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Thread: Chilled water hydraulic system design

  1. #1
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    Post Chilled water hydraulic system design

    Greetings,

    I start by presenting my self, I'm a junior engineer and i work in a company where we design air cooled chillers.

    I have this 7 Tons chiller, that i'll use a different system than the usual.
    Usually when we work with client we go for a system with 2 closed loops, with two pump.
    1st one is where the chiller work with the water tank and cool down the water contained in the tank,
    2nd one between the process that needs cooling and the water tank.

    This time the client wants only one pump and the water flow of needed in the evaporator is different than the water flow needed in the process machine.

    I want to know the applicable configurations in this type of installation.

    I am available for more details, and you can contact me with this email

    Thank in advance and have a wonderful day everyone.
    Last edited by Special-K; 05-14-2022 at 07:16 PM. Reason: Remove email

  2. #2
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    Flow must be within chiller acceptable range, limited by laminar flow, turbulent erosive flow, chiller delta/ control band, short cycling, potential temperature swing, & thermal inertia.

  3. #3
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    I would start by explaining to the client why there are 2 pumps, that in his sys there are 2 separate chill wtr flows reqd, 1st being the primary pump supplying the wtr flow reqd for the chlr evap and then there is the 2nd pump/ secondary loop which meets his process tool wtr flow req protected by ( a preset internal flow switch tied to the tool control voltage) and the heat rejection req before being ret back to the tank as warm wtr.
    If this original design is changed then a temp controlled modulating 3 way control valve could be installed before ch wtr enters the tool which will divert the unneeded chill water back to the open air tank. This wld also lower the temp of the water in the tank, lowering the load on the process chiller as unused very cold water is being ret into the tank.

  4. #4
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    Quote Originally Posted by VGA View Post
    I would start by explaining to the client why there are 2 pumps, that in his sys there are 2 separate chill wtr flows reqd, 1st being the primary pump supplying the wtr flow reqd for the chlr evap and then there is the 2nd pump/ secondary loop which meets his process tool wtr flow req protected by ( a preset internal flow switch tied to the tool control voltage) and the heat rejection req before being ret back to the tank as warm wtr.
    If this original design is changed then a temp controlled modulating 3 way control valve could be installed before ch wtr enters the tool which will divert the unneeded chill water back to the open air tank. This wld also lower the temp of the water in the tank, lowering the load on the process chiller as unused very cold water is being ret into the tank.
    Its very common to have a single pump. However you need to remember that your process needs valves too and for each process, you need to have a 3way control valve that will divert the flow back to the chiller. You cant stop the flow.

    Well, you can stop the flow and most chillers will just shut off due to low water temp or flow switch but it may take 10 minutes for the chiller to start again. Probably not acceptable.

    You can also modulate the valves or open/close them.

    Your chiller is small but if you have a lot of different processes, it is better to use a VFD to control pump flow.
    This can require controls but controls are not always necessary. In this case, you would need 2 way control valves, a bypass valve at the end of your water loop and a good flowmeter and wet DP sensor as the controlled value to modulate the valve to keep enough water flowing back to the chiller

  5. #5
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