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• 2018-11-21 03:06發(fā)布了問答

  紅外檢測中為什么要提取信號峰值

  　

  398人看過

• 2018-11-20 14:59發(fā)布了問答

  有沒有不受自然光線影響的探測成像系統(tǒng)

  　

  300人看過

• 2018-03-31 19:25發(fā)布了問答

  紅外幕簾探測器怎么裝

  紅外幕簾探測器怎么裝

  372人看過

• 2018-01-23 07:27發(fā)布了問答

  脫硫氧化風管堵塞的原因

  脫硫氧化風管堵塞的原因御防措施... 脫硫氧化風管堵塞的原因御防措施 展開

  514人看過

• 2015-08-31 16:43發(fā)布了問答

  建筑業(yè)鋼管的正常損耗是百分之幾？

  　

  571人看過

• 2015-07-07 02:53發(fā)布了問答

  熱釋電紅外傳感器一般探測半徑是多少??？不加鏡片

  探測半徑在20 30cm怎么做

  320人看過

• 2015-05-07 22:04發(fā)布了問答

  怎么使用手持機的紅外測試啊?

  菜鳥求問，怎么使用手持機的紅外測試啊?

  435人看過

• 2012-05-01 02:52發(fā)布了問答

  環(huán)境監(jiān)控系統(tǒng)的誤報率應該是多少

  　

  540人看過

• 2012-04-03 17:07發(fā)布了問答

  規(guī)范要求多少層的建筑必須做外墻飾面磚紅外法檢測

  　

  438人看過

• 2011-11-13 10:20發(fā)布了問答

  無線紅外線對射報警器 或者無線紅外線報警器 要大功率的探測遠的

  　

  427人看過

• 2009-03-12 04:13發(fā)布了問答

  高分請高手幫忙翻譯英文文獻資料（4）

  Whenliquidisheateditevaporates.Theevaporationprocessisdependentonpressure，temperatureandcompositionoftheliquidandgas.Gascanalsocondense.Inadditionthereisaconvectiveheattr... When liquid is heated it evaporates. The evaporation process is dependent on pressure， temperature and composition of the liquid and gas. Gas can also condense. In addition there is a convective heat transfer between the liquid and gas zone that must be considered. The surfaces in the gas zone also radiates from the shell to the liquid. During the blowdown process mass is usually evacuated from the gas zone， but also liquid might be released. The rate of release is dependent on density and pressure as well as the release area. As pressure and temperature change， the properties of all materials change. This has to be considered in a prediction of a blowdown process. The main purpose of a blowdown process is as earlier stated to maintain integrity of the equipment. The strength properties of the shell are the key factor on that matter. The strength is dependent on the inside pressure as well as the support forces. If the exposing forces produce stress that exceeds the ultimate tensile stress (UTS) in some regions， the integrity of the equipment is no longer maintained. In the design phase of a process plant， these aspects are crucial and must be included as a dimensional factor. For that reason prediction of the blowdown process is essential. Lately some new standards has been introduced to the industry on this matter [3] and [4]. VessFire [1] and [2] is a multi physics system designed for calculation of this kind of problems. It has been applied for some time in the oil and process industry on many projects. The system satisfies the requirements for predictions outlined in [3] and [4]. It includes all aspects described above including integrity of the shell. As part of the verification process some experiments where performed. Some of the experiments are presented here. EXPERIMENTAL STUDY The purpose of the experiments was to investigate the evaporation process and the heat transfer to the liquid and vapour. In a complex system it is important to reduce unknown parameters as far as possible. Exposure from a flame is difficult to control. Flux measurements are point values and not necessarily representative for the average exposure. In order to control the heat exposure it was decided to apply an electric heating system. The system and the verification of the system is described in [5]， [6] and [8]. The furnace was built inside a supporting tube. Figure 2 shows a general arrangement of the experimental outfit. A 0.05 mm stainless steel foil formed as a tube， 300 mm in diameter， generated the heat. The power supply was based on a 3-phase alternating current system giving 48 Volt output as maximum. The top exposure had a limit of 300 kW. The foil had a surface of about 1 m2， giving a heat flux up to 300 kW/m2. The power input could be continuously regulated from zero to maximum load. Each experiment was started from zero and brought up to the required load within a few seconds. After that the surface temperature of the heating foil was kept constant during the exposure period. Experiments with both dry objects as well as water filled object were performed. In this paper only water filled experiments are presented Figure 2 General arrangements drawing of the experimental furnace including the specimen and its support Figure 3 Illustration of the heating unit. The black part is copper conductors for the foil. The grey part is the heating foil exposing the specimen. The foil is equipped with thermo-elements all marked H， except H5 which is the temperature in a copper ring and H6 which is the temperature between the insulation and the supporting tube. 展開

  539人看過