Evaporation area and heat exchange area How the evaporation space affects the refrigeration capacity

The influence of ammonia cooler liquid level on the size of refrigeration capacity: 1The ammonia cooler has a high liquid level, a large heat exchange area between liquid ammonia and the process medium, but a small evaporation space and a small actual refrigeration capacity.

Moreover, it is easy to cause ammonia cooler to carry liquid. 2. The liquid level of the ammonia cooler is high, the heat exchange area of liquid ammonia and process medium is small, but the evaporation space is large, and the actual refrigeration capacity is small. Therefore, in the normal production process, the control of the liquid level of the ammonia cooler should be in the right position, too high and too low are not suitable.

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Of course, the larger the evaporation area and the heat transfer area, the better, but the evaporation space will become smaller due to the large evaporation area, and the larger the evaporation space, the better, but to ensure that there is enough liquid ammonia for flash evaporation, which requires the best control of the liquid level of the ammonia cooler, which can ensure the evaporation space and the evaporation of liquid ammonia. View the original post

Friends on the 3rd floor are ammonia coolers, not ammonia condensers. To add: if the evaporation space is insufficient, the amount of liquid ammonia entrained by gas ammonia will increase, which may increase the load of ammonia compressor, affect the evaporation pressure of ammonia, reduce the cooling capacity, and increase consumption. View the original post

This requires a design formula, within a certain range, of course, the larger the area, the better the heat exchange effect. View the original post

The evaporation area and heat exchange area have a great influence on the heat exchange of the ammonia cooler, which will reduce the evaporation space and cause insufficient heat exchange. Gas ammonia is not liquid ammonia when it is cooled. View the original post

Summary. How to calculate the evaporation capacity and heat exchange area of the ammonia evaporator.

The simple formula for calculating the heat exchange area is f=q kk*tm, f is the effective local heat exchange area of the heat exchanger, q is the total heat exchange, k is the dirt coefficient generally, k is the heat transfer coefficient, and tm is the logarithmic average temperature difference. Heat transfer refers to the heat transfer of family macros between hot and cold fluids, and is a unit operation that belongs to the heat transfer process. The main purposes of heat exchange are:

Heating, cooling, vaporization, or condensation of materials to achieve or maintain the temperature or phase required by the production process. Improve the comprehensive utilization rate of heat, and use the hot fluid to be cooled to supply heat to the cold fluid to be heated, so as to improve the heat utilization rate.

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Evaporation capacity of 1000 kg hour, what is the heat exchange area of the double-tube evaporator?

3 Calculation of the heat transfer area of the evaporator According to the basic equation of the heat transfer source, the average tkqa formula, where a - the heat transfer area of the heat exchanger, m2; Q——Heat load of evaporator, w; Mean t —average temperature difference of heat transfer, k — total heat transfer coefficient of heat exchanger, w ( m2· According to the heat balance, the heat load drq of the evaporator; The evaporation process is a constant temperature heat transfer between the condensation of the heated steam and the boiling of the solution, all 1ttt; The k-value can be calculated according to the formula provided in the Heat Transfer Chapter. 1ttt Sail Branches—Effective Temperature Difference (Driving Force of Evaporation) Class Exercise: Exercise 6-2 Exercise 6-3 Supplementary Exercise:

1) It is known that the single-effect atmospheric pressure evaporator processes 2 tNAO h aqueous solution per hour, and the solution concentration is concentrated from 15 (mass) to 25 (mass). The heated vapor pressure hail car plex is 400kpa (absolute pressure), and after condensation, it is discharged at saturation temperature. It is assumed that the heat loss of the evaporator is negligible.

The boiling point of the solution is 113, and the heating steam consumption and unit steam consumption are obtained by feeding at 20 and boiling point respectively. [Answer: d.]