Steady‐state and transient hydrothermal analyses of single‐phase natural circulation loop using water‐based tri‐hybrid nanofluids

AIChE Journal ◽  
2021 ◽  
Author(s):  
Mayaram Sahu ◽  
Jahar Sarkar ◽  
Laltu Chandra
Keyword(s):  
Steady State ◽  
Single Phase ◽  
Natural Circulation ◽  
Circulation Loop ◽  
Natural Circulation Loop ◽  
Water Based ◽  
Hybrid Nanofluids

Steady-State Energetic and Exergetic Performances of Single-Phase Natural Circulation Loop With Hybrid Nanofluids

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Mayaram Sahu ◽  
Jahar Sarkar
Keyword(s):  
Steady State ◽  
Mass Flow Rate ◽  
Entropy Generation ◽  
Mass Flow ◽  
Flow Rate ◽  
Natural Circulation ◽  
Circulation Loop ◽  
Hybrid Nanofluid ◽  
Natural Circulation Loop ◽  
Hybrid Nanofluids

Energy and exergy performances of natural circulation loop (NCL) with various water-based hybrid nanofluids (Al2O3 + TiO2, Al2O3 + CNT, Al2O3 + Ag, Al2O3 + Cu, Al2O3 + CuO, Al2O3 + graphene) with 1% volumetric concentration are compared in this study. New thermophysical property models have been proposed for hybrid nanofluids with different particle shapes and mixture ratio. Effects of power input, loop diameter, loop height, loop inclination and heater/cooler inclination on steady-state mass flow rate, effectiveness, and entropy generation are discussed as well. Results show that both the steady-state mass flow rate and energy–exergy performance are enhanced by using the hybrid nanofluids, except Al2O3 + graphene, which shows the performance decrement within the studied power range. Al2O3 + Ag hybrid nanofluid shows highest enhancement in mass flow rate of 4.8% compared to water. The shape of nanoparticle has shown a significant effect on steady-state performance; hybrid nanofluid having cylindrical and platelet shape nanoparticles yields lower mass flow rate than that of spherical shape. Mass flow rate increases with the increasing loop diameter and height, whereas decreases with the increasing loop and heater/cooler inclinations. Both effectiveness and entropy generation increase with the decreasing loop diameter and height, whereas increasing the loop and heater/cooler inclinations. This study reveals that the particle shape has a significant effect on the performance of hybrid nanofluids in NCL, and the use of hybrid nanofluid is more effective for higher power.

Experimental and Numerical Investigation of a Single-Phase Square Natural Circulation Loop

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Ritabrata Saha ◽  
Swarnendu Sen ◽  
Saikat Mookherjee ◽  
Koushik Ghosh ◽  
Achintya Mukhopadhyay ◽  
...  
Keyword(s):  
Steady State ◽  
Ambient Temperature ◽  
Single Phase ◽  
Numerical Models ◽  
Natural Circulation ◽  
Circulation Loop ◽  
Periodic Oscillations ◽  
Heater Power ◽  
Natural Circulation Loop ◽  
Moderate Power

Experimental and numerical analyses are carried out for a natural circulation loop (NCL) under low and moderate heater power. The effect of ambient temperature variation on the loop thermal behavior has been taken into account in present study. The effect of liquid inertia has a role in the initial transience, as revealed by the numerical and experimental observations. The steady-state results from the present analyses are validated with the reported dimensionless results for NCL. The experimental steady-state results are in fair agreement with the developed lumped numerical models. At moderate power, the numerical and experimental results indicate periodic oscillations.

Steady State Performance of a Single Phase Natural Circulation Loop With End Heat Exchangers

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
N. M. Rao ◽  
B. Maiti ◽  
P. K. Das
Keyword(s):  
Steady State ◽  
Heat Exchangers ◽  
Iterative Procedure ◽  
Single Phase ◽  
Natural Circulation ◽  
Circulation Loop ◽  
Circulation Rate ◽  
Natural Circulation Loop ◽  
Analytical Expressions ◽  
Steady State Performance

In the present investigation, the steady state performance of a rectangular single phase natural circulation loop (NCL) with end heat exchangers is studied. One-dimensional governing equations are considered in developing the mathematical model. Analytical expressions are derived for the circulation rate and temperature profile. However, the individual performance parameters are to be computed iteratively as the equations are strongly coupled. A suitable iterative procedure is given to evaluate the important loop parameters such as steady state flow rate, and riser and downcomer temperatures. Few special cases are discussed where analytical expressions for circulation rate and temperature distribution can be obtained directly without any iterative procedure. It is also shown that both the hot and cold end heat exchangers should have equal conductance (UA) for maximization of circulation rate. This feature of NCL is identical with heat power cycle and can be explained in light of equipartition principle.

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