15 to 25 chilled water with P(max)=0.15 bar

[naifmbo]

Hi every body,
we have heat exchanger needs chilled water with the following :
150 L/Hr
15-25 C , Inlet chilled water temperature
0.15 bar, Max inlet pressure
Can we use closed system with this very low allowble pressure? If We can't:
When we use an open system,does the pressure being produced by the pump will be more than 0.15 bar even that ,this pump is pumping to the atmosphere?

 

[ChasBean1]

naifmbo - the pressure and flow are very small. Your application requires water that is warmer than what a chilled water system would typically provide, but city water temperature could also be low out of the range during winter. What you might want to consider is a large reservoir (i.e., a tank) stored in a cool place, equipped with an electric heater that comes on when tank temperature drops to ~17°C. Have a low volume centrifugal pump take a suction from the tank, and discharge through a throttling valve that is locked in place at the necessary flow rate and pressure at the inlet to the heat exchanger. Re-collect the discharged water in the tank. If the tank is large enough and uninsulated, losses to ambient should keep the temperature from getting to high (depending of course on the heat exchanger outlet temp). Attach a make-up water line to the tank with a float to maintain level, level and temperature indications, and a drain with a sample port. Equip the pump suction with a bypass chemical feed tank.

 

[naifmbo]

Thank you ChasBean1 for response.
Our city water circuit (in summer) has high temperature around 30-35 C, I think we should use refrigeration device to get water temperature within the specified range.

About the throttling valve, I think the required valve should have very low flow cofficient depend on the pump discharge pressure. So, Is there a valve with this low Cv.

 

[ChasBean1]

naif - I would think any 1/2-inch or 3/8-inch globe valve would do the trick, or some sort of circuit setter with about 1/2-inch diameter. For an example, try

http://www.bellgossett.com/contract/csetter.htm

Best of luck. -CB