| Project/Area Number |
10450078
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B).
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Thermal engineering
|
|---|
| Research Institution | TOHOKU UNIVERSITY |
|---|
Principal Investigator |
NIIOKA Takashi INSTITUTE OF FLUID SCIENCE, TOHOKU UNIVERSITY, PROFESSOR, 流体科学研究所, 教授 (90208108)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HANAI Hironao INSTITUTE OF FLUID SCIENCE, TOHOKU UNIVERSITY, RES.ASSO, 流体科学研究所, 助手 (30312664)
KOBAYASHI Hideaki INSTITUTE OF FLUID SCIENCE, TOHOKU UNIVERSITY, ASSO., 流体科学研究所, 助教授 (30170343)
丸田 薫 東北大学, 流体科学研究所, 講師 (50260451)
|
|---|
| Project Period (FY) |
1998 – 2000
|
| Project Status |
Completed (Fiscal Year 2000)
|
| Budget Amount *help |
¥8,300,000 (Direct Cost: ¥8,300,000)
Fiscal Year 2000: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1999: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1998: ¥4,100,000 (Direct Cost: ¥4,100,000)
|
|---|
| Keywords | Reduction of CO_2 / NO_x / Radiation heat loss / Burning velocity / Lifted flame / Premixed flame / Diffusion flame / NO_x / 予混合火炎 / 二酸化炭素 / 酸化窒素 / 予混合火災 / 非灰色ふく射 / 拡散火災 / CO_2希釈 / 酸素燃焼 / 可燃限界 / 層流燃焼速度 / 光学的厚さ |
|---|
| Research Abstract |
To develop a combustion system that is suitable for CO_2 recovery and has less emission of pollutants, a new combustion method using CO_2/O_2as oxidant has been proposed. However, the epically thin and gray-gas radiation model with Planck mean absorption coefficient, which has no reabsorption, has overestimated the emission, especially for "low-speed" flames. The effects of nongray radiation on the propagation and flammability limit of premixed CH_4/O_2/CO_2 flames were numerically analyzed. The results can be summarized as follows :
1. The nongray radiation effects described by the statistical narrow-band (SNB) model on the laminar
burning velocity and flammability limit become larger as the dilution ratio of CO_2 is increased.
2. The gray radiation described by the optically thin model (OTM) loses effectiveness for higher CO_2 dilution ratios and lower equivalence ratios.
An experimental and numerical study of diluent (CO_2 or N_2) effects on structure and stability of axisymmetric lifted laminar diffusion CH_4/(Diluent+O_2) flames were also performed over a wide range of the dilution ratio, Z.Results showed that
3. As increasing the Z, attached flames are lifted off at the Z_<lim> (0.72 for CO_2, 0.83 for N_2 diluted flame, respectively) and there were steady responses that the flame length. L_f, shortened and the lift off height, H_f, increased as well as the spreading out of the flame base in the radial direction until the Z_b (0.78 for CO_2, 0.86 for N_2 diluted flame, respectively).
4. The leading edge structure of the lifted flame has a triple flame, where fuel rich premixed wing is smaller than lean one and the trailing nonpremixed flame inclines immediately to the fuel side from trip point.
5. It is also shown that CO_2 effects are stronger than N_2 on the structure and stability due to high heat capacity and low transport rate of Co_2.
|
