Day 152

In Brewing Equipment, it was all about steam and glycol. Steam is what you use to heat your mash tun and kettle, and glycol is what you use to cool down your heat exchanger, fermenters and bright tank.

As any student of physics knows, they actually both work on the same principle: if a liquid absorbs enough heat, it will change to a gas; and if the gas loses that heat, it turns back into a liquid.

So if you heat water in a boiler until it turns to steam, then you send that steam into hollow “jackets” inside the walls of your mash tun, the hot steam will transfer its heat to the cooler metal of the jacket walls (which is then transferred to your mash). With the loss of heat, the steam will condense as water and return the boiler, where it can take on a new load of heat, re-evaporate into steam, and head on back to the mash tun.

The cooling system works in exactly the same way: cold liquid glycol takes on heat from wort. This heats up the glycol, which evaporates. The gaseous glycol is sent to a compressor, which squeezes the glycol so hard, the glycol turns into a liquid again. This forces the glycol to release all of the heat it gained from the hot wort. The heat is dispersed by a fan, and the cold liquid glycol returns to the hot wort to get another load of energy.

Maybe I’m just Mr. Cranky Pants today, but I got a tiny bit annoyed when Gordo Slater described boiler capacity in BTUs (British Thermal Units). A BTU is an antiquated term describing the heat needed to raise the temperature of 1 pound of water by 1 Fahrenheit degree.

I grew up having to memorize the absurdities of Imperial measures: A yard was originally the distance between the king’s nose and his outstretched hand. Huh? 1760 yards = 5280 feet = 1 mile. Whuh? Water freezes at 32° and boils at 212°. Seriously?

Then Canada converted to the beautifully simple metric system: One millilitre of water weighs one gram and measures 1 cubic centimetre. There are 1,000 millilitres in 1 litre. There are 1,000 millimetres in a metre and 1,000 metres in 1 kilometre. Water freezes at 0° and boils at 100°.

So I find it hard to believe someone in a 21st century classroom is still using BTUs (pounds of water? Fahrenheit degrees?) to describe a heating system. The way we roll today is joules.

On to Chemistry Lab, where we were measuring alcoholic content of various liquids using a refractometer and a hydrometer. I was still wearing my cranky pants, so I was a bit put out that there were only two apparatus stations set up for 15 students. On the other hand, once I made it to the front of the line, the actual work only took 15 minutes. And the sun was shining when I walked outside. Who can be Mr. Cranky Pants when the sun is shining in February?

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6 Comments on “Day 152”

  1. Joel Baxter Says:

    Hey future brew master. I’ve been following your blog since day one, and have been captivated since, as I would love to take this course sometime in the future. I’ve included your blog in my top five craft beer resources article here: http://www.whattopair.com/craft_beer_blogs.a5w as you really offer a fresh take on an exciting industry.

    Cheers,

    Joel

  2. Joel Baxter Says:

    I agree, and you’ve got a front seat ride! Thanks for sharing Alan, and hopefully you’ll get a great summer work placement (and perhaps you’ll blog a bit about that too).

  3. Jolly Rodger Says:

    Celsius makes more sense for science, even if I’ve felt a system choosing water to base calculations is still arbitrary.

    Your average person isn’t really concerned with needing to know what temperature water is boiling and in terms of outdoor temps which are what your average person only cares about… 0F is really cold, 100F is really hot.

    Also temp controllers tend to be more finely tuned in Fahrenheit. Most Celsius controllers I’ve come across round up to the whole degree and don’t have decimals so a Fahrenheit controller dealing in whole degrees can be more finely tuned as the difference between between say 20C and 21C is almost 2 degrees F.

    • Alan Brown Says:

      There were several reasons why water was chosen as the arbitrary scale of temperature. Firstly, it’s liquid at room temperature, but freezes about the time we start looking for our toques and mittens–so its physical states are a visual reminder to us about when it is time to either bundle up or take off the parka. Secondly, it’s fairly common. You probably have some lying around your house. Thirdly, despite its ubiquity, it is fairly unique:
      – its nickname is the Universal Solvent because it dissolves a lot of substances.
      – it expands when it freezes. (Most liquids contract when they freeze.)
      – it has the highest enthalpy of vaporization of any common substance. (Enthalpy of vaporization is the energy that is required to change a liquid to a gas once it has been brought to its boiling point. Boiling water still requires an incredible 2257 joules per millilitre to change it from liquid to gas.By comparison, ammonia only requires 1371 joules, and butane requires a measly 320 joules.)

      • Canageek Says:

        It also is among the most analyzed substances to exist, due to its massive ubiquity, the fact life requires it, and the fact that steam engines, power generators and about a thousand other things work on it. Therefore we know the physical constants of water to far more precision then we do just about any other substance to exist.

        Actually, Centigrade was the system based on the freezing and boiling points of water. Celsius is based on the triple point of water. I can’t remember why, but I think is it because then we only have one point of reference instead of two, thus reducing the number of measurements we are relying on.The two systems only differ by something like 0.001 degree though, so very few people care.

        Also all SI units have to be based on a physical constants of some sort (Except mass, which they are working on). The metre is now based on the distance a specific frequency of light travels in a set amount of time, time is defined based on the half-life of a specific radioisotope, etc. The idea is that we shouldn’t be relying on a physical object somewhere, in case it is damaged, changes over time, etc. Mass is the last unit of measurement still based on a physical object, and they have to bring all the standards together every certain number of years and remeasure and average the results, as they will all be slightly different. They then synchronize the masses and put them back in their vaults all over the world.

        Actually, the really good system of measurement for temperature is Kelvin, based on absolute 0. No negative temperatures at all, 0 degrees C= 173.15 K, but each degree is the same size, so 1 degree C = 1 degree K. Also no annoying degree symbol on the units, just 298 K.


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