Thermal Characterization of Prototypical Integral Collector Storage Systems With Immersed Heat Exchangers

2005 ◽  
Vol 127 (1) ◽  
pp. 21-28 ◽  
Author(s):  
W. Liu ◽  
J. H. Davidson ◽  
F. A. Kulacki
Keyword(s):  
Large Scale ◽  
Tube Bundle ◽  
Characteristic Temperature ◽  
Storage System ◽  
Fluid Motion ◽  
Thermal Characterization ◽  
Transfer Coefficients ◽  
Average Water Temperature ◽  
Operating Modes ◽  
Tube Wall Temperature

Natural convection is measured in an enclosure that represents an integral collector storage system (ICS) with an immersed tube-bundle heat exchanger. Heat transfer coefficients for bundles of 240 tubes contained in a thin enclosure of aspect ratio of 9.3:1 and inclined at 30 deg to the horizontal are obtained for a range of transient operating modes and pitch-to-diameter ratios of 1.5, 2.4, and 3.3. Results for isothermal and stratified enclosures yield a correlation for the overall Nusselt number NuD=2.45±0.03RaD0.188,230⩽RaD⩽9800. The characteristic temperature difference in the Rayleigh number is that between the average water temperature within the bundle and the tube wall temperature. Nusselt numbers are three times larger than those for a similarly configured single-tube and an eight-tube bundle. This increase is attributed to stronger fluid motion within the bundle and higher overall large scale circulation rates in the enclosure.

Thermal Characterization of Prototypical ICS Systems With Immersed Heat Exchangers

Solar Energy ◽  
2004 ◽  
Author(s):  
Wei Liu ◽  
Jane H. Davidson ◽  
F. A. Kulacki
Keyword(s):  
Heat Exchangers ◽  
Tube Bundle ◽  
Fluid Motion ◽  
Thermal Characterization ◽  
Transfer Coefficients ◽  
Single Tube ◽  
Operating Modes ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers

Natural convection is measured in an enclosure that represents an integral collector storage solar system with an immersed heat exchanger. The enclosure has an aspect ratio of 9.3:1 and is inclined 30 deg to the horizontal. Heat transfer coefficients for bundles of 240 tubes are obtained for a range of transient operating modes and pitch-to-diameter ratios of 1.5, 2.4, and 3.3. Results for isothermal and stratified enclosures yield a correlation for the overall Nusselt number, NuD=(2.45±0.03)RaD0.188,230≤RaD≤9800. Nusselt numbers are three times larger than those for a similarly configured single-tube and an eight-tube bundle. This increase is attributed to stronger fluid motion within the bundle and greater overall circulation rates in the enclosure.

Natural Convection From a Tube Bundle in a Thin Inclined Enclosure

2003 ◽  
Author(s):  
Wei Liu ◽  
Jane H. Davidson ◽  
F. A. Kulacki
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Tube Bundle ◽  
Storage System ◽  
Convection Heat Transfer ◽  
Constant Heat Flux ◽  
Working Fluid ◽  
Measured Temperature ◽  
Transfer Coefficients ◽  
Rectangular Array

Natural convection heat transfer coefficients for a rectangular array of eight tubes contained in a thin enclosure of aspect ratio 9.3:1 and inclined at 30 degrees to the horizontal are measured for a range of transient operating modes typical of a load side heat exchanger in unpressurized integral collector-storage systems. Water is the working fluid, and thermal charging is accomplished via a constant heat flux on the upper boundary. All other boundaries are well insulated. Results for isothermal and stratified enclosures yield the following correlation for the overall Nusselt number: NuD=(0.728±0.002)RaD0.25,4.0×105≤RaD≤1.4×107. The flow field in the enclosure is inferred from measured temperature distributions. The temperature difference that drives natural convection is also determined. The results extend earlier work for the case of a single tube and provide limiting case heat transfer data for a tube bundle that occupies the upper portion of the collector storage system.

Natural Convection From a Tube Bundle in a Thin Inclined Enclosure

2004 ◽  
Vol 126 (2) ◽  
pp. 702-709 ◽  
Author(s):  
W. Liu ◽  
J. H. Davidson ◽  
F. A. Kulacki
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Tube Bundle ◽  
Convection Heat Transfer ◽  
Constant Heat Flux ◽  
Working Fluid ◽  
Measured Temperature ◽  
Transfer Coefficients ◽  
Rectangular Array ◽  
Operating Modes

Natural convection heat transfer coefficients for a rectangular array of eight tubes contained in a thin enclosure of aspect ratio 9.3:1 and inclined at 30 deg to the horizontal are measured for a range of transient operating modes typical of a load side heat exchanger in unpressurized integral collector-storage systems. Water is the working fluid, and thermal charging is accomplished via a constant heat flux on the upper boundary. All other boundaries are well insulated. Results for isothermal and stratified enclosures yield the following correlation for the overall Nusselt number: NuD=0.728±0.002RaD0.25,4.0×105⩽RaD⩽1.4×107. The flow field in the enclosure is inferred from measured temperature distributions. The temperature difference that drives natural convection is also determined. The results extend earlier work for the case of a single tube and provide limiting case heat transfer data for a tube bundle that occupies the upper portion of the collector storage.

Performance Increase of Steam Turbine Condensers by CFD Analysis

2014 ◽  
Author(s):  
Simon Hecker ◽  
Andreas Auge ◽  
Tobias Ellsel ◽  
Johan Flegler ◽  
Christian Musch ◽  
...  
Keyword(s):  
Power Plant ◽  
Power Plants ◽  
Large Scale ◽  
Tube Bundle ◽  
Cooling Water ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Condenser Tube ◽  
Transfer Coefficients ◽  
Effective Measure

An effective measure to increase the performance of turbine power plants is to minimize flow losses in the condenser resulting in a smaller terminal temperature difference (TTD) — the more the TTD of the condenser can be reduced in an optimization process of a given power plant configuration, the more the exhaust pressure will decrease. With an optimized condenser tube bundle design the TTD can be improved. This study presents the modification of a commercial CFD code to simulate the three-dimensional flow field around and within tube bundles. Additionally the temperature distribution of the cooling water is part of the numerical solution without modeling each individual condenser tube. To show the accuracy of the CFD code the flow in a large scale power plant condenser is simulated and compared to measurements of local heat transfer coefficients in the bundles. The comparison shows that the presented CFD tool is valid to predict the performance of such condensers. Based on the results of the study, areas with low cooling performance are identified and suggestions are made for the increase of the overall condenser efficiency.

scholarly journals Research on capacity optimization of micro-grid hybrid energy storage system based on simulated annealing artificial fish swarm algorith with memory function

2020 ◽  
Vol 185 ◽  
pp. 01023
Author(s):  
Yuan An ◽  
Jianing Li ◽  
Cenyue Chen
Keyword(s):  
Simulated Annealing ◽  
Energy Storage ◽  
Large Scale ◽  
Memory Function ◽  
Storage System ◽  
Energy Storage System ◽  
Hybrid Energy ◽  
Hybrid Energy Storage ◽  
Hybrid Energy Storage System ◽  
With Memory

The intermittence and uncertainty of wind power and photovoltaic power have hindered the large-scale development of both. Therefore, it is very necessary to properly configure energy storage devices in the wind-solar complementary power grid. For the hybrid energy storage system composed of storage battery and supercapacitor, the optimization model of hybrid energy storage capacity is established with the minimum comprehensive cost as the objective function and the energy saving and charging state as the constraints. A simulated annealing artificial fish school algorithm with memory function is proposed to solve the model. The results show that the hybrid energy storage system can greatly save costs and improve system economy.

scholarly journals Heat Transfer in Rotating Serpentine Passages With Trips Normal to the Flow

1992 ◽  
Vol 114 (4) ◽  
pp. 847-857 ◽  
Author(s):  
J. H. Wagner ◽  
B. V. Johnson ◽  
R. A. Graziani ◽  
F. C. Yeh
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Large Scale ◽  
Flow Direction ◽  
Operating Conditions ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Flow Equations ◽  
Turbine Blade Cooling ◽  
Heat Transfer Coefficients

Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large-scale, multipass, heat transfer model with both radially inward and outward flow. Trip strips on the leading and trailing surfaces of the radial coolant passages were used to produce the rough walls. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages: coolant-to-wall temperature ratio, Rossby number, Reynolds number, and radius-to-passage hydraulic diameter ratio. The first three of these four parameters were varied over ranges that are typical of advanced gas turbine engine operating conditions. Results were correlated and compared to previous results from stationary and rotating similar models with trip strips. The heat transfer coefficients on surfaces, where the heat transfer increased with rotation and buoyancy, varied by as much as a factor of four. Maximum values of the heat transfer coefficients with high rotation were only slightly above the highest levels obtained with the smooth wall model. The heat transfer coefficients on surfaces where the heat transfer decreased with rotation, varied by as much as a factor of three due to rotation and buoyancy. It was concluded that both Coriolis and buoyancy effects must be considered in turbine blade cooling designs with trip strips and that the effects of rotation were markedly different depending upon the flow direction.

scholarly journals Multi-scale modelling of a large scale shell-and-tube latent heat storage system for direct steam generation power plants

2020 ◽  
Author(s):  
Clément Beust ◽  
Erwin Franquet ◽  
Jean-Pierre Bédécarrats ◽  
Pierre Garcia ◽  
Jérôme Pouvreau ◽  
...  
Keyword(s):  
Power Plants ◽  
Large Scale ◽  
Storage System ◽  
Steam Generation ◽  
Latent Heat Storage ◽  
Multi Scale ◽  
Direct Steam ◽  
Scale Modelling ◽  
Shell And Tube ◽  
Generation Power
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