Predicted Performance of a Ceramic Foam Gas Phase Heat Recuperator for a Solar Thermochemical Reactor

2014 ◽  
Author(s):  
Rohini Bala Chandran ◽  
Aayan Banerjee ◽  
Jane H. Davidson
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Gas Phase ◽  
Heat Recovery ◽  
Porous Alumina ◽  
Porous Ceramic ◽  
Thermal Reduction ◽  
Operating Conditions ◽  
Ceramic Foam ◽  
Solar Thermochemical

The efficiency of solar thermochemical cycles to split water and carbon dioxide depends in large part on highly effective gas phase heat recovery. Heat recovery is imperative for approaches that rely on an inert sweep gas to reach low partial pressures of oxygen during thermal reduction and/or use excess oxidizer to provide a higher thermodynamic driving potential for fuel production. In this paper, we analyze heat transfer and pressure drop of a tube-in-tube ceramic heat exchanger for the operating conditions expected in a prototype solar reactor for isothermal cycling of ceria. The ceramic tubes are filled with reticulated porous ceramic (RPC). The impacts of the selection of the composition and morphology of the RPC on heat transfer and pressure drop are explored via computational analysis. Results indicate a 10 pore per inch (ppi), 80–85% porous alumina RPC yields effectiveness from 85 to 90 percent.

Single-Phase Heat Transfer and Pressure Drop of Water Cooled Inside Horizontal Smooth Tubes in the Transitional Flow Regime

2010 ◽  
Author(s):  
Josua P. Meyer ◽  
Leon Liebenberg ◽  
Jonathan A. Olivier
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Transition Region ◽  
Heat Exchangers ◽  
Operating Conditions ◽  
Transitional Flow ◽  
Working Fluid ◽  
Tube Heat Exchanger ◽  
Smooth Tubes

Heat exchangers are usually designed in such a way that they do not operate in the transition region. This is usually due to a lack of information in this region. However, due to design constraints, energy efficiency requirements or change of operating conditions, heat exchangers are often forced to operate in this region. It is also well known that entrance disturbances influence where transition occurs. The purpose of this paper is to present experimental heat transfer and pressure drop data in the transition region for fully developed and developing flows inside smooth tubes using water as the working fluid. The use of different inlet disturbances were used to investigate its effect on transition. A tube-in-tube heat exchanger was used to perform the experiments, which ranged in Reynolds numbers from 1 000 to 20 000, with Prandtl numbers being between 4 and 6 while Grashof numbers were in the order of 105. Results showed that the type of inlet disturbance could delay transition to a Reynolds number as high as 7 000, while other inlets expedited it, confirming results of others. For heat transfer, though, it was found that transition was independent of the inlet disturbance and all commenced at the same Reynolds number, 2 000–3 000, which was attributed to secondary flow effects.

scholarly journals Experimental Investigation of Embedded Micropin-Fins for Single-Phase Heat Transfer and Pressure Drop

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Chirag R. Kharangate ◽  
Ki Wook Jung ◽  
Sangwoo Jung ◽  
Daeyoung Kong ◽  
Joseph Schaadt ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Friction Factor ◽  
Integrated Circuit ◽  
Single Phase ◽  
Absolute Error ◽  
Heat Fluxes ◽  
Operating Conditions ◽  
Working Fluid ◽  
Pin Fin

Three-dimensional (3D) stacked integrated circuit (IC) chips offer significant performance improvement, but offer important challenges for thermal management including, for the case of microfluidic cooling, constraints on channel dimensions, and pressure drop. Here, we investigate heat transfer and pressure drop characteristics of a microfluidic cooling device with staggered pin-fin array arrangement with dimensions as follows: diameter D = 46.5 μm; spacing, S ∼ 100 μm; and height, H ∼ 110 μm. Deionized single-phase water with mass flow rates of m˙ = 15.1–64.1 g/min was used as the working fluid, corresponding to values of Re (based on pin fin diameter) from 23 to 135, where heat fluxes up to 141 W/cm2 are removed. The measurements yield local Nusselt numbers that vary little along the heated channel length and values for both the Nu and the friction factor do not agree well with most data for pin fin geometries in the literature. Two new correlations for the average Nusselt number (∼Re1.04) and Fanning friction factor (∼Re−0.52) are proposed that capture the heat transfer and pressure drop behavior for the geometric and operating conditions tested in this study with mean absolute error (MAE) of 4.9% and 1.7%, respectively. The work shows that a more comprehensive investigation is required on thermofluidic characterization of pin fin arrays with channel heights Hf < 150 μm and fin spacing S = 50–500 μm, respectively, with the Reynolds number, Re < 300.

Reduction of Gaseous Emission From Turbine Combustor

2005 ◽  
Author(s):  
R. S. Amano ◽  
J. Xie ◽  
Shyam Singh ◽  
R. E. Peck
Keyword(s):  
Heat Transfer ◽  
Porous Layer ◽  
Operating Conditions ◽  
Ceramic Foam ◽  
Spray Combustion ◽  
Hydrocarbon Emissions ◽  
Flame Zone ◽  
Enhanced Heat Transfer ◽  
Firing Rates ◽  
Unburned Hydrocarbon

A study of spray combustion with porous inserts was performed using an on-axis fuel used in a concentric Jet-A. Combustion performance was evaluated by measuring exhaust emissions and gaseous temperatures for different operating conditions with and without ceramic foam inserts. The results indicated that the enhanced heat transfer in the flame zone could reduce nitrogen oxides and unburned hydrocarbon emissions. Placing a second porous layer downstream could yield further reductions in both emissions. The results for different firing rates and equivalence ratios revealed the residence time in the porous layer is an important factor in controlling the combustor performance.

CFD Simulation of Fin-and-Tube Heat Exchanger with Louvered Fin Configuration: Technical Note

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
M. Sabari ◽  
D. Channankiah ◽  
D. Shivalingappa
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Cfd Simulation ◽  
Calculated Data ◽  
Technical Note ◽  
Operating Conditions ◽  
Tube Heat Exchanger ◽  
Louvered Fin ◽  
Almost All

Heat exchanger plays a major role in almost all mechanical industries. Enhancement of heat transfer surface plays major role in numerous applications such as in heat exchangers, refrigeration and air conditioning systems etc. This paper examines the fluid flow and heat exchange on the air side of a multi-row fin-and-tube heat exchanger. A brief comparison is given between fin-and-tube heat exchanger attributes with louvered fins in a wider range of operating conditions defined by inlet air velocities. The brief representation on the calculated data for the louvered heat exchanger shows better heat transfer characteristics with a slightly higher pressure drop. The CFD procedure is validated by comparing the numerical simulation results with different inlet air velocities. Best combination of higher heat transfer and minimum pressure drop are occurred in inlet air velocity of 2.5 m/s.

1213 Heat Transfer and Pressure Drop Characteristics in Latent Heat Recovery Type Heat Exchanger : Effects of Fin Pitch of Offset Type Fin

2005 ◽  
Vol 2005.42 (0) ◽  
pp. 405-406
Author(s):  
Kiyoshi KAWAGUCHI ◽  
Kenichi OKUI ◽  
Takahiro SHIMOURA ◽  
Takaki OHKOUCHI ◽  
Hiroyuki OSAKABE ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Latent Heat ◽  
Heat Recovery

Performance Evaluation of Tube-in-Tube Heat Exchanger Using Nanofluids

2015 ◽  
Vol 787 ◽  
pp. 72-76 ◽  
Author(s):  
V. Naveen Prabhu ◽  
M. Suresh
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Transfer Rate ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Element Analysis ◽  
Tube Heat Exchanger

Nanofluids are fluids containing nanometer-sized particles of metals, oxides, carbides, nitrides, or nanotubes. They exhibit enhanced thermal performance when used in a heat exchanger as heat transfer fluids. Alumina (Al2O3) is the most commonly used nanoparticle due to its enhanced thermal conductivity. The work presented here, deals with numerical simulations performed in a tube-in-tube heat exchanger to study and compare flow characteristics and thermal performance of a tube-in-tube heat exchanger using water and Al2O3/water nanofluid. A local element-by-element analysis utilizing e-NTU method is employed for simulating the heat exchanger. Profiles of hot and cooling fluid temperatures, pressure drop, heat transfer rate along the length of the heat exchanger are studied. Results show that heat exchanger with nanofluid gives improved heat transfer rate when compared with water. However, the pressure drop is more, which puts a limit on the operating conditions.

Experimental and Numerical Investigation of Heat Transfer Characteristics of Liquid Flow With Micro-Encapsulated Phase Change Material

2008 ◽  
Author(s):  
Rami Sabbah ◽  
Jamal Yagoobi ◽  
Said Al Hallaj
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Pressure Drop ◽  
Phase Change ◽  
Phase Change Material ◽  
Operating Conditions ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Encapsulated Phase Change Material ◽  
Change Material

This experimental and numerical study investigates Micro-Encapsulated Phase Change Material (MEPCM) heat transfer characteristics and corresponding pressure drop. To conduct this study, an experimental setup consisting of a steel tube with an inner diameter of 4.3mm, outer diameter of 6.5mm and a length of 1,016mm is selected. A MEPCM mass concentration of 20% slurry with particle diameter ranging between 5–15μm is included in this study. Tube wall temperature profile, fluid inlet, outlet temperatures, the pressure drop across the tube are measured and corresponding Nusselt number are determined for various operating conditions. The experimental results are used to validate the numerical model predictions. The numerical model results show good agreement with the experimental data under various operating conditions. The controlling parameters are identified and their effects on the heat transfer characteristics of micro-channels with MEPCM slurries are evaluated.

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