Kiyan Parham

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).

Applications of innovative configurations of double absorption heat transformers in water purification technology

AbstractIn this study, first law of thermodynamics has been employed to analyze the performances of two different configurations of double absorption heat transformers (DAHTs) in water purification system. The upgraded heat in the absorber of the absorption heat transformers provides the heat for desalination process. The first investigated configuration is the most efficient DAHT according to the literature, and the second one is a novel configuration proposed by the authors. The aim of this research was to investigate the effects of different parameters on the studied configurations of DAHTs and the desalination system and to compare their performances in detail. Additionally by considering the quantity of the produced water, both the configurations were optimized. The results revealed that the proposed configuration is capable of producing freshwater for 806 residual units.

A Parametric Performance Analysis of a Novel Geothermal Based Cogeneration System

This work is an attempt to propose and analyze a geothermal based multi-generation system. The proposed cogeneration system consists of different sections, namely: organic Rankine cycle, geothermal wells, absorption heat transformer, domestic water heater and proton exchange membrane electrolyzer. To assess the cycle’s performance, thermodynamic models were developed and a parametric study was carried out. For this purpose, energetic analysis are undertaken upon proposed system. Also, the effects of some important variables such geothermal water temperature, turbine inlet temperature and pressure on the several parameters such as energy efficiencies of the proposed system, water production, net electrical output power, hydrogen production, are investigated. It is shown that, by boosting geothermal water temperate, COP of the AHT increases and flow ratio decreases. Additionally, increasing absorber temperature leads to the reduction of energy utilization factor.

Numerical Study of Thermal Radiation Effect on Confined Turbulent Free Triangular Jets

The present study investigates the effects of thermal radiation on turbulent free triangular jets. Finite volume method is applied for solving mass, momentum, and energy equations simultaneously. Discrete ordinate method is used to determine radiation transfer equation (RTE). Results are presented in terms of velocity, kinetic energy, and its dissipation rate fields. Results show that thermal radiation speeds the development of velocity on the jet axis and enhances kinetic energy; therefore, when radiation is added to free jet its mixing power, due to extra kinetic energy, increases.