Chiller & electric cooling ton-hour
Chiller & electric cooling ton-hour
(OP)
Hi all,
If I have this Co-Gen unit that can generate enough hot water to power a 600 ton absorbtion chiller and the system runs about 8000 hours a year, then what would equivalent "ton-hours" of electric cooling be?
I am guessing it would be 600 * 8000 = 4,800,000 ton-hour of electric cooling but I am not sure.
I am at a loss
if there are inefficiencies (sp?) that I need to consider.
If I have this Co-Gen unit that can generate enough hot water to power a 600 ton absorbtion chiller and the system runs about 8000 hours a year, then what would equivalent "ton-hours" of electric cooling be?
I am guessing it would be 600 * 8000 = 4,800,000 ton-hour of electric cooling but I am not sure.
I am at a loss
if there are inefficiencies (sp?) that I need to consider. 




RE: Chiller & electric cooling ton-hour
Running the value over a year run time does not take into the variations in load. The number your getting can be very misleading. Many times the load is broken into hourly values and added up to achieve the ton hour number.
I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int.
RE: Chiller & electric cooling ton-hour
I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int.
RE: Chiller & electric cooling ton-hour
Thanks
Mike
RE: Chiller & electric cooling ton-hour
No. There is nothing like 4,800,000 ton-hours of electrical energy. The coefficient performance of electrical prime moved refrigeration systems (for example vapor compression systems) have better COP than an absorption system. A 600 ton capacity centrifugal chiller will consume about 0.6 kW/ ton cooling at full load.
Though it may exist, ton-hr seems to be the most inconsistent unit (unlike kW-hr) I came across and can enhance already existing confusion about tons. It will be simple and prudent to use either btu/hr or kW and btu or kJ when you take up energy savings calculation.
RE: Chiller & electric cooling ton-hour
If I understand your comment correctly, the offset would be in the order of 4,800,000 * 0.6 = 2,880,000 ton-hour (or even half that amount 2,400,000) am I right?
Thanks
Mike
RE: Chiller & electric cooling ton-hour
First of all, just because the chiller nameplate states "600 ton chiller" doesn't mean that it is running at rated capacity all of the time. Is this a process chiller, or space cooling?
1 ton = 12,000 BTU/hr
And 1 BTU/hr = .29 watts
However, if you put .29 watts into an electrically driven chiller you do not get 1 BTU of cooling out. You get more. You need to consider the coefficient of performance of the chiller.
So
Step 1: Figure out how many tons of cooling is really produced annually.
Step 2: Figure out what types of electrically driven chillers might be used in place of the existing system, and calculate how many kW-hr it would suck down to produce the same cooling calculated in step 1.
Step 3: Don't forget to consider the utility rate structure. (that is, the client's demand charges will go up too)