Hot Tip #9 – Latent heat of evaporation

One pound of water at 32 degrees F. plus 180 BTU’s = One pound of water at 212 degrees F.  One pound of water at 212 degrees F. plus 971 BTU’s = One pound of steam at 212 degrees F. and at 0 PSIG.                                                                                                                                                                             One pound of steam at 212 degrees F. and at 0 PSIG plus 46 BTUs = One pound of steam at 366 degrees F. and at 150 PSIG.

To one pound of water at 32 degrees, we have added a total of 1197 BTU’s to produce one pound of steam at 366 degrees F. and at 150 PSIG.

Out of the total 1197 BTU’s added, 971 BTU’s were required to change its state from liquid to vapor (81.1%). This is one of the reasons that steam is such a great conveyor of energy; but only if you convert the steam back into a liquid (condensate) in a useful process.

When you see steam exiting your washers this is not a useful process. You have not captured the 971 BTU’s (latent heat of evaporation) and you are wasting more than 81.1% of this available energy. “Steaming up” in a washer needs to be avoided as much as corporate taxes, swine flu, and traffic cameras!  If you must steam up, reduce the steam rate of flow. The best way to do this is with a steam pressure-reducing valve.

Be aware that steam exiting your washers is a hazardous substance. Boiler treatment chemicals, which are present in this steam, are the most hazardous chemicals within most laundries. Some are class 4 carcinogens.