Thermal mass

In practice, direct insertion of samples requires a somewhat more elaborate arrangement than might be supposed. The sample must be placed on an electrode before insertion into the plasma flame. However, this sample support material is not an electrode in the usual meaning of the term since no electrical current flows through it. Heating of the electrode is done by the plasma flame. The electrode or probe should have small thermal mass so it heats rapidly, and it must be stable at the high temperatures reached in the plasma flame. For these reasons, the sort of materials used... 

Samples to be examined by inductively coupled plasma and mass spectrometry (ICP/MS) are commonly in the form of a solution that is transported into the plasma flame. The thermal mass of the flame is small, and ingress of excessive quantities of extraneous matter, such as solvent, would cool the flame and might even extinguish it. Even cooling the flame reduces its ionization efficiency, with concomitant effects on the accuracy and detection limits of the ICP/MS method. Consequently, it is necessary to remove as much solvent as possible which can be done by evaporation off-line or done on-line by spraying the solution as an aerosol into the plasma flame. 

General Principles There are two main types of mass flowmeters (1) the so-called true mass flowmeter, which responds directly to mass flow rate, and (2) the inferential mass flowmeter, which commonly measures volume flow rate aud flmd density separately. A variety of types of true mass flowmeters have been developed, including the following (a) the Maguus-effect mass flowmeter, (b) the axial-flow, transverse-momentum mass flowmeter, (c) the radial-flow, transverse-momentum mass flowmeter, (d) the gyroscopic transverse-momentum mass flowmeter, aud (e) the thermal mass flowmeter. Type b is the basis for several commercial mass flowmeters, one version of which is briefly described here. 

Gas-cooled, graphite moderated reactors have several significant advantages over other reactor designs by virtue of their inherent passive safety characteristics. These are the result of the large thermal mass of the graphite core, the high... 

The thermal mass of parts and tools and the heating capacity of the autoclave naturally limit the maximum heating rate. Attempting to increase the heat-up rate by overheating the autoclave air can result in overheating of areas of the assembly with low thermal mass. 

The vent sizing package (VSP) was developed by Fauskes Associates, Inc. The VSP and its latest version VSP2 employ the low thermal mass test cell stainless steel 304 and Hastelloy test cell with a volume of 120 ml contained in a 4-1, high-pressure vessel as shown in Figure 12-13. The typical ([t-factor is 1.05-1.08 for a test cell wall thickness of 0.127-0.178 mm. Measurements consist of sample temperature Tj and pressure Pj, and external guard temperature Tj and... 

The device consists of a low thermal mass test cell of 110 ml volume. This is made of stainless steel with a 0.015-mm wall thickness, but test cells made from other materials can be used. The contents of the cell are mixed using either a magnetically driven stirring bar or a direct drive agitation test cell. The test cell is... 

Position and direction, U-value, solar factor, and thermal mass of the different construction elements. 

Estimate maximum temperature increase in the room, taking into consideration the actual heat release from people and machinery, shading for solar radiation, assuming no thermal mass, and using a typical airflow for ventilation. 

The sensor is the element of an instrument directly influenced by the measured quantity. In temperature measurement the thermal mass (capacity) of the sensor usually determines the meter s dynamics. The same applies to thermal anemometers. In IR analyzers used for concentration measurement, the volume of the flow cell and the sample flow rate are the critical factors. Some instruments, like sound-level meters, respond very fast, and follow the pressure changes up to several kHz. 

Modern low-density insulation such as those based on ceramic fibers can be used to save energy in plant operating on a batch basis. The low thermal mass permits a rapid heating and cooling period that can save a substantial amount of energy. With continuously operating plant the advantages are not so pronounced. 

Thermal mass transfer (see also Section 2.9) When a temperature gradient... 

Simultaneous Differential Thermal-Mass Spectrometer Analysis of Nitrate Salts of Mono-methylhydrazine and Methylamine , SAMSO TR-70-117(1970) 54) Anon, Propellants,... 

Let us think that a temperature sensitive good is inside a well insulated box. To stabilize the temperature at the desired value, the thermal mass of the interior is strongly increased by adding PCM with suitable melting point and mass. Everybody has done this before when adding ice packs to a picnic basket. 

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