Onder Kizilkan

Bio: Onder Kizilkan is an academic researcher from Süleyman Demirel University. The author has contributed to research in topics: Exergy & Refrigeration. The author has an hindex of 14, co-authored 36 publications receiving 747 citations.

A new design approach for shell-and-tube heat exchangers using genetic algorithms from economic point of view

Abstract: A heat exchanger is a device that is used to transfer heat between two or more fluids that are at different temperatures. Heat exchangers are essential elements in a wide range of systems, including the human body, automobiles, computers, power plants, and comfort heating/cooling equipment. The most commonly used type of heat exchanger is the shell-and-tube heat exchanger, the optimal design of which is the main objective of this study. A primary objective in the heat exchanger design is the estimation of the minimum heat transfer area required for a given heat duty, as it governs the overall cost of the heat exchanger. However there is no concrete objective function that can be expressed explicitly as a function of design variables and in fact many numbers of discrete combinations of the design variables are possible. In the present study, genetic algorithms (GA) has been successfully applied for the optimal design of shell-and-tube heat exchanger by varying the design variables: outer tube diameter, tube layout, number of tube passes, outer shell diameter, baffle spacing and baffle cut. LMTD method is used to determine the heat transfer area for a given design configuration.

Thermoeconomic optimization of a LiBr absorption refrigeration system

Abstract: Optimization of thermal systems is generally based on thermodynamic analysis. Thermoeconomic optimization technique combines thermodynamic analysis with economic constraints to obtain an optimum configuration of a thermal system. In this study, the thermoeconomic optimization technique is applied to a LiBr absorption refrigeration system. Various components of the system such as condenser, evaporator, generator, and absorber heat exchangers are optimized. Additionally, optimum heat exchanger areas with corresponding optimum operating temperatures are determined. A cost function is specified for the optimum conditions. Finally, an example for the optimum design of a 20 kW LiBr system is given.

Performance and exergetic analysis of vapor compression refrigeration system with an internal heat exchanger using a hydrocarbon, isobutane (R600a)

Abstract: Hydrocarbons (HCs) are excellent refrigerants in many ways such as energy efficiency, critical point, solubility, transport and heat transfer properties, but they are also flammable, which causes the need for changes in standards, production and product. There are increasing number of scientists and engineers who believe that an alternative solution, which has been overlooked, may be provided by using HCs. The main objective of this study is to perform energy and exergy analyses for a vapor compression refrigeration system with an internal heat exchanger using a HC, isobutene (R600a). For a refrigeration capacity of 1 kW and cold chamber temperature of 0°C, energy and exergy balances are taken into account to determine the performance of the refrigeration system. Energy and exergy fluxes are determined, and irreversibility rates are calculated for every component of the system. It is seen that the compressor has the highest irreversibility rate, and the heat exchanger has the lowest. Also from the result of the analysis, it is found that condenser and evaporator temperatures have strong effects on energetic and exergetic performances of the system such as coefficient of performance (COP), efficiency ratio (τ), exergetic efficiency (ξ) and irreversibility rate. Copyright © 2008 John Wiley & Sons, Ltd.

A Comprehensive Review of Thermal Energy Storage

Abstract: Thermal energy storage (TES) is a technology that stocks thermal energy by heating or cooling a storage medium so that the stored energy can be used at a later time for heating and cooling applications and power generation TES systems are used particularly in buildings and in industrial processes This paper is focused on TES technologies that provide a way of valorizing solar heat and reducing the energy demand of buildings The principles of several energy storage methods and calculation of storage capacities are described Sensible heat storage technologies, including water tank, underground, and packed-bed storage methods, are briefly reviewed Additionally, latent-heat storage systems associated with phase-change materials for use in solar heating/cooling of buildings, solar water heating, heat-pump systems, and concentrating solar power plants as well as thermo-chemical storage are discussed Finally, cool thermal energy storage is also briefly reviewed and outstanding information on the performance and costs of TES systems are included

A review of solar thermal technologies

Abstract: The use of solar energy in recent years has reached a remarkable edge. The continuous research for an alternative power source due to the perceived scarcity of fuel fossils is its driving force. It has become even more popular as the cost of fossil fuel continues to rise. The earth receives in just 1 h, more energy from the sun than what we consume in the whole world for 1 year. Its application was proven to be most economical, as most systems in individual uses requires but a few kilowatt of power. This paper reviews the present day solar thermal technologies. Performance analyses of existing designs (study), mathematical simulation (design) and fabrication of innovative designs with suggested improvements (development) have been discussed in this paper.

A review on exergy analysis of vapor compression refrigeration system

Abstract: This paper reviews on the possibilities of researches in the field of exergy analysis in various usable sectors where vapor compression refrigeration systems are used. Here, it is found that exergy depends on evaporating temperature, condensing temperature, sub-cooling and compressor pressure. It also depends on environmental temperature. Nowadays, hydrocarbons are considered as refrigerant having low ODP and GWP, and these are considerable in the aspect of exergy analysis. Refrigerants R 407a, R 600a, R 410a and R 134a are considered and analyzed with respect to exergy efficiency. Mixtures of hydrocarbons with R134a also show better performance with respect to other refrigerants. Among the components of the vapor compression system, much research showed that major part of exergy losses is occurred in the compressor. Nanofluid and nanolubricant cause to reduce the exergy losses in the compressor indirectly.