Using Industrial Cooling Water With Heat Pump

Big-Al_2

Where I work, we circulate about a thousand gallons a minute in process cooling water through a large injection molding plant.  The return water is at about 80 degrees.  We send it through an evaporative cooling tower right now, but there may be a better way to do it, and get some heat back into other parts of the building. 



We'd need to circulate a LOT of 80 degree water through BIG coils to get much heat out of it.  But . . . I'm thinking that maybe we could install heat pump(s) to serve office areas, and use our process cooling return water to heat the evaporator(s).  We could get the double benefit of process cooling and less expensive heat for the non manufacturing areas.  (We already have excess heat year-round in the manufacturing plant, just from the equipment there.)



Can anybody here shed some light on this topic, or direct me to a web site on this kind of thing, or to somebody with this kind of experience?  I'm in Wisconsin.

Mark Eatherton

It CAN be done....

However, with approach temperatures that high, you will need to lower the temperature of the supply to the water source heat pumps, or you will blow up the compressors.



This would entail any of the off shelf methodology that is typically utilized to owner the temperature going to a radiant panel, i.e. variable speed mixing, fixed thermostatic mixing valves etc.



The max temp of availability would probably fall into the 130 degree F. range.



If you have a continuous demand for hot potable water in your operations, THAT would be another place to use the waste heat.



Here is a link to a web site that deals in commercial WSHP. http://www.mcquay.com/McQuay/ProductInformation/WSHP/WSHPpageHTH



ME

Tom Blackwell_2

Heating chiller

This is a fairly common idea in the south. The Orlando airport uses a "heating chiller" to remove heat from the chilled water plant condenser water and move that heat into a 125 degree heating system. McQuay markets a "Templifier" chiller expressly for this use. For a small load a WSHP would fit the bill as long as there is some way to prevent the cooling water system from overheating, as Mark said. Standard WSHP's can tolerate water up to 105 degrees or so, but this is an absolute maximum. In addition, the condenser passages in a WSHP are quite small and will not tolerate particulate matter in the water system. If you are using a closed circuit evaporative cooler this should be no problem, but if the cooling system is an open cooling tower the captured insects will stop up the water passages in short order.