Reciprocating Compressors

The suction process in reciprocating compressors is strongly affected by the valve dynamics and the pulsating flow throughout the suction muffler. This paper describes a simplified computational fluid dynamics (CFD) model to simulate the flow through the muffler, suction valve and a small region inside the cylinder. The proposed method is applied to predict the suction process of a small reciprocating compressor and its adequacy is compared with a more time elaborate model in terms of accuracy, computation cost and usability.

Heating is an undesirable effect of the compression process at least as far as compressors are concerned and heat transfer is nature's way of driving systems towards stability. This has not only provided food for thought for researchers trying to understand its influence and quantify its effects, but also challenged designers to mitigate its impact and develop safe and efficient designs. Also, just as any other unwanted phenomenon would spur curiosity and inventiveness, this has led to the development of a host of new materials both metallic as well as non-metallic to withstand the vagaries of high temperatures, in addition to the toxic environment present in many gas compressors used in pumping and process industries. Also this investigation is concerned with the improving efficiency of two stage reciprocating air compressor by providing water cooling source, radiator coolant and ethylene glycol. The experiments of a two double-cylinder reciprocating compressor system with air, water and different inter coolants were performed.

This project work deals with the design and fabrication of a pedal powered hacksaw cutting machine. The aim of this work is to develop a modernized and less stressful operation for cutting wood, metals and plastic materials. It is very useful for cutting PVC materials (pipes) and can be used widely in lather and in furniture making industries. This work can also serve as an exercising machine for fitness while cutting, it uses the principle of a slider crank mechanism which converts the rotary motion of the flywheel to the reciprocating motion of the hacksaw during pedaling. The machine was tested and continued to be very efficient with an ideal mechanical Advantage of 0.5 (less than 1), velocity ratio of 0.65 (less than 1), a power output of 5.72KW and an efficiency of 76.9%, which makes it very adequate and capable for cutting.

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.

Natural companies employ turbine flow meters to measure natural gas which delivered to Compressed Natural Gas stations. The stations utilize compressors to increase pressure. The compressor produces a flow pulsation, which affects the accuracy of the measurement. The main aim of this article is to decrease the compressor effects on measurement accuracy by utilizing a snubber between the turbine flow meter and the reciprocating compressors. For this aim, numerical modeling has been built to simulate natural gas flow through a snubber. The effects of various snubber parameters on pressure pulsation have been investigated. The parameters included snubber volume to the minimum volume ratio, the ratio of height to diameter, outlet pipe length, and the existence and non-existence a buffer. The Ansys Fluent has been used for numerical modeling with transient analysis. Results show that in H/D value of 3, the maximum reduction in the percentage of pressure pulsation drop is about 47% and increasing the outlet pipe length to the 10 times of initial length causes a decrease of about 83% in pressure pulsations. Besides, for the ratio of snubber volume to the minimum volume from 1 to 16.7, the amplitude of pressure pulsations decreases from 4.1% to 0.25%. ARTICLE HISTORY

Measures to reducing friction inside the reciprocating machine make a decisive contribution to further improvements of machines efficiency. A number of influencing parameters have already been tested on diesel and gasoline engines. The friction between piston and cylinder liner is a major contributor to overall engine friction. Reducing friction in reciprocating machines can be achieved by using appropriate materials and optimizing the structure of the piston and piston group. Tribological materials and coatings are one of the options for increasing strength of the aluminum parts of reciprocating engines and compressors. This initial manuscript describes the influences of the piston skirt and cylinder liner design. The differences in frictional losses are determinate for the entire compressor operating map for base aluminum construction, as well as coated aluminum construction.

ÖZET Teknolojide yaşanan gelişmeler günümüzde her alanda hızlı bir şekilde ilerlemektedir. Otomotiv alanındaki çalışmalar teknolojide yaşanan bu gelişmeler arasında en büyük paylardan birine sahiptir. Birkaç yüz yıl öncesine dayanan içten yanmalı motor teknolojisi üzerine yapılan binlerce etkili çalışma sonucu elde edilen; motor gücünden, egzoz emisyonlarının iyileştirilmesine, güvenlik ekipmanlarından, konfora elektronik sistemlerin de katkısıyla göz ardı edilemeyecek kadar önemli gelişmeler ortaya çıkarılmıştır. Günümüzde depolanmış basınçlı havaya bazı sınıf araçlarda ve sanayi kuruluşlarında fazlaca ihtiyaç duyulmaktadır. Bununla birlikte basınçlı hava en pahalı enerji depolama metodudur. Basınçlı hava, elektrik enerjisinin kullanımının uygun olmadığı ya da tehlikeli olduğu durumlarda çoğunlukla üretim sektöründe, servis sektöründe, ağır hizmet tipi vasıtalarda ve günümüzde traktörlerde de kullanımı yaygınlaşan depolanabilir bir enerji türüdür. Basınçlı hava sistemleri enerji tüketimi çok yoğun sistemler oldukları için verimlilik göz önünde bulundurulması gereken en önemli parametrelerden biridir. En uygun koşullar sağlanmış olsa bile, kompresörlere verilen enerjinin oldukça büyük bir bölümü ziyan edilir. Bu atık enerjiyi faydalı enerjiye dönüştürmenin yolları aranmalı ve basınçlı hava sistemi olabilecek en verimli şekilde tasarlanmalıdır. Durum böyle olunca araçlarda verimi arttırmak için kullanılan aşırı doldurma sisteminin ana parçası olan turbo şarj çalışma sistemine benzetilerek Yıldız Pul Otomotiv Motor Parçaları Sanayi A.Ş. Ar-Ge test laboratuvarında ağır hizmet tipi araçlarda kullanılan çift silindirli, pozitif deplasmanlı bir kompresörün çalışma verimliliği incelenmiştir. Kompresör hava giriş hattı şartlandırılmış hava ile beslenerek klasik duruma göre kompresörün verimini arttırmak ve kullandığı enerji tüketimini azaltmak amaçlanmıştır.

The article considers the issues of using different physical processes parameters in systems for real-time condition monitoring of reciprocating compressors. The locations for sensors of absolute and relative vibration are defined. Trends of parameters of absolute and relative vibration at emergence of malfunctions and defects are given. Examples of diagnosing of reciprocating compressors in parameters of relative and absolute vibration are reviewed. It is shown that real-time monitoring of the absolute vibration parameters and the relative position of rod provides observability of the piston compressors’ condition and, consequently, their safe operation.

This experimental model presents a method of reduce energy consumption and enhance the refrigerating effect. With the help of two phases condensing ejector it is found that ejector work as sub compressor in refrigeration flow cycle. That helps to reduce compressor load effectively and hence improve refrigerating effect. The new cycle includes a second step compression by an ejector device, the compressor compresses the vapour to approximately 4/5 of the final pressure and additional compression (i.e. 1/5 of final pressure) is provided in an ejector, the thermodynamic model has developed for R134 and R22 refrigerant showing a possible efficiency improvement as compared to the traditional vapour compression cycle. The investigation of a new cycle for vapour compression refrigeration with using a novel device for non-mechanical compression of refrigerants is called a condensing ejector has carried out within this project. This novel device is a hybrid of simple vapour compression refrigeration system [SVCRS] and ejector refrigeration system [ERS] is more attractive than traditional refrigeration system because of higher coefficient of performance [COP].That leads the energy saving for same amount of cooling.

Reciprocating Compressors - Protection against Crank Case Explosions
1 SCOPE
2 OIL MIST/AIR MIXTURE EXPLOSIONS
3 PREVENTION AND PROTECTION
3.1 Design
3.2 Maintenance and Operation

FIGURES

1 FLAMMABILITY LIMITS AND SPONTANEOUS IGNITION REGION FOR MIXTURES OF LUBRICATING OIL VAPOR IN AIR.

Development of methodology and technology for piston compressors health control, diagnostics and monitoring by means of vibroacoustic diagnostics, as well as algorithms of automatic systems for piston compressors monitoring which provide their fault-free operation, is an actual problem.
Data collection and processing is the basis of piston compressors monitoring and diagnostics technology, thus providing compressors defects and malfunctions detection with a specified depth of their detailing and reliability and a hazard level.
Realization of monitoring and diagnostics technology is based on application of vibroacoustic signals structure models upon occurrence of various defects and malfunctions in piston compressors components, set of malfunctions and standard values diagnostic features, methods of vibroacoustic signals transformation and a system for their parameters estimation.
The paper considers methodology of the diagnostic signal processing and the monitoring system functional diagram.
The proposed monitoring and diagnostics methodology is based on measurement of vibroacoustic oscillations parameters and characteristics, as well as measurement of direct structural and thermodynamic parameters.
The structure and functioning principles of the expert system for decision making  support have been presented.
Functioning algorithm of the automatic expert system includes calculation of the  diagnostic features values based on their normative ones, formation of the diagnostic features sets which correspond to individual malfunctions classes and formation of the expert system messages.
The scheme of the system for piston compressors real-time health monitoring has been considered.
The system has a series-parallel structure of a data-measuring complex for data collection and processing, which allows to measure the vibroacoustic signals parameters for piston compressors and their operating modes monitoring. Besides,
the system allows to measure other physical processes parameters, for example, for
monitoring and diagnosis-making purposes it has been provided to measure and apply pressure in decreasing spaces (an indicator diagram), gas temperature, a rod position, leakage through stuffing boxes and others.

The article presents the results of reciprocating compressors operation under the control of Vibration-Based Diagnostics monitoring systems, dwells upon the issues of usage of reciprocating compressors valves by various vendors and their influence
on compressors’ vibroactivity. An adequate evaluation of vibroactivity of piston machines is provided by the Russian regulative database on vibration parameters.
Main differences of Russian and global methods of reciprocating compressors health evaluation, particularly, used frequency range, are presented in the article. It is shown that the approach laid in Russian standards on reciprocating compressors vibration regulations, ensures true-to-life assessment of reciprocating compressors assemblies and details condition.
The examples given in the article confirm that the criteria of reciprocating compressors repair correctness assessment should be the machinery health, including its vibroactivity, not just mindless usage of new components purchased from the global brands.
Practical examples of operation and monitoring of reciprocating compressors show that Russian developments and products,
particularly, scientific-methodological and standards base of Vibration-Based Diagnostics monitoring, reciprocating compressors monitoring systems, reciprocating compressors valves are highly competitive with foreign ones, and sometimes even superior to them in parameters and characteristics, which is a positive factor under the conditions of current economic situation and import substitution policy.

Places and the reasons of refusals of the reciprocating compressors applied, mainly, for compression of gases, containing hydrogen are analysed. Various methods of monitoring and diagnostics of a technical condition of compressors also are subjected to the analysis. Efficiency of a vibroacoustic method of diagnostics is shown high in comparison with others. The system of condition monitoring of reciprocating machines COMPACS is described.

Степень обеспечения безопасной и безаварийной эксплуатации поршневых компрессоров (ПК) опасных производственных объектов (ОПО) неразрывно связано с развитием методо-логии и средств диагностирования и мониторинга технического состояния машин и меха-низмов возвратно-поступательного действия. Поэтому разработка методологии и техноло-гии диагностирования и мониторинга ПК, в частности, методами виброакустической (ВА) диагностики, а также алгоритмов для автоматических систем диагностики и мониторинга (СДМ) ПК, обеспечивающих безаварийную их эксплуатацию, является актуальной проблемой.

Natural companies employ turbine flow meters to measure natural gas which delivered to Compressed Natural Gas stations. The stations utilize compressors to increase pressure. The compressor produces a flow pulsation, which affects the accuracy of the measurement. The main aim of this article is to decrease the compressor effects on measurement accuracy by utilizing a snubber between the turbine flow meter and the reciprocating compressors. For this aim, numerical modeling has been built to simulate natural gas flow through a snubber. The effects of various snubber parameters on pressure pulsation have been investigated. The parameters included snubber volume to the minimum volume ratio, the ratio of height to diameter, outlet pipe length, and the existence and non-existence a buffer. The Ansys Fluent has been used for numerical modeling with transient analysis. Results show that in H/D value of 3, the maximum reduction in the percentage of pressure pulsation drop is about 47% and increasing the outlet pipe length to the 10 times of initial length causes a decrease of about 83% in pressure pulsations. Besides, for the ratio of snubber volume to the minimum volume from 1 to 16.7, the amplitude of pressure pulsations decreases from 4.1% to 0.25%.

The statistic analysis of instantaneous values of vibration and acoustic signals showed that in particular the form of probability density function of instantaneous vibroacoustic signal values changes depending on the condition of the device under vibrationbased diagnostics. The shape of the probability density curve can be described by the  characteristic function. With regard to the diagnostics of reciprocating compressors the hypothesis had been put forward that the characteristic function of the vibroacoustic signal of reciprocating compressor is an informative diagnostic parameter of the technical condition of the unit. The article presents the results of a study of the statistical moments of the characteristic function parameters obtained for the different conditions of the test device. The studies revealed that the module of the characteristic function is the informative diagnostic symptom of reciprocating compressors faults and allows to assess the state of their units and parts.