Newcomers don’t know how to calculate the heat exchange area
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A client asked us to calculate the heat exchange area for a device used to treat waste ammonia water, with an initial temperature of 100 degrees Celsius that needs to be reduced to 50 degrees Celsius, and a flow rate of 20 m3/h； The cooling water flow rate is 40 m3, the pressure is 0.4 MPa, and the heat exchange tubes have a diameter of φ108*4. How can the heat exchange area be calculated using this information?
According to the heat balance formula Q=K.S.ΔT, the information you currently have is only the temperature difference on the heat side, as well as some of the parameters needed to calculate the heat transfer amount Q and the overall heat transfer coefficient K; it is therefore not possible to determine the heat exchange area S. What you also need to know are the basic physical properties of the fluids on the hot and cold sides, the flow conditions of those fluids, the material of the heat exchange tubes, the type of heat exchanger, and many other details in order to carry out the calculations.
This post was last edited by wiseboy on 12/8/2016 at 10:42, version 1. What is the concentration of the waste ammonia solution? An approximate value will work too ； 2. Are you sure it’s a 108X4 tube? This is completely illogical ； 3. This design can be created quickly and reliably.
Isn’t calculating the heat exchange area simply the effective area where the outer surface of the heat exchange tube comes into contact with the medium? All that’s needed to do the calculation is to know the number of heat exchange tubes, their specifications, and their effective length (the length of the tube minus the length extending into the tube sheet minus the length by which the tubes protrude from the tube sheets at both ends). What does it have to do with flow rate or the temperatures at the inlet and outlet? You’re trying to calculate the heat transfer efficiency or something like that, right? Maybe I’m thinking too simply. Waiting for experts
Then it’s time for process calculation! Find a professional!
The heat transfer coefficient K is related to the properties of the materials on both sides as well as the flow velocity. Without knowing the value of K, one must refer to heat transfer manuals; the heat transfer coefficient K is a range of values
First, there is the heat exchange area, and only then can one know the specifications and quantity of the tubes, right?
Floor 4 covers the calculation methods for heat exchanger design, while floors 2 and 6 deal with the algorithms related to the process. It mainly depends on the user’s specialty – is it equipment or process engineering?
In the operating conditions described by the poster, if a plate-type heat exchanger is used, it is quite easy to calculate the heat exchange area. Among the parameters you provided, it is also necessary to specify what the inlet and outlet temperatures of the cold water are. In conditions with such large temperature differences, plate heat exchangers need to be designed with multiple flow paths.
There is specialized software for this; the calculation methods vary depending on the type of heat exchanger. The conditions you have provided are insufficient