Direct Analytical Modeling for Optimal, On-Design Performance of Ejector for Simulating Heat-Driven Systems

In this paper, a first- and second-law analysis of vapor compression refrigeration is presented to estimate and propose the replacement of R134 with working fluids having less global warming potential (GWP) and less exergy destruction and irreversibilities. Six different refrigerants were studied, namely, R717, R1234yf, R290, R134a, R600a, and R152a. A thermodynamic model was designed on Engineering Equation Solver (EES) software, and performance parameters were calculated. The model was deployed on all six refrigerants, while the used output parameters of performance were cooling capacity, coefficient of performance, discharge temperature, total exergy destruction, relative exergy destruction rates of different components, second-law efficiency, and efficiency defect of each component. The performance parameters were estimated at different speeds of the compressor (1000, 2000, and 3000 rpm) and fixed condenser and evaporator temperatures of 50 °C and 5 °C, respectively. The isentropic efficiency of the compressor was the same as the volumetric efficiency, and it was taken as 75%, 65%, and 55% at the compressor speeds of 1000 rpm, 2000 rpm, and 3000 rpm, respectively. A comparison of the performance parameters was presented by importing the results in MATLAB. It was found that the compressor had the highest exergy destruction compared to the other components. It was found that R152 was the refrigerant with zero ozone depletion potential (ODP) and a GWP value of 140 with less exergy destruction and irreversibilities. Moreover, it was easy to use R152a with good thermodynamic characteristics. It is estimated that R152a is a suitable replacement for R134a, as it can be used with few modifications.

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“…The efficiency defects of the compressor, condenser, expansion valve, and evaporator are depicted by Equations ( 17)- (20), respectively:…”

Section: Mathematical Modelmentioning

confidence: 99%

Energy and Exergy Analysis of Vapor Compression Refrigeration System with Low-GWP Refrigerants

et al. 2022

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“…The idea of energy efficiency is reinforced by a similar case study from Italy, where an office building cut short its energy usage and emission to an extent of about 40% solely by retrofitting [15,16]. Another Canadian study came up with the conclusion that energy consumption can be reduced by 45%, only by insulating the roof and walls and replacing the windows of an office building in Vancouver city.…”

Section: Introductionmentioning

confidence: 99%

Modelling Framework for Reducing Energy Loads to Achieve Net-Zero Energy Building in Semi-Arid Climate: A Case Study

Azam,

Farooq,

Munir

et al. 2023

Buildings

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Buildings consume a significant 40% of global energy, where, reducing the building energy consumption to a minimum, virtually zero, has become a thriving research area. Accordingly, this research aimed to determine and portray the huge potential of energy conservation in existing structures by making a retrofit at relatively low costs in finance strained economies. A walk-through of the survey of energy consuming appliances determined the energy consumption based on the power rating; the appliances were then virtually replaced and the reduced energy consumption was determined in terms of the cooling loads. Modelling these intervention using the hourly analysis program (HAP) showed significantly positive results. The pre- and post-retrofit model analysis of an institutional building in Pakistan exhibited significant potential for reducing the cooling load of 767 kW (218 TON) to 408 kW (116 TON) with an investment payback period of 2.5 years. The additional benefit is the reduced greenhouse gas (GHG) emissions which reduce the overall energy requirements. The study continues with the design of a solar energy source using the system advisor model (SAM) for the reduced energy demand of a retrofitted building. It is then concluded that using the available area, a solar energy source with a capital payback period of 5.7 years would bring an institutional building within its own energy footprint making it a net-zero building, since it will not be consuming energy from any other source outside of its own covered area. The study has the limitation to exposure and climate related conditions. In addition, the decline in heating and cooling loads represents model values which may vary when calculated after an actual retrofit for the same structure due to any site related issues.

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“…It was concluded that decreasing the wetness of the secondary inlet flow could potentially optimize system performance, signified by a substantial increase in the entrainment ratio. Riaz et al [10] similarly conducted direct analytical modeling for optimal, on-design performance of an ejector for simulating heat-driven systems. Li et al [11] examined the effect of different pressure conditions on shock waves in a supersonic steam ejector, demonstrating that the intensity and number of oblique shock waves in the diffuser increase with an elevation in motive pressure and suction pressure, or a reduction in discharge pressure.…”

Section: Introductionmentioning

confidence: 99%

Supersonic Nozzle Location in Steam Ejector Effect on the Mass Fraction and Vacuum of Second Fluid

Salim,

Jassim

2023

IJHT

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The steam ejector, an essential auxiliary device, finds extensive use in various applications, including Multiple Effect Evaporation Desalination systems. The present study endeavored to evaluate the impact of different Converging-Diverging Nozzle placements. Initially, a vapor ejection was designed under certain conditions, utilizing one-dimensional compressible flow equations. Subsequently, the flow within the vapor ejection was simulated via a computational fluid dynamics (CFD) application, specifically the ANSYS program. The investigation entailed the selection of multiple nozzle locations and the examination of their effects under two scenarios: one with a constant back pressure for various suction pressures at each nozzle location, and the other with a fixed suction pressure coupled with several exit pressures. Results from the first scenario indicated that the optimal nozzle location was 5 mm from the commencement of the mixing area. For the second scenario, it was observed that closer proximity of the nozzle to the mixing area enhanced the performance of the steam ejector.

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Direct Analytical Modeling for Optimal, On-Design Performance of Ejector for Simulating Heat-Driven Systems

Cited by 8 publications

References 43 publications

Energy and Exergy Analysis of Vapor Compression Refrigeration System with Low-GWP Refrigerants

Energy and Exergy Analysis of Vapor Compression Refrigeration System with Low-GWP Refrigerants

Modelling Framework for Reducing Energy Loads to Achieve Net-Zero Energy Building in Semi-Arid Climate: A Case Study

Supersonic Nozzle Location in Steam Ejector Effect on the Mass Fraction and Vacuum of Second Fluid

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