Browsing by Author "Basaran, A"

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    Comparison of drinking milk production with conventional and novel inductive heating in pasteurization in terms of energetic, exergetic, economic and environmental aspects
    Basaran, A; Yilmaz, T; Azgin, ST; Çivi, C
    Scarcity of natural resources and global warming increase the importance of environmental awareness while making an economic decision for any kind of industry. The dairy industry is one of the impactful areas with high labor, water and energy demand is responsible for air pollution among other sectors in the food industry. In this study, drinking milk production was investigated for milk pasteurization system and its' utilities such as steam, air, and water were studied in terms of energetic, exergetic, economic, and environmental aspects. A novel system including inductive heating (IMP) was proposed in this study with the aim of improving energy and exergy efficiencies and reducing environmental impacts. Each system was selected providing a temperature profile for high-temperature short time (HTST) for processing drinking milk. It was found that a novel design could be performed for 10 ton.h-1 milk with 44.35% less energy and less 53.27% exergy input compared to conventional application. In terms of processing cost, just replacing the heating process help reducing expenditure 3.38 EUR to 2.88 EUR per m3 milk. Apart from thermodynamic and economic performance, simplified Life Cycle Assessment (LCA) results showed that the IMP system generated smaller global warming potential (41%) and ozone layer depletion (51%) impact per m3 milk comparing the conventional system.
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    Prediction of heat and fluid flow in microchannel condensation
    Basaran, A; Benim, AC; Yurddas, A
    The condensing flow inside the microchannel has gained importance as the microchannel heat exchangers are widely used in the industry. In this study, a number of numerical simulations on condensing flow inside the microchannel were conducted to investigate heat transfer characteristic. Circular microchannel geometries with the various diameters were considered. The Volume of Fluid model was used to model two-phase flow. The phase change at the saturation temperature was modeled by the Lee model. In the considered geometries, different from the conventional channels, surface tension forces can be important compared to other forces. Therefore, surface tension was considered in the simulations. Constant wall heat flux and constant saturation temperature were applied as simulation conditions, similar to actual operating conditions. The predictions were validated by comparisons with the experimental results that exist in the literature. A satisfactory agreement of the present predictions with the experimental data was observed.
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    Investigation of the effect of different refrigerants on performances of binary geothermal power plants
    Basaran, A; Ozgener, L
    The paper tries to review the argument of the use of working fluids for binary cycle power plants and has been dedicated to this specific argument with a more general perspective. Binary cycle that allows the production of electricity from geothermal energy sources is one of these systems. In this cycle, thermal energy obtained from geothermal sources is transferred to second working fluid. Therefore, selection of second working fluid plays a key role on the cycle performance. In this study, a sample geothermal binary power cycle was modeled and 12 refrigerants that are HFC, HC, and zoetrope refrigerant mixtures were selected as working fluid. Energy and exergy efficiencies of binary cycle were calculated for 12 refrigerants. Dry type fluids of investigated refrigerants R 236ea, R 600, R 600a, and R 227ea showed higher energy and exergy efficiencies, respectively. On the other hand, R 143a, R 415A, R 290, and R 413A that are wet fluids indicated lower energy and exergy efficiencies, respectively. (C) 2013 Elsevier Ltd. All rights reserved.
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    Numerical Simulation of the Condensation Flow of the Isobutane (R600a) inside Microchannel
    Basaran, A; Benim, AC; Yurddas, A
    A numerical investigation of the condensing flow of isobutane inside microchannel has been performed. Impact of mass flux, hydraulic diameter, and vapor quality on the heat transfer rate and pressure drop is determined. To this purpose, steady-state numerical simulations of condensation flow of isobutane have been performed at mass fluxes ranging from 200 to 600 kg/m(2)s inside a single circular microchannel with varying diameter. Similar to the usual operation conditions, the simulations have been conducted for constant saturation temperature and constant wall heat flux as the thermal boundary condition. The proposed model has been based on the volume of fluid approach, which is an interface tracking method. The Lee model has been used to model the phase change mass transfer at the interface. A verification study has been performed by comparing the proposed model results with the experimental and visual data available in the literature. The currently available correlations are assessed by comparisons with the simulation results. Based on the presently validated simulations, a new correlation has been proposed for the heat transfer coefficient and pressure drop of isobutane condensing flow inside small-scale channels. This is a novel aspect of the present paper, since such a correlation does not yet exist.
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    Experimental investigation of R600a as a low GWP substitute to R134a in the closed-loop two-phase thermosyphon of the mini thermoelectric refrigerator
    Basaran, A
    Various energy efficiency and environmental regulations around the world, such as the European Union's (EU) FGas regulation, are pushing refrigerator manufacturers to replace halogenated refrigerants with environmentallyfriendly alternatives with low Global Warming Potential (GWP) without energy efficiency decrease. In this respect, increasing energy conversion performance by using a low GWP refrigerant in the mini thermoelectric refrigerators (MTERs) gains important for revealing sustainable and environmentally friendly refrigerators. To make this possible, the paper provides a comprehensive examination of the effect of climate-friendly refrigerant replacement in the closed-loop two-phase thermosyphon (CLTPT) on the performance of the MTER. This study treats the experimental investigation of the R600a as a low GWP substitute to R134a in the CLTPT of the MTER. Different from the other study in the literature, an extensive performance evaluation of the commercial MTER in terms of exergy as well as energy was performed and the various filling ratios (FR) of the R600a from 19% to 78% were analyzed for the best performance. The results showed that the MTER with a 46% and 32% FR of R600a had the highest exergy efficiency with 8.55% and 8.11%, respectively while reference MTER with R134a had 5.27%. It is concluded that 32% and 46% FR of the R600a enhanced the MTER energy conversion performance according to the 19% FR of the R134a, in line with the F-Gas regulation. The 32% and 46% FR of the R600a for MTER are the best refrigerant replacement, both from thermal performance and environmental points of view.
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    Condensation Flow of Refrigerants Inside Mini and Microchannels: A Review
    Basaran, A; Benim, AC
    Nowadays, the demand for obtaining high heat flux values in small volumes has increased with the development of technology. Condensing flow inside mini- and microchannels has been becoming a promising solution for refrigeration, HVAC, air-conditioning, heat pumps, heat pipes, and electronic cooling applications. In these applications, employing mini/microchannels in the condenser design results in the working fluid, generally refrigerant, undergoing a phase change inside the mini/microchannels. On the other hand, the reduction in the hydraulic diameter during condensation gives rise to different flow regimes and heat transfer mechanisms in the mini- and microchannels compared to the conventional channels. Therefore, the understanding of fluid flow and heat transfer characteristics during condensation of refrigerant inside mini- and microchannels has been gaining importance in terms of condenser design. This study presents a state-of-the-art review of condensation studies on refrigerants inside mini- and microchannels. The review includes experimental studies as well as correlation models, which are developed to predict condensation heat transfer coefficients and pressure drop. The refrigerant type, thermodynamical performance, and compatibility, as well as the environmental effects of refrigerant, play a decisive role in the design of refrigeration systems. Therefore, the environmental impacts of refrigerants and current regulations against them are also discussed in the present review.
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    Thermal modeling and designing of microchannel condenser for refrigeration applications operating with isobutane (R600a)
    Basaran, A; Yurddas, A
    The present study has focused on thermally performance modeling and designing of microchannel condenser (MC-C). It is aimed at contributing to new MC-C designs for refrigeration applications working with isobutane (refrigerant R600a). To this purpose, a novel thermal simulation model has been developed as a design tool to predict the heat capacity, outlet temperature and pressure of the MC-C. The existing correlations in the literature about heat transfer and pressure drop of refrigerant flow inside the microchannel have been evaluated to improve the accuracy of the thermal simulation model. A new heat transfer coefficient correlation has been employed in the model with the purpose of further improvement of the accuracy. An experimental study has been performed to validate thermal simulation model results. It is found that the model predicted isobutane temperature at the outlet of the MC-C and heat transfer capacity with deviations in the range of +/- 2% and +/- 1%, respectively. The model has an average of 6.8% MAE for the prediction of the isobutane pressure at the outlet of the MC-C The theoretical air-cooled MC-C designs have been performed to investigate the effect of hydraulic diameter microchannels and pass arrangement on heat transfer performance. The theoretical air-cooled MC-C designs have been modeled and discussed with the experimentally validated thermal simulation model for refrigeration applications. According to the model results, although the heat transfer coefficient inside microchannels increases as the hydraulic diameter decreases, heat transfer capacity decreases. When the pass arrangement is modeled, it is concluded that the designs with high tube numbers in the passes at which vapor quality is still high exhibit higher heat transfer capacity in the MC-C.
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    Development of Correlations Based on CFD Study for Microchannel Condensation Flow of Environmentally Friendly Hydrocarbon Refrigerants
    Basaran, A; Benim, AC
    A CFD simulation of the condensation flow of R600a and R290 within microchannels was conducted to explore the effect of mass flux, hydraulic diameter, and vapour quality on heat transfer rate and pressure drop. Data obtained from CFD simulations were used to develop new heat transfer and pressure drop correlations for the condensation flows of R600a and R290, which are climate-friendly refrigerants. Steady-state numerical simulations of condensation flow of refrigerants were carried out inside a single circular microchannel with diameters varying between 0.2 and 0.6 mm. The volume of fluid approach was used in the proposed model, calculating the interface phase change using the Lee model. The CFD simulation model was validated via a comparison of the simulation results with the experimental data available in the literature. It is found that the newly developed Nu number correlation shows a deviation, with an Ave-MAE of 11.16%, compared to those obtained by CFD simulation. Similarly, the deviation between friction factors obtained by the newly proposed correlation and those obtained by CFD simulation is 20.81% Ave-MAE. Widely recognized correlations that are applicable to the condensation of refrigerants within small-scale channels were also evaluated by comparing newly developed correlations. It is concluded that the newly proposed correlation has a higher accuracy in predicting the heat transfer coefficient and pressure drop. This situation can contribute to the creation of a sustainable system via the use of microchannels and climate-friendly refrigerants, like R600a and R290.
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    A Numerical Study to Understand Heat Transfer Characteristics of the Condensing Flow of Climate Friendly R290 Refrigerant Inside the Microchannel
    Basaran, A
    The current study involves a series of numerical simulations aimed at elucidating the heat transfer characteristics associated with the condensing flow of R290 (propane) within microchannels. Specifically, circular microchannels with various diameters were examined to understand the effects of hydraulic diameters on heat transfer coefficients. Different mass fluxes (200-1200 kg/m(2)s) and inlet vapor qualities (0.3-0.9) were considered for a comprehensive examination. To accurately solve the two-phase flow dynamics inherent in condensation, the Volume of Fluid (VOF) model was employed, coupled with the Lee model to account for phase change at the saturation temperature. It is worth noting that within considered cases in numerical simulations, surface tension forces assume importance relative to other forces, in contrast to conventional channels. The accuracy of the numerical predictions was assessed against existing experimental data in the literature, revealing an agreement between the present simulations and the experimental data in the literature. It is found that the heat transfer coefficient increases with increasing mass flux and inlet vapor quality.
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    Experimental investigation and evaluation of the thermodynamical performance of a novel hybrid design for milk pasteurization
    Basaran, A; Yilmaz, T; Çivi, C
    In this study, a novel pasteurization system with an electrical-assisted, waste heat-recovered hybrid design was proposed for more clean and more versatile production. The novel system is designed to recover both the dissipated and extracted heat for milk pasteurization in a single thermodynamic cycle, thus enhancing energy and exergy efficiency. For experimental design, system parameters were selected as an LTLT and the target temperature was set to 65 & PLUSMN; 5 degrees C. It was experimentally determined that 2.328 kW of heat was recovered in the specifically designed heat exchanger. The novel pasteurization system had 0.71% energy efficiency whereas the pasteurization system without energy recovery shows 0.48% energy efficiency. It is concluded that heat recovery thanks to a specific condenser may increase energy efficiency by about 148%. Considering computed exergy input (4.303 kW) and output (0.3096 kW), the exergy efficiency of the whole pasteurization system was nearly 7.2%. It is found that the compressor had a 0.9884 kW exergy destruction rate corresponding to a 25% exergy destruction percentage. It is followed by the evaporator with 0.5662 kW, the secondary condenser with 0.2297 kW, by condenser with 0.1555 kW, and by expansion valve with 0.08221 kW, respectively. Consequently, the novel system has a promising design by performing good thermodynamic efficiency and recovering waste heat to reduce secondary heating energy requirement which is not valorized in conventional systems. The novel system causes approximately 33% fewer carbon emissions compared to a pasteurization system without energy recovery for the same amount of milk processing.
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    Energy and exergy analysis of induction-assisted batch processing in food production: a case study-strawberry jam production
    Basaran, A; Yilmaz, T; Çivi, C
    Traditional and additive free conservation techniques for long shelf life of fruits can be counted as drying and canning or processing to jam-marmalade. Conventional systems consume fuel or electricity to produce required energy with low efficiency due to losses and irreversibilities through heat transfer. For strawberry jam production, heat is applied as a batch system by vacuum-jacketed agitated vessel with a water or heating oil (heat transfer fluid-HTF), which is heated by electricity inside the jacket. In this study, energy and exergy efficiencies of conventional jacketed vessels and inductive heater were compared theoretically for jam processing. It is found that water and HTF used systems works with 82.27% and 93.38% energy efficiencies, respectively, while inductive processing system works with 95.00% efficiency. In terms of irreversibilities, the inductive system generates 79.90 kJ K-1 entropy, while other systems generate 674.19 kJ K-1 for HTF system and 753.90 kJ K-1 for the water system. It is determined that the batch system with induction heater needs less energy and exergy input than conventional electrical heater systems to provide the same desired output. Direct heating by induction heater has several benefits at thermal food processing systems as strawberry jam production by lowering energy and exergy losses. Graphic abstract
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    Application of inductive forced heating as a new approach to food industry heat exchangers: A case studyTomato paste pasteurization
    Basaran, A; Yilmaz, T; Çivi, C
    Heat exchangers are one of the main equipment used in food industry because of their convenience to transfer energy to both auxiliary facilities and various food products. In food industry, there are several reasons for heat transfer such as pre-heating, pasteurizing and sterilizing in which heat exchangers require high amount of energy. On the other hand, as being a unique quality assurance unit heat exchangers should be cleaned easily and extensively. Having high operating costs due to energy consumption and requiring high investment cost due to ensure a reliable hygienic design make heat transfer units an expensive and energy-consuming unit. Therefore, developing new approaches to generate energy and transferring it hygienically with minimum loses will be an opportunity for the food industry. With the view of developing new equipment for industry, induction-driven heating system was investigated in this study and energy and exergy efficiencies were calculated and compared with conventional heat exchanger system. Selected food system was the tomato paste sterilization/pasteurization which is a part of tomato paste production line. After assumptions and theoretical calculations for both conventional application and inductive heating, it was found that inductive heating system has 95.00% energy efficiency and 46.56% second law efficiency while the conventional heating system with electric boiler has 75.43% energy efficiency and 16.63% exergy efficiency. As a consequence, inductive method was found more beneficial compared to a commercial method having higher energy and exergy efficiencies.
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    The determination of the thermal characteristics of the microchannel heat exchangers for single-phase R600a flow
    Basaran, A; Yurddas, A
    In this study, the mathematical modeling of microchannel heat exchangers (MCHEs) has been experimentally examined for applications where there is a single-phase refrigerant flow such as pre-heating/cooling, superheating/subcooling. A mathematical simulation model has been developed for louvered fin MCHEs where the working fluid is R600a, which estimates the outlet temperature, total heat transfer capacity and entropy generation of the R600a. To imrpove the accuracy of the model, different mass velocities in the passes and uniform air velocities at the face of MCHE have been taken into consideration in the proposed model. Different from other models in the literature, a calculation system created by two discretization level has been applied to take into account these effects. Non-uniform air velocities have been taken into consideration via dividing the face of the MCHE into airflow regions in the model. Experimental study has been performed to validate the model results. It concluded that the model predicts the outlet temperature with an average absolute deviation within +/- 10% for all investigated test conditions. It is found that the taking into consideration non-uniform air velocity improves accuracy of the model. The entropy generation mechanisms in the MCHE have been investigated and it has been determined that the contribution of the fluid flow irreversibility to entropy generation is quite low compared to heat transfer irreversibility.