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Think about Loose Coupling

Warming the pot

by Random_Walk (Prior)
on Oct 16, 2007 at 12:38 UTC ( #645159=CUFP: print w/ replies, xml ) Need Help??

Every afternoon I produce tea for the local barbarians (Dutch, Belgium). Of course this involves warming the pot. The other day I had an extra guest for tea so I could not use as much water as usual for warming. What warming water I could spare I used in two steps claiming this would be more efficient. The Dutch dissented so I did what any sane monk would do and wrote a script ...

#/usr/bin/perl use strict; use warnings; # Teapot warming with various splits of water from 10 to 200 ml # # wild assumptions: # pot and warming fraction are allowed to reach equilibrium tempera +ture # pot heat loss between warmings is just a random guess # pot specific heat capacity is a wild guess # warming water is always 100 Celsius # entire pot is one temperature # temperatures handled in Celsius not Kelvin, assume this makes no o +dds # assumed heat capacities are linear # # heat capacity joules per Kelvin for 1 teapot or 1 gram water my %hc = ( pot => 1500, water => 4.2 ); my $T_env = 20; # Celsius my $T_water = 100; # Celsius my $total_water = 1500; # ml my $cool_factor = 0.05; { printf "********** the evil of an unwarmed pot ... "; my $T_tea = warm_pot( $T_env, $total_water, ); printf "temp tea: %5.2fC ********** \n\n", $T_tea; } for my $warming_water ( 1 .. 10 ) { $warming_water *= 10; my $T_pot = $T_env; # we split the water into various fractions my $max_step = 4; for my $split ( 1 .. $max_step ) { my $ml = $warming_water / $split; printf "warming with $warming_water in %2i steps (%5.1f water each +step) ", $split, $ml; for ( 1 .. $split ) { $T_pot = warm_pot( $T_pot, $ml ); print "."; } print " " x ( 1 + $max_step - $split ); printf "warmed pot: %5.2fC ", $T_pot; $T_pot = cools($T_pot); # now throw in 1500 ml hot water my $T_tea = warm_pot( $T_pot, $total_water - $warming_water, ) +; printf "temp tea: %5.2fC\n", $T_tea; } print $/; } sub warm_pot { my $T_pot = shift; my $ml_h2o = shift; my $total_joules = $T_pot * $hc{pot} + $ml_h2o * $hc{water} * $T_w +ater; my $total_heat_capacity = $hc{pot} + $ml_h2o * $hc{water}; return $total_joules / $total_heat_capacity; } sub cools { my $T_pot = shift; my $delta_T = $T_pot - $T_env; return $T_pot - ( $delta_T * $cool_factor ); }

Here are some results

********** the evil of an unwarmed pot ... initial temp tea: 84.62C ** +******** using 10ml in 1 steps 10.0 water each . warmed pot: 22.18C temp te +a: 84.93C using 10ml in 2 steps 5.0 water each .. warmed pot: 24.21C temp te +a: 85.30C using 10ml in 3 steps 3.3 water each ... warmed pot: 26.09C temp te +a: 85.65C using 10ml in 4 steps 2.5 water each .... warmed pot: 27.82C temp te +a: 85.97C . . . using 60ml in 1 steps 60.0 water each . warmed pot: 31.51C temp te +a: 86.27C using 60ml in 2 steps 30.0 water each .. warmed pot: 41.22C temp te +a: 88.11C using 60ml in 3 steps 20.0 water each ... warmed pot: 49.18C temp te +a: 89.61C using 60ml in 4 steps 15.0 water each .... warmed pot: 55.66C temp te +a: 90.83C using 70ml in 1 steps 70.0 water each . warmed pot: 33.11C temp te +a: 86.50C using 70ml in 2 steps 35.0 water each .. warmed pot: 43.97C temp te +a: 88.56C using 70ml in 3 steps 23.3 water each ... warmed pot: 52.67C temp te +a: 90.22C using 70ml in 4 steps 17.5 water each .... warmed pot: 59.56C temp te +a: 91.52C using 80ml in 1 steps 80.0 water each . warmed pot: 34.64C temp te +a: 86.72C using 80ml in 2 steps 40.0 water each .. warmed pot: 46.55C temp te +a: 88.99C using 80ml in 3 steps 26.7 water each ... warmed pot: 55.87C temp te +a: 90.77C using 80ml in 4 steps 20.0 water each .... warmed pot: 63.07C temp te +a: 92.15C using 90ml in 1 steps 90.0 water each . warmed pot: 36.10C temp te +a: 86.92C using 90ml in 2 steps 45.0 water each .. warmed pot: 48.97C temp te +a: 89.39C using 90ml in 3 steps 30.0 water each ... warmed pot: 58.80C temp te +a: 91.28C using 90ml in 4 steps 22.5 water each .... warmed pot: 66.21C temp te +a: 92.70C using 100ml in 1 steps 100.0 water each . warmed pot: 37.50C temp t +ea: 87.12C using 100ml in 2 steps 50.0 water each .. warmed pot: 51.23C temp t +ea: 89.77C using 100ml in 3 steps 33.3 water each ... warmed pot: 61.49C temp t +ea: 91.75C using 100ml in 4 steps 25.0 water each .... warmed pot: 69.04C temp t +ea: 93.21C using 110ml in 1 steps 110.0 water each . warmed pot: 38.84C temp t +ea: 87.30C using 110ml in 2 steps 55.0 water each .. warmed pot: 53.37C temp t +ea: 90.13C using 110ml in 3 steps 36.7 water each ... warmed pot: 63.97C temp t +ea: 92.19C using 110ml in 4 steps 27.5 water each .... warmed pot: 71.59C temp t +ea: 93.66C using 120ml in 1 steps 120.0 water each . warmed pot: 40.12C temp t +ea: 87.48C using 120ml in 2 steps 60.0 water each .. warmed pot: 55.37C temp t +ea: 90.46C using 120ml in 3 steps 40.0 water each ... warmed pot: 66.26C temp t +ea: 92.59C using 120ml in 4 steps 30.0 water each .... warmed pot: 73.89C temp t +ea: 94.08C . . . using 200ml in 1 steps 200.0 water each . warmed pot: 48.72C temp t +ea: 88.64C using 200ml in 2 steps 100.0 water each .. warmed pot: 67.82C temp t +ea: 92.55C using 200ml in 3 steps 66.7 water each ... warmed pot: 79.31C temp t +ea: 94.90C using 200ml in 4 steps 50.0 water each .... warmed pot: 86.00C temp t +ea: 96.27C . . . using 300ml in 1 steps 300.0 water each . warmed pot: 56.52C temp t +ea: 89.61C using 300ml in 2 steps 150.0 water each .. warmed pot: 77.53C temp t +ea: 94.19C using 300ml in 3 steps 100.0 water each ... warmed pot: 87.91C temp t +ea: 96.45C using 300ml in 4 steps 75.0 water each .... warmed pot: 92.78C temp t +ea: 97.51C

The physics model sucks so the numbers are not true but I think the broad conclusion is valid. Now can anyone suggest a nice 3 axis plotting module so I can plot the pot warming space ?


Pereant, qui ante nos nostra dixerunt!

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Re: Warming the pot
by sg (Pilgrim) on Oct 17, 2007 at 05:14 UTC

    Plotting tool: gnuplot (name is a misnomer; gnuplot has nothing to do with gnu of fsf). (Update: forgot to mention that it is possible to send data and control gnuplot from a perl script via sockets, even on Windows.)

    OT: what is "warming the pot" and why is it done with warm water? I would have thought that making tea involves pouring water into a pot, warming the pot on a stove, then mixing the hot water with tea leaves and finally filtering/separating.

      Making tea involves three types of vessel. The first is the kettle, in which you boil water on a stove. The second is the teapot. This should be somewhat heated with warm water (which is then thrown away) before you put the tea leaves in and transfer the boiled water. This is so that the boiling water doesn't instantly cool down when it contacts the cold pot. It may also help prevent disasters like the boiling water causing the pot to break thus wasting tea.

      The third type of vessel is, of course, a half pint mug.

      It should be noted that ISO 3103 disagrees. This is because it aims to define a precisely repeatable process. Swirling a small amount of warm water around in the pot isn't repeatable.

      update: see also The Russian Tea HOWTO for a different tea-making tradition which nevertheless includes warming the pot. Daniel is a very clever hacker with a splendid sense of humour so is obviously right.

        Being a heavy tea drinker and enthusiast myself, I agree with your general approach, but I disagree with any standards any organization or individual may try and put on making tea. Tea, which includes the preparation, the right company (sometimes just you alone), and the drinking, should never have a formalized, lifeless list of scientifically repeatable steps.

        The Japanese tea ceremony is an exception, because it is a ceremony: the objective is not to make tea, but to observe certain ritualistic rules, of which preparing and drinking tea is an important part.

        Here's what I have found both an effective way and producing tasty results: use a French press as the first pot. An added bonus is being able to observe the tea leaves as they release their aromas, which is particularly nice with Jasmine Dragon Tears (or Pearls, depending on who your distributor is), and other kinds of hand-rolled tea that opens up while brewn. It will also be easier to determine when the tea is just right, if you don't have a timer or don't like timers in this context.

        Update: Actually, I misread a part of your original reply. You use a three-step process: kettle, pot, cup. I use a four-step process: kettle, pot, pot, cup. The function of the first pot is to brew the tea, and nothing more, while the tea is served from the second pot. This has the benefits that 1) the strength and flavour of the tea will stay constant in the serving pot, and 2) the tea will get mixed when you pour it from the brewing pot to the serving pot. The latter is a matter of taste, but I've found it helps in making homogeneous tea; usually the strongest stuff is at the bottom, if you use only one pot.

        print "Just Another Perl Adept\n";

        Wow.. i never realised that there was an ISO standard for making tea!
Re: Warming the pot
by andreas1234567 (Vicar) on Oct 17, 2007 at 07:55 UTC
Re: Warming the pot
by cmv (Chaplain) on Oct 19, 2007 at 12:45 UTC

    In regards to tea, I guess I would qualify as a local barbarian. When I get to hankering for a cup, it's basically tea-bag, sugar, water, cup, microwave (apologies to those offended by this, but what can I say? I also put water in my scotch).

    Being as my horizons are expanding quite a bit, ever since visiting PM on a regular basis, I'm intrigued by all this fuss over something I used to think of as just warm brown water. Please take me under your wing and help me understand the mysteries I've been too ignorant to understand, and answer a few simple questions for a poor uneducated slob such as myself.

    I was once chastized for not boiling the water in my (feeble) attempt to make tea for a guest. Is there any concrete reason to boil the water, or is that just a ceremonial item?

    You spoke nothing of the accessories involved in the process. Is sugar required? What kind? Granulated? Cubed? Can honey be substituted? What about any associated edible thingies (does anybody actually know what a scone is, and how do you capture one?) Should the cup have residual tea stains in it to show it has been broken in, and if so, how many, what color, and should they be in any particular location(s)?

    I've got a million more questions, but let me stop here to see if I have not offended too much.

    Hoping to understand this strange new thing...


      I like tea. I like my teas in a particular way (plural intended). What I will now expose to you is a result of deep meditation on this subject, conducted while sipping tea at various occasions in the past three years since I was introduced to the idea that tea is not just warm, brown water (by my girlfriend, who is the expert between the two of us). No, I'm kidding. You can find this information from Wikipedia and with Google.

      I subscribe to the idea that there are few wrong ways and many right ways. Since tea is an edible (or in this case, drinkable) substance, and since there exists at least one gene that affects your perception of bitterness, there are no doubt more genes involved in the sense of taste, and thus everyone will taste things slightly differently. However, I have a few generic remarks:

      • Clean water. This is essential and probably the most important component after tea leaf quality in the taste of the tea.
      • Water temperature: this depends on what kind of tea you drink. Tea brews best in hot water, but you can't use too hot since it will be bitter. The numbers here try to minimize bitterness and maximize taste.
        • For white tea, never use hotter than 80°C. This has a huge difference in taste, as brewing white in too hot water makes it unpleasantly bitter.
        • For green tea, never use hotter than 80°C or so. Again, you'll notice the bitterness.
        • For oolong, 90°C seems to be the best.
        • For black, 100°C is just fine.
        How do you know, if using a kettle, when the water is of the right temperature? When water boils, there are three observable "stages" (you'll find this list with Google easily, and the origin seems to be a Chinese legend): when you get lots of small bubbles, the temperature is getting closer to 80°C; when you get long strings of small bubbles from the bottom to the top, 90°C; and huge bubbles when the water boils at 100°C.
      • Brewing time: this again varies with the type of tea. The more you brew, the more you'll get the bitter chemicals in the tea. As far as I remember, the bitterness of tea does not start to increase until after the first minute of seeping or so. The instructions on the bag are usually good enough; I generally vary the time and figure out the right one for myself (how I like it).
      • Leaf type: loose leaf or bagged. If you only can, go for loose leaf tea. Not only will your tea taste better, you will also be able to get more tea out of them. Bagged tea is lower quality, containing not only the "effective" parts of the leaf but bits and pieces of the central stalk (whatever it is called). This doesn't matter if you only use the bag once; the taste will be the same. However, with high quality loose leaf, you can reuse the leaves 4-6 times. Quite often the best brew will be the second one. To prepare loose leaf, take a look at the other replies in this node.
      • Tea type (oxidization): There are four main types: white, green, oolong, and black, in the order of how much they have been oxidized. Black has the strongest and fullest taste, and white the most delicate. You can also vary the type on the axes of when the leaves where picked, if they have essential oils added, etc.

      That should get you started. Wikipedia is another nice starting point. As for what to put into tea or eat with tea, there are many different traditions about it. Most kinds of black are good with or without milk. I don't recommend putting anything in green, white or oolong; their taste is too delicate for milk, sugar, or honey (but do try it out if you like). Often, with green, you serve something sweet (though not excessively sweet).

      The best method is to try things out for yourself, but this requires some reading at first, and preferably a high quality teashop where you can ask about teas before buying. If you're used to bagged black, I recommend going to your local supermarket and shop for loose leaf black (Twinings is not a bad choice), and experiment with it at first.

      print "Just Another Perl Adept\n";

Re: Warming the pot
by teabag (Pilgrim) on Oct 26, 2007 at 20:43 UTC
    Guess I'm in hot water again....
    Blessed is the end user who expects nothing, for he/she will not be disappointed.
Re: Warming the pot
by chanio (Priest) on Oct 24, 2007 at 05:59 UTC
    2 English Breakfast tea bags makes 1 liter of good black tea.

    Oolong tea is also called red tea. Black tea is a green one that is always fermented for some weeks. The best is the tiny chinese one.

    The logic in boiling is the level of oxigen that is left in the water when pouring. When boiling too much, you risk to loose too much oxigen and so drinking a tea with no taste or flavour.

    You should try some delicious Swiss flavoured teas...

    Or make your own by adding some pieces of apple or orange in the same box where you keep your black tea...

    To enjoy drinking any tea, it is better to learn to drink it without any sweetener. When you drink some tea, you take your time.

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