Talk:Heat transfer

Isn’t “heat transfer” redundant?

Hi. Isn’t the phrase “heat transfer” redundant, since “heat” is defined in thermodynamics already as energy being transferred by mechanisms other than work and transfer of matter? Alej27 (talk) 00:13, 4 November 2021 (UTC)

It is the commonly used term in the field. Just look at the names of the references and external links. Meters (talk) 00:17, 4 November 2021 (UTC)

Dew point

.[8] An example of steady state conduction is the heat flow through walls of a warm house on a cold day—inside the house is maintained at a high temperature and, outside, the temperature stays low, so the transfer of heat per unit time stays near a constant rate determined by the insulation in the wall and the spatial distribution of temperature in the walls will be approximately constant over time.

This does not take into account the dew point of the walls. A better example could be found. 86.150.117.77 (talk) 17:52, 5 October 2022 (UTC)

Restored the History section

I have restored the History section, but moved it to the end of the article so as to deemphasize its importance. I agree with Sgubaldo that a History section is not really necessary, but I think it would be nice to have one. At the end of the article it will hopefully offer minimal distraction. As for now the section is woefully inadequate and unbalanced (my fault) consisting mainly of a long, quote-heavy account of just one series of experiments by Benjamin Thompson and subsections copied from other parts of Wikipedia. Some little editing has been done to the latter though, while leaving them mainly unchanged at their original pages.

The relevant parts of the History section could be moved to the articles Thermal conduction, Thermal conductivity, Convection (heat transfer), and Thermal radiation respectively, and I might try that if it is not suitable here. I was thinking of adding historical content to Convection (heat transfer), but found that there were two seemingly overlapping articles: Convection (heat transfer) and Convection; the former more relevant on account of its title, the latter—in my opinion—better and more complete. I wasn't sure where best to put it.

If some senior editor feels there should be no, or just a brief History section, I'll leave it at that. For all I have to offer is expansion. Unfortunately, I don't have time to scour the literature for a nice, balanced section covering all different time periods. My additions must rather happen as I come across them for other reasons, meaning—for now—few and far between additions of more Thompson and other 17th and 18th centuries investigators. The Cosmic Ocean (Please feel free to modify or undo any of my edits as deemed appropriate.) 16:07, 16 January 2024 (UTC)

Lead Image

Simulation of thermal convection in the Earth's mantle. Colors span from red and green to blue with decreasing temperatures. A hot, less-dense lower boundary layer sends plumes of hot material upwards, and cold material from the top moves downwards.

Hi all.

The lead image of this article is a simulation of thermal convection in the Earth's mantle. I see several issues with this as a lead image:

• It conveys only convection, despite there generally being 2 other kinds of heat transfer that are just as important in physics.
• It is overused, as the image is present on 4 other Wikipedia articles and a portal page.
• The image doesn't display an everyday subject that most readers would relate to easily.

So, instead, I have been looking at some alternative lead image candidates. One option in particular stands out to me because it is rarely used yet is very effective pedagogically in illustrating all three modes of heat transfer. This is a diagram of a hookah/shisha:

This image, Hookah-lookthrough.svg, clearly shows conduction, convection, and radiation within a single, compact system. Briefly:

• The glowing red charcoal transfers heat to the bowl primarily by radiation, represented by the red arrows.
• Heat then moves from the bowl through the body and into the water by conduction, shown by the dark green arrows.
• Heat convects up to the surface of the water, represented by the arrows whose colour transitions from dark green to lime.

Furthermore,

• advection is involved twice here, as the blue arrows and lime arrows respectively represent cool air being swept into the shisha and warm air being swept out during use.

• The distinction between convection (heat flow through fluids) and advection (matter flow through fluids) is clearly visible — something rarely achieved in diagrams, where these processes are often conflated.

• After heat rises to the water’s surface, vaporisation occurs, so this example also naturally demonstrates phase transitions and latent heat.

• The image is sharp and high‑quality.

• It is an example of applied thermodynamics and thermal engineering.

• This scenario is seldom used in physics‑education contexts, making it original rather than redundant.

This makes it a surprisingly comprehensive real‑world illustration of multiple heat‑transfer mechanisms.

Obviously, many editors may have concerns about using this image. That’s fair, and I think these points can be addressed:

• Cultural associations: A shisha has cultural and social associations that may make it initially seem inappropriate for physics education. However, the purpose of physics education is not to avoid culturally specific objects, but instead to illustrate concepts clearly and accurately. Neutrality is important, but nothing about this diagram violates NPOV — it is presented purely as a heat‑transfer system.

• Health concerns: The device is associated with smoking, which some may feel is unsuitable for a lead image. This is a valid concern. However, the diagram does not depict smoking behaviour — it is a neutral, labelled schematic of a heat‑transfer apparatus. Many educational diagrams use devices associated with fire, combustion, weaponry or other potentially sensitive contexts. If needed, a brief footnote can clarify that the example is used solely with the intention of educational purposes for thermodynamics.

• Unusual example: It is indeed an unconventional choice, but unconventional examples are not prohibited. What matters is whether the image illustrates the concept well. This diagram shows conduction, convection, and radiation simultaneously in a compact, easy‑to‑follow system — something few everyday examples can do as clearly.

• Potential distraction: Some may worry that the object itself could distract from the physics. However, the diagram is schematic rather than photographic, and the arrows and labels guide the reader’s attention directly to the heat‑transfer processes. The focus remains on the physics, not the cultural context.

Now let’s take a look at two alternatives.

Heat Transfer.png is a diagram of an induction stove boiling water in a pot. This example is familiar to most readers and does illustrate all three modes of heat transfer:

• Radiation: Heat radiates from the burner to the pot.
• Conduction: Heat conducts through the pot’s handle to the hand.
• Convection: Circulating currents form within the boiling water.

This option, like the hookah diagram, is also very strong in terms of pedagogical clarity (and also includes phase transitions, which is not a necessity but definitely a nice bonus). It is less likely to raise concerns, and the image itself is high‑quality and easy to interpret. My only two hesitations are that

• This example is extremely common in physics education, so using it here may feel somewhat redundant.
• The convection currents in the boiling water are valid, but they are not directly visible and therefore may be less intuitive for readers. By contrast, in the hookah diagram, the convection pathway is an explicit part of the device’s functioning, as the upwards flow of heat in the water is easily identifiable as convection.

The third option is a campfire, another traditional example. This image example, however, is already being used in the Mechanisms section of the article, the image being Heat-transmittance-means2.jpg. In it,

• Conduction: Heat is transferred along the metal rod from the hot end near the fire to the hand holding the other end.
• Convection: Warm air heated by the fire rises, transferring heat to the hands above the flames.
• Radiation: Infrared radiation from the fire travels outward, warming the hands at a distance.

And additionally, advection is included as a fourth, less typically discussed kind of heat transfer. Although this example is immediately recognisable and uncontroversial, I think it is pedagogically weaker for a few reasons:

• Convection and advection are included, but the diagram does not clearly distinguish their mechanisms visually, making the processes less intuitive.
• The conduction pathway relies on a metal rod placed in the fire, which is not inherently part of the system itself. Heat transfer between the rod and the surrounding air is minimal, and radiation would also significantly contribute to heating the rod.
• This example is also overused in educational contexts, and this particular image isn't especially high in quality.

All in all, I think the two strongest candidates for the lead image are the hookah diagram and the boiling‑pot diagram (for the reasons outlined above). Both illustrate the three modes of heat transfer, but not equally clearly. The convection currents in the boiling‑pot example are valid, but they are not easily identifiable in real life — you wouldn’t naturally notice them without added arrows or explanation. By contrast, in the hookah diagram the convection pathway is an explicit and intuitive part of the device’s functioning, making it much more immediately noticeable to readers. Combined with the fact that the hookah example is not overused in physics education, it seems to tick more boxes pedagogically.

With that in mind, my suggestion would be to move the current mantle‑convection image to the convection section (which currently lacks an image), and to use the hookah/shisha diagram as the lead image, accompanied by a clear caption explaining each heat‑transfer mechanism and any necessary contextual notes.

Knowing Wikipedia norms, I understand it's unlikely the shisha will be accepted as a lead image. But I still think it's worth proposing because if accepted, it would really be a clever improvement to the article.

I’d really appreciate any thoughts, questions, or alternative suggestions from other editors. If there are concerns I haven’t considered, I’m more than happy to discuss them and adjust the proposal accordingly.

Kind regards, Xyqorophibian (talk) 15:21, 8 January 2026 (UTC)

Which of these images have or could have sources? Johnjbarton (talk) 02:19, 19 January 2026 (UTC)

The campfire and boiling‑pot examples can easily be sourced using standard thermodynamics literature, for example A Heat Transfer Textbook (Lienhard & Lienhard 2013) and Fundamentals of Heat and Mass Transfer (Incropera & DeWitt 2007) respectively.

There are papers on waterpipes, but they tend to focus on toxicology, aerosol formation, charcoal combustion, and airflow rather than heat‑transfer pathways. So while the diagram is physically accurate, it’s harder to verify it directly in the same way. The closest relevant sources would be Shihadeh 2003, Monzer et al. 2008, and the WHO advisory notes.

This may seem like a limitation, but it isn’t necessarily a problem because:

• Lead images rarely require direct sourcing, as they serve as representative visuals rather than specific factual claims.
• In this case, the mechanisms shown follow standard, well‑established heat‑transfer principles, so additional verification is probably unnecessary.

So although the shisha example is less directly sourceable, it still works as a valid potential lead image.

Thoughts?

Kind regards, Xyqorophibian (talk) 00:57, 20 January 2026 (UTC)

I suppose you can guess my reply. IMO everything needs sourcing. It's not just about "being correct", sources are a way readers can learn more and editors can expand articles. The encyclopedia is a summary of knowledge. The difficulty of sourcing the shisha image as an example of heat transfer shows that including it isn't a act of summarization. Johnjbarton (talk) 01:50, 20 January 2026 (UTC)

Fair stance, and I understand the preference for sourcing wherever possible.

In this case the diagram is showing the heat‑transfer processes that occur in the setup, but it isn’t making any device‑specific claim about how shishas work. It’s simply illustrating radiation, conduction, convection and advection, all of which are already sourced in the article through standard thermodynamics texts.

Similarly, the boiling‑pot diagram illustrates these same transport mechanisms without making any claim about the detailed operational principles of induction stoves or cookware. The same distinction applies, more clearly, to heat‑transfer diagrams (as opposed to blueprints or operational sketches) of, say, car radiators or computer CPU cooling systems — they’re simply familiar contexts used to visualise the physics.

Happy to hear what other editors think.

Kind regards, Xyqorophibian (talk) 07:01, 20 January 2026 (UTC)

I'm not familiar with a hookah, but it looks like drug-user paraphernalia and is not really appropriate for a physics article. Almost everyone has experience with boiling water in a pot, fewer have experience with campfires. I would say the boiling pot image is the most familiar context for briefly illustrating types of heat transfer. --{{u|Mark viking}} {Talk} 18:49, 26 January 2026 (UTC)

Hi, and thanks for commenting.

Just to clarify, hookahs are widely used as cultural and social smoking devices in many regions and aren’t considered drug paraphernalia in reliable sources. In this context, the diagram is purely schematic — it’s intended to illustrate heat‑transfer pathways, not to depict or promote any particular activity.

I understand that some readers may associate the object with smoking, but from an educational standpoint the key question is how effectively the underlying physics is conveyed. This example illustrates radiation, conduction, convection and advection clearly, distinctly and accurately within a single coherent setup.

The boiling‑pot diagram is certainly familiar, but in my view the hookah diagram does a better job of showing all four transport mechanisms clearly, distinctly and accurately. For that reason I think it’s the stronger option for this article.

Kind regards, Xyqorophibian (talk) 23:17, 27 January 2026 (UTC)

We'll have to disagree on this one. Even if it wasn't drug paraphernalia (smoking is for ingesting drugs and damaging epithelial tissues), the diagram itself directly shows none of the heat transfer concepts--a reader would need to read a long caption to figure out what was going on and unfamiliarity with the complex device would just make those associations more difficult to understand. For instance, what is a bowl? Where is the water, exactly--is the bowl submerged in water, or is there some sort of air transport between the bowl and the water bottle below? Normally heat rises--is there some sort of external force causing it to flow down? I would guess there must be some sort of pump at the top or at the bottom of the device that is not illustrated. At the least, the hookah diagram should have all of these heat transfer processes clearly labeled in the diagram itself. Underlying my somewhat strong opinions here is the notion that a good lead image should be understandable at a glance. --{{u|Mark viking}} {Talk} 00:50, 28 January 2026 (UTC)

Hi Mark.

Thanks for the follow‑up. I think some of your concerns arise from a misreading of the diagram, since the labelled parts, their roles, and the heat‑transfer processes it depicts are actually quite straightforward.

A shisha‑type water pipe is mechanically very simple: there’s no pump, no submerged bowl, and no hidden components. Cool air is drawn in from the top past the windguard and charcoal; the charcoal radiates heat to the bowl; that heat then conducts downward through the plate and body into the water jar at the bottom. Heating the water drives convection within the jar and produces vapor at the surface, and that vapor is advected out through the hose when the user inhales. The diagram’s arrows correspond directly to these four transport processes.

On the point that the diagram “shows none of the heat‑transfer concepts”: it shows them in the same schematic way that most physics diagrams do—using arrows, colour cues, and spatial separation rather than literal labels on the image. That’s standard practice for heat‑transfer illustrations, including boiling‑pot diagrams, radiator schematics, and heat‑engine cycles. If the consensus is that the modes should be explicitly labelled on the image, that’s easy to adjust, but it isn’t a limitation of the example itself.

Regarding the concern about unfamiliarity: nothing in the diagram requires specialised prior knowledge of shisha construction. The bowl, water jar, and charcoal area are all visually clear, and the arrows already indicate the relevant heat‑transfer modes (by colour) and their pathways (by direction). Many lead images in physics articles rely on a short caption to orient the reader—Carnot cycles, P–V diagrams, heat exchangers, and Feynman diagrams all require a moment of interpretation. The shisha diagram isn’t unusually demanding in that respect. What makes it pedagogically useful is that it illustrates radiation, conduction, convection, and advection clearly, without conflation and within a single coherent setup, which is rare in everyday examples.

I hope this clarifies why the diagram is both accurate and appropriate for illustrating the four fundamental modes of heat transfer.

Kind regards, Xyqorophibian (talk) 01:44, 28 January 2026 (UTC)