Steam Ejector Refrigeration System Research Articles

Simulation and Experimental Investigation of Performance and Flow Behavior for Steam Ejector Refrigeration System

Simulation and Experimental Investigation of Performance and Flow Behavior for Steam Ejector Refrigeration System

Design and experimental study of a steam ejector refrigeration system

Design and experimental study of a steam ejector refrigeration system

Numerical Investigation of the Effect of Air Leaking into the Working Fluid on the Performance of a Steam Ejector

This paper investigated the effect of air leaking into the working fluid on the performance of a steam ejector. A simulation of the mixing of air into the primary and secondary fluids was performed using CFD. The effects of air with a 0, 0.1, 0.3 and 0.5 mass fraction on the entrainment ratio and internal flow structure of the steam ejector were studied, and the coefficient distortion rates for the entrainment ratios under these air mass fractions were calculated. The results demonstrated that the air modified the physical parameters of the working fluid, which is the main reason for changes in the entrainment ratio and internal flow structure. The calculation of the coefficient distortion rate of the entrainment ratio illustrated that the air in the primary fluid has a more significant impact on the change in the entrainment ratio than that in the secondary fluid under the same air mass fraction. Therefore, the air mass fraction in the working fluid must be minimized to acquire a precise entrainment ratio. Furthermore, this paper provided a method of inspecting air leakage in the experimental steam ejector refrigeration system.

The Effect of Operating Parameters on The Performance of A Steam Ejector Refrigeration System with Barometric CONDENSER.(Dept.M)

The Effect of Operating Parameters on The Performance of A Steam Ejector Refrigeration System with Barometric CONDENSER.(Dept.M)

A Steam Ejector Refrigeration System Powered by Engine Combustion Waste Heat: Part 2. Understanding the Nature of the Shock Wave Structure

In general, engine fuel combustion generates 30% waste heat, which is disposed to the environment. The use of the steam ejector refrigeration to recycle the waste heat and transfer them to useful energy source could be an environmentally friendly solution to such an issue. The steam ejector is the main component of the ejector refrigeration system, which can operate at a low-temperature range. In this article, the internal shock wave structure of the ejector is comprehensively studied through the computation fluid dynamics (CFD) approach. The shock wave structure can be subdivided into two regions: firstly the pseudo-shock region consisting of shock train and co-velocity region; secondly the oblique-shock region composed of a single normal shock and a series of oblique shocks. The effect of the shock wave structure on both pumping performance and the critical back pressure were investigated. Numerical predictions indicated that the entrainment ratio is enhanced under two conditions including (i) a longer pseudo-shock region and (ii) when the normal shock wave occurs near the outlet. Furthermore, the system is stabilized as the back pressure and its disturbance is reduced. A critical range of the primary fluid pressure is investigated such that the pumping is effectively optimized.

A Steam Ejector Refrigeration System Powered by Engine Combustion Waste Heat: Part 1. Characterization of the Internal Flow Structure

With the escalating production of automobiles, energy efficiency and environmental friendliness have always been a major concern in the automotive industry. In order to effectively lower the energy consumption of a vehicle, it is essential to develop air-conditioning systems that can make good use of combustion waste heat. Ejector refrigeration systems have become increasingly popular for this purpose due to their energy efficiency and ability to recycle waste heat. In this article, the elements affecting the performance of a typical ejector refrigeration system have been explored using both experimental and numerical approaches. For the first time, the internal flow structure was characterized by means of comprehensive numerical simulations. In essence, three major sections of the steam ejector were investigated. Two energy processes and the shock-mixing layer were defined and analyzed. The results indicated that the length of the choking zone directly affects the entertainment ratio under different primary fluid temperature. The optimum enterainment ratio was achieved with 138 °C primary fluid temperature. The shock-mixing layer was greatly affected by secondary fluid temperature. With increasing of back pressure, the normal shock gradually shifted from the diffuser towards the throat, while the shock train length remains lunchanged.

Comparative investigation on the exergoeconomic analysis of solar-driven ejector refrigeration systems

In this article, the economic performance of the solar-driven steam ejector refrigeration system is addressed due to the rising beneficial adoption of this system with regard to using low-grade heat sources. For this purpose, a detailed exergoeconomic analysis on four proposed configurations of this system integrated with either or both of a precooler and a preheater is performed. At a refrigeration load of 5 kW, the results of this analysis show that it is more advantageous for all configurations to have evaporators work at 278 K with condensers remain at 311 K, whilst the generators are kept working at 362 K. The characteristics of each configuration are comprehensively discussed and compared. Based on the assessment of economic parameters, the fourth configuration provides the highest exergetic efficiency and the lowest total investment cost (0.1891 $/h) compared to the other configurations. The current work furnishes essential information that paves the way for future exergoeconomic studies in this field.

Experimental Studies on the Effect of Suction Chamber Angle on the Entrainment of Passive Fluid in a Steam Ejector

In this experimental study, the impact of suction chamber angle (SCA) on the entrainment ratio of a steam ejector refrigeration system (ERS) of 700 W was investigated. The basic dimensions of the ejector were derived from the compressible fluid flow equations using matlab. The system was tested with six different SCAs with various operating conditions, and its performance was analyzed. It is inferred that the entrainment of passive fluid from the evaporator is the strong function of the SCA. For all the active steam pressures, the entrainment of the passive fluid increases up to 12 deg of SCA, and above that the performance decreases significantly. Optimum angle of suction chamber increases the entrainment ratio for at least 49.96%. It is also found that the SCA has a minor influence on the back pressure.

The performance of steam ejector refrigeration system based on alternative analysis

The performance of a steam ejector refrigerator was analyzed based on an “alternative analysis”. The alternative analysis reflects an actual operation of an ejector refrigerator. In this analysis, the evaporator saturation temperature associated with cooling load was varied while the boiler saturation temperature and the condenser pressure were fixed. Form this test, the critical evaporator temperature was determined. The critical evaporator temperature is the lowest point that ejector still operated under choked flow condition. A 1 kW experimental ejector refrigerator was constructed. Variation of operating conditions and primary nozzles were implemented. It was found that the variation in operating conditions and the nozzle throat diameters significantly affected the critical evaporator temperature. Variation of condenser pressure had a strong effect on critical evaporator temperature Meanwhile the entrainment ratio in the choked flow condition was independent of the condenser pressure. The critical evaporator temperature decreased with increasing the condenser pressure and vice versa. Variations of the boiler saturation temperature and the primary nozzle throat diameter affect the mass flow of primary fluid. Either increasing the boiler saturation temperature or the primary nozzle throat diameter, the mass flow of primary fluid increased. When the primary fluid mass flow was increased, the critical evaporator temperature was reduced. On the other hand, entrainment ratio in the choked flow condition decreased. However, if the primary fluid mass flow was increased to a certain value, evaporator temperature didn’t decrease as expected.

Numerical Investigation of Miniature Ejector Refrigeration System Embedded with a Capillary Pump Loop.

A miniature steam ejector refrigeration system embedded with a capillary pump loop can result in a compact design which can be used for electronics cooling. In this paper, computational fluid dynamics (CFD) is employed to investigate the effects of the area ratio of the ejector constant-area mixing section to the nozzle throat, the length of the constant-area section, and the nozzle exit position (NXP), on the performance of a miniature steam ejector. Results show that the performance of the miniature steam ejector is very sensitive to the area ratio of the constant-area mixing section to the nozzle. For the needs of practical application, the area ratio of the constant-area mixing section to the nozzle should be smaller than 16 when the temperature of the primary flow is 60 °C. The NXP plays an important role in the flow phenomena inside the miniature ejector. The critical back pressure is more sensitive to length of the constant-area mixing section than the entrainment ratio. Results of this investigation provided a good solution to the miniature steam ejector embedded with a capillary pump loop for electronics cooling application.

Experimental investigation on low-temperature thermal energy driven steam ejector refrigeration system for cooling application

In recent years, ejector refrigeration has been a hot topic for research because it can utilize low-grade energy such as solar energy or industrial waste heat. Even more importantly, it uses the most environmentally friendly substance, water, as the working fluid. According to the literatures, the utilization of the thermal energy from a low-temperature heat source below 80°C is a considerable challenge for the steam ejector refrigeration system. In this paper, an experimental prototype of the steam ejector refrigeration system was designed and built up. Three ejectors with a same nozzle for the primary nozzle and three different constant-area sections were designed and fabricated. The effects of the operating temperatures, the nozzle exit position (NXP) and the area ratio of the ejector (AR) on the working performance of the steam ejector were investigated. The generating temperature is ranged from 40°C to 70°C. The experimental results show that a steam ejector can operate successfully for a certain configuration size of the steam ejector with a generating temperature ranging from 40°C to 70°C and an evaporating temperature of 15°C. The results of this investigation provided a better understanding for the cooling application of the steam ejector refrigeration system powered by low-temperature heat source. It demonstrates that the steam ejector refrigeration system is a very promising alternative to the absorption refrigeration system, when the heat source temperature is lower than 80°C.

An experimental investigation of steam ejector refrigeration system powered by extra low temperature heat source

A steam ejector refrigeration system is a low capital cost solution for utilizing industrial waste heat or solar energy. When the heat source temperature is lower than 80°C, the utilization of the thermal energy from such a low-temperature heat source can be a considerable challenge. In this investigation, an experimental prototype for the steam ejector refrigeration system was designed and manufactured, which can operate using extra low-temperature heat source below 80°C. The effects of the operation temperature, the nozzle exit position (NXP) and the diameter of the constant area section on the working performance of the steam ejector were investigated at generating temperatures ranging from 40°C to 70°C. Three ejectors with a same de Laval nozzle for the primary nozzle and three different constant-area sections were designed and fabricated. The experimental results show that a steam ejector can function for a certain configuration size of the steam ejector with a generating temperature ranging from 40°C to 70°C and an evaporating temperature of 10°C. For a given NXP, the system COP and cooling capacity of the steam ejector decreased until inoperative as the diameter of the constant area section reduced. The results of this investigation provided a good solution for the refrigeration application of the steam ejector refrigeration system powered by an extra low-temperature heat source.

Energy and exergy analyses of a novel combined heating, power and absorption-ejector refrigeration cycle driven by biomass fuel

In this paper, a new combined power, heating and refrigeration system is proposed, which combines the ammonia-water power/refrigeration system and steam ejector refrigeration system (SERS). This system was driven by biomass fuels and can produce both power and refrigeration simultaneously, besides according to the temperature of inlet streams into absorbers and rate of heat losses, these heat losses are used as floor heating. Moreover, high grade heat source is used in SERS; therefore, the entrainment ratio and efficiency of system are increased. The results show that the turbine inlet ammonia-water concentration, turbine outlet mass flow rate and turbine efficiency have effects on the turbine power output, refrigeration output, efficiency and exergy destruction in each component in the combined cycle.

Exergoeconomic evaluation and optimisation of a novel combined power and absorption-ejector refrigeration cycle driven by natural gas

This study deals with exergoeconomic analysis of a combined power and refrigeration system. Actually, in the presented cycle, the ammonia-water power/refrigeration system and the steam ejector refrigeration system (SERS) are combined. This system has the capability to produce refrigeration in diverse temperatures and quantities. It is worth noting that, the high level energy source is used to produce refrigeration in SERS due to which, the proper refrigeration capacity has been obtained. Moreover, according to exergoeconomic point of view, the exergy cost balance for each component is considered, so the rate of exergy cost generation within the system is determined. The sensitivity analysis is done to investigate the effect of changes effective parameters of system on the product cost rate. Finally, the optimisation process is carried out by minimising the investment cost of equipment and cost of exergy destruction.

Development and performance of steam ejector refrigeration system operated in real application in Thailand

This paper presents the design and construction of a prototype steam ejector refrigeration system which can be operated under the actual condition of Thai environment, which is rather hot and humid. The prototype refrigerator was designed to produce a cooling capacity of approximately 3 kW. Water was selected to be used as the working fluid. The steam boiler used was a vertical fire tube type and it was designed to be used with LPG compact gas burner. The condenser was cooled by water obtained from a conventional cooling tower. The prototype refrigerator was used to produce chilled water which was used to cool a small tested room. It was observed that the room temperature of 24.2 °C was obtained at the cooling load of 3000 W. The cooling water was supplied to the condenser at about 30 °C. The COP obtained was 0.45. This prototype refrigerator is proven to be practical and can be used in actual environment of Thailand.

An Experimental Investigation of Steam Ejector Refrigeration Systems

A steam ejector refrigeration system with a movable primary nozzle was developed in order to determine the nozzle exit position (NXP) effect on the coefficient of performance (COP). Experimental results show that there exists an optimum NXP for the ejector system investigated herein. The effects of the operating temperature, diffuser size, nozzle throat diameter, and mixing chamber configuration on the COP and critical back pressure were investigated experimentally. It is found that the critical back pressure and COP can be increased by increasing the low temperature evaporator (LTE) temperature and pressure. Although an increase of the high temperature evaporator (HTE) temperature can increase the critical condenser pressure, the system COP does not increase as the HTE temperature increases. The diffuser size significantly affects the critical back pressure but had almost no effect on the system COP. A finned mixing chamber was tested at NXP = 0 mm and NXP = 36 mm. Compared with the regular mixing chamber, the finned mixing chamber can increase the critical back pressure.

Thermodynamic analysis of a tri-generation system based on micro-gas turbine with a steam ejector refrigeration system

In the present work, performance of new configuration of Micro-gas turbine cogeneration and tri-generation systems, with a steam ejector refrigeration system and Heat recovery Steam Generator (HRSG) are studied. A micro-gas turbine cycle produces 200 KW power and exhaust gases of this micro-gas turbine are recovered in an HRSG. The main part of saturated steam in HRSG is used through a steam ejector refrigeration system to produce cooling in summer. In winter, this part of saturated steam is used to produce heating. In the first part of this paper, performance evaluation of this system with respect to Energy Utilization Factor (EUF), Fuel Energy Saving Ratio (FESR), thermal efficiency, pinch point temperature difference, net power to evaporator cooling load and power to heat ratio is carried out. It has been shown that by using the present cogeneration system, one can save fuel consumption from about 23% in summer up to 33% in winter in comparison with separate generation of heating, cooling and electricity. In the second part of this paper, exergy analysis of the system has been done. It has been shown that combustion chamber; HRSG and heat exchanger are recognized as the largest sources of exergy losses respectively.

Experimental study on the performance of a solar driven steam jet ejector chiller

This study experimentally investigated the performance of a solar driven (by parabolic trough collector) steam jet ejector chiller (SJEC) having a cooling capacity of 1 kW. The experiments show the particular characteristics of a SJEC with the strong influence of the condenser temperature, T cond, and evaporator temperature, T evap, on the coefficient of performance (COP). A decrease in the condenser temperature by 12 °C, in case of an evaporator temperature of T evap = 7 °C the COP was increased by 57%, while for T evap = 13 °C the COP was increased by 41% and for T evap = 17 °C the COP was increased by 34.4%, respectively. While at a constant condensation temperature an increase in the evaporator temperature, T evap, from 7 to 13 °C, leads to increased COP values ranging from 14% to 56.7%, and increases T evap from 7 to 17 °C, lead to increases in COP values ranging from 53% to 132%, respectively. These results in general indicate that the COP increases with decreasing condenser temperature, which is determined by the source temperature of the cooling medium and it has the limiting factors controlling the operation of the solar steam ejector refrigeration system.

Exergy analysis of ejector-refrigeration cycle using water as working fluid

Exergy is based on the second law of thermodynamics and is the only rational basis for evaluating the system performance. The aim of this paper is to study in detail the irreversibilities in the steam-ejector refrigeration system. The influence of the cycle parameters is analysed on the basis of the first and second law and the results indicated the components with the greater irreversibility. A better quality of the ejector has more effect on the system performance than the better quality of other components, because the ejector at first and the condenser at second have the greater exergy loss of the system. For the refrigeration system the maximum coefficient of performance varying between 0.4 to 0.6 and the second law efficiency remains close to 0.17 for generator pressure 6 bar, condenser temperature 44–50°C and evaporator temperature 4–8°C. Also the study showed that the second law analysis quantitatively visualizes losses within a system and gives clear trends for optimization. Copyright © 2005 John Wiley & Sons, Ltd.

Estimation of ejector's main cross sections in steam-ejector refrigeration system

This paper describes the calculation of main cross sections of a steam-ejector, operating in a refrigeration system. For the detailed calculation of ejector a method has been developed which employs functions describing the thermodynamic properties of steam. The influence of three major parameters: generator pressure, condenser and evaporator temperature on cross sections of ejector is discussed. The design conditions were: generator pressure (6–8 bar), condenser temperature (40–50 °C) and evaporator temperature (4–10 °C). It is confirmed that the dimensions of ejector depend on the operation conditions.