Abstract: Swing vane compressor (SVC) is a novel rotary compressor, which is structurally simple with a small size, a light weight and smooth operation. The SVC also has advantages, such as reduced frictional losses and improved mechanical efficiency at high speed. In this paper, a mathematical model including the geometrical, thermodynamic, flow and input power aspects was formulated, which was then linked to an optimization algorithm to search for three main structural design parameters under three sets of design constraints, for an optimum compressor performance with maximum energy efficiency ratio (EER). In the end, the mathematical simulation of the compressor were given and the theoretical optimization study predicted that a large reduction in frictional loss could be possibly achieved, which brings about an improvement in EER of the compressor of about 8.55%.
Abstract: Dynamic characteristics of a critical speed of the rotor components at generator geothermal power plant is evaluated using finite element method. In this study, the critical speed is evaluated based on the over speed scenario at 100%, 120% and 150% of rated speed. The critical speed of the rotor is investigated in the Campbell diagram, which shows the relationship between natural frequency and rotational velocity of the system. Based on the rotordynamic evaluation using finite element, the critical speed at 100% and 120% of the operating speed occurs in the rotational speed of 2750 and 2837 rpm, while at 150%, the critical rotation occurs in the rotational speed of 2750, 2762 and 4051 rpm. It can be concluded that the speed ranges are the critical speed or the resonance region which can be as a direct cause of the component damage, therefore the operating speed should not work too long on that critical speed.
Abstract: The aim of this paper is to study the ultimate bearing capacity of steel tubular transmission tower’s joint with annular plate based on the theoretical analysis. A simplified model of annular plate joints was performed to investigate the force distribution of the tube-gusset joints. To obtain the state of stress and ultimate bearing capacity, the annular plate with clamped boundary condition on the inner edges and subjected to diametric loading is employed in this study by the direct integration and thin plate energy principle theory. Experiment and finite element analysis are carried out and the results show that both are the similar.
Abstract: As heating transportation technology is widely used in waxy crude pipelines, elements that affect flow safety in pipeline transportation are uncertain and have wave property, thus impacting safety margin variation of the heater. This text proposes an assessment method for direct-heater performance of waxy crude pipeline station and establishes the risk assessment model for heater techniques based on waxy crude flow safety, to technically support safe and efficient waxy crude transportation.
Abstract: In this paper, two kinds of adhesive polystyrene with different proportions and one retardant polystyrene board were studied by test of non combustibility, calorific value and single combustion test. By analysis and comparison, on the premise of the roughly same cost and thermal conductivity, adhesive polystyrene materials showed much less fire risk than that of the polystyrene board.
Abstract: Research on building insulation materials and their safety is an important topic in the field of building energy conservation. The objective of this paper is to analyze the coupling effects of the width and external radiation on the downward RPU foam flame spread characteristics. The most important flame characteristics including flame height, mass loss rate, flame spread rate were studied experimentally. The results suggest that with increasing external radiation levels, flame spread rate was larger. Under the condition of the external radiation heat flux exceeds a critical level, the RPU foam would be deformed and detached from the board when the flame spread to a certain distance. It also leads to a much higher flame height due to sufficient combustion. Additionally, the flame propagation firstly accelerated when it reaches to a certain distance and then becomes a stable subject to the preheating of the external radiation heat resource.
Abstract: An experimental study on downward flame spread over extruded polystyrene (XPS) foam at a high elevation is presented. The flame shape, flame height, mass loss rate and flame spread rate were measured. The influences of width and high altitude were investigated. The flame fronts are approximately horizontal. Both the intensity of flame pulsation and the average flame height increase with the rise of sample width. The flame spread rate first drops and then rises with an increase in width. The average flame height, mass loss rate and flame spread rate at the higher elevation is smaller than that at a low elevation, which demonstrates that the XPS fire risk at the higher elevation area is lower. The experimental results agree well with the theoretical analysis. This work is vital to the fire safety design of building energy conservation system.
Abstract: The structural integrity of heat exchanger tube at high pressure heater of coal-fired power plant has been evaluated using fitness for service (FFS) assessment level 2 and 3. The purpose of this study isto determine the root cause of failure and the remaining life of components thereforethe possibility of failure due to improper design and operation can be known and it become a reference fordesigning a new design tubein a retubing process. Based on the evaluation results using level 2 assessment, the failureon the heat exchanger tubesisnotcaused bythe material creep becausethe total damage due to creep has been successfully met the requirements with the operating life3.873x109hours. However, base on the results of level 3 assessment using finite element, the minimum safety factor against yielding is below 1.0 and itdoesn’t meet the plastic collapse criterion, therefore the possibility of leakage failure on the tube is caused by the improper design which the construction of the tube is not able to withstand the operating load.
Abstract: Flash point and boiling point are the important physical property of the flammable liquids, and are important parameters to evaluate their combustion behavior. In this study, as series of measurement of two mono compound fuels (N-decane and N-hexanol) and two mixture compound fuels (0# diesel and Jet A) at different pressure were carried out by using the flash point (open-closed cup) and boiling point measuring apparatus in an altitude chamber at different sub-atmospheric pressures at 35 KPa, 45 KPa, 55 KPa, 65 KPa, 75 KPa, 85 KPa, 95 KPa and 101 KPa were conducted. Based on the theoretical formula between the flash point (TF) and the boiling point (TB) and the atmosphere pressure, the relationship between TB and TF has been derived. The experiment results and the theoretical formula all show that the flash point is in linear relationship with the boiling point. The results can provide a more scientific insight into the production, storage, transport and use of fuel and the safety design in aircraft fuel tank.
Abstract: The recent work found the physical properties that greatly affected the transport phenomena; enthalpy values and thermal conductivity values in the pyrolysis process. In the previous work, it was assumed as constant variable. Meanwhile, there were a dependence between the variables and the pyrolysis temperature. Then, it would be calculated both physical properties by using bomb calorimeter and thermal conductivity testing apparatus.In the experimental runs, biomass was shaped in the form of needle particles about 1 μm and run 3 hours to produce char and tar yields. It was carried out at a temperature setting from 250°C to 800°C. To support analysis of the thermal conductivity values, the char yields were visualized by using direct photograph and SEM by 3000 times magnification to investigate the char quality based on the color and the structure of char material imaging their porrosities. The results showed that the entalpy values of char increased with the increasing of pyrolysis temperatures, however, the enthalpy values of tar inclined up to temperature of 500°C. Afterward, it decreased for the reason that the biomass was decomposed gas products in secondary reaction. Another result presented the thermal conductivity increased up to 500°C then it reached almost constant values. The increasing of the thermal conductivity values due to carbon and porosity of char.