Ask The Brewmasters

Hello Forum,

I'm trying to get a handle on direct utility costs of producing a barrel of beer. One area I'm struggling with is the cost of operating the glycol chiller. Calculating the energy required to cold crash a tank seems straight forward, the energy required to maintain temperature during active fermentation or post cold crashing a little more convoluted but I've seen some estimates out there. The part I really struggle with is estimating how efficiently the chiller operates and how much energy it consumes during this process.

I found some estimates on another forum as follows:

Active fermentation is ((BBL * 4200 BTU) / HOURS-OF-FERMENTATION) = BTU/HOUR
Pulldown is ((BBL * 271 * (start temp - finish temp)) / HOURS-OF-COOLING = BTU/HOUR

So if those formulas are correct or close enough for a decent estimate, how do I figure out the energy consumption in kWh at the chiller?

Thanks,

Corey

Always a tricky one. You're trying to attempt a mass energy balance and I commend you for it. 

You're off to a good start, as for the chiller, you're going to want to look at the name and see what it takes in COP (coefficient of performance). This will also (hopefully) have a whole chart giving you the amount of power consumed by the chiller to effect a given amount of cooling. Where it gets tricky is the temperature on the condenser (hot side) of the chiller has a lot to do with its efficiency. The lower the difference between the hot side and medium that's absorbing the heat (the air most likely) the worse it gets. Keep this especially in mind if you'll be operating in a hot area of the globe and make sure you de-rate your chiller accordingly (oversize the chiller to make up for poor environmental performance). 

Not doing this kind of mass balance work is why that vast vast majority of chillers are undersized and summer is filled with instagram photos of brewers hosing down condenser coils... 

If you're looking for a more in-depth series of calculations let me know. 

Hello Forum,

I'm trying to get a handle on direct utility costs of producing a barrel of beer. One area I'm struggling with is the cost of operating the glycol chiller. Calculating the energy required to cold crash a tank seems straight forward, the energy required to maintain temperature during active fermentation or post cold crashing a little more convoluted but I've seen some estimates out there. The part I really struggle with is estimating how efficiently the chiller operates and how much energy it consumes during this process.

I found some estimates on another forum as follows:

Active fermentation is ((BBL * 4200 BTU) / HOURS-OF-FERMENTATION) = BTU/HOUR
Pulldown is ((BBL * 271 * (start temp - finish temp)) / HOURS-OF-COOLING = BTU/HOUR

So if those formulas are correct or close enough for a decent estimate, how do I figure out the energy consumption in kWh at the chiller?

Thanks,

Corey

Always a tricky one. You're trying to attempt a mass energy balance and I commend you for it. 

You're off to a good start, as for the chiller, you're going to want to look at the name and see what it takes in COP (coefficient of performance). This will also (hopefully) have a whole chart giving you the amount of power consumed by the chiller to effect a given amount of cooling. Where it gets tricky is the temperature on the condenser (hot side) of the chiller has a lot to do with its efficiency. The lower the difference between the hot side and medium that's absorbing the heat (the air most likely) the worse it gets. Keep this especially in mind if you'll be operating in a hot area of the globe and make sure you de-rate your chiller accordingly (oversize the chiller to make up for poor environmental performance). 

Not doing this kind of mass balance work is why that vast vast majority of chillers are undersized and summer is filled with instagram photos of brewers hosing down condenser coils... 

If you're looking for a more in-depth series of calculations let me know. 

Hello Forum,

I'm trying to get a handle on direct utility costs of producing a barrel of beer. One area I'm struggling with is the cost of operating the glycol chiller. Calculating the energy required to cold crash a tank seems straight forward, the energy required to maintain temperature during active fermentation or post cold crashing a little more convoluted but I've seen some estimates out there. The part I really struggle with is estimating how efficiently the chiller operates and how much energy it consumes during this process.

I found some estimates on another forum as follows:

Active fermentation is ((BBL * 4200 BTU) / HOURS-OF-FERMENTATION) = BTU/HOUR
Pulldown is ((BBL * 271 * (start temp - finish temp)) / HOURS-OF-COOLING = BTU/HOUR

So if those formulas are correct or close enough for a decent estimate, how do I figure out the energy consumption in kWh at the chiller?

Thanks,

Corey

Hello Forum,

I'm trying to get a handle on direct utility costs of producing a barrel of beer. One area I'm struggling with is the cost of operating the glycol chiller. Calculating the energy required to cold crash a tank seems straight forward, the energy required to maintain temperature during active fermentation or post cold crashing a little more convoluted but I've seen some estimates out there. The part I really struggle with is estimating how efficiently the chiller operates and how much energy it consumes during this process.

I found some estimates on another forum as follows:

Active fermentation is ((BBL * 4200 BTU) / HOURS-OF-FERMENTATION) = BTU/HOUR
Pulldown is ((BBL * 271 * (start temp - finish temp)) / HOURS-OF-COOLING = BTU/HOUR

So if those formulas are correct or close enough for a decent estimate, how do I figure out the energy consumption in kWh at the chiller?

Thanks,

Corey