Dynamic Modeling of a Compact Heat Exchange Reformer for High Temperature Fuel Cell Systems

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Jeongpill Ki ◽  
Daejong Kim ◽  
Srikanth Honavara-Prasad
Keyword(s):  
Heat Exchange ◽  
Current Trend ◽  
Convection Heat Transfer ◽  
Fuel Mixture ◽  
Energy System ◽  
Channel Length ◽  
Heat Management ◽  
Counter Flow ◽  
Flow Configuration ◽  
Internal Reforming

Solid oxide fuel cells (SOFC) are the most advanced energy system with the highest thermal efficiency. Current trend of research is on less than 10 kW scale, which requires compact fuel processing systems. Even if internal reforming in the stack is also a possible option, it causes significant temperature gradients and thermal stress. As an alternative, a compact heat exchange reformer (CHER) with a plate-fin co-flow or counter-flow configuration is proposed. Such a system integrates the heat management and reforming in one compact unit. This paper focuses on simulation of transient characteristics of CHER during the initial phase of start-up of small SOFC systems. Steam reforming (SR) and water-gas shift (WGS) reactions are chosen as the most appropriate reforming model. CHER is modeled as two-dimensional array of finite control volumes, and they are modeled with transient energy equations and dynamic molar balance equations. In addition, both reaction enthalpy and convection heat transfer between the catalyst-coated fins and fuel-steam mixture channels are considered. Several parametric simulations are performed as methane steam as a primary fuel mixture as a function of different operating temperature, steam-to-carbon ratio at the inlet, pressure gradient across the CHER, channel length, and flow configuration (co-flow and counter-flow).

Reducing Roof Solar Heat Gain by Using Double-Skin Ventilated Roofs

2020 ◽  
Vol 38 (3A) ◽  
pp. 402-411
Author(s):  
Mohannad R. Ghanim ◽  
Sabah T. Ahmed
Keyword(s):  
Inclination Angle ◽  
Convection Heat Transfer ◽  
Ventilation Rate ◽  
Channel Length ◽  
Air Gap ◽  
Galvanized Steel ◽  
Heat Gain ◽  
Solar Heat ◽  
Double Skin ◽  
Solar Heat Gain

Double skin ventilated roof is one of the important passive cooling techniques to reduce solar heat gain through roofs. In this research, an experimental study was performed to investigate the thermal behaviour of a double skin roof model. The model was made of two parallel galvanized steel plates. Galvanized steel has been used in the roof construction of industrial buildings and storehouses in Iraq. The effect of inclination angle (ϴ) from the horizontal and the spacing (S) between the plates was investigated at different radiation intensities. It is found that using a double skin roof arrangement with a sufficient air gap (S) can reduce the heat gain significantly. The higher the inclination angle (ϴ) the higher the ventilation rate, the lower the heat gain through the roof. In this study, increasing the air gap from 2 cm to 4 cm reduced the heat gain significantly but when the gap was further increased to 6 cm, the reduction in the heat flux was insignificant. A dimensionless correlation was also reduced between Nusselt number () and the single parameter  where L is the channel length. This correlation can be handily utilized for designing of engineering applications dealing with high temperature difference natural convection heat transfer.

Local Heat Exchange in the Combustion Chamber of a Hydrogen Engine Running on a Lean Fuel Mixture

2021 ◽  
Vol 50 (1) ◽  
pp. 79-87
Author(s):  
R. Z. Kavtaradze ◽  
A. M. Kondratev ◽  
Ch. Rongrong ◽  
Ch. Citian ◽  
S. Baigang ◽  
...  
Keyword(s):  
Heat Exchange ◽  
Combustion Chamber ◽  
Fuel Mixture ◽  
Local Heat ◽  
Lean Fuel

scholarly journals CFD analysis for counter flow in concentric tube heat exchangers

2018 ◽  
Vol 7 (2.20) ◽  
pp. 250
Author(s):  
Banoth Mohan ◽  
V Ashok Kumar
Keyword(s):  
Heat Exchange ◽  
Heat Exchangers ◽  
Associate Degree ◽  
Cfd Analysis ◽  
Sensible Heat ◽  
Counter Flow ◽  
Cooling Medium ◽  
In Transit ◽  
Parallel Stream ◽  
Coaxial Tube

A device may be a device worked for the sensible heat exchange beginning with one liquid then onto the attendant, paying very little reference to whether or not the liquids square measure isolates by a powerful divider in order that they ne'er mix, or the liquids square measure particularly in touch. reliably get some data concerning in device progression is creating to form productive, traditionalist and stinting heat exchangers, where for the duration of the planet. Strengthening the function for this alteration wants associate degree association. In most up-to-date 5 years coaxial tube heat exchangers use unnatural convection to cut down the temperature of a operating liquid whereas raising the temperature of the cooling medium. The motivation driving this paper is to utilize ANSYS FLUENT12.1 programming and hand counts to interrupt down the temperature drops as a neighborhood of each straight speed and delta temperature and the way each modification with the opposite. every gleam money dealer show was worked in steps and examined in transit till the purpose that the instant that each parallel stream and counter stream heat money dealer models were created. The outcomes were thought of between every model and among parallel and counter stream with fouled funneling. Turbulent stream was conjointly impecunious down amidst the distinction within the shine exchangers to choose its impact on heat exchange. whereas clearly the fouled heat money dealer had a lower execution and during this manner cooled the operating liquid less, the execution of the counter heat money dealer out of the blue of the parallel heat money dealer.

scholarly journals Modular reactor model for the solar thermochemical production of syngas incorporating counter-flow solid heat exchange

Solar Energy ◽  
2015 ◽  
Vol 122 ◽  
pp. 1296-1308 ◽  
Author(s):  
Christoph P. Falter ◽  
Andreas Sizmann ◽  
Robert Pitz-Paal
Keyword(s):  
Heat Exchange ◽  
Reactor Model ◽  
Counter Flow ◽  
Solar Thermochemical

Comparative Performance Analysis of Internal and External Reforming of Methanol in SOFC-MGT Hybrid Power Plants

2006 ◽  
Vol 129 (2) ◽  
pp. 478-487 ◽  
Author(s):  
Daniele Cocco ◽  
Vittorio Tola
Keyword(s):  
Performance Analysis ◽  
Power Plants ◽  
Alternative Fuels ◽  
Fuel Reforming ◽  
Heat Management ◽  
Comparative Performance ◽  
Internal Reforming ◽  
Hybrid Power ◽  
Near Term ◽  
Power Outputs

SOFC-MGT hybrid power plants are a very attractive near term option, as they achieve efficiencies of over 60% even for small power outputs (200-400kW). The SOFC hybrid systems currently developed are fuelled with natural gas, which is reformed inside the same stack at about 800-900°C. However, the use of alternative fuels with a lower reforming temperature can lead to enhanced performance of the hybrid power plant. This paper reports a comparative performance analysis of SOFC-MGT power plants fuelled by methane and methanol. Since the reforming temperature of methanol (250-300°C) is significantly lower than that of methane (700-900°C), for the methanol fuelled plant both internal and external reforming have been examined. The performance analysis has been carried out by considering different values for the most important operating parameters of the fuel cell. The comparative analysis has demonstrated that simply replacing methane with methanol in SOFC-MGT power plants with internal reforming slightly reduces the efficiency. However, the use of methanol in SOFC-MGT power plants with external reforming enhances efficiency significantly (by about 4 percentage points). The use of methanol with external fuel reforming raises efficiency of the stack thanks to the improved heat management and to the higher hydrogen partial pressure at the anode inlet.

Developing and Fully Developed Non-Newtonian Fluid Flow and Heat Transfer Through Concentric Annuli

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Mohammad Sefid ◽  
Ehsan Izadpanah
Keyword(s):  
Heat Transfer ◽  
Power Law ◽  
Convection Heat Transfer ◽  
Channel Length ◽  
Laminar Flows ◽  
Rheological Parameter ◽  
Power Law Fluid ◽  
Thermal Boundary Conditions ◽  
Flow And Heat Transfer ◽  
Power Law Index

Developing and fully developed laminar flows of power law fluid with forced convection heat transfer through a concentric annular duct are numerically analyzed. The results are presented for the following ranges: 0.2 ≤ n ≤ 1.8 (power law index), 10 ≤ Re ≤ 1000 (Reynolds number), and r* = 0.2, 0.5, 0.8 (aspect ratio). In addition, the influences of different thermal boundary conditions on the thermal performance are delineated. The effects of rheological parameter on the developing length, friction factor, temperature distribution, velocity profile, and Nusselt number along the channel length are investigated. The results are compared with earlier research and excellent agreement was observed.

scholarly journals Influence of Fin Length on Magneto-Combined Convection Heat Transfer Performance in a Lid-Driven Wavy Cavity

2021 ◽  
Vol 5 (3) ◽  
pp. 107
Author(s):  
Md. Fayz-Al-Asad ◽  
Mehmet Yavuz ◽  
Md. Nur Alam ◽  
Md. Manirul Alam Sarker ◽  
Omar Bazighifan
Keyword(s):  
Nusselt Number ◽  
Heat Exchange ◽  
Convection Heat Transfer ◽  
Heat Removal ◽  
Fluid Temperature ◽  
Convection Heat ◽  
Substantial Impact ◽  
Cool Wall ◽  
The Right ◽  
Fin Length

In the existent study, combined magneto-convection heat exchange in a driven enclosure having vertical fin was analyzed numerically. The finite element system-based GWR procedure was utilized to determine the flow model’s governing equations. A parametric inquiry was executed to review the influence of Richardson and Hartmann numbers on flow shape and heat removal features inside a frame. The problem’s resulting numerical outcomes were demonstrated graphically in terms of isotherms, streamlines, velocity sketches, local Nusselt number, global Nusselt number, and global fluid temperature. It was found that the varying lengths of the fin surface have a substantial impact on flow building and heat line sketch. Further, it was also noticed that a relatively fin length is needed to increase the heat exchange rate on the right cool wall at a high Richardson number. The fin can significantly enhance heat removal performance rate from an enclosure to adjacent fluid.

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