A simulation study of performance evaluation of single-stage absorption refrigeration system using conventional working fluids and alternatives

This study presents a literature review, especially in recent years, on the absorption refrigeration systems (ARSs), the currently used refrigerant-absorbent pairs and their alternatives. Additionally, in this study, the thermodynamic analysis of ARS using commonly encountered solution pairs in the literature was carried out, and a user-friendly software package including visual components was developed. The effects of operating temperatures, the effectivenesses of solution, refrigerant and solution-refrigerant heat exchangers (SHE, RHE, SRHE), and selection of working fluid pair on the system performance were examined by using the developed package. It was concluded that performances of the cycles improve with increasing generator and evaporator temperatures, but reduce with increasing condenser and absorber temperatures. The performance of system was affected from the SHE more than the RHE and SRHE. While the use of SHE improves the system COP up to 66%, RHE and SRHE have an effect of only 14% and 6%, respectively. For that reason, the SRHE may not be considered practically significant. Suitable solutions depending on operating conditions showed variations with respect to generator and evaporator temperatures.Absorption refrigeration Simulation Heat exchangers Solutions Alternative solutions

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

Efficient Cooling of a Generic Car Cabin by Novel Ventilation Systems

A simplified state-of-the-art dashboard ventilation system was compared to novel ventilation concepts regarding the cooling dynamics in a full-scale generic car cabin (GCC). The concepts are based on the principle of displacement ventilation with air inlets at floor and ceiling level, well known from studies in aircraft cabins. In the present study, three vertical ventilation concepts were investigated experimentally in the GCC. With the aim to study different climate conditions, a jacket heating system was used to simulate summer conditions. Four thermal manikins were placed in the GCC to simulate the heat release and the obstruction of passengers as well as to measure the thermal comfort. To determine the relevant heat fluxes, a plethora of temperature sensors was installed at significant positions in the GCC. Furthermore, the surface temperatures were measured by means of an infrared camera. The study reveals significant differences in terms of cooling efficiency and thermal comfort for the different ventilation concepts