scholarly journals Performance Evaluation Criterion of Nanofluid

2018 ◽  
Author(s):  
Sudarmadji Sudarmadji ◽  
Bambang SAP ◽  
Santoso
Keyword(s):  
Performance Evaluation ◽  
Evaluation Criterion ◽  
Performance Evaluation Criterion

scholarly journals Investigation of Overlapped Twisted Tapes Inserted in a Double-Pipe Heat Exchanger Using Two-Phase Nanofluid

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1656 ◽  
Author(s):  
Mehdi Ghalambaz ◽  
Hossein Arasteh ◽  
Ramin Mashayekhi ◽  
Amir Keshmiri ◽  
Pouyan Talebizadehsardari ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Performance Evaluation ◽  
Heat Exchanger ◽  
Evaluation Criterion ◽  
Twisted Tape ◽  
Performance Evaluation Criterion ◽  
Twisted Tapes ◽  
Double Pipe ◽  
Pipe Heat

This study investigated the laminar convective heat transfer and fluid flow of Al2O3 nanofluid in a counter flow double-pipe heat exchanger equipped with overlapped twisted tape inserts in both inner and outer tubes. Two models of the same (co-swirling twisted tapes) and opposite (counter-swirling twisted tapes) angular directions for the stationary twisted tapes were considered. The computational fluid dynamic simulations were conducted through varying the design parameters, including the angular direction of twisted tape inserts, nanofluid volume concentration, and Reynolds number. It was found that inserting the overlapped twisted tapes in the heat exchanger significantly increases the thermal performance as well as the friction factor compared with the plain heat exchanger. The results indicate that models of co-swirling twisted tapes and counter-swirling twisted tapes increase the average Nusselt number by almost 35.2–66.2% and 42.1–68.7% over the Reynolds number ranging 250–1000, respectively. To assess the interplay between heat transfer enhancement and pressure loss penalty, the dimensionless number of performance evaluation criterion was calculated for all the captured configurations. Ultimately, the highest value of performance evaluation criterion is equal to 1.40 and 1.26 at inner and outer tubes at the Reynolds number of 1000 and the volume fraction of 3% in the case of counter-swirling twisted tapes model.

Exergo-Economic Performance Evaluation of Enhanced Tube under Equivalent Pump Power Consumption

2011 ◽  
Vol 354-355 ◽  
pp. 310-314
Author(s):  
Shuang Ying Wu ◽  
Lan Xiao ◽  
Si Min Chen ◽  
Feng Hua Guo
Keyword(s):  
Performance Evaluation ◽  
Power Consumption ◽  
Economic Performance ◽  
Evaluation Criterion ◽  
Smooth Tube ◽  
Corrugated Tube ◽  
Performance Evaluation Criterion ◽  
Enhanced Tube ◽  
Engineering Significance ◽  
Profit Value

Based on the first and second laws of thermodynamics as well as exergo-economic theory, comprehensive performance evaluation criterion has been proposed for enhanced tube under the condition of equivalent pump (fan) power consumption, accounting for a variety of factors such as heat transfer, flow and investment costs. Performance evaluation criterion formula, namely, net profit value (NPV) has been derived from the perspective of the exergy recovery. Take spirally corrugated tube as an example, the results show that the exergo-economic performance of the spirally corrugated tube is superior to smooth tube for the range considered in the present study. From the viewpoint of NPV, although NPV of enhanced tube is greater than that of smooth tube, there exist critical values of Re and Nq exceeding which NPV of enhanced tube would be less than zero, showing no engineering significance.

Research on Improved CCHP System Based on Comprehensive Performance Evaluation Criterion

2014 ◽  
Vol 672-674 ◽  
pp. 1873-1878
Author(s):  
Fei Xiang Chen ◽  
Jian Qun Xu ◽  
Zhao Yu Li ◽  
Ming Tao Liu
Keyword(s):  
Performance Evaluation ◽  
Energy Consumption ◽  
Carbon Dioxide Emissions ◽  
Operating Mode ◽  
Evaluation Criterion ◽  
Industrial Park ◽  
Low Grade ◽  
Generation System ◽  
Performance Evaluation Criterion ◽  
Comprehensive Performance

In view of energy consumption characteristics of a typical industrial park, to further improve the low-grade waste heat utilization of CCHP system, an improved CCHP triple-generation system (ITRI) equipped with thermal storage device (TSD) and electric chiller (EC) is proposed. A comprehensive performance evaluation criterion (CPEC) is established, the capacity of triple-generation system is configured by using nonlinear programming method. A hybrid operating mode optimization strategy is proposed based on the different CPEC values of different operating mode. The results demonstrate that: after adopting ITRI, compared with traditional triple-generation system (TTRI), although annual cost increased by 0.63%, the primary energy consumption rate and lower carbon dioxide emissions decreased by 5.45% and 3.72% respectively, CPEC value increased by 19.7%. This paper has a theoretical guidance for design of triple-generation system in new industrial park and has a certain reference value for operating mode optimization of triple-generation system in the industrial parks which has been built.

Numerical Study on Heat Transfer and Resistance of a Tube Fitted With New Twisted Tapes for Lubricating Oil

2017 ◽  
Author(s):  
Xiaoya Liu ◽  
Ming Ding ◽  
Haozhi Bian ◽  
Changqi Yan ◽  
Chun Li
Keyword(s):  
Heat Transfer ◽  
Performance Evaluation ◽  
Numerical Study ◽  
Evaluation Criterion ◽  
Lubricating Oil ◽  
Twisted Tape ◽  
Steam Turbines ◽  
Transition Flow ◽  
Performance Evaluation Criterion ◽  
Twisted Tapes

Oil coolers are widely-used in nuclear power plants which cool oil flowed through the bearing of steam turbines to a suitable temperature in order for the safe operation of steam turbines. Owing to the high viscosity, the flow state of oil is generally laminar flow or transition flow, which easily leads to poor heat transfer capability and thus a large volume of the oil coolers. The insertion of twisted tapes in circular tube is a passive method widely-used for enhancing heat transfer of laminar or transition flow. However, little research focuses on the heat transfer of highly-viscous fluids inside tube using the twisted tapes. The article will present the numerical simulations of the swirling flow induced by a new coaxial cross twisted tape inserts in a heat transfer tube with lubricating oil. The effects of the clearance ratios and twist ratios on oil side heat transfer coefficient, friction factor and performance evaluation criterion will be numerically investigated using CFD computer software STAR-CCM+. The clearance ratios are 0.077, 0.154 and 0.231. The twist ratios are 2.0 and 4.0. The boundary condition of simulation is constant wall temperature for the Reynolds number ranging from 200 to 1300. The results indicate that the new coaxial cross twisted tapes are efficacious in enhancing the heat transfer of the lubricating oil inside tube. When the clear ratio is 0.077, the effect of heat transfer enhancement of the coaxial cross twisted tapes is better than that of traditional twisted tapes. Furthermore, the highest performance evaluation criterion is up to 2.3.

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