Design Considerations for a Concentric Heat Exchanger with Steam and Water Flow

In summary, the conversation is about designing a concentric heat exchanger with steam flowing on the shell side and water flowing on the inside. The person is seeking advice on how to size the length of the heat exchanger and determine the steam flow rate for a given heat load. They also mention a calming section and ask for considerations and external references for calculations. The location of the heat exchanger is not specified, but the expert raises concerns about safety and following pressure vessel codes. They also suggest hiring a professional engineer for help in designing the heat exchanger.
  • #1
selvam
1
0
I need to design a concentric heat exchanger. I have steam flowing on the shell side( annular region of the heat exchanger) at 2 bar and water flowing on the inside. I am maintaining constant wall temperature with steam flow. How should i size the length of the heat exchanger and how should i decide the steam flow rate for a given heat load. Also before the water is sent into the heat exchanger i am letting it flow through a calming section. How should i size the length of the calming section. Please give me the considerations i need to do. Please cite external references for calculations.
 
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  • #2
Where is this heat exchanger located? In your house, neighborhood? etc ...

2 bar is about 30 psia which would make it be at about 15 psig. That would make your heat exchanger a pressure vessel in the United States. Are you in the United States? If so you must follow the rules of the American Society of Mechanical Engineers (ASME) pressure vessel code.

At 2 bar the saturation temperature is 250 F (121 C) that steam can cause burns. Have you taken any precautions for overpressurization such as a pressure operated relief valve?

As for your "calming" section, I am assuming that you are trying to have laminar flow enter the exchanger. Why? Turbulent flow promotes much better heat transfer.

As far as mass flow, what are you trying to do with steam?

If you are not capable of designing this heat exchanger on your own and it operates in an area where people can be harmed if it losses steam or explodes, I recommend you hire a professional engineer for help before you continue any further.

Thanks
Matt
 

Related to Design Considerations for a Concentric Heat Exchanger with Steam and Water Flow

1. What is a heat exchanger and how does it work?

A heat exchanger is a device used to transfer heat from one fluid to another without the two fluids coming into direct contact with each other. It typically consists of two separate chambers or tubes that allow for the exchange of heat between the fluids. The exchange of heat occurs through a process called convection, where the warmer fluid transfers its heat energy to the cooler fluid, resulting in a temperature change.

2. What factors should be considered when designing a heat exchanger?

Several factors should be taken into account when designing a heat exchanger, including the type of fluids being used, the desired temperature change, the flow rate and pressure of the fluids, and the available space for the heat exchanger. Other considerations include the materials used for construction, the cost and efficiency of the design, and the maintenance requirements.

3. What are the different types of heat exchangers?

There are several types of heat exchangers, including shell and tube, plate and frame, and finned tube. Shell and tube heat exchangers are the most commonly used and consist of a bundle of tubes inside a larger outer shell. Plate and frame heat exchangers use plates to separate the fluids, while finned tube heat exchangers have fins attached to the tubes to increase the heat transfer surface area.

4. How is the efficiency of a heat exchanger determined?

The efficiency of a heat exchanger is typically calculated by the effectiveness or the heat transfer coefficient of the design. Effectiveness is a measure of how well the heat exchanger is able to transfer heat between the two fluids, while the heat transfer coefficient is a measure of the rate at which heat is transferred. Other factors such as pressure drop and fouling should also be considered when evaluating the efficiency of a heat exchanger.

5. What are some common challenges in heat exchanger design?

Some common challenges in heat exchanger design include maintaining a balance between heat transfer efficiency and pressure drop, ensuring compatibility of materials with the fluids being used, and considering the potential for fouling or corrosion. Other challenges may include meeting specific performance requirements, such as temperature changes or flow rates, and optimizing the design for cost-effectiveness and ease of maintenance.

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