Theoretical Performance Analysis of an R1234yf Refrigeration Cycle Based on the Effectiveness of Internal Heat Exchanger

I n this paper, the effects of internal heat exchanger IHX effectiveness on the performance parameters of the refrigeration cycle with R1234yf were theoretically investigated. For this purpose, a mathematical model was developed based on the energy balance of the cycle. The analysis were performed between -20°C and 0°C evaporation and 40°C and 50°C condensation temperatures based on the effectiveness value of IHX. The cooling capacity, coefficient of performance COP , subcooling, superheat and compressor discharge temperature of the refrigeration cycle was examined. Finally, the performance results of the cycle with R1234yf were compared with the baseline cycle that utilizes with R134a. As a result, it was determined that the critical effectiveness to supply the same COP with R1234yf was determined 50% in comparison the baseline cycl

A novel method for prediction of gas turbine power production: Degree-day method

Gas turbines are widely used in the energy production. The quantity of the operating machines requires a special attention for prediction of power production in the energy marketing sector. Thus, the aim of this paper is to support the sector by making the prediction of power production more computable. By using the data from an operating power plant, correlation and regression analysis are performed and linear equation obtained for calculating useful power production vs atmospheric air temperature and a novel method, the gas turbine degree day method, was developed. The method has been addressed for calculating the isolation related issues for buildings so far. But in this paper, it is utilized to predict the theoretical maximum power production of the gas turbines in various climates for the first time. The results indicated that the difference of annual energy production capacity between the best and the last province options was calculated to be 7500 MWh approximately

Introduction of a Novel Design Approach for Tunnel-Type Induction Furnace Coil for Aluminium Billet Heating

UNVER, Umit/0000-0002-6968-6181; KELESOGLU, Alper/0000-0001-7139-6653WOS: 000425983400006In this paper, a user-friendly algorithm was developed by analysis of induction heating of aluminium in a radial direction using analytic, numerical and experimental methods. The aim of this study was to investigate the design data required for the coil and the power supply. The mathematical model of the heating process was simplified into one dimension. The general equation of heat conduction was solved analytically in cylindrical coordinates. The results are validated with the results of experimental and numerical methods. In the study, it is seen that the radial temperature distribution can be modelled with a second-degree equation with a 7% error rate. An important benefit of this paper is the homogenization time coefficient that is a useful tool for calculating the total resting time. Finally, a basic and user-friendly method was described to investigate the length of a tunnel-type induction furnace coil design.Kirikkale University Scientific Studies Coordination Unit [2014/057]This study was granted by Kirikkale University Scientific Studies Coordination Unit with the Project No: 2014/057. We also gratefully thank to Mr. I. Muzaffer UNVER and Mr. Lenny CRAGG for their valuable supports

Design of a passive rainwater harvesting system with green building approach

In this study, a passive rainwater harvesting system was designed. The system is planned to be installed on the roof of the building of Engineering Faculty of Yalova University. The meteorological rain data of Yalova province was analysed and the most suitable rainwater silo dimensions were determined accordingly. A suitable location for the silo was recommended considering the statics of the building. The passive rainwater harvesting system requires no additional pump power and no complex filtration systems. A rainwater delivery system is designed from the roof to the reservoirs for flushing without any additional energy consumption according to the storage location. The minimum height between the tank and the floor was determined to compensate the pressure losses along the critical length. The results of the economic analysis showed that this system can save about 8.5 tons of water/year and 2900 €/year water costs from one building

Analysis of a novel high performance induction air heater

UNVER, Umit/0000-0002-6968-6181; KELESOGLU, Alper/0000-0001-7139-6653WOS: 000441484700007This study represents an experimental and numerical investigation of the enhanced prototypes of the induction air heaters. For this purpose, flow field is enhanced in order to avoid turbulence. The air mass flow rate, outlet construction and the application of insulation of the outer surface of the heater were selected as the performance enhancing parameters. Depending on the exit construction, the new designed prototypes are named as K-2 and K-3. Experiments were performed under two groups for three various flow rates. In the first group, non-insulation situation is examined. In the second group tests, insulation is applied to the outside of windings and inlet-outlet flaps which constitute the boundary of the control volume for the prevention of heat losses. The increasing flow rate boosted the thermal efficiency by 9%. Each of insulation and enlarging exit cross section increased the thermal efficiency by 13%. It was observed that the thermal power transferred to air with the new prototypes increased about 246 W more than the previous designs. The thermal efficiencies of the K-2 and K-3 type heaters were calculated as 77.14% and 87.1%, respectively.University of Yalova Scientific Research Coordination Unit [2015/YL/059]This study was granted by University of Yalova Scientific Research Coordination Unit with the Project No:2015/YL/059. We would like to thank I. Muzaffer UNVER from KEMAS Co. and Mehmet OZDESLIK from Sistem Teknik Co. for their valuable contributions in this study

Analysis of a novel high performance induction air heater

This study represents an experimental and numerical investigation of the enhanced prototypes of the induction air heaters. For this purpose, flow field is enhanced in order to avoid turbulence. The air mass flow rate, outlet construction and the application of insulation of the outer surface of the heater were selected as the performance enhancing parameters. Depending on the exit construction, the new designed prototypes are named as K-2 and K-3. Experiments were performed under two groups for three various flow rates. In the first group, non-insulation situation is examined. In the second group tests, insulation is applied to the outside of windings and inlet-outlet flaps which constitute the boundary of the control volume for the prevention of heat losses. The increasing flow rate boosted the thermal efficiency by 9%. Each of insulation and enlarging exit cross section increased the thermal efficiency by 13%. It was observed that the thermal power transferred to air with the new prototypes increased about 246 W more than the previous designs. The thermal efficiencies of the K-2 and K-3 type heaters were calculated as 77.14% and 87.1%, respectively

Analysis of the effect of construction parameters on energetic and exergetic efficiency of induction air heaters

KELESOGLU, Alper/0000-0001-7139-6653; UNVER, Umit/0000-0002-6968-6181WOS: 000428177300005This study is concerned with the energy and exergy efficiency analysis of a novel air heater that operates with induction principle. The aim of this paper is investigation of the energy and the exergy efficiency augmentation of the new K-1 induction air heater prototype. Energy and exergy performance of the K-1 prototype was analysed and compared with the previous K-0 prototype. The analyses were performed with experimental study and with computational fluid dynamics (CFD) simulations. The new design boosted the energy efficiency about 22.98%. The exergy efficiency was calculated to be around 11.5% max. The CFD simulation results showed that a 1 m/s increase in the inlet velocity yields 3.1% and 0.06% augmentation in the energy and the exergy efficiency respectively. The inlet temperature increase negatively affects the energy and the actual exergy efficiencies. It was concluded that efficiencies of these heaters can be enhanced with more appropriate construction