Talk:2790: Heat Pump

2023-06-17T05:25:34Z

Marta:

woah! an xkcd with color what was the last one with color? (im kinda new to xkcd) [[Special:Contributions/172.71.122.48|172.71.122.48]] 21:17, 16 June 2023 (UTC)Erfaniom

I suppose color was needed to show the air temperature. Odd, though, that in summer (in the northern hemisphere), the character is trying to increase the indoor temperature. [[User:Davidhbrown|Davidhbrown]] ([[User talk:Davidhbrown|talk]]) 21:27, 16 June 2023 (UTC)
:He's not. He's moving the hot air from inside to the cooler outside. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 22:18, 16 June 2023 (UTC)
::he's actually heating it, the comic is set in winter. It's a reference to the discussion about regulating heating systems in Germany. I added something about that in the explanation, but I don't think I made the citation right (I'm not to editing wikis) [[User:Marta]]
::I actully think he's warming the inside, already warmer than outside, by effectively (and literally!) squeezing the heat out of the cooler outdoors air.
::By compressing the cool outdoor air, he increases its temperature (p1v1/t1=p2v2/t2) to warmer than the warm indoor air, creating a squeezebox->room flow of heat energy, then returns to the outside before decompressing and lowering the temperature in his squeezebox below the cool-air temperature in order to create an outdoors->squeezebox flow of energy and repeat. (The comic has the cycle start at roughly half-way through that, and wraps round, but the heat-to-room seemed the most obvious starting place here.)
::Right now, I'd not wish to heat my indoors up (even at 11:30pm, like now), so I agree that it's a funny time of year show heat-adding (rather than heat removing), but it definitely is that. [[Special:Contributions/172.70.86.154|172.70.86.154]] 22:31, 16 June 2023 (UTC)
:::Assumption(?): Indoors is on the LHS and higher, outdoors on the RHS and lower, door opens outwards and steps down to "outside". He COULD instead be cooling a basement apartment with a door that opens inwards (like mine)... however he seems to make a noticeable difference to the red, not the blue, so... probably not. :-/ [[Special:Contributions/172.70.34.160|172.70.34.160]] 02:36, 17 June 2023 (UTC)

Wasnt there a "My hobby is to open my refrigerator and when people tell me that doesnt help, I sneak into their house and use their AC?" Comic? I cant find it, but we should link it in the "how leaving a fridge open doesnt help" section [[Special:Contributions/172.71.142.158|172.71.142.158]] 23:36, 16 June 2023 (UTC)

I think it's talking about leaving the door open in general i.e. forgetting to close it when getting groceries, not specifically when he's moving the heat pump [[User:Firestar233|Firestar233]] ([[User talk:Firestar233|talk]]) 23:40, 16 June 2023 (UTC)

I can't think of a good reason to say this, but my new fridge doesn't warm up on the back. It warms on the sides. A bad (and quite a PITA reason) is I had to get a new fridge. Protip: don't panic, and do put the sacks of ice into something that won't leak. First time I've met a fridge that doesn't warm on the back.
Btw, red hot blue cold. Pink? Light blue? A light blue a pink? Shrug. [[Special:Contributions/172.70.43.31|172.70.43.31]] 23:57, 16 June 2023 (UTC)

How many trips would this take? I'll leave the exact parameters of the calculation up to you. (Nerd sniping attempt.) ~ Megan she/her [[user talk:megan|talk]]/[[special:contribs/megan|contribs]] 00:20, 17 June 2023 (UTC)
: 42. But stick figures are just lines and have no surface area for heat transfer.
[[Special:Contributions/172.70.134.236|172.70.134.236]] 01:02, 17 June 2023 (UTC)

2790: Heat Pump

2023-06-17T05:20:24Z

Marta: /* Explanation */

{{comic
| number = 2790
| date = June 16, 2023
| title = Heat Pump
| image = heat_pump_2x.png
| imagesize = 740x400px
| noexpand = true
| titletext = If I'm not going to upgrade to a powered one, I should at LEAST stop leaving the door open so often.
}}

==Explanation==
{{incomplete|Created by a BIG CHUNGUS HEAT PUMPER. Do NOT delete this tag too soon.}}

This comic appearing on 16 June, 2023 is likely in reference to the conversation in German media and politics about a controversial drafted law to regulate heating systems in homes and buildings [[https://www.theguardian.com/world/2023/jun/14/germany-coalition-staves-off-implosion-with-11th-hour-heating-law-amendment]]

A {{w|heat pump}} is a system which applies the {{w|ideal gas law}} to transfer heat from a relatively cold area to a relatively hot area, i.e. to heat an insufficiently warm room/building or to cool an insufficiently chilled room/building, even if the outside air is at the opposite heat-gradient for the purpose. The extra energy used to achieve this prevents the {{w|second law of thermodynamics}} from being violated, and is usually assumed to be added to the warmer side of the system. This is why the back of a refrigerator will feel hot, as it maintains the cooler internal temperature (and why leaving its door open does not cool the room that it is in down, just heats it up as it fruitlessly attempts to both heat and cool the same air-mass).

In this comic, [[Cueball]] has a ''manual'' heat pump, and he is manually heating an area by walking from the warm area (colored in ''red'') to a colder area (colored in ''blue''), and "drawing" residual heat into the "bellows" (accordion-shaped device) by expanding them to cool them below the outside air temperature (more intense blue). He then returns back to the warm area and compresses the bellows to concentrate heat above the sustained room-temperature (more intense red), then letting it radiate away and increasing room temperature before going back outside to repeat the process of drawing heat out of the cooler air. As expected, this is a laborious process, as captioned in the text below the panel. Manual heat pumps of this kind do not exist in real life{{cn}}, but are partly emulated by devices such as {{w|fire piston}}s. The {{w|air source heat pump}} effectively does the same thing as this comic, but by using components installed across a wall (letting fluids/vapors flow between the two sides) rather than moving physical components through doors.

The title text refers to the problem of having to open the door to carry the device in and out. This would let the warmed air flow out, and cool air flow in, to undo some of the effort used to attempt to increase the difference. In lieu of some device that does not require the door to be opened at all, he should at least promptly close it between each passage through it.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Cueball indoors (light red background) holding a (matchingly light red) accordion-shaped device in his hands and walking towards an open door.]

:[Cueball outdoors (light blue background) with the door closed, the device is still light red.]

:[Cueball extends the device and it turns blue.]
:''Release''

:[Cueball looks behind while the device has turned light blue to match the area it is in.]

:[Cueball walking back inside through an open door, the device is still light blue.]

:[Cueball indoors with the door closed. He squeezes the device and it turns red.]
:''Squeeze''

:[Cueball looks at the door while the device is glowing in bright red.]
:''Radiate''

:[Cueball is leaving the indoors area (now having a slightly more intense red background, to closely match the now less bright red of the device) through an open door.]

:[Caption below the panel:]
:Manual heat pumps are such a pain.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics with color]]
[[Category:Physics]]

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Talk:2790: Heat Pump

2790: Heat Pump