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Following scenario: Shell&tube heat exchanger will be designed with f.e. pressurized water flowing on shell side. Baffles are to be installed to increase heat transfer. Now my topic: I would assume that there will be "normal" friction losses due to contact of water with wall; but also I assume...

We are trying to find out the design criteria for a heat exchanger which condenses carbon dioxide. What makes it somewhat tricky is the fact that a yet unknown small (0-10 mass percent) amount of hydogren will be in the gas flow, too. (Evaporating ammonia will provide the refrigeration) There...

Planned operation time will be approx. 8760 h/a; this means fultime. I do not prefer to install plate heat exchangers to an open cooling tower system. I am afraid of downtime due to cleaning activities. And also the temperature loss is not negligible. System is designed for 28° wet bulb and...

Thank you SAK9 and LittleInch for your answers. I am still think about operating sub-atmospherical; by this I could save a lot of electricity; we need to pump about 500m3/h and 1,5 bar more or less is quite considerable. I am also thinking about installing variable speed drive (frequency...

If "your previous suggestion is preferred", what problems are you solving with this suggestion? Why don't you prefer an installation like I described in my 1st post. That is why I put the three questions. I like to identify possible problems first.

lilliput1, thanks for your answer! Of course we could consider other devices like you suggested but currently we want to stick to our system due to investment costs and "efficiency". So any further comments to my questions are very welcome :-)

We are considering an installation with an open cooling tower mounted nearly on ground floor (pumps below) while the consumers will be elevated about 10-15m higher. Cooling water flow will be about 500 m3/h. 1) Concerning this I would like to know whether it is "allowed" to operate the return...

We have built and still build this type of heat exchanger (Steam in u-bundle tubes and boiling out of water-ammonia-solution) since nearly 20 years without any problems. Heat transfer we know and have our experience and concerning leakages we until now never had a serious problem. My "problem"...

With a shell&tube heat exchanger we need to heat an ammonia/water-solution. On the tube side will be the heating steam. The condensing pressure of the steam will be about 2.8 bar absolute. The steam is provided with a pressure slightly higher and/but with a temperature of about 371°C. Customer...

What program(s) do you suggest for the drawing of process&instrumentation diagrams (P&I-D) with Mac-computers? Is there any experience? Kind regards virk

Thank you Mark! We will design high pressure as well as low pressure section for 18 barg. Regards virk

1) Let us assume the expected (maximum) ambient temperature is 40°C and there will be no insolation from solar radiation; the plant will be installed into steel frames outside. 2) Minimum ambient temperature is -10°C. Why this is important? Regard virk

Thank you Mark. The system will condense the ammonia at 14 bars absolute and the low operation pressures will be 0,28 bars absolute and 0,35 bars absolute. I think I need a hint to any specific requirements there in Mexico. Regard virk

Nobody has an idea? Probably the minimum design pressure in the United States could also be helpful because we heard that Mexico often follows American rules. Any support kindly appreciated! Kind regard virk

We have the order for an NH3 refrigeration plant for the south of Mexico. We need to know the required design pressures there for as well low pressure section as high pressure section. (We have agreed that the design code for pressure vessels to follow will be PED (European Pressure Directive)...

Hi Compositepro! If you have saturated liquid you at the most have the suction column as NPSH. I also think the lower the suction velocity the better. But is gets more expensive. Does anyone have any experience in designing a suction line diameter with more than 1m/s for saturated liquids (here...

Hi Chris! Probably it is a bit confusing. What I wanted to ask: Is it possible to design the suction line diameter for a suction line speed of approx. 1,8 m/s. What parameters I have to consider? Kind regards virk

Hello! I have one question which some of you perhaps can answer: We often design suction line of saturated liquids like ammonia in a way that the velocity in this suction pipe is about 0,8 m/s. Additionally we consider NPSH issues. We never had problems. My problem is that I do not know why it...

Dear magicme One further remark. I had a first look at your link. The "air" speed through the holes in your table seems to be quite high. Do you really trust these high velocities. In my calculation your much higher than sound speed at these large Reynolds numbers. Kind regards virk

magicme Thank you for your link. I will work through it within the next days and also make an spreadsheet of your equations, after I have understood what they are telling me:-) Kind regards virk