Ugur Atikol

Overview of Ionic Liquids Used as Working Fluids in Absorption Cycles

The cycle performance of refrigeration cycles depends not only on their configuration, but also on thermodynamic properties of working pairs regularly composed of refrigerant and absorbent. The commonly used working pairs in absorption cycles are aqueous solutions of either lithium bromide water or ammonia water. However, corrosion, crystallization, high working pressure, and toxicity are their major disadvantages in industrial applications. Therefore, seeking more advantageous working pairs with good thermal stability, with minimum corrosion, and without crystallization has become the research focus in the past two decades. Ionic liquids (ILs) are room-temperature melting salts that can remain in the liquid state at near or below room temperature. ILs have attracted considerable attention due to their unique properties, such as negligible vapor pressure, nonflammability, thermal stability, good solubility, low melting points, and staying in the liquid state over a wide temperature range from room temperature to about 300°C. The previously mentioned highly favorable properties of ILs motivated us for carrying out the present research and reviewing the available ILs found in the literature as the working fluids of absorption cycles. Absorption cycles contain absorption heat pumps, absorption chillers, and absorption transformers.

Evaluation and Optimization of Single Stage Absorption Chiller Using (LiCl + H2O) as the Working Pair

The thermodynamic performance of the absorption chiller using (H2O + LiCl) as the working pair was simulated and compared with the absorption chiller using (H2O + LiBr). The effects of evaporation temperature on the performance coefficient, COP, generation temperature, concentration of strong solution, and flow rate ratio were also analyzed. At the same condensing and absorbing temperature, the simulating results indicated that the performance coefficient for (H2O + LiCl) is approximately equal to (H2O + LiBr) and the generation temperature was lower than that for (H2O + LiBr). On the other hand, the exergetic efficiency, ECOP, which is based on the second law of thermodynamics, for the absorption chiller using (H2O + LiCl), was more than the system using (H2O + LiBr) under the same operating conditions. The absorption chiller cycle was then optimized based on the coefficient of performance. The results show that the coefficient of performance of the absorption chiller, using (H2O + LiBr) at the optimum conditions, was around 1.5–2% higher than that of (H2O + LiCl).

Identification of residential end-use loads for demand-side planning in northern Cyprus

We propose a method for residential end-use load analysis in developing countries. The times of use of home appliances were established by conducting face-to-face surveys, from which typical hourly load curves are obtained. For N. Cyprus, where the winter peak is the critical load, electrical heating of water and space is the dominant activity. DSM measures can reduce the peak by approximately 53 MW at the expense of US

Feasibility of DSM-technology transfer to developing countries

12 million. A capital investment of

Impact of cogeneration on integrated resource planning of Turkey

100 million for a new power plant may be deferred for 20 years.

Feasibility Assessment of Basin Solar Stills

This study sought to determine a methodology for enabling the demand-side management (DSM) technology transfer to developing countries. Readily available economic and social indicators, supported with a more detailed end-use research, were used to decide which technologies were suitable for a given developing country. Case studies were performed in N. Cyprus and Turkey to validate the theory. In N. Cyprus, DSM-technology transfer would be more successful in the residential and commercial sectors, whereas in Turkey it would be more feasible to consider DSM options in the industrial sector.

Effect of heat transfer on the reduction of the detailed chemical kinetics mechanism in a homogeneous charge compression ignition combustion engine

In most developing countries, difficulties in finding sector-specific data on heat rate and power demands make energy planning a hard task. In some countries, although this data is available, it may be four or five years old. In the present work, a new low-cost method is proposed for developing countries aiming at obtaining such data for the industrial sector quickly. Fifty-two textile factories were selected for a survey to represent the industrial sector. The data were processed and used to generate two scenarios of cogeneration applications in the industrial sector; one sized according to the electrical load of the factories, and the other one according to the thermal load. The costs and primary energy requirements of these programs were compared with that of the nuclear alternative. It was found that the most energy efficient and economical option for Turkey was the cogeneration program, the equipment sizing of which was based on the process heat demand of the industrial sector. Turkey would not only save US

A Compact Design of Water Heating–Humidification Processes for Solar HDD Systems

72.6-billion by deferring the nuclear program, but it will also reduce the total primary energy demand by 11% in 2020.

Development of a Reduced Mechanism for n-Heptane Fuel in HCCI Engines

The present study assesses the feasibility of exploiting single- and double-basin solar stills in our daily lives. An investigation is carried out to determine the thermal performance and economic viability of making use of solar stills in water desalination. The climatic conditions of Tehran (35°44ʹN, 51°30ʹE) are considered to assess the feasibility of the basins. Transient energy and mass balance equations are utilized for modeling the thermal performance. The equations are solved by using fourth-order Runge–Kutta method in FORTRAN. The daily productivities of single- and double-basin solar stills are found to be 5.22 kg/m2 and 7.73 kg/m2, respectively, while the effect of different water masses (20–100 kg) on the productivity of each system was found to be optimum at 20 kg/m2. The results are compared with experimental work performed under different climatic conditions to examine the validity of the feasibility of basins in general. A life cycle cost analysis performed for Tehran, yields that single- and double-basin solar stills have savings-to-investment ratios of 4.2 and 4.8, respectively, indicating that they are economically feasible.

An experimental study on an inclined solar water distillation system

In homogeneous charge compression ignition engines, the ignition takes place in the absence of any external source, initiated by the autoignition of the well-mixed in-cylinder charge. The heat loss from the hot combustion gases to the surroundings causes the thermal conditions in the cylinder to deteriorate. These conditions are governed by the interaction of the chemical processes with the temperature and pressure changes in the cylinder. As a result, the heat release rate and the heat transfer inside the combustion chamber play significant roles in the homogeneous charge compression ignition combustion mode. The use of detailed chemical kinetics mechanisms in predictive combustion models increases the simulation time, which makes the utilization of these mechanisms questionable. As a result, reduced mechanisms of smaller sizes are required. However, in developing a reduced chemical kinetics mechanism from the detailed chemical kinetics mechanism, it is not common to consider the role of heat transfer, and this is needed to focus on only the kinetics aspects of homogeneous charge compression ignition. The objective of this work is to investigate the effect of heat transfer (through the boundaries of the combustion chamber) on the development of the reduced mechanisms from the detailed mechanisms. A single-zone combustion model is used to simulate the homogeneous charge compression ignition engine. Insignificant species and reactions of the detailed GRI-Mech 3.0 mechanism are eliminated by employing a two-stage reduction process based on a directed relation graph with error propagation and principal-component analysis methods respectively. Several different operating conditions are considered. The results demonstrate that the reduction process based on the directed relation graph with error propagation is hardly affected by considering the heat transfer. However, taking into account the heat transfer slightly influences the reduction process based on the principal-component analysis. Simulation outcomes from the generated mechanisms under adiabatic conditions and non-adiabatic conditions agree closely with the results obtained from the detailed mechanism. The differences in the crank angle when 50% of heat is released, the peak pressure and the maximum heat release between the original mechanisms and the reduced mechanisms are less than 1° crank angle, 1% and 1% respectively. Therefore, for a chemical mechanism reduction strategy, considering the heat transfer component will lead to only a minor effect on the generated reduced mechanism.