Thermodynamic efficiency of a household refrigeration compressor is considerably affected by supe... more Thermodynamic efficiency of a household refrigeration compressor is considerably affected by superheating that occurs inside the compressor. This phenomenon can be defined as the temperature increment of the refrigerant before entering the compression volume. On its flow path; refrigerant gains heat from suction pipe, suction muffler, suction chamber and related compressor components, which are at higher temperatures. In purpose of investigating conjugated heat transfer mechanism inside a hermetic reciprocating compressor a detailed numerical model is presented. The numerical conjugate heat and flow model is formed both with fluid domain (refrigerant) and solid domain (compressor components). Effects of using different materials on temperature distribution of some key components such as the crankcase, cylinder head and the valve plate are investigated. In addition to steady state analysis, transient CFD analysis is performed in order to understand fluid flow characteristics and its influence on superheating of the refrigerant.
La presente invention porte sur un sechoir (1) comprenant un filtre a autonettoyage (3) dispose s... more La presente invention porte sur un sechoir (1) comprenant un filtre a autonettoyage (3) dispose sur le trajet d'ecoulement d'air, empechant ainsi les particules de peluches et de lambeaux de tissu dans l'air a l'interieur du tambour (2) d’entrer de nouveau dans la circulation d'air. L'element de filtre (5) peut etre nettoye par l'action d'un actionneur a memoire de forme (6) qui retrecit et relâche l'element de filtre (5) avec des changements de temperature.
In this study, detailed temperature and pressure measurements were performed at the inlet, outlet... more In this study, detailed temperature and pressure measurements were performed at the inlet, outlet and outer boundaries of the suction muffler of a hermetic reciprocating compressor. The measurements were conducted without effecting real phenomena. After experimental studies, detailed computational fluid dynamic analysis of the refrigerant flow (isobutane) in the suction muffler was performed. Experimental pressure and temperature values at the inlet, outlet and outer boundaries of the suction muffler were used as boundary conditions. The effect of suction valve (opening and closing) at the exit of the suction muffler has been considered. 3dimensional time dependent calculations were completed when statistically steady state convergence was reached for one crank period. Realizable k-є turbulence model with appropriate parameters, second order discretizations for time and space derivatives and real gas model for isobutane (R600a) were applied for the numerical analysis. Mesh dependency of the analysis and solver algorithms were also investigated. The results of the numerical analysis has shown that the time integrated average of the numerically calculated mass flow rate is close to average mass flow rate measured with a calorimeter test system. Furthermore thermal mapping inside the suction muffler shows good agreement with experimental results. Time dependent flow analysis results inside the suction muffler help to characterize the flow and acoustic function of the muffler which leads to the new and better muffler designs.
International Conference on Electrical and Electronics Engineering, Nov 26, 2020
Smart Building Systems are finding common usage by accessing technology easily and making living ... more Smart Building Systems are finding common usage by accessing technology easily and making living areas more comfortable. Many big firms are entering this area with the increase of demanding request and this shows how this sector is growing and becoming future's technology. In this study, KNX (Konnex) protocol is used, which is worlds only accepted (ISO / IEC 14543) standard for commercial and residential building, together with first illumination protocol named DALI (Digital Addressable Lighting Interface) and also new version DALI2 (IEC 62386). A unique gateway design has been done enabling the communication protocols those mentioned above.
2021 13th International Conference on Electrical and Electronics Engineering (ELECO), Nov 25, 2021
With the cheapening of the technological products, users have started to use intelligent building... more With the cheapening of the technological products, users have started to use intelligent building automation systems for saving purposes especially in the European Market. The impact of rising energy prices and taxes on this situation is quite large. In this study, a novel dimmable lighting control unit has been developed to control and manage lighting systems, which is one of the most important parts of intelligent building automation. By controlling multiple lighting units from a single point, energy savings have been achieved by choosing the optimal operating conditions that will be necessary for the environment. The novel lighting control unit, which also provides control via mobile devices, supports the KNX infrastructure, which is used quite widely in the Global Market. It is also integrated into systems running on a network infrastructure with an Ethernet connection. In addition, it will be used in old buildings with no automation infrastructure with the help of digital inputs.
This study presents an analytical flow model for the screw pump and compares it with the numerica... more This study presents an analytical flow model for the screw pump and compares it with the numerical simulations for the lubrication system of a variable speed hermetic reciprocating compressor used mainly in household refrigerators. Since variable capacity compressors (VCC) can be operated at different rotational speeds, a sufficient lubrication is required even at low rotational speeds where centrifugal effects are at a minimum. The lubrication system of such compressors includes a screw pump inside their crankshaft for this purpose. Using the analytical flow model, effects of the main design parameters for the screw pump to maximize the mass flow rate of the lubricant released from the upper part of the crankshaft are predicted and compared with numerical results. Specifically, the effects of the rotational speed, the oil viscosity, the submersion depth of the crankshaft in the oil sump and screw aspect ratio are investigated in this paper.
2021 13th International Conference on Electrical and Electronics Engineering (ELECO), 2021
With the cheapening of the technological products, users have started to use intelligent building... more With the cheapening of the technological products, users have started to use intelligent building automation systems for saving purposes especially in the European Market. The impact of rising energy prices and taxes on this situation is quite large. In this study, a novel dimmable lighting control unit has been developed to control and manage lighting systems, which is one of the most important parts of intelligent building automation. By controlling multiple lighting units from a single point, energy savings have been achieved by choosing the optimal operating conditions that will be necessary for the environment. The novel lighting control unit, which also provides control via mobile devices, supports the KNX infrastructure, which is used quite widely in the Global Market. It is also integrated into systems running on a network infrastructure with an Ethernet connection. In addition, it will be used in old buildings with no automation infrastructure with the help of digital inputs.
2020 12th International Conference on Electrical and Electronics Engineering (ELECO), 2020
Smart Building Systems are finding common usage by accessing technology easily and making living ... more Smart Building Systems are finding common usage by accessing technology easily and making living areas more comfortable. Many big firms are entering this area with the increase of demanding request and this shows how this sector is growing and becoming future's technology. In this study, KNX (Konnex) protocol is used, which is worlds only accepted (ISO / IEC 14543) standard for commercial and residential building, together with first illumination protocol named DALI (Digital Addressable Lighting Interface) and also new version DALI2 (IEC 62386). A unique gateway design has been done enabling the communication protocols those mentioned above.
In this study a numerical investigation of a suction muffler in a hermetic reciprocating compress... more In this study a numerical investigation of a suction muffler in a hermetic reciprocating compressor of a domestic refrigerator is performed using a finite volume based flow solver (Fluent). In order to reveal the behavior of the flow realistically, unsteady experimental pressure data has been used in the outlet boundary condition for the simulations. Detailed investigations are carried out to reveal the instantaneous flow behavior in different muffler sections such as channel and chambers based on the mass flow rate variation with respect to crankshaft angle. It is shown that there is a phase shifting between the mass flow rates through the chamber inlets. Future studies are underway to improve and optimize the muffler design in an effort to maximize the flow rate while keeping the noise levels at a minimum.
Bu calismada ev tipi buzdolaplarinda kullanilan degisken devirli hermetik pistonlu kompresorlerin... more Bu calismada ev tipi buzdolaplarinda kullanilan degisken devirli hermetik pistonlu kompresorlerin yaglama sisteminde bulunan vidali pompa etrafindaki akis analitik olarak modellenmis olup, sayisal modellemeler ile karsilastirilmistir. Degisken kapasiteli kompresorler (VCC) farkli devir sayilarinda calistirilabildikleri icin, merkezkac etkilerin en az seviyede oldugu dusuk devir sayilarinda dahi yeterli bir yaglamaya ihtiyac duyulmaktadir. Bu amac icin, krank mili icerisinde yer alan vidali pompa bu tip kompresorlerin yaglama sisteminin bir parcasidir. Analitik akis modeli kullanilarak, krank mili ucundan cikan kutlesel yag debisini arttiracak ana tasarim parametrelerinin etkileri tahmin edilmis ve sayisal sonuclar ile karsilastirilmistir. Bu calismada ozellikle devir sayisinin, yag viskozitesinin, krank milinin yag haznesi icerindeki daldirma derinliginin ve vida dis oraninin etkileri incelenmistir
ABSTRACT Volume of Fluid (VoF) a b s t r a c t This study presents a numerical investigation of a... more ABSTRACT Volume of Fluid (VoF) a b s t r a c t This study presents a numerical investigation of an oil supply system for a hermetic reciprocating compressor used in household refrigerators. It is aimed to investigate the geometric parameters of the crankshaft affecting the mass flow rate of the lubricant released from the outlet of the crankshaft. The change of the mass flow rate from the outlet of the crankshaft associated with helix-screw indicates that with reducing the screw pitch, the mass flow rate decreases. An important finding is that increasing the depth of the helical channel plays a more significant role than increasing the width of the helical channel. The mass flow rate increases when the distance between the suction hole of the crankshaft and the oil sump bottom increases. The wall thickness of the crankshaft does not significantly affect the mass flow rate whereas it plays a crucial role in formation of the vortices around the crankshaft. Une etude num erique sur le syst eme lubrifiant pour un compresseur a piston herm etique utilis e dans les r efrig erateurs domestiques Mots cl es : Compresseur a piston herm etique ; Lubrification ; Canal h elicodal ; Dynamique des fluides m ecanique (CFD) ; Volume du frigorig ene (VoF) ScienceDirect jo urnal homepage: www.e lsevie r. com/ lo cate/ijrefrig i n t e r n a t i o n a l j o u r n a l o f r e f r i g e r a t i o n 4 8 (2 0 1 4) 2 1 0 e2 2 0
International Journal of Materials, Mechanics and Manufacturing, 2015
Efficiency of hermetic reciprocating compressors, which are used in household refrigerators, is s... more Efficiency of hermetic reciprocating compressors, which are used in household refrigerators, is subjected to thermodynamic, mechanical and electrical losses. Heat transfer analyses reveal reference points that involve improvement of the compressors. A proper understanding of heat transfer and temperature distribution of various components in compressor helps in determining the parts geometry and materials selection. However, the temperature of each compressor component is affected by several phenomena that act simultaneously, making the temperature distribution harder to predict. This paper presents computational thermal analysis of components of a reciprocating compressor and comparison of the results with the measured data. Especially influence of component materials of exhaust region is investigated. Analyses are carried out by commercially available CFD code with use of temperature, mass flow rate and pressure values as boundary conditions which were obtained experimentally.
Bu çalışmanın amacı buzdolaplarında kullanılan hermetik kompresörlerin yağlama sistemindeki yağla... more Bu çalışmanın amacı buzdolaplarında kullanılan hermetik kompresörlerin yağlama sistemindeki yağlayıcı (yağ) –soğutkan iki fazlı akışına etki eden parametrelerin sayısal modelleme ile incelenmesidir. Kompresör muhafazası içinde biriken yağ, krank milinin yağ emme bölgesine açılmış asimetrik bir delikten dönme hareketi ile merkezkaç kuvvet etkisi altında yukarıya doğru taşınır ve krank milinin dış-yüzeyinde açılmış olan helisel bir kanal üzerinden yağ filmi halinde tırmanır. Bu yağ filmi, krank mili çıkışına doğru yönlendirilerek soğutucu akışkan içerisinde savrularak piston başta olmak üzere yatakların yağlanmasında kullanılır. Yağ hava ile çözünmeyen bir karışım oluşturmaktadır bu nedenle çalışmada ayrı fazların bir arada bulunmasına izin veren akışkan hacmi "Volume of Fluid" (VoF) yaklaşımı iki fazlı akış modeli olarak kullanılmıştır. Bu çalışmada krank mili devir sayısı, yağ viskozitesi ve yağ-soğutkan arasındaki yüzey gerilmesinin etkileri sayısal olarak incelenmiştir. ...
Volume 2: Dynamics, Vibration and Control; Energy; Fluids Engineering; Micro and Nano Manufacturing, 2014
ABSTRACT The aim of this numerical study is to investigate the lubrication system of a household ... more ABSTRACT The aim of this numerical study is to investigate the lubrication system of a household hermetic reciprocating compressor. The effects of the rotational speed, oil viscosity and crankshaft-to-oil sump bottom distance on the oil-air two phase flows are investigated in detail. Necessary oil to lubricate the components of the compressor is sucked from the oil sump through an asymmetrically opened suction hole of the crankshaft by its rotational movement and climbs as an oil film on the helical channel carved on the shaft wall. This oil film is directed to crankshaft outlet. The oil forms an immiscible mixtu re with air, thus a two phase flow model should be analyzed using Volu me of Fluid (VoF) method in the flow solver. Main findings related to the oil mass flow rate released fro m the crankshaft outlet reveal that with increasing rotational speed, the mass flow rate fro m the crankshaft outlet also increases, but with increasing viscosity and decreasing crankshaft-to-oil sump bottom distance, the oil mass flow rate decreases. Keywords: Hermetic reciprocating co mpressor, Volu me of Flu id (VoF), Lubrication, Co mputational Fluid Dynamics (CFD). INTRODUCTION Hermet ic co mpressor is a key co mponent in a household refrigeration system as it affects the overall efficiency of the refrigeration unit. Lubricat ion system in a hermet ic co mpressor has a number of important parameters to influence the efficiency of the compressor work. Site cooling, sealing, protecting against corrosion, acting as hydraulic flu id, reducing the noise level and maintaining low equalizing pressures during the off-cycle are among the tasks of the lubrication in a compressor [1]. Recently, the lubricat ion involving two phase flow in a reciprocating co mpressor is investigated numerically by means of CFD. They present a hydrodynamic analysis of the lubricant oil pump ing system in reciprocating co mpressors. The Volu me of Fluid (Vo F) method is mostly applied to model a mu lti-phase flow where coolant-oil interface is resolved. An important design parameter is the time required by oil to reach bearings once the crankshaft gets in motion. Furthermore steady-state oil flo w rate has been reported in [2]. In a similar study, the oil pumping system is modeled both numerically and analytically. Nu merical results after reaching steady-state condition are compared to analytically obtained results. Parametric analysis including the effect of the inlet diameter with the shaft eccentricity, the helix ratio and the submersion depth are performed [3]. It is shown that the flow rate increases with the inlet d iameter and the shaft eccentricity. Lubrication system of a hermet ic recip rocating compressor is visualized by a h igh speed camera and oil-climb ing time fro m CFD results are validated by experiments. Furthermore, the effect of viscosity and rotational speed on the flow rate is investigated in detail [4]. It is shown that the mass flow rate increases with increasing rotational speed. On the other hand, the mass flow rate decreases when the viscosity increases. Another study shows similar results as in [4] such that a drop in the flow rate with increasing viscosity and a raise with increasing rotational speed [5]. In another numerical study regarding the scroll co mpressor oil pump ing system, the flo w rate to the bearings is calculated and the oil free-surface shape in the crankshaft is visualized numerically and validated by experiments [6].
Volume 2: Dynamics, Vibration and Control; Energy; Fluids Engineering; Micro and Nano Manufacturing, 2014
The aim of this experimental study is to investigate the mass flow rate of the lubricating oil in... more The aim of this experimental study is to investigate the mass flow rate of the lubricating oil in a hermetic reciprocating compressor. Essential parameters affecting the performance of the lubrication are the rotational speed of the crankshaft, the viscosity of the oil, the operating temperature and the submersion depth of the crankshaft. An experimental setup was built as to measure the oil mass flow rate with respect to the oil temperature variation during different operating conditions. The influence of the governing parameters such as the rotational speed, temperature (viscosity) and the submersion depth on the mass flow rate from crankshaft outlet are studied in detail. In addition, the oil flow visualization from the upper hole of the crankshaft is performed using a high-speed camera in order to observe the effectiveness of the lubrication of the various parts of the compressor. This study reveals that with increasing rotational speed, the submersion depth of the crankshaft an...
Volume 2: Dynamics, Vibration and Control; Energy; Fluids Engineering; Micro and Nano Manufacturing, 2014
In this study a numerical study of a suction muffler in a hermetic reciprocating compressor of a ... more In this study a numerical study of a suction muffler in a hermetic reciprocating compressor of a domestic refrigerator is performed using a finite volume based flow solver (Fluent). In order to reveal the behavior of the flow realistically, unsteady experimental pressure data has been used in the outlet boundary condition for the simulations. Detailed investigations are carried out to reveal the instantaneous flow behavior in different muffler sections such as channel and chambers based on the mass flow rate variation with respect to crankshaft angle. Power spectrum of pressure fluctuations at selected points help to reveal the noise characteristics of the muffler. This study gives a comprehensive insight into the interaction of muffler chambers with flow through the channel. In a previous study, the ratio of the chamber volumes were shown to be an important design parameter. To verify this assumption, three prototype muffler geometries were simulated. In these prototypes, the plate...
ABSTRACT In the present study, the path followed by the oil and the rotation of the crankshaft in... more ABSTRACT In the present study, the path followed by the oil and the rotation of the crankshaft in a lubrication system of a hermetic reciprocating compressor have been visualized by the means of a high speed camera. Then, the climbing time and the time variation in the speed of the crankshaft have been computed by the means of FLUENT software. The variation of the crankshaft speed with respect to time has been used as an input of the simulation. The predicted climbing time, on the other hand, was the output of the computations, evaluated as a tool to validate the model. Both the accelerated and constant start-up conditions have been considered for the modeling. The change of the crankshaft speed at the start-up has been correlated and used as the initial condition, by writing a step function in the Fluent software. For the sake of applicability and simplicity, no refrigerant is used in the experiments and the computations. Due to the Reynolds number calculated based on the channel diameter, laminar flow conditions have been considered. The two-phase flow of the air–oil pair has been studied by both VOF and Eulerian models.
Thermodynamic efficiency of a household refrigeration compressor is considerably affected by supe... more Thermodynamic efficiency of a household refrigeration compressor is considerably affected by superheating that occurs inside the compressor. This phenomenon can be defined as the temperature increment of the refrigerant before entering the compression volume. On its flow path; refrigerant gains heat from suction pipe, suction muffler, suction chamber and related compressor components, which are at higher temperatures. In purpose of investigating conjugated heat transfer mechanism inside a hermetic reciprocating compressor a detailed numerical model is presented. The numerical conjugate heat and flow model is formed both with fluid domain (refrigerant) and solid domain (compressor components). Effects of using different materials on temperature distribution of some key components such as the crankcase, cylinder head and the valve plate are investigated. In addition to steady state analysis, transient CFD analysis is performed in order to understand fluid flow characteristics and its influence on superheating of the refrigerant.
La presente invention porte sur un sechoir (1) comprenant un filtre a autonettoyage (3) dispose s... more La presente invention porte sur un sechoir (1) comprenant un filtre a autonettoyage (3) dispose sur le trajet d'ecoulement d'air, empechant ainsi les particules de peluches et de lambeaux de tissu dans l'air a l'interieur du tambour (2) d’entrer de nouveau dans la circulation d'air. L'element de filtre (5) peut etre nettoye par l'action d'un actionneur a memoire de forme (6) qui retrecit et relâche l'element de filtre (5) avec des changements de temperature.
In this study, detailed temperature and pressure measurements were performed at the inlet, outlet... more In this study, detailed temperature and pressure measurements were performed at the inlet, outlet and outer boundaries of the suction muffler of a hermetic reciprocating compressor. The measurements were conducted without effecting real phenomena. After experimental studies, detailed computational fluid dynamic analysis of the refrigerant flow (isobutane) in the suction muffler was performed. Experimental pressure and temperature values at the inlet, outlet and outer boundaries of the suction muffler were used as boundary conditions. The effect of suction valve (opening and closing) at the exit of the suction muffler has been considered. 3dimensional time dependent calculations were completed when statistically steady state convergence was reached for one crank period. Realizable k-є turbulence model with appropriate parameters, second order discretizations for time and space derivatives and real gas model for isobutane (R600a) were applied for the numerical analysis. Mesh dependency of the analysis and solver algorithms were also investigated. The results of the numerical analysis has shown that the time integrated average of the numerically calculated mass flow rate is close to average mass flow rate measured with a calorimeter test system. Furthermore thermal mapping inside the suction muffler shows good agreement with experimental results. Time dependent flow analysis results inside the suction muffler help to characterize the flow and acoustic function of the muffler which leads to the new and better muffler designs.
International Conference on Electrical and Electronics Engineering, Nov 26, 2020
Smart Building Systems are finding common usage by accessing technology easily and making living ... more Smart Building Systems are finding common usage by accessing technology easily and making living areas more comfortable. Many big firms are entering this area with the increase of demanding request and this shows how this sector is growing and becoming future's technology. In this study, KNX (Konnex) protocol is used, which is worlds only accepted (ISO / IEC 14543) standard for commercial and residential building, together with first illumination protocol named DALI (Digital Addressable Lighting Interface) and also new version DALI2 (IEC 62386). A unique gateway design has been done enabling the communication protocols those mentioned above.
2021 13th International Conference on Electrical and Electronics Engineering (ELECO), Nov 25, 2021
With the cheapening of the technological products, users have started to use intelligent building... more With the cheapening of the technological products, users have started to use intelligent building automation systems for saving purposes especially in the European Market. The impact of rising energy prices and taxes on this situation is quite large. In this study, a novel dimmable lighting control unit has been developed to control and manage lighting systems, which is one of the most important parts of intelligent building automation. By controlling multiple lighting units from a single point, energy savings have been achieved by choosing the optimal operating conditions that will be necessary for the environment. The novel lighting control unit, which also provides control via mobile devices, supports the KNX infrastructure, which is used quite widely in the Global Market. It is also integrated into systems running on a network infrastructure with an Ethernet connection. In addition, it will be used in old buildings with no automation infrastructure with the help of digital inputs.
This study presents an analytical flow model for the screw pump and compares it with the numerica... more This study presents an analytical flow model for the screw pump and compares it with the numerical simulations for the lubrication system of a variable speed hermetic reciprocating compressor used mainly in household refrigerators. Since variable capacity compressors (VCC) can be operated at different rotational speeds, a sufficient lubrication is required even at low rotational speeds where centrifugal effects are at a minimum. The lubrication system of such compressors includes a screw pump inside their crankshaft for this purpose. Using the analytical flow model, effects of the main design parameters for the screw pump to maximize the mass flow rate of the lubricant released from the upper part of the crankshaft are predicted and compared with numerical results. Specifically, the effects of the rotational speed, the oil viscosity, the submersion depth of the crankshaft in the oil sump and screw aspect ratio are investigated in this paper.
2021 13th International Conference on Electrical and Electronics Engineering (ELECO), 2021
With the cheapening of the technological products, users have started to use intelligent building... more With the cheapening of the technological products, users have started to use intelligent building automation systems for saving purposes especially in the European Market. The impact of rising energy prices and taxes on this situation is quite large. In this study, a novel dimmable lighting control unit has been developed to control and manage lighting systems, which is one of the most important parts of intelligent building automation. By controlling multiple lighting units from a single point, energy savings have been achieved by choosing the optimal operating conditions that will be necessary for the environment. The novel lighting control unit, which also provides control via mobile devices, supports the KNX infrastructure, which is used quite widely in the Global Market. It is also integrated into systems running on a network infrastructure with an Ethernet connection. In addition, it will be used in old buildings with no automation infrastructure with the help of digital inputs.
2020 12th International Conference on Electrical and Electronics Engineering (ELECO), 2020
Smart Building Systems are finding common usage by accessing technology easily and making living ... more Smart Building Systems are finding common usage by accessing technology easily and making living areas more comfortable. Many big firms are entering this area with the increase of demanding request and this shows how this sector is growing and becoming future's technology. In this study, KNX (Konnex) protocol is used, which is worlds only accepted (ISO / IEC 14543) standard for commercial and residential building, together with first illumination protocol named DALI (Digital Addressable Lighting Interface) and also new version DALI2 (IEC 62386). A unique gateway design has been done enabling the communication protocols those mentioned above.
In this study a numerical investigation of a suction muffler in a hermetic reciprocating compress... more In this study a numerical investigation of a suction muffler in a hermetic reciprocating compressor of a domestic refrigerator is performed using a finite volume based flow solver (Fluent). In order to reveal the behavior of the flow realistically, unsteady experimental pressure data has been used in the outlet boundary condition for the simulations. Detailed investigations are carried out to reveal the instantaneous flow behavior in different muffler sections such as channel and chambers based on the mass flow rate variation with respect to crankshaft angle. It is shown that there is a phase shifting between the mass flow rates through the chamber inlets. Future studies are underway to improve and optimize the muffler design in an effort to maximize the flow rate while keeping the noise levels at a minimum.
Bu calismada ev tipi buzdolaplarinda kullanilan degisken devirli hermetik pistonlu kompresorlerin... more Bu calismada ev tipi buzdolaplarinda kullanilan degisken devirli hermetik pistonlu kompresorlerin yaglama sisteminde bulunan vidali pompa etrafindaki akis analitik olarak modellenmis olup, sayisal modellemeler ile karsilastirilmistir. Degisken kapasiteli kompresorler (VCC) farkli devir sayilarinda calistirilabildikleri icin, merkezkac etkilerin en az seviyede oldugu dusuk devir sayilarinda dahi yeterli bir yaglamaya ihtiyac duyulmaktadir. Bu amac icin, krank mili icerisinde yer alan vidali pompa bu tip kompresorlerin yaglama sisteminin bir parcasidir. Analitik akis modeli kullanilarak, krank mili ucundan cikan kutlesel yag debisini arttiracak ana tasarim parametrelerinin etkileri tahmin edilmis ve sayisal sonuclar ile karsilastirilmistir. Bu calismada ozellikle devir sayisinin, yag viskozitesinin, krank milinin yag haznesi icerindeki daldirma derinliginin ve vida dis oraninin etkileri incelenmistir
ABSTRACT Volume of Fluid (VoF) a b s t r a c t This study presents a numerical investigation of a... more ABSTRACT Volume of Fluid (VoF) a b s t r a c t This study presents a numerical investigation of an oil supply system for a hermetic reciprocating compressor used in household refrigerators. It is aimed to investigate the geometric parameters of the crankshaft affecting the mass flow rate of the lubricant released from the outlet of the crankshaft. The change of the mass flow rate from the outlet of the crankshaft associated with helix-screw indicates that with reducing the screw pitch, the mass flow rate decreases. An important finding is that increasing the depth of the helical channel plays a more significant role than increasing the width of the helical channel. The mass flow rate increases when the distance between the suction hole of the crankshaft and the oil sump bottom increases. The wall thickness of the crankshaft does not significantly affect the mass flow rate whereas it plays a crucial role in formation of the vortices around the crankshaft. Une etude num erique sur le syst eme lubrifiant pour un compresseur a piston herm etique utilis e dans les r efrig erateurs domestiques Mots cl es : Compresseur a piston herm etique ; Lubrification ; Canal h elicodal ; Dynamique des fluides m ecanique (CFD) ; Volume du frigorig ene (VoF) ScienceDirect jo urnal homepage: www.e lsevie r. com/ lo cate/ijrefrig i n t e r n a t i o n a l j o u r n a l o f r e f r i g e r a t i o n 4 8 (2 0 1 4) 2 1 0 e2 2 0
International Journal of Materials, Mechanics and Manufacturing, 2015
Efficiency of hermetic reciprocating compressors, which are used in household refrigerators, is s... more Efficiency of hermetic reciprocating compressors, which are used in household refrigerators, is subjected to thermodynamic, mechanical and electrical losses. Heat transfer analyses reveal reference points that involve improvement of the compressors. A proper understanding of heat transfer and temperature distribution of various components in compressor helps in determining the parts geometry and materials selection. However, the temperature of each compressor component is affected by several phenomena that act simultaneously, making the temperature distribution harder to predict. This paper presents computational thermal analysis of components of a reciprocating compressor and comparison of the results with the measured data. Especially influence of component materials of exhaust region is investigated. Analyses are carried out by commercially available CFD code with use of temperature, mass flow rate and pressure values as boundary conditions which were obtained experimentally.
Bu çalışmanın amacı buzdolaplarında kullanılan hermetik kompresörlerin yağlama sistemindeki yağla... more Bu çalışmanın amacı buzdolaplarında kullanılan hermetik kompresörlerin yağlama sistemindeki yağlayıcı (yağ) –soğutkan iki fazlı akışına etki eden parametrelerin sayısal modelleme ile incelenmesidir. Kompresör muhafazası içinde biriken yağ, krank milinin yağ emme bölgesine açılmış asimetrik bir delikten dönme hareketi ile merkezkaç kuvvet etkisi altında yukarıya doğru taşınır ve krank milinin dış-yüzeyinde açılmış olan helisel bir kanal üzerinden yağ filmi halinde tırmanır. Bu yağ filmi, krank mili çıkışına doğru yönlendirilerek soğutucu akışkan içerisinde savrularak piston başta olmak üzere yatakların yağlanmasında kullanılır. Yağ hava ile çözünmeyen bir karışım oluşturmaktadır bu nedenle çalışmada ayrı fazların bir arada bulunmasına izin veren akışkan hacmi "Volume of Fluid" (VoF) yaklaşımı iki fazlı akış modeli olarak kullanılmıştır. Bu çalışmada krank mili devir sayısı, yağ viskozitesi ve yağ-soğutkan arasındaki yüzey gerilmesinin etkileri sayısal olarak incelenmiştir. ...
Volume 2: Dynamics, Vibration and Control; Energy; Fluids Engineering; Micro and Nano Manufacturing, 2014
ABSTRACT The aim of this numerical study is to investigate the lubrication system of a household ... more ABSTRACT The aim of this numerical study is to investigate the lubrication system of a household hermetic reciprocating compressor. The effects of the rotational speed, oil viscosity and crankshaft-to-oil sump bottom distance on the oil-air two phase flows are investigated in detail. Necessary oil to lubricate the components of the compressor is sucked from the oil sump through an asymmetrically opened suction hole of the crankshaft by its rotational movement and climbs as an oil film on the helical channel carved on the shaft wall. This oil film is directed to crankshaft outlet. The oil forms an immiscible mixtu re with air, thus a two phase flow model should be analyzed using Volu me of Fluid (VoF) method in the flow solver. Main findings related to the oil mass flow rate released fro m the crankshaft outlet reveal that with increasing rotational speed, the mass flow rate fro m the crankshaft outlet also increases, but with increasing viscosity and decreasing crankshaft-to-oil sump bottom distance, the oil mass flow rate decreases. Keywords: Hermetic reciprocating co mpressor, Volu me of Flu id (VoF), Lubrication, Co mputational Fluid Dynamics (CFD). INTRODUCTION Hermet ic co mpressor is a key co mponent in a household refrigeration system as it affects the overall efficiency of the refrigeration unit. Lubricat ion system in a hermet ic co mpressor has a number of important parameters to influence the efficiency of the compressor work. Site cooling, sealing, protecting against corrosion, acting as hydraulic flu id, reducing the noise level and maintaining low equalizing pressures during the off-cycle are among the tasks of the lubrication in a compressor [1]. Recently, the lubricat ion involving two phase flow in a reciprocating co mpressor is investigated numerically by means of CFD. They present a hydrodynamic analysis of the lubricant oil pump ing system in reciprocating co mpressors. The Volu me of Fluid (Vo F) method is mostly applied to model a mu lti-phase flow where coolant-oil interface is resolved. An important design parameter is the time required by oil to reach bearings once the crankshaft gets in motion. Furthermore steady-state oil flo w rate has been reported in [2]. In a similar study, the oil pumping system is modeled both numerically and analytically. Nu merical results after reaching steady-state condition are compared to analytically obtained results. Parametric analysis including the effect of the inlet diameter with the shaft eccentricity, the helix ratio and the submersion depth are performed [3]. It is shown that the flow rate increases with the inlet d iameter and the shaft eccentricity. Lubrication system of a hermet ic recip rocating compressor is visualized by a h igh speed camera and oil-climb ing time fro m CFD results are validated by experiments. Furthermore, the effect of viscosity and rotational speed on the flow rate is investigated in detail [4]. It is shown that the mass flow rate increases with increasing rotational speed. On the other hand, the mass flow rate decreases when the viscosity increases. Another study shows similar results as in [4] such that a drop in the flow rate with increasing viscosity and a raise with increasing rotational speed [5]. In another numerical study regarding the scroll co mpressor oil pump ing system, the flo w rate to the bearings is calculated and the oil free-surface shape in the crankshaft is visualized numerically and validated by experiments [6].
Volume 2: Dynamics, Vibration and Control; Energy; Fluids Engineering; Micro and Nano Manufacturing, 2014
The aim of this experimental study is to investigate the mass flow rate of the lubricating oil in... more The aim of this experimental study is to investigate the mass flow rate of the lubricating oil in a hermetic reciprocating compressor. Essential parameters affecting the performance of the lubrication are the rotational speed of the crankshaft, the viscosity of the oil, the operating temperature and the submersion depth of the crankshaft. An experimental setup was built as to measure the oil mass flow rate with respect to the oil temperature variation during different operating conditions. The influence of the governing parameters such as the rotational speed, temperature (viscosity) and the submersion depth on the mass flow rate from crankshaft outlet are studied in detail. In addition, the oil flow visualization from the upper hole of the crankshaft is performed using a high-speed camera in order to observe the effectiveness of the lubrication of the various parts of the compressor. This study reveals that with increasing rotational speed, the submersion depth of the crankshaft an...
Volume 2: Dynamics, Vibration and Control; Energy; Fluids Engineering; Micro and Nano Manufacturing, 2014
In this study a numerical study of a suction muffler in a hermetic reciprocating compressor of a ... more In this study a numerical study of a suction muffler in a hermetic reciprocating compressor of a domestic refrigerator is performed using a finite volume based flow solver (Fluent). In order to reveal the behavior of the flow realistically, unsteady experimental pressure data has been used in the outlet boundary condition for the simulations. Detailed investigations are carried out to reveal the instantaneous flow behavior in different muffler sections such as channel and chambers based on the mass flow rate variation with respect to crankshaft angle. Power spectrum of pressure fluctuations at selected points help to reveal the noise characteristics of the muffler. This study gives a comprehensive insight into the interaction of muffler chambers with flow through the channel. In a previous study, the ratio of the chamber volumes were shown to be an important design parameter. To verify this assumption, three prototype muffler geometries were simulated. In these prototypes, the plate...
ABSTRACT In the present study, the path followed by the oil and the rotation of the crankshaft in... more ABSTRACT In the present study, the path followed by the oil and the rotation of the crankshaft in a lubrication system of a hermetic reciprocating compressor have been visualized by the means of a high speed camera. Then, the climbing time and the time variation in the speed of the crankshaft have been computed by the means of FLUENT software. The variation of the crankshaft speed with respect to time has been used as an input of the simulation. The predicted climbing time, on the other hand, was the output of the computations, evaluated as a tool to validate the model. Both the accelerated and constant start-up conditions have been considered for the modeling. The change of the crankshaft speed at the start-up has been correlated and used as the initial condition, by writing a step function in the Fluent software. For the sake of applicability and simplicity, no refrigerant is used in the experiments and the computations. Due to the Reynolds number calculated based on the channel diameter, laminar flow conditions have been considered. The two-phase flow of the air–oil pair has been studied by both VOF and Eulerian models.
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