This week, comment from guest blogger and International an are Station Associate regime Scientist Tara Ruttley, Ph.D., as she shows on the physical scientific research of boil in space.

You are watching: How is heat transferred in a pot of boiling water

If you don’t think the yourself as the type of human who might ever be interested in physics, let’s boil this down.

You’re hungry. That pasta time. Your pot the water is top top the stove, did you do it turned on the maximum heat, and the wait because that boiling begins. You are staring impatiently in ~ the pot as soon as the water looks prefer it’s beginning to swirl. She anxious to watch the balloon that represent that you deserve to put your pasta right into that water. However what perform those balloon tell you and what provides them the crucial indicator the perfect pasta water temperature?



On Earth, water boils via organic convection.(Image courtesy that Markus Schweiss via Wikipedia)


To leveling a bit, cook is actually a an extremely efficient warm transfer process and, in this case, boiling transfers the warm from the fire on your cooktop to the water the will cook your pasta. It appears straight-forward enough here on Earth: you turn on the burner, wait a few minutes, and when every those tiny bubbles appear, you’re ready to obtain cooking.

As friend wait for your pot that water to boil, there is a complex process going on in there. First, the fluid on the bottom that the pot closest come the heat resource starts to gain hot; as it does, the rises. The rising warm water is changed by the cooler, an ext dense water molecules. The water molecules in her pot continually exchange in this way, many thanks to gravity, ultimately warming the whole pot of liquid. This is known as herbal convection—the motion of molecules v fluid—which is a primary method of warmth (and mass) transfer.

Without buoyancy or convection, boil fluids act quite differently in space.(Video courtesy that


But organic convection is no enough, as it does no yet carry out those bubbles you need for her pasta. To obtain those bubbles, you need to wait long enough for the bottom the the pot to gain hotter 보다 the boiling allude of the water. As soon as the boiling point is breached, you finally start to check out the tiny bubbles of water vapor did you do it been waiting for! The balloon rise, due to buoyancy, and then collapse as they reach the denser, relatively cooler water in ~ the surface ar of the pot. This activity not only helps to relocate the water around much more quickly (think stirring), but the balloon themselves transport heat power as well. This bubble formation is referred to as nucleate boiling; a far much more effective method to transfer warm than herbal convection ~ above its own. In fact, so reliable that eventually it leader to more facility boiling called change boiling—the extremely turbulent bubble circulation that suggests the water is now hot enough to chef your pasta.

In space, however, balloon behave differently. There is no gravity, the results of buoyancy and convection are absent. The warmer water can not rise; rather it remains near the warm source, obtaining hotter and hotter. Meanwhile, the remaining water further away from the heat source stays relatively cool. Together the heated fluid reaches its boil point, the bubbles carry out not rise to the surface. Instead, the bubbles that do kind coalesce right into one huge bubble that sits top top the heated surface. In ~ the bubble lies precious heat energy, trapped! The result is a look at inefficient or at least really different, method to move heat.



Image of liquid boiling ~ above a heater variety during the low gravity produced by’s KC-135 aircraft. Blue regions indicate regions the low warm transfer. (Courtesy of university of Maryland)

As it turns out, there space plenty of researchers out there who are fascinated through the truth that if you cook water in space, you gain one huge bubble that often tends to “swallow” smaller sized bubbles. Why the fascination? Well, beyond the profit in basic thermodynamics “textbook” knowledge, due to the fact that boiling is such an efficient heat transfer process, understanding an ext about this complex process can aid to build much more efficient cooling systems for Earth and space. Because that example, automotive designers are interested in making compact, energy-efficient equipment to cool off hot vehicle engines, based on the heat transfer mechanics of boiling.

In fact, your very own refrigerator supplies a coolant with a low boiling point and some linked pressure transforms in order to save your food cold inside. By transferring warmth from the fridge air come the coolant to the suggest of boiling, heat eventually dissipates native the bubbles and radiates out right into the waiting in her home. In essence, back the air inside of your fridge might seem cold come you, the is actually warm sufficient to cook its coolant, i m sorry is the really heat transfer procedure responsible for maintaining your food cold.

The cook Experiment facility or BXF, which introduced on STS-133 in February 2010, will enable scientists come perform comprehensive studies the the complexities associated in bubble formation as a result of heat transfer. For instance, what roles carry out surface tension and also evaporation play during nucleate boiling when buoyancy and also convection space not in the equation? What about the sport in the nature of the heater surface? By controlling for gravity while on the International an are Station, scientists have the right to investigate the various elements of boiling, thus potentially driving boosted cooling mechanism designs. Improved performance in cooling an innovation can cause positive impacts on the an international economy and environment; two warm topics that have much to get from cook in space.

Dr. Tara Ruttley is an Associate regime Scientist because that the International an are Station (ISS) because that the national Aeronautics and space Administration ( in ~ Johnson space Center (JSC) in Houston. Her role in the routine Science Office consists of representing and communicating all research study on the room station, and supporting recommendations to the ISS program Manager and also to Headquarters, concerning research ~ above the ISS. Prior to her role in the ISS regimen Science Office, Dr. Ruttley served as the lead flight hardware engineer for the ISS health Maintenance System, and also later because that the ISS person Research Facility. She has actually a Bachelor of Science level in Biology and a grasp of Science degree in Mechanical design from Colorado State University, and also a physician of Philosophy degree in Neuroscience indigenous the university of Texas clinical Branch. Dr. Ruttley has actually authored publications varying from hardware style to neurological science, and additionally holds a U.S. Energy patent.

See more: How Many Cups Are In 2 Liters In Cups? How Many Cups Of Water Make A Liter



Dr. Tara Ruttley( Image)

Author jnimonPosted on April 15, 2011June 14, 2013Tags General

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