This week, comments from guest blogger and also International space Station Associate program Scientist Tara Ruttley, Ph.D., together she mirrors on the physical science of boiling in space.

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

If you nothing think the yourself together the form of human being who can ever be interested in physics, let’s cook this down.

You’re hungry. The pasta time. Your pot the water is on the stove, did you do it turned top top the maximum heat, and also the wait for boiling begins. You room staring impatiently in ~ the pot once the water looks like it’s beginning to swirl. You’re anxious to watch the bubbles that signify that you have the right to put your pasta into that water. But what execute those balloon tell you and what makes them the an essential indicator the perfect pasta water temperature?



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


To leveling a bit, cook is actually a an extremely efficient warmth transfer procedure and, in this case, boiling transfers the warmth from the fire ~ above your range to the water the will cook your pasta. It appears straight-forward sufficient here ~ above Earth: you turn on the burner, wait a few minutes, and when every those tiny bubbles appear, you’re all set to gain cooking.

As girlfriend wait for your pot the water come boil, over there is a complex process going on in there. First, the fluid on the bottom that the pot closest to the heat source starts to get hot; as it does, that rises. The rising hot water is changed by the cooler, more dense water molecules. The water molecules in your pot continually exchange in this way, thanks to gravity, eventually warming the entire pot the liquid. This is well-known as natural convection—the motion of molecules through fluid—which is a primary technique of warm (and mass) transfer.

Without buoyancy or convection, cook fluids law quite differently in space.(Video courtesy that


But natural convection is not enough, as it does no yet administer those bubbles you need for her pasta. To acquire those bubbles, you need to wait long enough for the bottom the the pot to gain hotter than the boiling allude of the water. When the boiling point is breached, girlfriend finally begin to watch the tiny bubbles the water vapor you’ve been waiting for! The balloon rise, as result of buoyancy, and climate collapse together they reach the denser, reasonably cooler water in ~ the surface of the pot. This movement not only helps to relocate the water around an ext quickly (think stirring), but the balloon themselves move heat power as well. This bubble development is called nucleate boiling; a far much more effective means to transfer heat than natural convection ~ above its own. In fact, so efficient that ultimately it leads to more complicated boiling called transition boiling—the highly turbulent bubble circulation that shows the water is currently hot sufficient to chef your pasta.

In space, however, balloon behave differently. Without gravity, the impacts of buoyancy and convection space absent. The warmer water can not rise; instead it remains close to the warm source, getting hotter and hotter. Meanwhile, the staying water more away native the heat source stays reasonably cool. As the heated liquid reaches its cook point, the bubbles do not climb to the surface. Instead, the bubbles the do form coalesce right into one big bubble the sits top top the cook surface. Within the bubble lies precious warmth energy, trapped! The result is a look at inefficient or in ~ least an extremely different, method to deliver heat.



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

As it transforms out, there room plenty of scientists out there who are fascinated v the fact that if you boil water in space, you gain one big bubble that often tends to “swallow” smaller sized bubbles. Why the fascination? Well, past the gains in an essential thermodynamics “textbook” knowledge, since boiling is such an efficient heat carry process, understanding much more about this complicated process can aid to build much more efficient cooling equipment for Earth and space. Because that example, automotive designers are interested in developing compact, energy-efficient equipment to cool off hot auto engines, based upon the warm transfer mechanics the boiling.

In fact, your very own refrigerator supplies a coolant v a short boiling point and some associated pressure transforms in order to keep your food cold inside. Through transferring heat from the fridge air to the coolant come the point of boiling, heat at some point dissipates from the bubbles and radiates out right into the air in your home. In essence, back the air inside of her fridge might seem cold to you, the is actually warm enough to boil its coolant, i beg your pardon is the an extremely heat transfer procedure responsible for maintaining your food cold.

The cook Experiment basic or BXF, which introduced on STS-133 in February 2010, will enable scientists to perform thorough studies of the complexities connected in bubble development as a result of heat transfer. Because that instance, what roles execute surface tension and evaporation play throughout nucleate boiling when buoyancy and convection space not in the equation? What around the sports in the nature of the heating surface? By managing for gravity while top top the International space Station, scientists deserve to investigate the various aspects of boiling, therefore potentially driving enhanced cooling system designs. Improved performance in cooling an innovation can result in positive effects on the worldwide economy and also environment; two warm topics that have actually much to gain from cook in space.

Dr. Tara Ruttley is an Associate routine Scientist for the International space Station (ISS) for the national Aeronautics and space Administration ( in ~ Johnson room Center (JSC) in Houston. Her role in the regime Science Office consists of representing and also communicating all study on the room station, and also supporting references to the ISS regime Manager and also to Headquarters, regarding research top top the ISS. Before her role in the ISS routine Science Office, Dr. Ruttley offered as the lead flight hardware engineer for the ISS wellness Maintenance System, and later because that the ISS human being Research Facility. She has actually a Bachelor that Science level in Biology and also a understand of Science degree in Mechanical engineering from Colorado State University, and a doctor of Philosophy degree in Neuroscience from the university of Texas clinical Branch. Dr. Ruttley has authored publications ranging from hardware design to neurological science, and additionally holds a U.S. Energy patent.

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Dr. Tara Ruttley( Image)

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

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