Advanced Materials Research Vols. 516-517

Abstract: For the use of boiler flame image analysis to detect the boiler flame combustion stability, when the combustion affected by coal, peaking , improper operation or other effects, the flame appeared short pulsation. In general, the traditional detection methods based on gray scale variance can not avoid the impact of flame pulsation on account of the inaccuracy of the boiler combustion stability detection. This paper presents a flame combustion instability detection method based on neural network and selects multiple features which are directly related to the flame stability as neural network input vector. Experiments show that this method can fight off the tiny ripple influence caused by the impurities combustion or peak and simultaneously, greatly improve the detection accuracy and stability.

Abstract: This paper progresses to dynamically simulate and study the heat transfer process of horizontal ground heat exchangers in the multi-grooves by the use of numerical simulation based on the layout and heat extraction or rejection conditions of horizontal ground heat exchangers under the artificial lake. Effect of buried pipe type and groove spacing on the heat exchanger process is analyzed in detail. The influence of annual average water temperature change on the surrounding environment is evaluated with the introduction of parameters including summer weekly average maximum temperature rise and winter weekly average maximum temperature drop, in which can take the technical supports for the design of horizontal ground source heat pump system.

Abstract: By study the development situation of blast furnace smelting in china and the blast furnace operation system and technology, combined with production conditions of JISC BF, based on a large number of the production data, the comparison analysis test on JISC BF operation system and technology was did. Through continuously optimization and practice, the relatively suitable operation system and technology of JISC BF at present was explored, which could reduce the coke ratio into furnace while increasing the coal injection ratio and making great economic effect.

Abstract: Abstract. Aim at the problems of acid corrosion and dust blocking in heating surface at the rear of heating surface for oil-fired boiler, which comes from industrial production practice, a analysis in detail is carried on the reason of the acid corrosion formation and the mechanism of dust deposition, base on that are some preliminary solutions put forward according to the work practice. It can be proved to have a good effect on the safety and energy saving during the use and maintenance process of the oil-fired boiler and it can also provide a reference to the enrichment and perfection about the correlation theory of the oil-fired boiler.

Abstract: During recent years,micro-channel heat transfer technique has been successfully used in many practical situations，and has notable advantages of high heat transfer efficiency and compact configuration.It is an important subject in modern hydrodynamic and heat transfer research field.Computational fluid dynamic program CFX will be used in this article to simulate flow and heat transfer of single-phase water in micro-channel ,flow and temperature felid will be described visually in CFX, and this object is searching a new method to research more flow and heat transfer of single-phase water.

Abstract: Through methods, such as microscope analysis, metallographic examination, the crack located nearby the fusion line between reheating hot pipe elbow and blocking valve is reheat crack. The base metal material and excessive welding residual stress are the primary inducement of crack. In replacing pipe elbow, the measures of reducing residual stress, such as hammer blowing ,lower welding heat input, post welding heat treatment and so on, were taken. The welding repair succeeded greatly.

Abstract: In this article, sensitivity analysis was performed using bidirectional single method with shell-and-tube heat exchanger as the basis and the entropy production in the working process of heat exchanger as target, to explore the optimizing direction for heat exchangers with the objective to reduce entropy production. First, the differential element analysis method was used in a case study of the entropy production of the heat transfer process - including the three heat transfer processes of convective heat exchange inside and outside the pipes and heat conduction across the pipe wall and the flow process - the fluid flowing process inside and outside the pipes, and the typical process parameter - dimensionless inlet heat exchange temperature difference, operation parameter - fluid flow rate inside the pipe and structural parameters - the heat transfer pipe inner diameter and length were used as characteristic parameters, to obtain the sensitivity coefficients under the conditions of the example, being respectively 0.95, 0.3, 0.3 and 0.38. The study in this article can provide some support to the energy efficiency evaluation of heat exchangers.

Abstract: LED have the special character that LED break out radiant power and heat when it is operating. Recently photo efficiency of LED is just 20% and almost residual power converts heat. But heat causes bad reliability and changes of electrical and optical character negatively. Therefore, the LED package design is the first issue for the solution of the heat problem. This study was to design a LED T-junction measurement platform which based on the required of JEDEC-51-1. The experiment results include four parts: (1) Manually retrieve VFss voltage, the temperature raised around 3~5°C between the chip junction temperature and LED pin; (2) Automatically retrieve VFss voltage, the temperature raised around 30~50°C for the same condition; (3) From trend of TJ vs. time, the definition of the steady state require at least 900 sec, but we would suggest 1200 sec in this study; (4) There is no significant difference of the TJ for the retrieval time 100 μs and 10μs. The important achievement of the results of this experiment can be used as a reference for TJ measurement.

Abstract: A relative full-scale numerical simulation has been conducted on oscillating heat pipe(OHP) with single passageway(S-OHP)and double passageway(D-OHP). Mathematical model for studying the influence on the heat transfer performance of the number of passageway was built, including turbulence model, volume of fluid model, continue surface force model, and heat and mass transfer model caused by phase change, and all of which were based on the consideration of gas-liquid interface, wall adhesion angle, surface tension and process of phase change. Results showed that, on the one hand, strong coherence of the initial gas-liquid distribution, as well as the flow phenomena during boiling stage, were found between S-OHP and D-OHP, on the other hand, the heat-transfer capability of the D-OHP is slightly higher than the S-OHP.

Abstract: The aim is to describe the irreversibility of energy system under transient conditions more scientifically and to lay foundation for further energy saving under transient conditions. On the basis of the existing research, a model for exergy destruction in single-phase heated surfaces of boiler under transient conditions was established. Taking a 1913t/h-boiler as an example, exergy destructions in single-phase heated surfaces of the boiler and their distributions among processes were calculated respectively. The results were compared with those calculated by models under steady conditions. The analysis shows that exergy destruction in each heated surface under transient condition is still mainly related to the difference of temperature and transferred heat. Some error occurs when models for steady conditions are used for simulation of transient conditions. The main reason is that the heat stored in metal as well as the time rate of exergy is ignored.