hydrogen is an unusual substance in that its molecule exists in two forms, known as ortho and para, with markedly different properties. energy level of the ortho molecule is higher than para, therefore, the latter is employed for industrial purposes. consequently, for a high  conversion of  ortho to para hydrogen a catalyst reactor must be employed.  therefore, one of  the main objectives of th...

This work addresses the optimization of ammonia–water absorption cycles for cooling and refrigeration applications with economic and environmental concerns. Our approach combines the capabilities of process simulation, multi-objective optimization (MOO), cost analysis and life cycle assessment (LCA). The optimization task is posed in mathematical terms as a multi-objective mixed-integer nonline...

This paper aims at studying a trigeneration system, based on an internal combustion engine and a steam ejector refrigeration system. The designed cycle is to generate cooling and heating energies, and supply power simultaneously. The cycle is studied from thermodynamics point of view and for this purpose, the first law of thermodynamics is applied to all components of the cycle. The efficiency ...

Running a refrigeration cycle at saturated liquid conditions at the evaporator inlet has a few interesting advantages in comparison to the conventional 2-phase situation. Opportunities in using novelty heat exchangers, increased cycle efficiency and significantly reduced main compressor sizes occur. Using the two rotor integrated compressor/expander idea developed by Olofsson (1993) in a refrig...

In this study, artificial neural networks (ANNs) have been used for performance analysis of a CO2/NH3 cascade refrigeration system using a data set, obtained from a thermodynamic model implemented in EES. Thermodynamic parameters of the system are estimated in terms of condensing temperature of ammonia, evaporating temperature of carbon dioxide, condensing temperature of carbon dioxide and temp...

Due to their contribution to the ozone depletion and the anthropogenic greenhouse warming effect caused by the refrigerant as well as the foam blowing agent household refrigerators and freezers were attracting public attention especially in Western Europe. The conversion to the use of environmentally benign fluids as refrigerants and foam blowing agents requires a large number of extensive, exp...

The interest in natural refrigerants, such as carbon dioxide, has been growing in recent years due to the high direct global warming potential of common HFC refrigerants. Despite the environment-friendly characteristics of CO2 as a refrigerant, due to high heat rejection temperatures and transcritical operation, CO2 cannot match the high energy efficiency associated with current HFC technology....

The energy demand of industries accounts for about 30–35% world yearly consumption, a relevant percentage is due to the need heating and cooling demand. Solar technologies can be integrated in industrial processes reduce fossil fuels consumption as well related greenhouse gas emissions. This paper reports experimental analysis novel hybrid sorption-compression chiller refrigeration purposes cas...

This paper examines the exergy efficiency and destruction rate of R744/R404A cascade refrigeration system (CRS) using an internal heat exchanger in supermarkets according to various conditions affecting system. A refrigerant a low-temperature cycle uses R744 high-temperature CRS R404A. Experiments were conducted by changing on high- side, analysis was performed accordingly. The main results are...

Direct expansion (DX) refrigeration technology is almost exclusively used in multi-temperature transport refrigeration systems. Multi-temperature systems use up to three evaporators, requiring large refrigerant charges and system pressure control to operate over a wide range of set-point conditions. Despite incremental design improvements over the past decade, environmental and control issues c...