heat

42 Articles

The London Underground Is Too Hot, But It’s Not An Easy Fix

December 4, 2024 by 90 Comments

The London Underground is an iconic piece of Victorian era engineering. What started in 1863 quickly became a core piece of infrastructure that would define the modern character of the British capital. It’s grown and changed immensely in the many years that have passed. Sadly, increasing patronage and more trains have created problems that the original designers never envisaged.

Deep in those London tunnels lies an engineering challenge. The Tube is literally cooking itself. Every day, millions of commuters descend into a network of tunnels that have been absorbing heat since the reign of Queen Victoria. Those clay-lined tubes have been soaking up excess thermal energy like a giant underground radiator, and now they’re giving it back with interest. The tunnels are simply too hot, and cooling them down is inordinately difficult.

The Perfect Storm of Thermal Chaos

The Tube’s heat problem isn’t just about one thing gone wrong – it’s about everything gone wrong at once. When Victorian engineers designed these tunnels, cooling wasn’t a major consideration. The tight, compact tunnels were built deep, nestled in the clay beneath London. In the early days, temperatures in the Underground were considered comfortably low.

“The Underground’s the only spot for comfort when the days are hot; it is cooler below.” – London Underground poster, 1926

Originally, the clay surrounding the tunnels sat at around 14°C, acting as a heat sink for the network. However, over the years, with more trains coming and going and more heat pouring in, the temperature has risen. It now typically sits anywhere from 19° to 26 °C. That’s just the earth around the tunnels, though. Air temperatures are worse—hitting as high as 47°C during a 2006 heatwave. The problem has been a continual bugbear of the beloved Tube, with concerns that future heatwaves could see temperatures rise ever higher. Continue reading “The London Underground Is Too Hot, But It’s Not An Easy Fix” →

Building AI Models To Diagnose HVAC Issues

August 8, 2024 by 10 Comments

HVAC – heating, ventilation, and air conditioning – can account for a huge amount of energy usage of a building, whether it’s residential or industrial. Often it’s the majority energy consumer, especially in places with extreme climates or for things like data centers where cooling is a large design consideration. When problems arise with these complex systems, they can go undiagnosed for a time and additionally be difficult to fix, leading to even more energy losses until repairs are complete. With the growing availability of platforms that can run capable artificial intelligences, [kutluhan_aktar] is working towards a system that can automatically diagnose potential issues and help humans get a handle on repairs faster.

The prototype system is designed for hydronic (water-based) systems and uses two separate artificial intelligences, one to analyze thermal imagery of the system and look for problems like leaks, hot spots, or blockages, and the other to listen for anomalous sounds especially relating to the behavior of cooling fans. For the first, a CNC-like machine was built to move a thermal camera around a custom-built model HVAC system and report its images back to a central system where they can be analyzed for anomalies. The second system which analyses audio runs its artificial intelligence on a XIAO ESP32C6 and listens to the cooling fans running in the model.

One problem that had to be tackled before any of this could be completed was actually building an open-source dataset to train the AI on. That’s part of the reason for the HVAC model in this project; being able to create problems to train the computer to detect before rolling it out to a larger system. The project’s code and training models can be found on its GitHub page. It seems to be a fairly robust solution to this problem, though, and we’ll be looking forward to future versions running on larger systems. Not everyone has a hydronic HVAC system, though. As heat pumps become more and more popular and capable, you’ll need systems to control those as well.

Candle Powered Lantern Isn’t As Silly As You Think

July 6, 2024 by 30 Comments

[Gilles Messier] at the Our Own Devices YouTube channel recently took a look at an interesting device — an electric lantern powered by a candle. At first glance, this sounds completely absurd. Why use a candle to power LEDs when you can use the light from the candle itself? This gadget has a trick up its sleeve, though. It lets candle light out and uses the heat from the candle flame to generate power for the LEDs.

The small Peltier “solid-state heat pump” module in the lantern acts as a thermoelectric generator, converting heat from the candle into electricity for the LEDs. The genius of the device is how it handles the candle “exhaust”.  A bimetallic disk in the chimney of the lantern closes when the air inside the device is hot. The Peltier device converts the heat differential to electricity, causing the air inside the lantern to cool. Meanwhile, the candle is beginning to starve for oxygen.  Once the air cools down a bit, the disk bends, allowing stale smoke out, and fresh air in, allowing the candle to burn brightly again. Then the cycle repeats.

[Gilles] does a deep dive into the efficiency of the lantern, which is worth the price of admission alone. These lanterns are pretty expensive — but Peltier modules are well-known by hackers. We’re sure it won’t be too hard to knock together a cheap version at home.

Continue reading “Candle Powered Lantern Isn’t As Silly As You Think” →

Using The Wind And Magnets To Make Heat

June 25, 2024 by 53 Comments

On the face of it, harnessing wind power to heat your house seems easy. In fact some of you might be doing it already, assuming you’ve got a wind farm somewhere on your local grid and you have an electric heat pump or — shudder — resistive heaters. But what if you want to skip the middleman and draw heat directly from the wind? In that case, wind-powered induction heating might be just what you need.

Granted, [Tim] from the Way Out West Blog is a long way from heating his home with a windmill. Last we checked, he didn’t even have a windmill built yet; this project is still very much in the experimental phase. But it pays to think ahead, and with goals of simplicity and affordability in mind, [Tim] built a prototype mechanical induction heater. His design is conceptually similar to an induction cooktop, where alternating magnetic fields create eddy currents that heat metal cookware. But rather than using alternating currents through large inductors, [Tim] put 40 neodymium magnets with alternating polarity around the circumference of a large MDF disk. When driven by a drill press via some of the sketchiest pullies we’ve seen, the magnets create a rapidly flipping magnetic field. To test this setup, [Tim] used a scrap of copper pipe with a bit of water inside. Holding it over the magnets as they whiz by rapidly heats the water; when driven at 1,000 rpm, the water boiled in about 90 seconds. Check it out in the video below.

It’s a proof of concept only, of course, but this experiment shows that a spinning disc of magnets can create heat directly. Optimizing this should prove interesting. One thing we’d suggest is switching from a disc to a cylinder with magnets placed in a Halbach array to direct as much of the magnetic field into the interior as possible, with coils of copper tubing placed there.
Continue reading “Using The Wind And Magnets To Make Heat” →

Concrete Clears Its Own Snow

March 24, 2024 by 26 Comments

Humans are not creatures well suited to cold environments. Without a large amount of effort to provide clothing, homes, and food to areas with substantial winters, very few of us would survive. The same is true of a lot of our infrastructure since things like ice, frost heave, and large temperature swings can all negatively impact buildings, roadways, and other structures. A team at Drexel University in Pennsylvania has created a type of concrete they hope might solve some issues with the material in cold climates.

Specifically when it comes to sidewalks and roadways, traditional methods of snow and ice removal such as plowing and salting are generally damaging to the surface material, with salting additionally being damaging to vehicles. Freeze-thaw cycles aren’t kind to these surfaces either. This concrete, on the other hand, contains a low-temperature liquid paraffin which releases heat when it has a phase change, from a liquid to a solid. By incorporating the material into the concrete, it can warm itself as temperatures drop, maintaining a temperature above freezing to melt ice and snow. The warming effect isn’t indefinite, but lasts a significant amount of time during testing.

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Upgrading PC Cooling With Software

March 9, 2024 by 21 Comments

As computing power increases with each new iteration of processors, actual power consumption tends to increase as well. All that waste heat has to go somewhere, and while plenty of us are content to add fans and heat sinks for a passable air-cooled system there are others who prefer a liquid cooling solution of some sort. [Cal] uses a liquid cooler on his system, but when he upgraded his AMD chip to one with double the number of cores he noticed the cooling fans on the radiator were ramping quickly and often. To solve this problem he turned to Python instead of building a new cooling system.

The reason for the rapid and frequent fan cycling was that the only trigger for the cooling fans available on his particular motherboard is CPU temperature. For an air cooled system this might be fine, but a water cooled system with much more thermal mass should be better able to absorb these quick changes in CPU temperature without constantly adjusting fan speed. Using a python script set up to run as a systemd service, the control loop monitors not only the CPU temperature but also the case temperature and the temperature of the coolant, and then preferentially tries to dump heat from the CPU into the thermal mass of the water cooler before much ramping of cooling fans happens.

An additional improvement here is that the fans can run at a much lower speed, reducing dust in the computer case and also reducing noise compared to before the optimizations. The computer now reportedly runs almost silently unless it has been under load for several minutes. The script is specific to this setup but easily could be modified for other computers using liquid cooling, and using Grafana to monitor the changes can easily be done as [Cal] also demonstrates when calibrating and testing the system. On the other hand, if you prefer a more flashy cooling system as a living room centerpiece, we have you covered there as well.

Rocket Stove Efficiently Heats Water

August 4, 2023 by 19 Comments

Rocket stoves are an interesting, if often overlooked, method for cooking or for generating heat. Designed to use biomass that might otherwise be wasted, such as wood, twigs, or other agricultural byproducts, they are remarkably efficient and perform relatively complete combustion due to their design, meaning that there are fewer air quality issues caused when using these stoves than other methods. When integrated with a little bit of plumbing, they can also be used to provide a large amount of hot water to something like an off-grid home as well.

[Little Aussie Rockets] starts off the build by fabricating the feed point for the fuel out of steel, and attaching it to a chimney section. This is the fundamental part of a rocket stove, which sucks air in past the fuel, burns it, and exhausts it up the chimney. A few sections of pipe are welded into the chimney section to heat the water as it passes through, and then an enclosure is made for the stove to provide insulation and improve its efficiency. The rocket stove was able to effortlessly heat 80 liters of water to 70°C in a little over an hour using a few scraps of wood.

The metalworking skills of [Little Aussie Rockets] are also on full display here, which makes the video well worth watching on its own. Rocket stoves themselves can be remarkably simple for how well they work, and can even be built in miniature to take on camping trips as a lightweight alternative to needing to carry gas canisters, since they can use small twigs for fuel very easily. We’ve also seen much larger, more complex versions designed for cooking huge amounts of food.

Continue reading “Rocket Stove Efficiently Heats Water” →