Numerical investigation on mass and heat transfer in an ammonia oil-free twin-screw compressor with liquid injection

2017 ◽  
Vol 120 ◽  
pp. 175-184 ◽  
Author(s):  
Yafen Tian ◽  
Hao Yuan ◽  
Chuang Wang ◽  
Huagen Wu ◽  
Ziwen Xing
Keyword(s):  
Heat Transfer ◽  
Numerical Investigation ◽  
Screw Compressor ◽  
Liquid Injection ◽  
Twin Screw ◽  
Mass And Heat Transfer

Performance Optimization of Mechanical Vapor Compression Desalination System Using a Water-Injected Twin-Screw Compressor

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Yousif Alkhulaifi ◽  
Esmail M. A. Mokheimer ◽  
Jihad H. AlSadah
Keyword(s):  
Heat Transfer ◽  
Performance Optimization ◽  
System Performance ◽  
Seawater Temperature ◽  
Injection Pressure ◽  
Screw Compressor ◽  
Vapor Compression ◽  
Compression Process ◽  
Twin Screw ◽  
Brine Salinity

In this study, the thermal and operational characteristics of a 400 m3/day mechanical vapor compression desalination (MVCD) system that uses a water-injected twin-screw compressor have been studied and presented. A mathematical model of the MVCD system has been developed including mass and energy conservation equations, heat transfer equations, as well as thermophysical correlations. The effects of the MVCD system design and operation parameters on the system performance are analyzed and discussed. The effect of different boiling-point elevation correlations on the specific area is investigated. The brine and distillate preheaters' areas are studied as a function of inlet seawater temperature. The effect of the injection pressure on system performance is studied. Results show that the optimal injection point is close to the beginning of the compression process. Using this optimum injection pressure, the reduction in power consumption was found to be about 7.3% for high compression ratios. The effects of the brine and feed salinity on system performance are also analyzed. It is found that the specific heat transfer area strongly depends on the brine salinity, especially at temperature differences less than 6 °C. It increases by 44% and 32% at a temperature difference of 4 and 6 °C, respectively. The compressor inlet volume flowrate increases by 9% when the brine salinity increases from 50,000 to 150,000 ppm at all brine boiling temperatures considered. The feed-to-distillate ratio increases rapidly with rising feed salinity, while it decreases with rising brine salinity.

scholarly journals Numerical and Experimental Research in Heat Transfer to Screw Compressor Rotors

2011 ◽  
Author(s):  
Nikola Stosic ◽  
Ian K. Smith ◽  
Ahmed Kovacevic
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Screw Compressor ◽  
Relative Significance ◽  
Axial Coordinate ◽  
Transfer Rates ◽  
Design Changes ◽  
Liquid Injection ◽  
Lower Temperature ◽  
Flow Study

Due to fast rotation of screw compressor rotors, temperature is uniform in a cross section and temperature field is a function of the axial coordinate only. The rotors in one cross section the rotors are simultaneously heated by hot gas on one side while cooled at another side by cold gas. As a result of identification of the main modes of heat transfer both in the rotors and between the rotors and their surroundings and the relative significance of each, a novel procedure is suggested to cool the rotors by injection of minute quantities of a volatile fluid. By this means the compressed gas should attain higher temperatures without rotor distortion. To confirm these concepts and quantify both the heat transfer rates and the rate of liquid injection required for rotor cooling, both a one dimensional flow study and a more complex 3-D numerical analysis were performed, the latter with the aid of a CFD code. The results indicated that the rotors could be maintained at a far lower temperature than that of the discharged gas by flash evaporative cooling, as a result of injecting a fractional percentage by mass of a volatile fluid. This was confirmed by experiment. This technique may be used to operate dry compressors at substantially higher pressure ratios than are currently possible in such machines. It is also shown that only minor design changes are needed to implement it.

Experimental and numerical investigation of direct liquid injection into an ORC twin-screw expander

Energy ◽  
2019 ◽  
Vol 178 ◽  
pp. 867-878 ◽  
Author(s):  
Sebastian Eyerer ◽  
Fabian Dawo ◽  
Florian Rieger ◽  
Andreas Schuster ◽  
Richard Aumann ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Liquid Injection ◽  
Twin Screw ◽  
Direct Liquid Injection

scholarly journals A critical review of the experimental studies related to twin screw compressors

2019 ◽  
Vol 234 (1) ◽  
pp. 157-170
Author(s):  
Hitesh H Patel ◽  
Vikas J Lakhera
Keyword(s):  
Experimental Studies ◽  
Industrial Applications ◽  
Experimental Investigations ◽  
Screw Compressor ◽  
Pressure Losses ◽  
Numerical Studies ◽  
Liquid Injection ◽  
Twin Screw ◽  
Visualization Techniques ◽  
Fluid Solid Interaction

Twin-screw compressors are often used for generating compressed fluids useful for various industrial applications, thereby necessitating the need for evolving energy efficient designs. In the past few decades, several experimental studies were conducted to understand the phenomenon inside the twin-screw compressor, thereby leading to performance improvement and design optimization. The present study summarizes the various experimental investigations on screw compressors which include analysis related to various parameters such as leakages, pulsations, noise, liquid injection, capacity control, pressure losses, optimization of rotor, indicator diagrams, etc. In order to improve the understanding of thermo-fluid-solid interaction phenomenon in twin-screw compressor, further investigations using visualization techniques such as LDV/PIV are suggested. As the leakages within the screw compressor are complex phenomenon, it is suggested to explore simplified experimental and numerical studies by simulating the leakages using equivalent nozzles and developing appropriate leakage models.

Theoretical and experimental research on the performance of twin screw compressor using R513A as R134a replacement

2020 ◽  
pp. 095440892095114
Author(s):  
Zhiping Zhang ◽  
Ying Wang ◽  
Xiaokun Wu ◽  
Xi Pan ◽  
Ziwen Xing
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Pressure Ratio ◽  
Volumetric Efficiency ◽  
Screw Compressor ◽  
Test Results ◽  
Lubricant Oil ◽  
Twin Screw ◽  
The Cost ◽  
Significant Attention

The refrigerant R513A receives significant attention as an alternative to R134a used in water chiller, due to its lower global warming potential. However, whether R513A can directly and efficiently take the place of R134a in the twin screw compressor has not been verified. In this paper, a thermodynamic model is applied to compare the performance of R513A and R134a in a twin screw compressor. The leakage process and heat transfer between refrigerant and lubricant oil are taken into account. With this model, the volumetric efficiency and adiabatic efficiency are simulated and p- V indicator diagram is presented. Simulated results show that R513A is the refrigerant with low temperature lift, low pressure ratio but high pressure difference. Experimentally, the test compressor originally designed for R134a is used to compare the performance of R134a and R513A. Test results show that the differences of volumetric efficiency and adiabatic efficiency between R134a and R513A are very small and acceptable. The COP of R513A is only a little bit lower than that of R134a. Hence, taking the cost of replacing equipment and GWP into account, R513A can directly take the place of R134a in the twin screw compressor.

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