Contaminated heating/cooling fluid

[1COOK2]

My process heating and cooling fluid has become contaminated. Normal fluid is a mixture of propylene glycol and water. Some small amount of hydraulic fluid has entered the closed loop system. Actual percentage of contaminant being analyzed now. Outside winter temperatures proving to be no problem with plant equipment, worried if system will loose efficiency when warm weather returns. How can I gage a rough estimate of any potential decrease in heat transfer efficiency based on the oil that is now part of the fluid?

 

[willard3]

If you know the percentage of contamination, you can find specific heat of the oil and reduce heat transfer as a ratio of (original specific heat/new specific heat).

The oil will also have different viscocity characteristics than the glycol mix that will influence the film coefficient which will affect heat transfer and change the pumping horsepower.