Analysis of Ammonia -Water (NH3-H2O) Vapor Absorption Refrigeration System based on First Law of Thermodynamics (original) (raw)
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Energies
The interest in employing absorption refrigeration systems is usually related to electricity’s precariousness since these systems generally use thermal rejects for their activation. The application of these systems is closely linked to the concept of energy polygeneration, in which the energy demand to operate them is reduced, which represents their main advantage over the conventional vapor compression system. Currently, the solution pairs used in commercial absorption chillers are lithium bromide/water and ammonia/water. The latter pair has been used in air conditioning and industrial processes due to the ammonia operation’s low temperature. Few review papers on absorption chillers have been published, discussing the use of solar energy as the input source of the systems, the evolution of the absorption refrigeration cycles over the last decades, and promising alternatives to increase the performance of absorption refrigeration systems. There is a lack of consistent studies about ...
In the current trends globally, the excessive utilization of the energy and overconsumption of fuel has resulted in the global warming and environmental pollution. The Absorption cooling offers the possibility of using heat to provide cooling. For cooling purpose the required heat input is obtained from the excessive heat of the boiler or from non conventional power sources like solar energy. NH3-H2O system ammonia used as a refrigerant and water is used as an absorbent, these two liquids served as standard and a refrigerant cycle is produced. The system VARS in environment friendly and does not deplete the atmosphere. Thus it is essential to create awareness in the world for this system for it is an alternative system which is more environmental friendly. The objective of this paper is to present empirical relations for evaluating of the performance of a single stage vapor absorption system.
Comparison of the Performances of NH 3 -H 2 0 and Libr-H 2 O Vapour Absorption Refrigeration Cycles
Developments in absorption cooling technology present an opportunity to achieve significant improvements on micro-scale to buildings, cooling, heating and power systems for residential and light commercial buildings. Their resultant effects are effective, energy efficient and economical. This study therefore contributes an important knowledge and method in the development, fabrication and application of an absorption refrigerator as a better alternative to the commonly used compressor refrigerators. Two fluid gas absorption refrigerators use electric based heater installed generator and no moving parts, such as pumps and compressors, and operate at a single system pressure. In this paper the performances analysis of the NH 3-H 2 O and possible alternative cycles as lithium bromide-water are compared in respect of the (COP) and different operating conditioning. The highest COP was found as a function of the absorber, generator, condenser, and evaporating temperature. This paper compares the performance of vapour absorption refrigeration cycles that are used for refrigeration temperatures below 0°C. Since the most common vapour absorption refrigeration systems use ammonia-water solution with ammonia as the refrigerant and water as the absorbent, research has been devoted to improvement of the performance of ammonia-water absorption refrigeration systems in recent years.
The continuous development of countries led in massive increase for the demand of energy utilization. For this implication of renewable energy, such as solar energy for an eco-friendly process of refrigeration by vapour absorption method is seemed to be a boon in the present scenario. Replacing the electrical energy with solar energy will reduce the consumption of high grade electrical energy. Also the replacement of compression system with absorption system eliminates the energy consumption by compressors. The objective of this work is to hypothetical design an ammonia water absorption Refrigeration system using solar energy. Our major challenge for this system is to increase COP and Efficiency. We have gone through various research papers and calculated the advancement in the system. The coefficient of performance (COP) varies to a small extent (0.65-0.75) with the heat source and the cooling water temperatures. This paper gives analytical usage of solar refrigeration, advanced method of refrigeration as vapour absorption method.
Performance Analysis of Absorption Refrigeration Cycles
— The thermodynamic analysis of a vapor absorption refrigeration system employing ammonia as the refrigerant are presented. The thermodynamic analysis of these three combination of the absorption pairs namely NH3/H2O, NH3/LiNO3, NH3/NaSCN are performed. The best alternative to the ammonia water absorption pair are proposed as ammonia lithium nitrate and ammonia-sodium thiocyanate. It is very much important to select a prominent working substance and their properties have great effect on the system performance. Detailed thermodynamic properties of these fluids are expressed in polynomial equations. Energy and entropy balance equations are applied to analyse each of the process to estimate the individual heat transfer and entropy generation rates for all the systems. Among these three pairs NH3/ NaSCN yields the highest coefficient of performance. Cooling/Heating of the generator/absorber results in significant entropy generation in all the systems. The solution heat exchanger significantly improves the performance of the cycle and yields in the better cooling output.
International Journal of Mechanical and Materials Engineering, 2008
Solar absorption refrigeration systems increasingly attract research interests. The most common cycles are H 2 O-LiBr and NH 3 -H 2 O, absorption machines that have served as standards for comparison in studying and developing new cycles and new refrigerant-absorbent pairs. In recent years, research has been devoted to improvement of the performance of ammonia-water absorption refrigeration systems. In the present study, thermodynamic properties for ammonia-water, ammonia-lithium nitrate and ammoniasodium thiocyanate solutions are compiled and are used in cycle simulation. Detailed thermodynamic design data and optimum design results are presented. Thermodynamic properties of these binary fluids are expressed in polynomial equations. The performances of these three cycles against various generator, evaporator, absorber and condenser temperatures are compared. The results show that the ammonia-lithium nitrate and ammonia-sodium thiocyanate cycles give better performance than the ammonia-water cycle, not only because of higher COP values, but also because of no requirement for analyzers and rectifiers. The ammonia-sodium thiocyanate cycle cannot operate at evaporator temperatures below -10°C for the possibility of crystallization. These results form a source of reference for developing new cycles and searching for new refrigerant-absorbent pairs. They can also be used in selecting operating conditions for existing systems and achieving automatic control for maintaining optimum operation of the systems.
Energetic analysis of a commercial absorption refrigeration unit using an ammonia-water mixture
Acta Scientiarum. Technology, 2017
The ROBUR ® absorption refrigeration system (ARS), model ACF60, with a capacity of 17.5 kW, is tested, modeled and simulated in the steady state. To simulate the thermal load a heating system with secondary coolant was used, in which a programmable logic controller (PLC) kept the inlet temperature EVA at around 285.15 K. The mathematical model used was based on balancing the mass, energy and ammonia concentrations and completed by closing equations such as, Newton's cooling equation. The mathematical model was implemented using the Engineering Equation Solver-EES ®. The results obtained after modeling and a numerical permanent simulation are studied using the Duhring diagram. Potential points of internal heat recovery are visualized, and by using graphs of the binary mixture, it is possible to identify the thermodynamic states of all monitored points. The data obtained in the numerical simulation of the ARS was compared with data acquired in the actual tests of the ARS with the ROBUR ® apparatus.
Design Analysis Of 3 TR Aqua Ammoniavapour Absorption Refrigeration System
2012
This paper presents the design of vapour absorption refrigerating system of capacity 3 tonne based on the basic concepts of thermodynamic principles. In design the area of all the major components of the system is calculated on the basis of enthalpy parameters at different points in the system. The data is analysed using the first and second laws of thermodynamics to determine the refrigerating effect, the net heat required to run the system and the coefficient of performance (COP). The COP of the system is calculated as 0.2079 working between the condenser pressure of 10.7 bar and evaporator pressure of 4.7 bar. Ammonia is used as the refrigerant in the system and water as absorbent in the physico-chemical process.
Comparison of the performances of absorption refrigeration cycles
J of WSEAS Transaction on Heat …, 2009
This paper compares the performance of absorption refrigeration cycles that are used for refrigeration temperatures below 0°C. Since the most common vapor absorption refrigeration systems use ammonia-water solution with ammonia as the refrigerant and water as the absorbent, research has been devoted to improvement of the performance of ammonia-water absorption refrigeration systems in recent years. In this paper the performances of the ammonia-water and possible alternative cycles as ammonia-lithium nitrate, ammoniasodium thiocyanate, monomethylamine-water, R22-DMEU, R32-DMEU, R124-DMEU, R152a-DMEU, R125-DMEU, R134a-DMEU, trifluoroethanol (TFE)-tetraethylenglycol dimethylether (TEGDME), methanol-TEGDME and R134a-DMAC are compared in respect of the coefficient of performance (COP) and circulation ratio (f). The highest COP and the lowest f, were found as a function of the generator, condenser, absorber and evaporating temperature.