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In this study, a branched GAX absorption cycle operating with NH3-H2O pair has been investigated to assess its performance under steady state conditions. The cycle modeling is implemented using Engineering Equation Solver (EES) software. Analysis includes equations of mass, species and energy conservation. The analysis is used to simulate a GAX absorption chiller utilization for air conditioning applications with a nominal capacity of 95 TR. This chiller uses solar collectors as heat source. The operating parameters are selected at different values of the heat source temperature (140 - 185°C), condenser exit temperature (30 to 48°C), evaporator exit temperature (2 to 11°C) ; split ratio (0 to 0.18); the difference in ammonia concentration(0.25-036), mass flow rate in solution pump mr=1 kg/s; heat exchanger effectiveness   0.8. The results showed that the average COP is sensitive to operating conditions where the average COP and cooling capacity of the branched GAX absorption chiller increase with increasing generator and evaporator temperature whereas they decrease with increasing condenser temperature. Simulation results also show that the split ratio and ammonia concentration difference have a significant impact on the performance of absorption chiller.

This study investigates numerically the thermodynamic analysis of various refrigerants on the basis of vapor compression refrigeration cycle. The refrigerants studied are R134a, R152a, R1234yf, R404A, R407C, R410A and R507A. The aim of this research is to find the alternative refrigerant of R134a numerically. EES Professional V9.944-3D is used in the modeling of thermodynamic cycle of VCRC and calculating the performance parameters of VCRC. The comparison of thermodynamic VCRC for all the refrigerants is made. The performance parameters include: cooling capacity, input power of compressor, COP, compression ratio and discharge temperature. These parameters are calculated at engine speeds of 1000 rpm, 2000 rpm and 3000 rpm, condenser temperature of 50∘C and evaporator temperature of 5∘C. The compressor volumetric efficiencies are taken as 0.75, 0.65 and 0.55 corresponding to engine speeds of 1000 rpm, 2000 rpm and 3000 rpm. The results of performance parameters for all refrigerants studied are exported to MATLAB R2017a software where the comparative analysis is performed. Results show that R152a is the only refrigerant which can be used as alternative in current AACS with minimum modification. The cooling capacity of R152a is slightly less than that of R134a, while its COP is found to be higher than that of R134a. R152a shows the highest COP improvement of 5.33% at engine speed of 1000 rpm. It has very low GWP and almost same saturation pressure corresponding to condenser and evaporator temperature as that of R134a, so it can serve as alternative refrigerant in current AACS. [ABSTRACT FROM AUTHOR]

• A trigeneration process of H 2 , electricity and desalinated water was proposed and studied. • It is based on the technologies Na-O-H cycle, SCWR power plant and MED desalination. • Mass, energy and exergy balances are applied to evaluate trigeneration thermal performance. • EES software was used to model the studied systems. • Such process has potential to produce 5 kg/s of H 2 , 400 MW e and 980 kg/s of H 2 O. Hydrogen (H 2) is a substance with a wide range of applications, especially ammonia (NH 3) production. It is the key chemical used to make fertilizers, a pillar of agriculture industry, an important activity for society. H 2 can be obtained according to different processes, including the recent method Na-O-H (sodium-oxygen-hydrogen) thermochemical water splitting cycle that produce it by cracking H 2 O (water) molecules into H 2 and O 2 (oxygen) through cyclic chemical reactions based on the elements Na, O and H. Such reactions are sustained by a heat source at specified temperature level. In this context, nuclear reactors, such as Supercritical Water Reactor (SCWR), are suitable energy options for this kind of process because they are designed to support electricity together with high temperature applications like H 2 production. At the same time, water could be get by means of MED (Multi-Effect Distillation), a desalination method able to harvest waste heat from thermal systems. This approach allows saving the available potable water to be used in essential human needs such as drinking and agriculture while the desalinated one would serve as hydrogen source in the sodium-oxygen-hydrogen technique. Then, H 2 production based on the technologies Na-O-H cycle through the heat supplied by SCWR coupled to a MED unit enables the trigeneration of electricity-hydrogen-water, three important goods for current society, what justifies the development of a paper covering this multigeneration approach. So, the main aim of this work is to evaluate the thermodynamic performance of this trigeneration case, a task never done before because those three systems were not coupled together aiming this multigeneration case as it was checked in the literature. It was considered a SCWR with output thermal power equal to 1000 MW th as the heat source to both Na-O-H hydrogen production facility plus MED installation. The work is developed by implementing mass and energy balances in Engineering Equation Solver (EES) software to determine the amount of H 2 , electricity and desalinated H 2 O acquired. According to the main results, this trigeneration process has potential to produce a maximum of 5 kg/s of hydrogen, 400 MW of electricity and 960 kg/s of desalinated H 2 O. [ABSTRACT FROM AUTHOR]