Window screens

[coppice]

I was surprised to see the comment that stainless steel wasn't that expensive, so did some searches and found that the relative prices of materials has changed a lot since I last bought any a couple of decades ago.

It depends a lot on where you are. In the UK stainless steel is treated like a precious metal. In East Asia a huge amount of stuff is made from stainless steel, and its not that expensive to have really thick stainless steel.

[Zero999]

Global warming has raised the average temperature of the planet only 0.8C per decade since 1981 according to what I've found. That's enough to cause problems but not likely going to be very perceptible to humans or affect the amount of time you'd want to open the windows. Where I live has weather similar to that in the UK and it does seem like our summers are a bit hotter than when I was a kid, but it's always gotten pretty hot for at least a few weeks.

You've put the decimal point in the wrong place. Global temperatures have risen by 0.08°C per decade.
https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature

Some regions have warmed more than others and there are a few places which have actually cooled, due to changes in atmospheric circulation. Care needs to be taken with temperature and precipitation measurements, since human activity can affect the local microclimate. For example, a weather station which was previously in a rural area, which has recently become urbanised, will show an increase in temperature. The Met Office actually subtract 0.2°C from the modern Central England average to account for this.

Pity we can't just invent something, which can turn heat (temperature) as opposed to temperature differences, into electricity.

Of course not. It would violate the second law of thermodynamics. There's no way to do work without a temperature differential. It would be like using ambient air pressure to spontaneously make a vacuum. Daily/seasonal changes in temperature and air pressure can be used to generate electricity, but only a tiny amount, as the differential is tiny.

[IanB]

Of course not. It would violate the second law of thermodynamics. There's no way to do work without a temperature differential. It would be like using ambient air pressure to spontaneously make a vacuum. Daily/seasonal changes in temperature and air pressure can be used to generate electricity, but only a tiny amount, as the differential is tiny.

In principle, if you could use outer space as your heat sink, where the temperature is about 4 K, then you could have quite a nice temperature differential of 300 K or so. Not huge, but plenty good enough for heat pumps. Unfortunately, it would require some kind of very efficient radiator with access to clear skies at night. It's a shame there is unlikely to be a way to engineer such a thing.

[Zero999]

Of course not. It would violate the second law of thermodynamics. There's no way to do work without a temperature differential. It would be like using ambient air pressure to spontaneously make a vacuum. Daily/seasonal changes in temperature and air pressure can be used to generate electricity, but only a tiny amount, as the differential is tiny.

In principle, if you could use outer space as your heat sink, where the temperature is about 4 K, then you could have quite a nice temperature differential of 300 K or so. Not huge, but plenty good enough for heat pumps. Unfortunately, it would require some kind of very efficient radiator with access to clear skies at night. It's a shame there is unlikely to be a way to engineer such a thing.

4 K to 300 K is a huge temperature differential. You've forgotten that the lower the overall temperature of the system, the higher the maximum theoretical efficiency of the heat engine.

Carnot's theorem.
η_MAX = 1 - T_C/T_H

T_C = 4 K
T_H = 300 K
η_MAX = 1 - 4/300 = 98 ²/₃%

It's obviously impractical to get anywhere near this. The atmosphere returns a huge amount of radiation back to the earth, which is obviously a good thing.

[MK14]

4 K to 300 K is a huge temperature differential. You've forgotten that the lower the overall temperature of the system, the higher the maximum theoretical efficiency of the heat engine.

Carnot's theorem.
η_i = 1 - T_C/T_H

T_C = 4 K
T_H = 300 K
η_i = 1 - 4/300 = 98 ²/₃%

It's obviously impractical to get anywhere near this. The atmosphere returns a huge amount of radiation back to the earth, which is obviously a good thing.

I wondered if a super-conductor, threaded through a massive space elevator, between the planet surface (Earth) and out-space, could conduct enough heat, to make a powerful energy source.  While making my earlier posts in this thread, about using temperature as an energy source.

But unfortunately, the reality seems to be that super-conductors, make very poor thermal conductors.  So I had to throw that idea out of the window.  Which worked, because there was no insect screen in the UK, for it to bounce off (this sentence is a joke).

[james_s]

You've put the decimal point in the wrong place. Global temperatures have risen by 0.08°C per decade.
https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature

Whoops, thanks, I thought something looked wrong when I went back to read it.

At any rate I didn't intend for this to turn into a global warming debate, I was merely curious how widespread window screens are, and the answer seems to be a lot less so than I had assumed. They're such a universal thing in my part of the world, and so simple, the technology having existed in some form for thousands of years, I just assumed they were everywhere. Sounds like outside of North America they are not really a thing except in Australia which is not too surprising given what I've heard about insects and other nasty critters there.

[james_s]

In principle, if you could use outer space as your heat sink, where the temperature is about 4 K, then you could have quite a nice temperature differential of 300 K or so. Not huge, but plenty good enough for heat pumps. Unfortunately, it would require some kind of very efficient radiator with access to clear skies at night. It's a shame there is unlikely to be a way to engineer such a thing.

Even if you ignore the distance, using outer space as a heat sink is is easier said than done. Dissipating heat from spacecraft is a significant challenge due to the fact that conduction and convection are not available, so all you have at your disposal is radiation. It's challenging enough to dissipate more than a few tens of watts here on earth without forced air cooling.

[james_s]

Unusual that the traffic would be backed up in both directions at the same time. Generally everyone is either going to work or coming home. Not impossible of course, just unusual.

That's certainly not unusual here. Try driving from Woodinville, Redmond, Kirkland, etc to Seattle or Everett and through much of the day it will be backed up both ways. It's typically worse in one direction than the other, but a shocking number of people live in the big city and work in the suburbs while another group lives in the suburbs and works in the big city. Beats me why anyone would want to live in an urban city other than for convenient access to a downtown job but some people do seem to love those crowded dirty dumps.

[james_s]

Your friend is correct about screens not being a thing. Firstly, your friend is a wuss. There are a few people who jump up and down and scream: "Ooh, a little flying insect, oh no, how scary!" Most people just shrug and ignore them.

I don't think he's jumping and screaming and scared of them, like me he just finds them to be a nuisance. I certainly don't want bugs in my house, not because I'm afraid of them but because it's extremely distracting and annoying to have a fly buzzing around or a moth attracted to the light of the TV or computer screen or flitting around a light, and flies carry disease (they crawl around on piles of animal shit) so I don't want them crawling around on my food. Also here where I am we have a large number of mosquitoes which love my blood and eat me alive given the chance, and wasps which I'm mildly allergic to which causes a very painful sting with lots of swelling.

[coppice]

In principle, if you could use outer space as your heat sink, where the temperature is about 4 K, then you could have quite a nice temperature differential of 300 K or so. Not huge, but plenty good enough for heat pumps. Unfortunately, it would require some kind of very efficient radiator with access to clear skies at night. It's a shame there is unlikely to be a way to engineer such a thing.

Even if you ignore the distance, using outer space as a heat sink is is easier said than done. Dissipating heat from spacecraft is a significant challenge due to the fact that conduction and convection are not available, so all you have at your disposal is radiation. It's challenging enough to dissipate more than a few tens of watts here on earth without forced air cooling.

There are a bunch of videos on YouTube where people have experimented with various coatings on a shaded surface to radiate upwards to space as an air con. They are interesting experiments, but get too small a result to be useful.

[Ed.Kloonk]

You've put the decimal point in the wrong place. Global temperatures have risen by 0.08°C per decade.
https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature

Whoops, thanks, I thought something looked wrong when I went back to read it.

That how it starts! 

 

[IanB]

I don't think he's jumping and screaming and scared of them, like me he just finds them to be a nuisance. I certainly don't want bugs in my house, not because I'm afraid of them but because it's extremely distracting and annoying to have a fly buzzing around or a moth attracted to the light of the TV or computer screen or flitting around a light, and flies carry disease (they crawl around on piles of animal shit) so I don't want them crawling around on my food. Also here where I am we have a large number of mosquitoes which love my blood and eat me alive given the chance, and wasps which I'm mildly allergic to which causes a very painful sting with lots of swelling.

We do find them to be a nuisance in Britain too, but not excessively so. There are a few factors which make a difference. Firstly, the UK tends to have very defined boundaries between urban areas and rural areas, and most of the rural areas are farmed, and not wild. There are vast numbers of flying insects in the UK, but mostly they tend to keep to their own habitat, and few venture inside houses. Yes, the odd fly or wasp or moth will come inside, but we just live with the annoyance and shrug it off.

On the other hand, if you drive through the countryside in the summer months, your car and windshield will get completely covered in squashed bugs, and it will be a real pain to clean them off. Also, if you go for a walk in parkland or a nature reserve, then swarms of midges will surround you and follow you. As a child I used to find it amusing to run for a distance to leave the midges behind, and then watch as the swarm followed me and regrouped around my head, just like in a cartoon.

[Ed.Kloonk]

On the other hand, if you drive through the countryside in the summer months, your car and windshield will get completely covered in squashed bugs, and it will be a real pain to clean them off.

Driving between Australian capital cities at twilight is a excellent way to fill the car's radiator with blanket of dead insect. Hard to remove.

[IanB]

I don't think he's jumping and screaming and scared of them...

Right, but you may not have seen the reaction of excitable people to crane flies 

I assume they are found in the USA, but when I was growing up they were as populous as CatalinaWOW described cicadas to be. Except that unlike cicadas, crane flies flutter around like crazy giant mosquitoes and give people the heebie-jeebies.

[IanB]

Since I was curious, I found that window screens are absolutely available in the UK, you just have to buy them and fit them.

It seems that mostly they are designed to fit on the inside, and they attach to the frame with velcro or magnets so they are easy to move aside.

[james_s]

I don't think he's jumping and screaming and scared of them...

Right, but you may not have seen the reaction of excitable people to crane flies 

I assume they are found in the USA, but when I was growing up they were as populous as CatalinaWOW described cicadas to be. Except that unlike cicadas, crane flies flutter around like crazy giant mosquitoes and give people the heebie-jeebies.

Yes we have those here, I think they're what my mom used to call galnippers. They're kind of gross but harmless, and when my cats were younger they used to catch them and eat them fairly quickly so any that got into the house didn't last long.

[TimFox]

Since I was curious, I found that window screens are absolutely available in the UK, you just have to buy them and fit them.

It seems that mostly they are designed to fit on the inside, and they attach to the frame with velcro or magnets so they are easy to move aside.

Another style of window screen that is popular in the US is an expanding rectangle, maybe 30 cm high, that goes under the bottom of a raised double-hung window.
Two halves slide past each other to cover a reasonable range of window opening width.
Retail price between $5.00 and $10.00 USD.

[jpanhalt]

Talk about swarming flies...  Lake Erie shore has Mayflies (attachment).  I saw them the first June I lived in the area.  Absolutely amazing.

https://www.facebook.com/people/The-Mayflies-of-Lake-Erie-Official-Site/100063660383987/

Screens help.  BTW, casement windows usually have the screens on the outside.  Windows that fold out have them on the inside.  Mine are on the inside.  They are easier to remove and clean.  That's also are an advantage when wanting to get a good shot at a groundhog or raccoon.

[TimFox]

Another grand tradition in the US:
Especially before air conditioning became ubiquitous, large houses in low-density urban or rural areas would have very large porches (usually in front, sometimes in back) that were screened (with removable screen frames) in summer to provide a ventilated bug-free area, sometimes used for sleeping in very hot weather.
The screen frames were numbered, to be installed in the right place, but as the house aged and became less Cartesian, one would have to remember which number screen went in which numbered location to fit the new geometry.

[PlainName]

We don't have a fly problem here. In fact, the more the merrier!

[jpanhalt]

Maybe God protects the righteous?

Edit:
Pope Leo X died of malaria in 1521.
Pope Sixtus V died of malaria in 1590.
Giambattista Castana was elected Pope Urban VII in 1590, but died of malaria before his coronation.
In 1623, when the Sacred College of Cardinals was convened to choose a successor to Pope Gregory XV, malaria felled many of these clergymen.

[EPAIII]

CO2 is not a pollutant. It is an absolute necessity for plant life.

CO2 levels are just barely just above their all time, in the entire history of the planet, low level. If we remove much of it, we will need a new food source because the plants will start dying out. And then the animals. And then, guess who!

Oh, and the oxygen, which the plants make, will run out too! Choke! Gasp!

Somebody needs to actually think this thing out. NOW!

That plus physical problems, especially drought.
Since biblical times, drought has resulted in migration and conflict.

Ironically, even electronics and computers, generally don't like the heat, either.

Pity we can't just invent something, which can turn heat (temperature) as opposed to temperature differences, into electricity.  Saving burning so much fossil fuels and reducing the global temperatures (maybe or maybe not, as that electricity would eventually be turned back into heat, when it is used, typically).

It would be great, if we could all (world wide) band together and invent/construct and pay for massive carbon-dioxide removal techniques, and perhaps then bury the excess CO2, back underground somewhere, out of the way.

Instead governments, seem to go for things like forced LED light ownership and electric vehicles.  Yet, they still need enormous amounts of energy and stuff, to be created in the first place.

E.g. An electric car and its batteries, must use up a huge amount of energy and precious materials, in their construction, and will need to get their electricity and spare parts, from somewhere.  So are they really saving the planet, like governments, seem to be implying (by their forced introduction, in the coming future, in many countries).

[EPAIII]

It is simple:

The ones who live on the east side of the city, WORK on the west side.

The ones who live on the west side of the city, WORK on the east side.

The ones who live on the north side of the city, WORK on the south side.

and

The ones who live on the south side of the city, WORK on the north side.

See, it's simple.

Unusual that the traffic would be backed up in both directions at the same time. Generally everyone is either going to work or coming home. Not impossible of course, just unusual.

[EPAIII]

Five words:

The second law of thermodynamics.

Pity we can't just invent something, which can turn heat (temperature) as opposed to temperature differences, into electricity.  Saving burning so much fossil fuels and reducing the global temperatures (maybe or maybe not, as that electricity would eventually be turned back into heat, when it is used, typically).

That's kind of how physics works though. Heat is a bit like static electricity, unless the heat (or electricity) is flowing somewhere, no work is getting done.

My understanding, is that it might be theoretically possible.

Example:
You use a very high efficiency heat pump, to turn the existing temperature into a temperature difference, perhaps using a fifth (or hopefully higher) of the electrical energy, that would have been needed, to create the heating (temperature increase) using resistive heating elements.

You then use that temperature difference to power a thermopile  https://en.wikipedia.org/wiki/Thermoelectric_generator  with perhaps an ...
 

efficiency is approximately 33-37%

can be used.  Then it might be possible, eventually, to make realistic ones, which can 'profitably' extract electricity, out of pure/fixed temperature.

Just that they need to invent, practicable heat-pumps and thermopiles, with the necessary high enough efficiencies, over compatible temperature ranges.

But don't worry.  I've heard about and/or spoken to one or more people, who strongly think that the Physics of what I just said, is relatively impossible and it would never work.

Anyway, as a backup solution.  Perhaps fusion power will be invented one day (by that I mean our own fusion generators, excluding calling solar cells/panels fusion as they use the suns natural fusion energy system).

[tom66]

Global warming has raised the average temperature of the planet only 0.8C per decade since 1981 according to what I've found. That's enough to cause problems but not likely going to be very perceptible to humans or affect the amount of time you'd want to open the windows. Where I live has weather similar to that in the UK and it does seem like our summers are a bit hotter than when I was a kid, but it's always gotten pretty hot for at least a few weeks.

Without getting too deep into the global warming "debate", there's a difference between average climate warming and actual weather.  So whilst global warming has only had a sub-degree rise so far compared to 1950, the number of days the UK experiences with weather over 30C has increased considerably as a result.