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Kocaturk S.,Arcelik R and nter | Met A.,Arcelik R and nter | Uslu I.,Arcelik R and nter | Kuddusi L.,Technical University of Istanbul
Refrigeration Science and Technology | Year: 2015

Physical parameters regarding the heat and mass transfer in a household refrigerator crisper were investigated in association with the resulting effects on the quality of the vegetables stored in the crisper. Storage temperatures, temperature difference between inner surfaces, air inlet velocity, and the type, amount and locational orientation of vegetable commodities in the crisper were taken into account as the physical parameters regarding a typical refrigerator crisper. An experimental set-up to control these physical parameters independently was built. Parametric effects on the humidity levels in the storage volume, amount of condensation on the surfaces, weight loss of the vegetable commodities, and quality and shelf-life of a variety of vegetables were investigated. Physical and chemical analyses and sensory evaluations were performed in order to determine the quality changes of different types of vegetables. With the parametric effects of physical parameters indicating design and storage conditions of a household refrigerator crisper, indicative quality parameters for shelf-life estimation of different types of vegetables were determined.

Kerpicci H.,Arcelik Randnter | Yagci A.,Arcelik Randnter
International Journal of Refrigeration | Year: 2013

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. © 2012 Elsevier Ltd and IIR. All rights reserved.

Ozdemir A.R.,Arcelik R and nter | Hacioglu B.,Arcelik A.S. Compressor Plant | Kasapoglu E.,Arcelik A.S. Compressor Plant
IOP Conference Series: Materials Science and Engineering | Year: 2015

A hermetic reciprocating compressor is the most energy consuming component of the refrigerators. Therefore performance improvement studies of the compressor play an important role to reduce overall energy consumption of the refrigerators. Design of bearings is one of the major study areas influencing reciprocating compressor performance. In this study crank pin and piston pin bearings in hermetic compressor applications are investigated and optimized. The effect of operating conditions, bearing offset between crank pin and piston pin, bearing clearance and bearing location along the shaft on the friction loss were investigated and optimal bearing designs were developed. Efficiency measurements of the compressor showed that the improved crank pin and piston pin bearing designs provide up to 3.8% increase in the COP as a result of reduction in mechanical loss that is significantly influenced by the length of the bearings, bearing location along the shaft and operating conditions. © Published under licence by IOP Publishing Ltd.

Ahn H.,Yeditepe University | Gul B.,Yeditepe University | Sahin Y.,Arcelik R and nter | Hartoka O.,Arcelik R and nter
ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) | Year: 2013

The condensation of steam in the presence of air has been investigated experimentally in the cross-flow flat-plate singlechannel condenser. In particular, the condensation efficiency which is defined by the ratio of heat released during the condensation process (the amount of latent heat) to the total heat extracted from the mixture of vapor and non-condensable gas (the sum of latent and sensible heats) is examined as a function of the air-steam mixture temperature and humidity at inlet and the flow rates of the air-steam mixture and cooling air. The preliminary results are obtained with the operating condition of the air-steam mixture flow at 70°C and 80, 85 and 90% relative humidity at inlet. The most notable result is that the condensation efficiency evidently decreases with the increase of the cooling air flow rate. With both mixture and cooling flow rates kept constant, the condensation efficiency increases, as expected, with the increasing air-steam mixture humidity at the inlet. On the other hand, the air-steam mixture flow rate appears to have little effect on the condensation efficiency. Copyright © 2013 by ASME.

Karaosmanoglu F.,Technical University of Istanbul | Yuzer S.,Arcelik Randnter | Kerpicci H.,Arcelik Randnter | Durak E.,Suleyman Demirel University of Turkey
Industrial Lubrication and Tribology | Year: 2013

Purpose - Refrigerant fraction and mixture viscosity values were determined for various operating conditions of compressors. The paper aims to discuss these issues. Design/methodology/approach - In this study, an experimental setup that can be used to obtain refrigerant mass fraction and mixture viscosity data is designed and constructed. With the experimental setup, R600a mineral and R134a polyolester compressor lubricant mixtures were examined. Findings - This study presents an experimental procedure for obtaining practical results related to refrigerants used in the refrigeration system. Some properties of refrigerant-lubricant mixtures are very important for the design of compressors and performance of the refrigeration cycle. Originality/value - The paper is of value in presenting an experimental procedure for obtaining practical results pertaining to the tribological and other properties performance of the refrigerants. Copyright © 2013 Emerald Group Publishing Limited. All rights reserved.

Kocaturk S.,Arcelik R and nter | Egrican A.N.,Suntek International
International Journal of Thermodynamics | Year: 2013

Food load and air-flow area within a refrigerated space having one air inlet and one air outlet have been taken as two separate control volumes interacting with each other at their boundaries. In the lower control volume, stored vegetable products have been located and heat and mass transfer due to respiration and transpiration of these products have been modeled for determining boundary conditions of the upper control volume, in which heat and mass transport within the air circulation above the products have been modeled and numerically investigated. Upper surface temperature of the said upper control volume has been compared with the dew point temperature, and condensation heat and mass fluxes through the surface have been calculated at the upper boundary. Time-dependent heat and mass transport equations of the control volume have been simultaneously solved together. An implicit finite difference approach has been applied for the numerical solution of transport equations. Fortran programming language has been used to develop the numerical model. As a result, temperature and humidity ratio distribution, the amount of vapor transpiration from food products, and the amount of condensation on the underside of the upper surface due to heat-and-mass transport and transpiration characteristics of the products have been time-dependently calculated for two different dimensions of the air inlet.

Kocaturk S.,Arcelik R and nter
Refrigeration Science and Technology | Year: 2014

Heat and mass transport and surface condensation in a refrigerated vegetable crisper having one air inlet and one air outlet were numerically investigated with heat and mass transfer due to food respiration and transpiration. In the numerical model developed, food load and air-flow area within the refrigerated space were taken as two separate control volumes interacting with each other at their boundaries, and timedependent transport equations of each control volume were simultaneously solved. Air inlet velocity was taken as Gr/Re2 in the crisper being in a range that natural convection conditions arise. In the parametric analyses, effects of the storing temperature and temperature difference between the top surface and other surfaces on momentum, heat and mass transport in the control volumes, moisture loss of the food load due to transpiration, and the amount of surface condensation through the top surface were determined. Weight loss of cucumbers in the situation of 4 K temperature difference between top surface and other boundary surfaces; were calculated to be ∼20% more than the weight loss in the situation of 2 K temperature difference.

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