فهرست مطالب امیر سرورالدین آبادی

In this article، a combined GAX-ejector absorption refrigeration cycle is proposed and its performance is compared with those of combined single effect-ejector، simple GAX and single effect absorption refrigeration cycles. For the ejector، based on the Keenan''s theory، a new model is developed and validated and then is combined with the developed models in the EES software (for simulating the processes in the cycles). After obtaining the optimum critical area ratio for the ejector، three different ejectors، with the mentioned specification، are selected for the combined GAX-ejector and combined single effect-ejector cycles. The performance of these cycles is investigated through changing their evaporator and generator temperatures. Results indicate that، at identical conditions، the COP and second law efficiency of the combined GAX-ejector cycle are around 25% and 16% higher than those of the combined single effect-ejector absorption refrigeration cycle. In addition، it is observed that as the generator temperature increases from 140 oC to170oC، the COP and second law efficiency of combined GAX-ejector cycle are maximized at a particular generator temperature. However، at similar condition، an increase in generator temperature results in a decrease of the COP and second law efficiency of combined single effect-ejector refrigeration cycle.

In this paper the performance of an ejector refrigeration cycle was investigated theoretically and experimentally. Making use of the conservation of mass and energy as well as the exergy balance equations, a two-dimensional thermodynamic model was developed. The influence of flow viscosity is taken into account through considering a two-dimensional flow near the ejector inner wall. The results indicate a decrease of COP with increasing generator temperature and an increase of second law efficiency with increasing evaporator temperature and/or decreasing generator temperature. It is found that at any generator temperature, there exist a particular evaporator temperature above which the exergy destruction in the condenser is higher than that in the ejector. The maximum relative and the root mean square errors in calculating the entrainment ratio at three generator temperatures of 77, 83 90 o C are obtained as 7.76% and 5.13% respectively. Also the exergy destruction in the evaporator at an evaporator temperature of 13.5 oC, was found to be the highest among those occur in the other components of the cycle.

In this paper, the theoretical and experimental performance of the ejector refrigeration cycle is investigated. Making use of EES software, laws of mass and energy conservation as well as the exergy balance equations, a one-dimensional thermodynamic model is developed and validated using experimental results obtained in the laboratory. It is assumed that mixing takes place at a constant pressure and a constant cross section part of the ejector. Two factors are considered as the most important effects in the modeling: the frictional loss due to the mixture of the flows and the efficiency at the different parts of the ejector. Also a parametric study is carried out to study the effects of evaporator and generator temperatures on the coefficient of performance and second law efficiency of the cycle. The results indicate an increase of COP with increasing evaporator temperature. The maximum exergy losses occur in the ejector, generator and condenser respectively. Also at any pressure in the generator, an optimum value exists for the second law efficiency. Also the exergy destruction distribution analysis indicate that the highest exergy destruction occur in the ejector, condenser and generator.