Abstract
Ejector flow in an ejector air conditioning system using R245fa is analysed for entrainment ratio and potential refrigeration effect, at varying temperature and heat input conditions in the generator ranging from 60C to 100C and 2kW to 5kW respectively. The effect of varying generator temperature in cooling capacity of the system when the vapour ejectoris operating at design evaporator and condenser temperatures of 10C and 35C respectively is investigated. The mathematical model of the vapour ejector with optimum area ratio is developed and validated. A critical entrainment ratio of 0.385 is obtained corresponding to generator temperature of 100C. When the generator temperature is varied from 60C to 100C, the cooling capacity range from 0.3kW at generator heat input of 2 kW to 1.78 kW at 5 kW heat input. Further, the operation of the system is analysed for off design operating condition corresponding to reduced heat input rate in the generator. In that case the state of primary refrigerant flow in ejector inlet will be two phase and a mathematical model for two-phase ejector flow is developed and validated. Ejector flow analysis revealed the minimum quality of flow at ejector inlet to maintain adequate backpressure for condensation to occur range from 0.72 at 60C to 0.22 at 100C. The corresponding refrigeration refrigeration effect produced is less than the respective designed operation value byits 12.2% to 8%. Further, analysis of the system shows that at least 7 kW heat input at 100C is required to produce 1 ton of cooling effect.
 Ejector flow in an ejector air conditioning system using R245fa is analysed for entrainment ratio and potential refrigeration effect, at varying temperature and heat input conditions in the generator ranging from 60C to 100C and 2kW to 5kW respectively. The effect of varying generator temperature in cooling capacity of the system when the vapour ejectoris operating at design evaporator and condenser temperatures of 10C and 35C respectively is investigated. The mathematical model of the vapour ejector with optimum area ratio is developed and validated. A critical entrainment ratio of 0.385 is obtained corresponding to generator temperature of 100C. When the generator temperature is varied from 60C to 100C, the cooling capacity range from 0.3kW at generator heat input of 2 kW to 1.78 kW at 5 kW heat input. Further, the operation of the system is analysed for off design operating condition corresponding to reduced heat input rate in the generator. In that case the state of primary refrigerant flow in ejector inlet will be two phase and a mathematical model for two-phase ejector flow is developed and validated. Ejector flow analysis revealed the minimum quality of flow at ejector inlet to maintain adequate backpressure for condensation to occur range from 0.72 at 60C to 0.22 at 100C. The corresponding refrigeration refrigeration effect produced is less than the respective designed operation value byits 12.2% to 8%. Further, analysis of the system shows that at least 7 kW heat input at 100C is required to produce 1 ton of cooling effect.
Highlights
Ejector flow in an ejector air conditioning system using R245fa is analysed for entrainment ratio and potential refrigeration effect, at varying temperature and heat input conditions in the generator ranging from 60 C to 100 C and 2kW to 5kW respectively
It is reported that system could produce 0.75kW cooling capacity with a COP of 0.225 working under Tg=90 C, Tc=37 C and Te=8.5 C.SzabolcsVargaet.al[7] analysed a solar ejector air-conditioning system using water as the refrigerant. They concluded that for producing effective cooling the generator temperature should be above 90 C, evaporator temperature should be above 10 C and the condenser temperature should be less than 35 C
This study focused on ejector air conditioning system making use of low grade heat in the range of 60 C to 100 C with generator heat transfer rate of 2 to 5kW.The aim is to estimate the entrainment ratio and the cooling capacity produced by the system under varying heat input rate
Summary
Ejector flow in an ejector air conditioning system using R245fa is analysed for entrainment ratio and potential refrigeration effect, at varying temperature and heat input conditions in the generator ranging from 60 C to 100 C and 2kW to 5kW respectively. Tg equal to 90 C-110 C, Te equal to 20 C and Tc equal to 35 C-40 C, the COP is in the range of 0.2 to o.22 with cooling capacity of 10.5 kW They comprehended that solar collector area requirement reported for the various theoretical and experimental studies range from 15m2 to 70 m2 depending on cooling capacity and operating conditions, which is quite large for a domestic air conditioner application.K.O. Shestopalov et al [3,4] designed and analysed experimentally a ejector refrigeration system using R245fa with cooling capacity 12 kW. It is reported that system could produce 0.75kW cooling capacity with a COP of 0.225 working under Tg=90 C, Tc=37 C and Te=8.5 C.SzabolcsVargaet.al[7] analysed a solar ejector air-conditioning system using water as the refrigerant They concluded that for producing effective cooling the generator temperature should be above 90 C, evaporator temperature should be above 10 C and the condenser temperature should be less than 35 C. The results show that the COP value decreases from 0.3 to 0.6 as the boiler pressure increased from 2 bar to 9 bar
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