Transient behavior of 5 kW class shell-and-tube methane steam reformer with intermediate temperature heat source

2019 ◽  
Vol 134 ◽  
pp. 600-609 ◽  
Author(s):  
Jinwon Yun ◽  
Sangseok Yu
Keyword(s):  
Heat Source ◽  
Transient Behavior ◽  
Intermediate Temperature ◽  
Steam Reformer ◽  
Methane Steam ◽  
Temperature Heat ◽  
Shell And Tube

A Reforming Characteristics of a Mid-Temperature Methane-Steam Reformer With Various Configurations

2018 ◽  
Author(s):  
Kyungin Cho ◽  
Jinwon Yun ◽  
Sangseok Yu
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Heat Source ◽  
Cell System ◽  
Inlet Temperature ◽  
System Efficiency ◽  
Fuel Cell System ◽  
Steam Reformer ◽  
Methane Steam ◽  
Reforming Catalyst

A external methane-steam reformer is applied to fuel delivery of high temperature fuel cell system. When the reformer is equipped for high temperature fuel cell system, the heat supply of the methane steam reformer is critical to improve the system efficiency. Typically, system efficiency is improved as the waste heat is utilized. However, the general performance of steam reformer is designed to provide the rated performance at high temperature. In this study, characteristics of mid-temperature steam reformer are investigated. At mid-temperature operation of steam reformer, it is important to understand the performance of the reformer include inlet flow rate, temperature, and reformer geometry, and so on. Among them, the characteristics of the reforming catalyst are the most fundamental and most important in the performance of the reformer. Also, it is possible to optimize the performance of the reformer by understanding the reforming rate depending on the reformer inlet temperature, the amount of heat source, and the SCR (Steam to Carbon Ratio). Therefore, experimental study was carried out to understand the characteristics of the reforming catalyst. In order to carry out the experiment, the length of the reformer and the number of the heat source tubes were made variously so that the performance characteristics according to the volume of the reforming catalyst layer were confirmed. Through analysis of the experimental results, the characteristics of the reforming catalyst, which is an important factor in the performance of the reformer, can be understood under various conditions.

scholarly journals Analysis and Comparison of Some Low-Temperature Heat Sources for Heat Pumps

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1853 ◽  
Author(s):  
Pavel Neuberger ◽  
Radomír Adamovský
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Heat Source ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Ambient Air ◽  
Heat Transfer Fluid ◽  
Heat Sources ◽  
Ground Heat Exchangers ◽  
Temperature Heat

The efficiency of a heat pump energy system is significantly influenced by its low-temperature heat source. This paper presents the results of operational monitoring, analysis and comparison of heat transfer fluid temperatures, outputs and extracted energies at the most widely used low temperature heat sources within 218 days of a heating period. The monitoring involved horizontal ground heat exchangers (HGHEs) of linear and Slinky type, vertical ground heat exchangers (VGHEs) with single and double U-tube exchanger as well as the ambient air. The results of the verification indicated that it was not possible to specify clearly the most advantageous low-temperature heat source that meets the requirements of the efficiency of the heat pump operation. The highest average heat transfer fluid temperatures were achieved at linear HGHE (8.13 ± 4.50 °C) and double U-tube VGHE (8.13 ± 3.12 °C). The highest average specific heat output 59.97 ± 41.80 W/m2 and specific energy extracted from the ground mass 2723.40 ± 1785.58 kJ/m2·day were recorded at single U-tube VGHE. The lowest thermal resistance value of 0.07 K·m2/W, specifying the efficiency of the heat transfer process between the ground mass and the heat transfer fluid, was monitored at linear HGHE. The use of ambient air as a low-temperature heat pump source was considered to be the least advantageous in terms of its temperature parameters.

Development of Convective Heat Transfer Near Suddenly Heated, Vertically Aligned Horizontal Wires

1987 ◽  
Vol 109 (4) ◽  
pp. 912-918 ◽  
Author(s):  
J. R. Parsons ◽  
M. L. Arey
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Fluid Layer ◽  
Convective Motion ◽  
Transient Behavior ◽  
Temperature Fields ◽  
Heat Sources ◽  
Transfer Coefficients ◽  
Vertically Aligned ◽  
The Wire

Experiments have been performed which describe the transient development of natural convective flow from both a single and two vertically aligned horizontal cylindrical heat sources. The temperature of the wire heat sources was monitored with a resistance bridge arrangement while the development of the flow field was observed optically with a Mach–Zehnder interferometer. Results for the single wire show that after an initial regime where the wire temperature follows pure conductive response to a motionless fluid, two types of fluid motion will begin. The first is characterized as a local buoyancy, wherein the heated fluid adjacent to the wire begins to rise. The second is the onset of global convective motion, this being governed by the thermal stability of the fluid layer immediately above the cylinder. The interaction of these two motions is dependent on the heating rate and relative heat capacities of the cylinder and fluid, and governs whether the temperature response will exceed the steady value during the transient (overshoot). The two heat source experiments show that the merging of the two developing temperature fields is hydrodynamically stabilizing and thermally insulating. For small spacing-to-diameter ratios, the development of convective motion is delayed and the heat transfer coefficients degraded by the proximity of another heat source. For larger spacings, the transient behavior approaches that of a single isolated cylinder.

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