Discussion on the way heat exchange media enter and exit the equipment?
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In chemical production, heating media are usually fed from above and discharged from below, while cooling media are usually fed from below and discharged from above. Is this always the case? Please discuss!
You’re absolutely right; that’s usually how the flow direction of the heat exchange medium is arranged.
Not necessarily; our condenser is designed with flow from top to bottom, and it uses chilled brine as the cooling medium.
Where the structure permits, a counter-current arrangement should be used as much as possible, as it yields better heat exchange efficiency.
I think in most cases, the flow is from bottom to top within the medium, and the two media move in opposite directions.
I don’t think it’s necessarily the case. The reasons are as follows: 1. From a design perspective, there are counterflow and co-flow modes of heat exchange. 2. In practice, different methods are adopted depending on the purpose of heating or cooling. 3. It depends on the state of the process medium, whether it is in gas phase or liquid phase. 4. Different methods are used based on the amount of heat to be exchanged. The guiding principles are cost-effectiveness and efficient heat exchange
The cooling medium should enter from below and exit from above, while the heat exchange medium should enter from above and exit from below.
The cooling medium should enter from below and exit from above, while the heat exchange medium should enter from above and exit from below.
The cooling medium enters from below and exits from above, while the heat exchange medium enters from above and exits from below; this results in the highest heat exchange efficiency.
I strongly agree with what was said on floor 6; what everyone has mentioned are general situations
Generally, it’s as the poster in #1 said; it depends on the specific circumstances. What is the selection process? In shell-and-tube heat exchangers, it is determined which fluid should flow through the tube side (or shell side) under what conditions. The general principles for making this choice are as follows: (1) Fluids that are dirty or prone to scaling should flow through the tube side, as cleaning inside the tubes is easier ； ? (2) Corrosive fluids should be passed through the tube side, so as to prevent both the tube bundle and the shell from being corroded, and to facilitate cleaning and maintenance ； (3) Fluids with high pressure should flow in the tube side to prevent the shell from being subjected to pressure as well ； ? (4) Toxic fluids should be routed in the tube side to reduce the risk of leaks ； ? (5) The cooled fluid should flow through the shell side, which facilitates heat dissipation and enhances the cooling effect ； ? (6) Saturated steam should flow in the shell side, as this facilitates the removal of condensate and non-condensable gases, and the steam remains clean without being contaminated ； ? (7) Fluids with low flow rates or high viscosity are better suited for use in the shell side, as the baffles allow turbulence to be achieved at low Reynolds numbers (Re＞100); however, multiple tube passes can also be employed inside the tubes ； ? (8) If there is a large temperature difference between the two fluids, it is advisable to let the fluid with a higher α flow in the shell side, thereby reducing the temperature difference between the tube wall and the shell wall. ? When making a specific choice, the above principles often cannot all be taken into account at the same time, as they may conflict with one another; in such cases, it is necessary to consider the actual situation and focus on the key issues as the basis for making the choice. ?
In my unit, the kettle-type heat exchanger has the refrigerant inlet located in the middle of the heat exchanger.