Flywheel in relation to water systems 1

[justincase]

Hi All--

could anybody please explain why is a "flywheel" is important in our industry and it's relationship to a water system?

Many Thanks--

 

[Yorkman]

I'm not sure what you mean by flywheel but if you mean system volume VS. tons of cooling. Usually a min. of 3-5 gallons per ton of cooling is what York has as a recommendation for comfort cooling and as much as 8 gallons per ton for process cooling. The idea is to increase system stability and decrease system short cycling.
If I'm off track with this response please describe what you mean by flywheel.

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[gepman]

"Flywheel" in the HVACR industry usually means thermal mass or heat capacity. The storing of thermal energy in thermal mass is analagous to storing kinetic energy in a rotating flywheel.

Yorkman gave one instance of flywheel in a chilled water system. The more gallons per ton the lower the temperature change in the water for a given btu load. The thermal mass is the water. Water has one of the highest heat capacities of any material. The higher the heat capacity the higher the thermal mass or flywheel effect.

Another example of flywheel is a building which has a large thermal mass in concrete or other materials. If this thermal mass is cooled off at night then it takes a lot of energy to warm it up even a few degrees. This can help it "flywheel" or "ride through" the day without using a lot of cooling energy. I have used this concept in cooling wine storage warehouses where it is hot in the day but cool at night. There is a lot of thermal mass in the barrels of wine (and the concrete walls).
I am sure that others have other examples of "flywheel" in the HVACR industry.

 

[gepman]

"Flywheel" in the HVACR industry usually means thermal mass or heat capacity. The storing of thermal energy in thermal mass is analagous to storing kinetic energy in a rotating flywheel.

Yorkman gave one instance of flywheel in a chilled water system. The more gallons per ton the lower the temperature change in the water for a given btu load. The thermal mass is the water. Water has one of the highest heat capacities of any material. The higher the heat capacity the higher the thermal mass or flywheel effect.

Another example of flywheel is a building which has a large thermal mass in concrete or other materials. If this thermal mass is cooled off at night then it takes a lot of energy to warm it up even a few degrees. This can help it "flywheel" or "ride through" the day without using a lot of cooling energy. I have used this concept in cooling wine storage warehouses where it is hot in the day but cool at night. There is a lot of thermal mass in the barrels of wine (and the concrete walls).

I am sure that others have other examples of "flywheel" in the HVACR industry.

 

[justincase]

Great guys---

Didn't know what the term "flywheel" was code for but now it makes more sense.

One of my instructors @ school told me water was one of the best refrigerants out there because of the "high heat capacity" as stated above.

Thank you for time

 

[Yorkman]

Justincase, I think you maybe misunderstanding what your instructor means by referencing water as a refrigerant and what the posting means by high heat capacity.

I think your instructor is refering to the latent heat of vaporization of water, and it's use as a refrigerant in absorbtion refrigeration. The latent heat value for water in that application is aprx. 1100 +/- BTU/LBS. Compared to R-22 at 70 BTU/LBS for typical A/C applications or 500 BTU/LBS for ammonia for similar temperatures. Water kicks BUTT!!

The heat capacity that Gepman and myself are refering to is the specific heat value of the water: in that when you are storing sensible heat BTUs in a mass(water) for every BTU you add or remove from one pound water(liquid state) the temperature of the water will change only one degree F. This is excellent compared to air with a specific heat value of .24 BTU/LBS/F.

Hope that didn't muddy the waters too much, but I thought it was important to note the difference.



I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[justincase]

Thank you Yorkman---

No muddy waters here,,,,better to hear it from you guys and get it straight then to spout off in the field only to eat humble pie.

You are right and I got the two confused so thanks for helping me on that one.