A two-phase geothermal turbine generates mechanical energy by means of a total flow system. Literature references are available for experimental investigation of such flow machines but there is no validated numerical model for prediction of flow field and flashing for optimal design of the turbine’s flow channels. This paper presents a test reaction-turbine design study with two-phase flow using CFD. An Eulerian-Eulerian multiphase model with the Thermal Phase-Change criteria for two-phase heat, mass and momentum transfer has been used. Phase change validation has been conducted on published experimental data on a converging-diverging nozzle flow at various operating conditions. The stationary nozzle model was then extended to curved nozzle turbine and the results of flow and power has been validated with the data available in literature. Liquid water and vapour distribution due to flash evaporation was predicted by the analysis. Two-phase turbine model so established has been used further to re-design and optimise turbine nozzle by evaluating its cross section, area ratio, throat design, specific torque variation and curvature. Two new channel geometries, square and blended, were compared with the base circular channel and it was found that a blended channel offers on an average 6% higher specific power at 4623rpm. For the same rotor diameters and feed water flow rate, the power output could thus be improved by 4.5%. Isentropic efficiency in the range of 10 to 19% was estimated. Final design will be prototyped and tested in the laboratory for validation of design and deployment in eastern Africa.
Experience of application the computer program based on a simplified mathematical model for industrial centrifugal compressors candidates
Authors: Rekstin A F , Soldatova K V , Galerkin Yu B 
Published: September 2019

Abstract
Various engineering techniques are used to calculate and design centrifugal compressors, one of which is the Universal Modelling Method developed at SPbPU. Variants’ of centrifugal compressors analysis is the first step in gas-dynamic design. Brief information on the simplified mathematical model of efficiency is presented. It is possible to compare the variants of compressors with different number of shafts, shafts RPM, the number and location of intercoolers, the type of impellers and diffusers. Examples of a variants’ calculation of a pipeline compressors, a compressor for underground gas storage and a general-purpose air compressor are presented. It is shown that single-shaft compressors for underground gas storages should be optimized by selecting the maximum possible number of stages, by selecting the ratio of loading factors and the diameters of the impellers. It is shown that the single-shaft scheme of a general-purpose air compressor is inferior in efficiency to a two-shaft scheme with larger number of intercoolers. The presented samples have demonstrated that computer program based on a simplified mathematical model for industrial centrifugal compressors provides reliable and sufficient information for different compressors variants’ analysis.
Experimental study and optimal control strategy of a transcritical CO2 heat pump water heater
Authors: Ye Zuliang , Wang Yikai , Cao Feng 
Published: September 2019

Abstract
In this study, a transcritical CO2 heat pump water heater prototype was experimentally investigated in order to clarify the effects of the opening of electronic expansion valve (EEV), research the optimal discharge pressure and obtain an optimal control strategy for performance optimization. The tests were carried out by regulating the opening of EEV in multiple working conditions. The results showed that the decrease of opening led to reduction in evaporator inlet pressure and gas cooler outlet temperature, augment in discharge temperature, and decrease first then increase in discharge pressure. The optimal opening to reach maximum coefficient of performance (COP) always existed in all working conditions, however, there were two different situations where the corresponding optimal discharge pressure was near or away from the minimal value of the pressure curve. The reason for this phenomenon was the difference in water inlet temperature. Moreover, a correlation for the optimal discharge pressure was established with ambient temperature, water inlet and outlet temperature as independent variables. Furthermore, an optimal control strategy, in which the control of discharge pressure and superheat degree was considered, was proposed based on the correlation. Testing results proved that the optimization of performance could be achieved by using the strategy and the deviations between the COP under the control strategy and the optimal COP measured by experiments were within 5%.
Experimental testing of pneumatically forced actuated compressor-expander valves
Authors: Stoeckel C , Thomas C , Nickl J , Hesse U 
Published: September 2019

Abstract
The possibility of forced actuation of valves enables new operation modes for existing reciprocating compressors, e.g. capacity control or reverse operation as expander. A pneumatically forced actuated valve was tested within a reciprocating compressor and a quite complex behaviour was found, as shown in previous publications. A test rig outside of the compressor was set up for a better understanding of the system. Two measurement techniques were used to observe the sealing element motion over the time at varying operating conditions, like applied pressure levels and actuation time. The dependency of the valve motion to those operation conditions is evaluated and discussed. Improvements to the test bench and measurement techniques are also proposed to achieve more accurate results.
Testing and calculation of impact fatigue strength of Flap-X and SS 716 flapper valve steel grades
Authors: Tofique Muhammad Waqas , Löf Alexander , Millward Chris , Günther Zippl 
Published: September 2019

Abstract
During the operation of reciprocating compressors, the flapper valve opens and closes under fluid pressure and flow. As it closes, it strikes against the valve seat, generating stresses and noise. This cycle of loading produces bending and impact fatigue stresses in the reed. This load pattern is repeated billions of times during the service life of a compressor and it defines the service life and reliability. The goal of this study was to calculate the impact fatigue strength of the Flap-X and the SS 716 grades and, to provide the compressor manufacturers with the information they can use to specify a steel grade to be used in their compressors, for reliable service. Impact fatigue tests were conducted on a custom-built impact fatigue test rig that used air pulses to produce movement of the reed valves manufactured by a major European compressor manufacturer Nidec Global appliance GmbH, at a frequency of 315 Hz and pulse width of 2.2 milliseconds. The testing was conducted according to the staircase test method detailed in the International Standard SS-ISO 12107:2012. The impact fatigue strength of the Flap-X and SS 716 steel valves was calculated in terms of the impact velocity according to the modified staircase test method in the standard. The test results and their statistical analysis showed that the impact fatigue strength of the Flap-X grade was higher compared to the SS 716 grade. The calculation and testing of the impact fatigue strength of the flapper valve steel grades could help the compressor designers to select the optimum material for their compressor designs, to provide reliable service. The higher impact fatigue strength of the Flap-X grade, lower failure rate and longer impact fatigue life will allow the compressor manufacturers to design thinner valves, as Flap-X can sustain higher impact fatigue stresses reliably for longer time and, at the same time help reduce noise, as thinner valves produce less noise for a given pressure and frequency.
Clean, flawless and thinner stainless steel valves by strip casting
Authors: Barani Araz Ardehali , Campbell Paul , Haggeney Manfred 
Published: September 2019

Abstract
Compressor valves are made of hardened and tempered martensitic stainless steels. They were first produced from ingot cast material. Later continuous casting technology largely replaced this process, which led to improved, more uniform, properties and higher yields in the production of hot strip. A further development was made around the turn of the millennium, when strip casting was first used for the production of stainless steel strip, directly from the melt. In this paper the steel grade Zapp 1.4028MO produced via both production routes: a) Continuous casting - hot rolling - cold rolling and b) Strip casting - cold rolling, are compared with respect to their microstructure evolution and static/dynamic mechanical properties. It is shown that strip cast material can not only substitute that of the traditional continuous casting route, but moreover deliver performance advantages with thin stainless steel valves used within air conditioning units and household refrigerators.
Experimental investigation on the extreme cold start-up of an air compressor for electric heavy vehicles
Authors: Valenti Gianluca , Murgia Stefano , Costanzo Ida , Ravidà Antonino , Piscopiello Giovanni Pio 
Published: September 2019

Abstract
Engine-driven reciprocating air compressors are employed on fuel-powered heavy vehicles to actuate a number of auxiliary systems, like brakes and suspensions. Electrically-driven sliding-vane air compressors turn particularly suited for electric heavy vehicles. Unlike in fuel-powered vehicles, the compressor is not heated up in the case of electric mobility, a situation that may lead to potential issues in extreme cold weathers. This paper investigates experimentally the start-up of a sliding-vane air compressor designed specifically for electric heavy vehicles. The compressors, equipped with instruments, is positioned in a climatic chamber. During the tests, the chamber is set to a desired ambient temperature, 0, -10, -20, - 30 °C or 20 °C taken as reference following ISO 1217, and the compressor is started-up when a steady-state initial condition is achieved. The delivery pressure is controlled at 10 bar(g) and all measurements are recorded until a temperature of 80 °C is reached in the air-lube oil separator. No issues are encountered during the tests, such as sudden damage due to improper lubrication. Moreover, the curves of the measured temperature within the air-lube oil separator show similar trends but higher initial plateaus and lower slopes at lower ambient temperatures resulting into lower oil flow rates, higher energy spent for heating up the system as well as higher warm-up times, from 15 minutes at 20 °C up to 69 minutes at -30 °C.
A Theoretical Study on the Novel Structure of Vane Compressor for High Efficiency
Authors: Hu Y S , Wei H J , Xu J , Wan P K , Wu F , Luo F Y , Ren L P 
Published: September 2019

Abstract
Aiming at the problem of excessive mechanical loss of the conventional vane compressor, this paper proposes a novel vane compressor structure. This compressor can significantly reduce the mechanical frictional loss through converting sliding friction between vane tip and cylinder into rolling friction by using a rolling bearing. The structure and operation principle are introduced in this paper, and mechanical friction loss calculation models of these two kinds of compressor are theoretically analyzed. The results show that mechanical loss of the novel vane compressor can be reduced by nearly 38% under the same working conditions. At the same time, the actual tested results indicated that the total power consumption of compressor decreased 160.1W (6.89%), and the COP increased by 11.89%.
Performance evaluation of a rotating sleeve vane compressor
Authors: Sarip A R , Musa M N 
Published: September 2019

Abstract
This paper presents the performance study of a new designed rotating sleeve vane (RSV) compressor. The aim of this study was to develop a more compact semi-hermetic refrigerant compressor for refrigeration and air-conditioning systems, which will improve the conventional design in terms of sizing and operating mechanism. Experimental study was carried out on the prototype of a single and multi-vane (three and five-vane) RSV compressor prototypes with identical size of rotor and sleeve and tested the in a test bench of R134a refrigeration system. Each test was carried out in a steady state of refrigeration thermodynamic cycle at operating speed varied between 1000 rpm to 1500 rpm to obtain the mechanical and volumetric efficiencies. The experimental results on the three of the new prototypes were analyzed and found that that the single vane compressor prototype has a similar volumetric efficiency of about 90% with that of rolling piston compressor of equivalent capacity. A double increment in capacity to about 48 cc was observed in the five vane prototype models with the same overall dimension and configuration of the rotating components to that of the single vane. The volumetric efficiency was also comparable of about 70% to an existing multi vane rotary compressor.
Study on leakage loss via the radial clearance in a double-swing vane compressor for electric vehicle air conditioning systems
Authors: Zhong Hua , Li Xiaoran , Yang Xu 
Published: September 2019

Abstract
The leakage loss in a novel double-swing vane compressor (DSVC) for use in electric vehicle air conditioning systems is theoretically analysed. The leakage flow through the radial clearance between the rotor and cylinder in the DSVC is modelled by considering both the section change of the leakage channel and the viscous friction of the working fluid. Under the same operating conditions and dimensions, the radial leakage loss of DSVC is more than that of the swing vane compressor (SVC) with a single swing vane. However, the theoretical suction volume of the DSVC is larger than that of the SVC. The relative volumetric leakage loss is almost equal to that of the SVC, which indicates that compared to the SVC, the effects of the structural changes of the DSVC on the volumetric efficiency is neglectable. Considering the larger work capacity and higher mechanical performance of the DSVC, it is suggested that the DSVC is a better choice for the electric vehicle air conditioning system.