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一、前言人们常用热导气体分析仪(即热导率检测器)来测量二元或准二元混合气的浓度(Daynes,1933年;Jessop,1966年;Warncke,1980年)。此法的依据是气体具有导热的能力和混合气热导率是其成份浓度的函数。典型的热导气体分析仪由一金属块组成。在这金属块里的一个或多个池中充满未知浓度的混合气,并用一种参考气作为清洗气体。每个池内都有一根铂丝(它是惠斯登电桥电路的一部分),并由电桥电流进行加热。金属块在恒定温度下起散热作用。为了使气体传导成为铂丝对周围进行热传递的主要机制,要把对流、辐射及通过支承的漏热等热损减到最小值。在较窄的通道中,在100℃以下,以很小的气流,选择一根细长的铂丝,通常就可达到上述目的。
I. Preface It is common to measure the concentration of binary or quasi-binary mixtures using a thermal conductivity gas analyzer (ie, thermal conductivity detector) (Daynes, 1933; Jessop, 1966; Warncke, 1980). This method is based on the ability of the gas to have thermal conductivity and the thermal conductivity of the gas mixture as a function of the concentration of its constituents. A typical thermal gas analyzer consists of a metal block. One or more cells in the metal block are filled with a mixture of unknown concentration and a reference gas is used as a purge gas. Each pool has a platinum wire (which is part of the Wheatstone bridge circuit) and is heated by the bridge current. The metal block acts as a heat sink at a constant temperature. In order for gas conduction to be the main mechanism for heat transfer around the platinum wire, heat losses such as convection, radiation, and heat leakage through the support should be minimized. In narrower passages, this is usually achieved by selecting a slender platinum wire with a small air flow below 100 ° C.