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The project "Glass". Part 2. Sugar, insulated walls and blow or not blow



While the Greek and paper apocalypse was happening outside the window, and the pasta monster was devouring vermicelli on the shelves of megastores, the work on measuring the heat loss of disposable cups was fruitfully busy in the walls of the research institute. True, not everyone went to work the next day. Some suffered in a crush on March 12 when leaving the assembly hall and got a day off.

But Zavlaba did not care about such trifles. He was shocked by the planned transition to a remote location, because he did not like computers and other technological bells and whistles since childhood, and a huge table in his office was occupied by piles of drawings and calculations borrowed from various projects of public importance. Some of them have been lying here, probably, since the time of Ivan the Terrible.

2020 year. The period from March 12 to 26. Top-secret laboratory of the Research Institute of Heat and Cold (NIITiHo). Somewhere in the suburbs.


“Is everyone ready for testing?”

* A concentrated positive hum is heard of the engineers who came to work *

- Lesha, pour it!

Transparent high-degree liquid poured from an experienced metal kettle into glasses placed along the ruler. The distance between the glasses was measured qualitatively (1m20cm), there could be no mistake. The glasses themselves were the same, scrupulously selected by the responsible junior researcher Alexei. Along the table, specialists with appliances sat on special chairs. They waited for the team ...

- Five seconds - the flight is normal. The temperature is 85 whole, 6 tenths of a degree. Lowers.

- At the 2nd point, evaporation at level N!

- So, do not run, do not run, comrades! You create additional convection, and this interferes with the measurements!

People in well-worn white and important dark blue robes bent over glasses and measuring equipment, trying not to breathe in the direction of the measurements. The metronome counted down the seconds, then once a minute a short bell rang, and the laboratory technicians began to write together the current readings in their notebooks and notebooks.

- Vasily, watch the time, after 25 seconds you add sugar and stir your glass.

- Are you Pavel? Not Paul? Why do I have Paul recorded? Ah, Pavel got sick, ahem ... I see ... What is your name? Grigory Melekhov? So let's write it down. You stir your glass in 33 ... 32 seconds according to the Master Plan.

Of course, the movement of each specialist was clearly planned and spoken out in advance, which was indicated in the Master Plan of Comrade Zavlab. The whole laboratory, as a well-functioning mechanism, realized this extremely difficult task, which, without a doubt, led to a breakthrough of national importance. This importance, apparently, was not very understood by engineer Samsonov, who, sticking out his tongue and concentrating puffing, twisted something with his fingers right in the measuring apparatus. There was a dull command voice from Zavlab:

“So, the 5th sensor is messing up.” Who do we have there? Samsonov, look at the contact. So ... More ... In! Send the data. - Samsonov coped with his mission and smiled cheerfully, winking at his neighbor.

It was time for the culmination of the whole action. The tension grew. A clear command cut through the air:

- So, the thermal imager went. Come on, come on darling!



Article 1: https://habr.com/en/post/493444

annotation


This article will unveil the veil of how we do our work and what difficulties we periodically encounter. The topic of this article was to study the influence of several external factors on a glass of hot drink. External factors are divided into the following categories:

  • Addition of sugar in various quantities;
  • Insulation of the walls of the cup;
  • And even what is the temperature of tea when it is blowed.

Agree, this is a completely unexpected turn!

And also, it turned out that we would have to go to a remote site and that’s right. It is a pity we do not have a transgressive sofa :(

As the main experimental subject, we took Sample # 1 from the previous article, which for some reason we purchased too many (hello to the cooperation department).



Add sugar


To begin with, we decided to look at the effect of adding sugar to a glass of hot drink. For research, we used common types of sugar, which we managed to find in the immediate vicinity, as well as various versions of the form factor - sand and refined.

We added half a spoonful of sugar to the contents of the cup and this is what happened:



That is, the addition of only half a teaspoon of sugar has led to the fact that we get to 67 degrees already not in 12 minutes, but in 11 (directly, “Formula 1”). This is because the chemical reaction of sugar with water requires thermal energy, which is taken from our drink. The warmer the water, the more willingly sugar reacts with it, turning water / tea / coffee into a solution containing sucrose. But we didn’t stop there and decided to check what would happen if 6 teaspoons of sugar were added to tea, as this is done by m.s. Alexey (now he is responsible for sugar purchases, not purchasers).



And here, quite unexpectedly (with our level of organization of the experiments!), We find that errors have crept into the data! The test results in a glass with a lot of sugar and without sugar are almost identical (which should not be, physics is an exact science). And how to repeat the measurements? At first we had a real panic - the whole experiment was down the drain. We tried to work with the data, but, firstly, it turned out to be some kind of nonsense, and, secondly, it would be absolutely unethical to use incorrect data and make some serious scientific conclusions on their basis. Shouting a little through the window and running around the rooms (each one at home), we realized that the yard is already the 21st century, which means that we have the opportunity to implement this experiment remotely.

Almost all employees of the top-secret laboratory were remotely involved in Skype tests. The tests themselves were carried out at home by the leading engineer Danila P., who dragged home two packs of disposable cups (and everyone knew about it). For some reason, a thermal imager and thermometers were also found in his house. Zavlab commanded the process, the others vied advised. Laboratory assistant Anechka wrote down testimonies in her notebook with butterflies. And Pavel - immediately to Excel; he had no notebook with butterflies. Sugar Danile P. promised to compensate.



Now you can see what really works. Up to 60 degrees in 15 minutes instead of 20 in the original cup without sugar. We also tested the theory that if you throw the refined sugar into a glass and not interfere, the drink will cool longer. It turned out whether we are stirring sugar or not - this practically does not affect the cooling rate (within the limits of the error of home measurements) - at high temperature the sugar itself dissolves, although it remains in a higher concentration at the bottom of the cup.

Insulated walls


Another interesting experiment was aimed at finally determining how strongly the warming of its walls affects the cooling rate of a glass. For starters, we tested two options for doubling cups. The first time we put one cup in another the same ( # 1 + 1 ). And in the second - we put a couple of thin napkins in a glass and placed a second glass on top - they say that they use it in aviation ( # 1 + napkin + 1 ). Thanks for the tipkey08rus


Reggie and Ronald Cray, twin brothers

The result was a rather unexpected result: There are practically no



differences between the two options with glass # 1 in the study area. That is, we are poorly insulated? No, it turns out we were well insulated. If before the temperature of the walls of the cup # 1 was from 60 to 67 degrees (average of about 65 a C) and keep it has been extremely difficult in the hand,



then for two cups ( # 1 + 1 ), the situation is much better. The average temperature of the walls 54 of the C:



A for aviation embodiment ( # 1 + napkin + 1 ), the situation for the hands maximum comfort. Here, the average temperature of 48 about C and at the bottom of even less:



Such a glass can already be easily held in your hand even with boiling water. Why is this happening? Because, in the case of # 1 + 1 , firstly, the number of walls doubles (there were 2, became 4), and, secondly, between these walls there are already 2 thin air layers. In the case of # 1 + napkin + 1 , we no longer just have 4 walls and 2 air layers, but also a complex mixture of napkins and air between them. And thin layers of air, as you know, the best simple heat insulator in the world.

But this practically did not affect the cooling rate. Thermos in full understanding did not work. Then we decided to insulate the walls as much as possible in order to completely remove the heat flux through them. At the same time, the result obtained was compared with the use of a cover from article 1 to understand how much this event will affect the decrease in the cooling rate of coffee / tea. As a result, we got such a schedule:



It can be seen from the chart that even the maximum insulation of the walls and the bottom of the cup has a much smaller effect than putting a simple lid on it.

Yes, by the way, if you hold the glass in your hands all the time, this will also not help much (by the cooling time), although it will warm your hands :)

Let's blow!


To solve this fundamental problem, we planted three people blowing.

One of them runs marathons and half marathons. And also triathlons and Ironman. The man is trained, seasoned. Let his name be Ilya.

The second smokes like a steam locomotive, so we made the absolutely logical conclusion that if by the age of 50 he can still smoke so much, it means he can also blow about the same amount and with the same strength. And this is Dmitry Gennadievich.

Well, the third was our admin Serega - simply because everyone was interested, and Serega, as it turned out, had a tricky plan.

They motivated us with a large cake (in the case of a marathon runner it should have been carrot) and a pack of medical masks FFP3. With a slight advantage, Sergey won by building a system of two coolers from old computers and connecting this miracle to a portable battery in his pocket. I respond to the reasonable comments of other project participants with legal language - the rules did not stipulate the non-use of technical means and devices. I’m writing just in case, all of a sudden a marathon runner will catch up with me (he really wanted a cake and the recognition of his colleagues).

As a result, the following happened:



Sergey reached a comfortable drinking temperature (67 oC) in 4 minutes using your device. Ilya did the same in 5 minutes. Well, it took Dmitry Gennadevich 7 whole minutes. The competitive spirit in them did not dry out immediately, so they brought the matter to 60 ° C, which is clearly seen on the graph.

Also, in parallel, an experiment was conducted in which only the first two minutes were blown into the water in a cup, and then left to cool.



As a result, it turned out that this accelerated the time to reach 67 ° C by 3 minutes (it became 9.5 minutes instead of 12.5). Perhaps if a marathon runner or the system of our system administrator were blowing, then the time would be reduced even more.

By the way, here https://habr.com/en/post/377107 already done something similar, which unconditionally and irrefutably confirms the conclusions of our study.

Interesting fact


Have you noticed that if you stir coffee / tea, then the temperature becomes a little lower and sometimes you can already start drinking it? This is because the density of water depends on its temperature (and these drinks are made on the basis of water and, accordingly, inherit its properties). The lower the temperature, the higher the density. Warmer water rises, colder sinks to the bottom, i.e. in a glass with a hot drink there are layers with different temperatures. Closer to the walls, the liquid loses more heat, so the water at the walls is also colder (not everywhere) than in the thickness. Due to these two processes, there is a slow mixing-movement of water inside the glass, even if you do not touch it.


The thermogram shows a non-linear temperature distribution on the surface of the water in the cup (white-yellow bubbles float to the surface and mix, and the dark yellow substance drops below, mixing there)

Very short conclusion


  1. If you put sugar in a glass, the contents will cool faster. The more sugar, the faster it will cool (minus 1-3 minutes to the standard cooling time).
  2. Insulating the walls of the cup will save your hands from discomfort, but cooling the tea / coffee will not practically slow down (plus 1-3 minutes to the standard cooling time).
  3. If you blow, save time and pump your lungs (minus 3-8 minutes to the standard cooling time).
  4. A hot drink based on water is a layered drink. We don’t know where this is useful to you, but this is an indisputable fact.

Thank you for your attention, be positive, solve non-standard tasks and do not get sick!

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