Heat transfer calculation problems for heat exchangers
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Among the device data specifications provided by the user, there is one item that states: \"Designed for 90% cleanliness\" – what does this mean? How should this be taken into account when calculating heat transfer processes?
According to the condenser standards, the fouling thermal resistance is not taken into account these days; instead, a cleaning coefficient is used in place of the fouling coefficient, thereby avoiding the need to calculate the fouling thermal resistance – it is sufficient to simply use the cleaning coefficient
I don’t understand; should the dirt coefficient be 0.9 times? If you figure it out, let me know
Can it be understood in this way that, during the operation of the heat exchanger, a cleanliness level of 90% must be maintained; that is, when calculating heat transfer, the fouling coefficient should take 10% of the empirical value. In that case, the equipment cleaning cycle becomes shorter.
What the user means is that the process calculations are not based on the fouling factor, but rather on the cleaning factor; in other words, a margin of about 10% is used. -------It’s not necessarily reliable.
Is your understanding to calculate without considering the dirt factor, with a 10% margin for the area?
Typically, for reboilers that use steam as the heat source, it is necessary to conduct additional calculations for the clean operation condition. These calculations determine the pressure drop that must be applied by the steam control valve in this condition, so that the reduction in the heat transfer temperature difference can exactly offset the effect of the high K-value during clean operation, thereby preventing excessive heating of the reboiler under those conditions. It also facilitates the proper selection of steam control valves, as well as addressing issues such as condensate collection at relatively low pressures after the use of steam control valves. The 90% cleanliness conditions listed by the original poster can be understood as scenarios where the dirt thermal resistance is taken as 10% of the normal design value to determine the cleanliness conditions.
Such a requirement is actually uncertain and represents a rather idealistic client demand. Handle it by calculating based on a clean condition, leaving a 10% margin. Moreover, such a requirement is dangerous and undesirable.
How is the area calculated using the cleaning factor?