Case temperature

Checks on environmental conditions within the instruments, such as verifying that the case temperature is within specifications. 

The gas usually deviates considerably from the perfect-gas laws, and in many cases temperature or other limitations necessitate a thor-... 

Temperature The temperature of the extraction should be chosen for the best balance of solubility, solvent-vapor pressure, solute diffusivity, solvent selectivity, and sensitivity of product. In some cases, temperature sensitivity of materials of construction to corrosion or erosion attack may be significant. 

Endurance Burn Under certain cou(itious, a successfully arrested flame may stabilize on the unprotected side of an arrester element. Should this condition not be corrected, the flame will eventually penetrate the arrester as the channels become hot. An endurance burn time can be determined by testing, which specifies that the arrester has withstood a stabilized flame without penetration for a given period. The test should address either the actual or worst-case geometry, since heat transfer to the element will depend on whether the flame stabilizes on the top, bottom, or horizontal face. In general, the endurance burn time identified by test should not be regarded as an accurate measure of the time available to take remedial action, since test conditions will not necessarily approximate the worst possible practical case. Temperature sensors may be incorporated at the arrester to indicate a stabilized flame condition and either alarm or initiate appropriate action, such as valve closure. 

Anodic protection against acids has been used in a number of processes in the chemical industry, as well as during storage and transport. It is also successful in geometrically complicated containers and tubings [12], Carbon steel can be protected from nitric and sulfuric acids. In the latter case, temperature and concentration set application limits [17]. At temperatures of up to 120°C, efficient protection can only be achieved with concentrations over 90% [ 18]. At concentrations between 67 and 90%, anodic protection can be used at up to 140°C with CrNi steels [19]. 

An important mixing operation involves bringing different molecular species together to obtain a chemical reaction. The components may be miscible liquids, immiscible liquids, solid particles and a liquid, a gas and a liquid, a gas and solid particles, or two gases. In some cases, temperature differences exist between an equipment surface and the bulk fluid, or between the suspended particles and the continuous phase fluid. The same mechanisms that enhance mass transfer by reducing the film thickness are used to promote heat transfer by increasing the temperature gradient in the film. These mechanisms are bulk flow, eddy diffusion, and molecular diffusion. The performance of equipment in which heat transfer occurs is expressed in terms of forced convective heat transfer coefficients. 

In the second case, temperature rises very rapidly, so the liquid is not heated to a temperature above the superheat limit temperature at failure, and no liquid flashing occurs. To demonstrate the influence of fill ratio, cases of 80% and 10% fill ratio are considered. 

As an additional aid to readers seeking further information of a specific subject, references are included at the end of each chapter. Throughout the text, different units are used interchangeably as they are in the industry. However, in most cases temperatures are in degrees Celsius, pressures in atmospheres, and energy in kilo joules. 

May be used on high-temperature hot water or low-pressure steam without casing temperature becoming dangerously high fairly rapid response to conhol. 

Prior to the now almost universal adoption of the SI system of units, the unit of heat was defined as the quantity of heat required to raise the temperature of unit mass of water by one degree. This heat quantity is designated the calorie in the cgs system and the kilocalorie in the mks system, and in both cases temperature is expressed in degrees Celsius (Centigrade). As the specific heat capacity is a function of temperature, it has been necessary to set a datum temperature which is chosen as 298 K or 25°C. 

The variable factor in reaction series usually was a substituent change, although solvent variation also has been given special attention (39-44). Variations of catalyst (4, 5, 23-25, 45-49), ionic strength (50), or pressure (51, 52) also have been studied. In exceptional cases, temperature can become the variable parameter if the kinetics has been followed over a broad temperature range and the activation parameters are treated as variable (53), or temperature as well as structural parameters can be changed (6). Most of the work done concerns kinetics, but isoequilibrium relationships also have been observed (2, 54-58), particularly with ionization equilibria (59-82). 

In that case, temperature is use for compensation, so if the feed flow is increased, the temperature might be increased such measures usually have a penalty in catalyst life. 

But we still need to know the actual local ambient in the immediate vicinity of the capacitor. Nearby components may also be heating the capacitor. Therefore a common and perhaps conservative industry practice is to cut the outer sleeving of the capacitor and to insert a thermocouple under the sleeve in contact with the metal case. That way small air draughts don t affect the results. We then take this measured case temperature as the effective ambient for the cap, unless of course we know better. Suppose the case temperature is measured to be 70°C in this way, then the conservative estimate of capacitor life is... 

Therefore a case temperature measurement may not suffice. We should also measure the ripple current passing through the capacitor. 

If the measured ripple current is confirmed to be within the rating, we can then take the case temperature measurement as the basis for applying the normal 10°C doubling rule, even if the heat is coming from adjacent sources. Again, that is only because the case to core temperature differential is actually within the capacitor s design expectations. 

Question We are using a 2200 xF/10V capacitor from Chemicon. Its catalog specifications are 8000 hours at maximum rated 1.69A, stated at 105°C and 100kHz. The measured case temperature in our application is 84°C and the measured ripple current is 2.2A. What is the expected life ... 

Rather than take the case temperature as the local ambient temperature of the capacitor, which is more of a worst-case calculation, we could try to actually measure the local ambient. Assume that the general ambient is Lamb ext- The local ambient near the capacitor is Lamb. The procedure to factor out the heat from nearby components (i.e., heat which is not due to ripple current) is as follows ... 

At the same time we place an exactly similar capacitor at the position where the original capacitor was, but this has one lead missing, so it is in effect not connected to the circuit. We measure its case temperature TcAse 2- This is... 

One quick test of whether the current passing through an electrolytic capacitor is within bounds is to touch it after it has been running for some time (high-voltage power supplies must be turned OFF just prior to this ). If an electrolytic capacitor has been designed with the normal recommended procedures for ensuring its life, the delta between its case temperature and the ambient temperature should be almost equal to the delta between its... 

Reaction calorimetry provides information on the maximum heat generation at process temperatures and on the adiabatic temperature rise. This ATad provides insight into the worst-case temperature consequences. 

Vinylcyclopropanes bearing a cis alkyl substituent undergo a competitive prototropic shift accompanying ring opening (Eq. 14)14). In such cases, temperature... 

The rate of chemical attack will depend on the concentration according to the order of the reaction (i.e. in a zero-order reaction the rate is independent of concentration, in a first-order reaction the rate depends linearly on concentration, and in second-order reaction the rate depends on the square of concentration). Increasing the concentration, therefore, provides a means of acceleration. Remember, however, that chemical attack on plastics is a liquid-solid and not a liquid-liquid reaction, such that the reaction laws only hold if there is free movement of all chemical species with no limitations due to diffusion or transport and no barrier layers. Since this is rarely the case, temperature is preferred as a means of acceleration. 

Functionalization can, of course, also be carried out in solution, e.g., in te-trahydrofuran. In this case, temperature control is much easier and the problem of undesired condensation in the functionalization step is reduced. The viscosity increase due to the stronger hydrogen bondings of the formed carboxylic acid end groups is not of importance in the modification step in solution as viscosity can be adjusted through the amount of solvent. Nevertheless, complete solvent removal afterwards sometimes turns out to be laborious. 

Spaces between the coal block and the reactor walls are filled with refractory cement to prevent accumulation of combustible gases, and leaks are exhausted from the outer casing. Temperatures are measured with 1/8" Type K SS sheathed thermocouples, which are cemented Into the block at predetermined locations. 

The separation selectivities in the hrst dimension shonld largely differ from that in the second dimension. Best results are achieved in so-called orthogonal systems with non-correlated retention times in both dimensions [172,173]. Mobile phase, flow rate, and in some cases, temperature should be optimized in each dimension to increase the number of resolved compounds in a single rnn. 

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