Fluidized bed biomass gasifiers can be employed to produce hydrogen-rich gas. A non-premixed combustion model is used for biomass air-steam gasification in the gasifier, and the simulations were carried out by using t...Fluidized bed biomass gasifiers can be employed to produce hydrogen-rich gas. A non-premixed combustion model is used for biomass air-steam gasification in the gasifier, and the simulations were carried out by using the FLUENT 6.0 software. The simulation results are compared with the experimental data. The effects of the steam to biomass ratio （S/B）, the equivalence ratio （ER）, and the size of biomass particles on the hydrogen yield were studied. Meanwhile, the distributions of hydrogen inside the gasifier at different conditions are also described.展开更多
Convective heat transfer coefficient is one of the most vital parameters which reveals the thermal efficiency of a pipe flow.To obtain such coefficients for problems with variable pipe wall temperature,numerical itera...Convective heat transfer coefficient is one of the most vital parameters which reveals the thermal efficiency of a pipe flow.To obtain such coefficients for problems with variable pipe wall temperature,numerical iterative methods should be used which could be time-consuming and less accurate.In this paper,thermophysical properties of fluids are assumed to be constant.We define a variable related to the temperature gradient of the pipe wall and study the varying law of the local coefficient.Then,a sample-based scheme is proposed to avoid the calculation of a time-consuming problem in the use of solutions with low computing cost.To verify its accuracy,several problems in normal circle pipes with variable factors,such as the various temperatures of the pipe wall,the different radius of the pipe,and various velocities of fluid flow,are well resolved.Meanwhile,its validity in a convergent pipe is also studied.From the obtained results,the high accuracy and efficiency of the proposed scheme can be confirmed.Therefore,the proposed scheme for determining the convective heat transfer coefficient has great potential in engineering problems.展开更多
文摘Fluidized bed biomass gasifiers can be employed to produce hydrogen-rich gas. A non-premixed combustion model is used for biomass air-steam gasification in the gasifier, and the simulations were carried out by using the FLUENT 6.0 software. The simulation results are compared with the experimental data. The effects of the steam to biomass ratio （S/B）, the equivalence ratio （ER）, and the size of biomass particles on the hydrogen yield were studied. Meanwhile, the distributions of hydrogen inside the gasifier at different conditions are also described.
基金the National Natural Science Foundation of China(Grant No.12072103)the Fundamental Research Funds for the Central Universities(Grant No.B200202126)+2 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20190073)the State Key Laboratory of Acoustics,Chinese Academy of Sciences(Grant No.SKLA202001)the China Postdoctoral Science Foundation(Grant Nos.2017M6I 1669 and 2018T110430).
文摘Convective heat transfer coefficient is one of the most vital parameters which reveals the thermal efficiency of a pipe flow.To obtain such coefficients for problems with variable pipe wall temperature,numerical iterative methods should be used which could be time-consuming and less accurate.In this paper,thermophysical properties of fluids are assumed to be constant.We define a variable related to the temperature gradient of the pipe wall and study the varying law of the local coefficient.Then,a sample-based scheme is proposed to avoid the calculation of a time-consuming problem in the use of solutions with low computing cost.To verify its accuracy,several problems in normal circle pipes with variable factors,such as the various temperatures of the pipe wall,the different radius of the pipe,and various velocities of fluid flow,are well resolved.Meanwhile,its validity in a convergent pipe is also studied.From the obtained results,the high accuracy and efficiency of the proposed scheme can be confirmed.Therefore,the proposed scheme for determining the convective heat transfer coefficient has great potential in engineering problems.
