Temperature coolant

The effect on the coolant temperature of latent and sensible heat transferred to the surface from the condensing vapor is as shown in equation 5 ... 

T Absolute temperature T, for bulk temperature T, for wall temperature T, for vapor temperature for coolant temperature Tg for temperature of emitter T,. for temperature of receiver K ... 

Environment Mill coolant temperature 160°F (71 °C), turbulent flow... 

For large motors, which use water as the secondary coolant in a closed circuit, the temperature of the cooling air, i.e. of the primary coolant, varies with the temperature of the cooling water inlet temperature and its rate of flow. For the performance of the motor output, this primary coolant, temperature has the same significance as the ambient temperature for an air-cooled motor. The motor output is unaffected by the ambient temperature. For such motors the output graph is shown in Figure 1.13 at different coolant temperatures and altitudes. The rating at 25°C inlet water temperature for water-cooled machines is the same as for air-cooled machines at an ambient temperature of 40°C. 

Water-Cooled motors, type CACW (cooling type ICW 37 A 81 or ICW 37A 91) (Section 1.16, Table 1.12) should be fitted with moisture detectors to provide an audio-visual alarm in the event of a leakage in the water circuit or a higher coolant temperature. 

Figure 8.1.4r Simulated temperature profiles with true kinetics and coolant temperature as parameters. ...

The above expression defines the minimum coolant temperature that can be used, with the corresponding U and S to remove the heat. A lower U and S, which would require lower temperature, would make the system sensitive. This seems to be counterintuitive in general, yet not for those who remember the introductory explanation at the first page of this chapter. 

Emission factors must be also critically examined to determine the tests from which they were obtained. For example, carbon monoxide from an automobile will vary with the load, engine speed, displacement, ambient temperature, coolant temperature, ignition timing, carburetor adjustment, engine condition, etc. However, in order to evaluate the overall emission of carbon monoxide to an area, we must settle on an average value that we can multiply by the number of cars, or kilometers driven per year, to determine the total carbon monoxide released to the area. 

The fractionator shell itself should often have some extra trays. Conventional instrumentation alone cannot always be expected to handle all the things that can happen to a fractionation system, such as changes in feed composition, reboiler steam pressure, or coolant temperature (especially for an air condenser during a sudden cold front). Experience for a given service is the best guide for extra trays. 

A = heat transfer surface area c = specific heat of batch liquid C = coolant specific heat M = weight of batch liquid Tj = initial batch temperature Tj = final batch temperature tj = initial coolant temperature U = overall heat transfer coefficient = coolant flowrate 6 = time... 

In any particular cycle calculation, with the inlet gas temperature known together with the inlet coolant temperature Tcj, and with an assumed allowable metal temperature Tb), E() was determined from Eq. (A7). W" was then obtained from Eq. (A 18) and the cooling flow fraction i/ from Eq. (A16). 

When forced coolant systems are used, care must be taken to provide the coolant at the proper temperature. If the cylinder is too cool, liquids could condense from the suction gas stream. Thus, it is desirable to keep the coolant temperature 10°F higher than that of the suction gas. If the cylinder is too hot, gas throughput capacity is lost due to the gas heating and expanding. Therefore, it is desirable to limit the coolant temperature to less than 30°F above that of the suction gas. 

Precondensers are recommended for any ejector system when the pressure conditions and coolant temperature will allow condensation of vapors, thus reducing the required design and operating load on the ejectors. This is usually the situation when operating a distillation column under vacuum. The overhead vapors are condensed in a unit designed to operate at top column pressure, with only the non-condensables and vapors remaining after condensation passing to the ejector system. 

The method is to switch off the compressor after a short running period, and so stop the flow of thermal energy into the condenser, hut continue to run the condenser until it has reached amhient conditions. The refrigerant vapour pressure can then he determined from the coolant temperature, and any increase indicates nonrefrigerant gas in the system. 

The process is indicated on the chart in Figure 24.9, taking point B as the tube temperature. Since this would be the ultimate dew point temperature of the air for an infinitely sized coil, the point B is termed the apparatus dew point (ADP). In practice, the cooling element will be made of tubes, probably with extended outer surface in the form of fins (see Figure 7.3). Heat transfer from the air to the coolant will vary with the fin height from the tube wall, the materials, and any changes in the coolant temperature which may not be constant. The average coolant temperature will be at some lower point D, and the temperature difference B — D will be a function of the conductivity of the coil. As air at condition A enters the coil, a thin layer will come into contact with the fin surface and will be cooled to B. It will then mix with the remainder of the air between the fins, so that the line AB is a mix line. 

Xn practice, temperature control is used on the coolant to maintain the reaction temperature at a higher, commercially acceptable, level while maintaining control. When the minimum coolant temperature is reached, however, any further increase in reaction rate will lead to ignition. 

Solution Now, Ar=107°C. Scaling with geometric similarity would force the temperature driving force to increase by S = 1.9, as before, but the scaled-up value is now 201°C. The coolant temperature would drop to —39°C, which is technically feasible but undesirable. Scaling with constant pressure forces an even lower coolant temperature. A scaleup with constant heat transfer becomes attractive. 

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