Performance of a Water Ammonia Absorption System Operating at Three Pressure Levels

2011 ◽  
Vol 312-315 ◽  
pp. 947-952 ◽  
Author(s):  
Nahla Bouaziz ◽  
R. Ben Iffa ◽  
Lakdar Kairouani ◽  
Salahs Chikh ◽  
Rachid Bennacer
Keyword(s):  
Cooling System ◽  
Single Stage ◽  
Working Fluid ◽  
The Novel ◽  
Evaporator Temperature ◽  
Intermediate Pressure ◽  
Condenser Temperature ◽  
Conventional Machine ◽  
Ammonia Absorption ◽  
Set Up

The present study deals with a compression-absorption machine. The proposed hybrid cooling system uses water-ammonia as a working fluid and operates at three pressure levels. The absorber is at an intermediate pressure (Pint) taken between the evaporator pressure (PEV) and the condenser pressure (PCD), unlike the single stage machine which works between two pressure levels. The proposed new system is studied and compared to the conventional machine. In order to evaluate the performance of the invoked machine, a procedure based on the MAPLE software is set up to compute accurately the thermodynamic properties of the working fluid. The analyses of the numerical results highlight that the performance of the novel proposed configuration is better than that relative to the conventional system. The study reveals the great impact of the intermediate pressure on the performance improvement and on reducing the generator temperature allowing the system to work at low enthalpy. In fact, for an evaporator temperature and a condenser temperature fixed respectively at -10°C and 40°C, the proposed hybrid refrigeration cycle operates at a generator temperature TGE = 75°C and the installation’s COP is about 0.56. While for the same conditions, the single stage machine COP cannot exceed 0.51 with a generator temperature of about 135°C. Consequently, our enhanced novel configuration presents the opportunity to operate at low enthalpy sources.

Optimized Refrigerant Flow Rate and Dimensions of the Ejector Employed in a Modified Ejector Vapor Compression System

2020 ◽  
Vol 28 (04) ◽  
pp. 2050038
Author(s):  
Dishant Sharma ◽  
Gulshan Sachdeva ◽  
Dinesh Kumar Saini
Keyword(s):  
Flow Rate ◽  
Cooling System ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Evaporator Temperature ◽  
Proposed Model ◽  
Condenser Temperature ◽  
Vapor Compression System ◽  
Vapor Compression Cooling

This paper presents the analysis of a modified vapor compression cooling system which uses an ejector as an expansion device. Expanding refrigerant in an ejector enhances the refrigeration effect and reduces compressor work. Therefore, it yields a better coefficient of performance. Thermodynamic analysis of a constant area ejector model has been done to obtain primary dimensions of the ejector for given condenser and evaporator temperature and cooling capacity. The proposed model has been used to design the ejector for three refrigerants; R134a, R152a and R1234yf. The refrigerant flow rate and the diameters at various sections of the ejector have been obtained by doing numerical modeling in Engineering Equation Solver (EES). Refrigerant R1234yf demanded the highest diameter requirements at a fixed 5∘C evaporator temperature and 40∘C condenser temperature for a given range of cooling load. Both primary and secondary refrigerants flow rates are higher for R1234yf followed by R134a and then R152a.

scholarly journals Exergetic performance analysis of low GWP alternative refrigerants for R404A in a refrigeration system

2021 ◽  
Author(s):  
Mehmet Altinkaynak
Keyword(s):  
Cooling System ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Refrigeration System ◽  
Alternative Refrigerants ◽  
Condenser Temperature ◽  
Parametric Analyses ◽  
Low Global Warming Potential ◽  
Very High

Abstract According to the regulation of European Union laws in 2014, it was inevitable to switch to low global warming potential (GWP) fluids in the refrigeration systems where the R404A working fluid is currently used. The GWP of R404A is very high, and the potential for ozone depletion is zero. In this study, energetic and exergetic performance assessment of a theoretical refrigeration system was carried out for R404 refrigerant and its alternatives, comparatively. The analyses were made for R448A, R449A, R452A and R404A. The results of the analysis were presented separately in the tables and graphs. According to the results, the cooling system working with R448A exhibited the best performance with a coefficient of performance (COP) value of 2.467 within the alternatives of R404A followed by R449A and R452A, where the COP values were calculated as 2.419 and 2.313, respectively. In addition, the exergy efficiencies of the system were calculated as 20.62%, 20.22% and 19.33% for R448A, R449A and R452A, respectively. For the base calculations made for R404A, the COP of the system was estimated as 2.477, where the exergy efficiency was 20.71%. Under the same operating conditions, the total exergy destruction rates for R404A, R448A, R449A and R452A working fluids were found to be 3.201 kW, 3.217 kW, 3.298 kW and 3.488 kW, respectively. Furthermore, parametric analyses were carried out in order to investigate the effects of different system parameters such as evaporator and condenser temperature.

scholarly journals Analysis of Hybrid Ejector Absorption Cooling System

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Doniazed Sioud ◽  
Ahmed Bellagi
Keyword(s):  
Water Cycle ◽  
Cooling System ◽  
Lithium Bromide ◽  
Steam Pressure ◽  
Entrainment Ratio ◽  
Evaporator Temperature ◽  
Condenser Temperature ◽  
Single Effect ◽  
Absorption Cooling System ◽  
Hybrid Cycle

In this paper, a hybrid ejector single-effect lithium-bromide water cycle is theoretically investigated. The system is a conventional single-effect cycle activated by an external steam-ejector loop. A mathematical model of the whole system is developed. Simulations are carried out to study the effect of the major parameters of the hybrid cycle on its performances and in comparison with the conventional cycle. The ejector performance is also investigated. Results show that the entrainment ratio rises with steam pressure and condenser temperature, while it decreases with increasing generator temperature. The effect of the evaporator temperature on ejector performance is negligible. It is shown also that the hybrid cycle exhibits better performances than the corresponding basic cycle. However, the performance improvement is limited to a specific range of the operating parameters. Outside this range, the hybrid system behaves similar to a conventional cycle. Inside this range, the COP increases, reaches a maximum, and then decreases and rejoins the behavior of the basic cycle. The maximum COP, which can be as large as that of a conventional double-effect cycle, about 1, is obtained at lower temperatures than in the case of single-effect cycles.

scholarly journals Experimental Analysis of Refrigeration Ejector System by using Different Organic Refrigerants

2021 ◽  
Vol 9 (VII) ◽  
pp. 281-288
Author(s):  
P. V. Wakchaure
Keyword(s):  
Experimental Analysis ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Optimum Operating ◽  
Working Fluid ◽  
Cfd Simulations ◽  
Evaporator Temperature ◽  
Optimum Operating Condition ◽  
Condenser Temperature ◽  
Ejector System

This paper presents the experimental analysis performed on ejectors to optimize operating conditions like evaporator temperature, condenser temperature and generator temperature. Using the environmentally friendly working fluid R134a, R152a, R600a, R717 (Ammonia). Parametric analysis was performed to review the effect of blending chamber geometry on ejector performance which has direct impact on coefficient of performance of ejector refrigeration cycles. Results show that operating conditions and thus the effect of the deflection of the primary flow on the secondary flow is set. CFD simulations was performed to identify optimum geometry and optimum operating condition

Indirect Cooling of IC Chips Using a Two Phase Closed Thermosyphon Loop

2003 ◽  
Author(s):  
Satoru Gima ◽  
Takashi Nagata ◽  
Xing Zhang ◽  
Motoo Fujii
Keyword(s):  
Surface Temperature ◽  
High Power ◽  
Heat Input ◽  
Cooling System ◽  
Working Fluid ◽  
Heater Surface ◽  
Two Phase ◽  
Notebook Computers ◽  
Power Ic ◽  
Set Up

This paper reports on indirect cooling of high-power IC chips of notebook computers using a two phase closed thermosyphon loop with Fluorinert (FC-72) as the working fluid. The experimental set-up consists of an evaporator and a condenser connected by flexible tubing. The evaporator corresponds to a high-power IC chip, and the condenser represents a cooling plate located behind the display of notebook computer. The evaporator and the condenser have the outer dimensions of 50mm × 50mm × 20mm and 150mm × 200mm × 20mm, respectively. The effects of the heat input Q and the charged volume of Fluorinert liquid F on the heat transfer characteristics of the cooling system were studied experimentally. Further, the experiment for the evaporator with plate fin to enhance the boiling in the evaporator was carried out. It has been confirmed that the heater surface temperature for the evaporator with plate fin reduces about 10% in comparison with those for the evaporator without fin. It is found that enhancing the boiling in the evaporator is very effective to reduce the surface temperature of heater. In the case of the evaporator with the plate fin, the temperature difference between the heater surface and ambient is kept around 60K for the highest heat input Q = 30W in the present experiments.

Exergetic Analyses of a Particular Absorption Cooling System

2012 ◽  
Vol 326-328 ◽  
pp. 641-646 ◽  
Author(s):  
Nahla Bouaziz ◽  
D. Lounissi ◽  
Lakdar Kairouani ◽  
M. El Ganaoui
Keyword(s):  
Exergy Analysis ◽  
Cooling System ◽  
Working Fluid ◽  
Exergy Destruction ◽  
Mass Energy ◽  
Intermediate Pressure ◽  
Absorption Cooling ◽  
Energy And Exergy ◽  
Absorption Cycle ◽  
Absorption Cooling System

The objective of this work is to present an exergy analysis of a novel absorption configuration using water-ammonia as working fluid. The proposed configuration operates at three pressure levels. The absorber is at an intermediate pressure (Pint). A thermodynamic model based on the mass energy and exergy balances is developed for this purpose. The parameters analyzed are the refrigeration systems performance (COP), the exergy efficiency, the global exergy destruction in the system, the exergy destruction and the irreversibility in different components. The effects of generator, absorber, condenser and evaporator on the performance of the system are examined. Numerical results highlight the great importance of the intermediate pressure on the performance of the system and specially on reducing the operating generator temperature. Consequently, the intermediate pressure is directly responsible on the adaptability of the proposed cooling absorption cycle to low enthalpy sources.

scholarly journals Mathematical Simulation of Fourth Generation Refrigerant R1243zf in Single Stage and Double Stage Vapour Compression Refrigeration System

2020 ◽  
Vol 9 (4) ◽  
pp. 1706-1710
Keyword(s):  
Mathematical Simulation ◽  
Single Stage ◽  
Fourth Generation ◽  
Maximum Pressure ◽  
Refrigeration System ◽  
Evaporator Temperature ◽  
Compression System ◽  
Condenser Temperature ◽  
Optimum Solution ◽  
Vapour Compression

In this paper a new fourth generation, environment friendly refrigerant R1243zf has been used in performance analysis between single stage and double stage vapour compression refrigeration system working between the same minimum and maximum pressure limits. The analysis has been done by mathematical simulation in Engineering Equation Solve (EES 10.439D, 2019). Results show that in low temperature cooling applications, a single stage vapour compression system does not perform well and a cascade system is the best optimum solution. In the given pressure limit, with the use of double stage vapour compression system, the increase in COP is 14% and decrease in compression work is 11.49%. The effects of evaporator temperature and condenser temperature have been seen on COP for both the systems and results show that with decrease in evaporator temperature, COP is decreasing, where as with decrease in condenser temperature COP is increasing.

Irreversibility Analysis of a Vapor Compression Cascade Refrigeration Cycle

2008 ◽  
Author(s):  
Ali Kilicarslan ◽  
Norbert Mu¨ller
Keyword(s):  
Low Temperature ◽  
Alternative Energy ◽  
Working Fluid ◽  
Energy Sources ◽  
Temperature Cycle ◽  
Refrigeration Cycle ◽  
Evaporator Temperature ◽  
Temperature Cycles ◽  
Condenser Temperature ◽  
Cascade Refrigeration

Hydrocarbon based energy sources such as coal, oil and natural gas have been diminishing in an increasing speed. Instead of finding alternative energy sources, we have to use the available sources more effectively. By means of the irreversibility analysis, we can determine the factors or conditions that cause the inefficiencies in any energy system. In this study, irreversibility analysis of a compression cascade refrigeration cycle that consists of a high and low temperature cycles is presented. In the high temperature cycle, the refrigerants from different classes, namely R12 (CFC), R22 (HCFC), R134a (HFC) and R404a (Azeotropic) are selected as working fluids. In the low temperature cycle, R13 is only used as a working fluid. Irreversibility analysis of refrigerant pairs, namely R12-R13, R22-R13, R134a-R13, and R404a-R13 are carried out in a compression cascade refrigeration cycle by a computer code developed. The effects of evaporator temperature, condenser temperature, and the temperature difference between the saturation temperatures of the lower and higher temperature cycles in the heat exchanger (ΔT) and the polytropic efficiency on irreversibility of the system are investigated. The irreversibility of the cascade refrigeration cycle decreases as the evaporator temperature and polytropic efficiency increase for all of the refrigerant couples considered while the irreversibility increases with the increasing values of the condenser temperature and ΔT. In the whole ranges of evaporator temperature (−65°C / −45°C), condenser temperature (30–50°C), ΔT (2–16K) and polytropic efficiency (%50/%100), the refrigerant pair R12-R13 has the lowest values of irreversibilities while the pair R404a-R13 has the highest ones. At the lower condenser temperature (<30°C) and higher polytropic efficiencies (85%–95%), the refrigerant couples except for R404a-R13 have approximately the same values of irreversibility.

Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts

2020 ◽  
Vol 92 (3) ◽  
pp. 30901
Author(s):  
Suvanjan Bhattacharyya ◽  
Debraj Sarkar ◽  
Ulavathi Shettar Mahabaleshwar ◽  
Manoj K. Soni ◽  
M. Mohanraj
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Performance ◽  
Working Fluid ◽  
The Novel ◽  
Heat Exchanger Tube ◽  
Heat Transfer Augmentation ◽  
Corrugated Tube ◽  
The Impact ◽  
Exchanger Tube

The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

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