The inverse estimation of the thermal boundary behavior of a heated cylinder normal to a laminar air stream

2000 ◽  
Vol 43 (21) ◽  
pp. 3991-4001 ◽  
Author(s):  
Jiin-Hong Lin ◽  
Cha’o-Kuang Chen ◽  
Yue-Tzu Yang
2002 ◽  
Vol 124 (4) ◽  
pp. 601-608 ◽  
Author(s):  
Jiin-Hong Lin ◽  
Cha’o-Kuang Chen ◽  
Yue-Tzu Yang

A two-dimensional inverse analysis utilizes a different perspective to simultaneously estimate the center and surface thermal behavior of a heated cylinder normal to a turbulent air stream. A finite-difference method is used to discretize the governing equations and then a linear inverse model is constructed to identify the unknown boundary conditions. The present approach is to rearrange the matrix forms of the governing differential equations and estimate the unknown boundary conditions of the heated cylinder. Then, the linear least-squares-error method is adopted to find the solutions. The results show that only a few measuring points inside the cylinder are needed to estimate the unknown quantities of the thermal boundary behavior, even when measurement errors are considered. In contrast to the traditional approach, the advantages of this method are that no prior information is needed on the functional form of the unknown quantities, no initial guesses are required, no iterations in the calculating process are necessary, and the inverse problem can be solved in a linear domain. Furthermore, the existence and uniqueness of the solutions can easily be identified.


Equipment ◽  
2006 ◽  
Author(s):  
M. Ren ◽  
C. C. M. Rindt ◽  
Anton A. van Steenhoven

2012 ◽  
Vol 33 (2) ◽  
pp. 231-242 ◽  
Author(s):  
Marek Juszczak ◽  
Katarzyna Lossy

Pollutant emission from a heat station supplied with agriculture biomass and wood pellet mixtureTests for combustion of hay and sunflower husk pellets mixed with wood pellets were performed in a horizontal-feed as well as under-feed (retort) wood pellet furnace installed in boilers with a nominal heat output of 15 and 20 kW, located in a heat station. During the combustion a slagging phenomenon was observed in the furnaces. In order to lower the temperature in the furnace, fuel feeding rate was reduced with unaltered air stream rate. The higher the proportion of wood pellets in the mixture the lower carbon monoxide concentration. The following results of carbon monoxide concentration (in mg/m3presented for 10% O2content in flue gas) for different furnaces and fuel mixtures (proportion in wt%) were obtained: horizontal-feed furnace supplied with hay/wood: 0/100 - 326; 30/70 - 157; 50/50 - 301; 100/0 - 3300; horizontal-feed furnace supplied with sunflower husk/wood: 50/50 - 1062; 67/33 - 1721; 100/0 - 3775; under-feed (retort) furnace supplied with hay/wood: 0/100 - 90; 15/85 - 157; 30/70 - 135; 50/50 - 5179; under-feed furnace supplied with sunflower husk/wood: 67/33 - 2498; 100/0 - 3128. Boiler heat output and heat efficiency was low: 7 to 13 kW and about 55%, respectively, for the boiler with horizontal-feed furnace and 9 to 14 kW and 64%, respectively, for the boiler with under-feed furnace.


Author(s):  
Erick Kim ◽  
Kamjou Mansour ◽  
Gil Garteiz ◽  
Javeck Verdugo ◽  
Ryan Ross ◽  
...  

Abstract This paper presents the failure analysis on a 1.5m flex harness for a space flight instrument that exhibited two failure modes: global isolation resistances between all adjacent traces measured tens of milliohm and lower resistance on the order of 1 kiloohm was observed on several pins. It shows a novel method using a temperature controlled air stream while monitoring isolation resistance to identify a general area of interest of a low isolation resistance failure. The paper explains how isolation resistance measurements were taken and details the steps taken in both destructive and non-destructive analyses. In theory, infrared hotspot could have been completed along the length of the flex harness to locate the failure site. However, with a field of view of approximately 5 x 5 cm, this technique would have been time prohibitive.


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