Beating the heat with geothermal cooling


A while back, [Erich]‘s oil heating system was due for a few repairs. Given the increasing price of fuel oil, and a few incentives from his Swiss government, he decided to go with a more green heating solution – geothermal heating. The system works well in the winter, but it’s basically useless in the summer. [Erich] decided to put his 180 meter investment to work for the summer heat, and made his geothermal heating system into a cooling system with a fairly low investment and minimal cost.

The stock system works by pumping cold liquid from [Erich]‘s under floor heating into the Earth. In winter, the surface is always colder than the ground, thus heating [Erich]‘s home. In the summer, the situation is reversed, with the cool earth insulated by the baked surface. All that was required to reverse the heating system was a few slight modifications to the heating controller.

Stock, [Erich]‘s heat pump controller doesn’t have the capability to run the system in reverse, so he turned to a Freescale board to turn the compressor off and the pump on. With the additions, [Erich] is using 50 Watts to pump 1.5 kW of heat directly into the Earth below, a fairly efficient cooling system that’s basically free if you already have a geothermal setup.

Timer-based cooling helps your network survive the summer

Start your week off with a smile thanks to the video [Sammy] put together. It shows off the cooling rack he made for his network equipment. The project was developed out of necessity as the summer weather was causing his modem and router to heat up and at some point one of them would just shutdown and refuse to work again for hours. We haven’t run into this ourselves but it’s good to know that over-temperature safeguards have been built into the equipment.

His solution was to build a rack that offers fan cooling above and below the two pieces of equipment. As with most of his projects, we think making the video (embedded after the break) was half the fun. In addition to playing around with a turntable for some extra special camera effects he gives us a good view of the overall build. The base includes spacers and velcro strips to hold the equipment in place above a pair of exhaust fans. The standoffs at each corner of the rack suspend a second pair of fans above the equipment. But it wouldn’t look nearly as good without some custom LED effects thrown into the mix.

This is purely timer-drive. It’s a plug-in module that uses mechanical timing to switch mains. But some creative circuitry (or a small microcontroller) could implement temperature-based switching instead.

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Checking out the temperature of a Raspberry Pi

[Remy] has access to a very nice Fluke thermal camera, so when his Raspberry pi came in he pointed the thermal camera at the Raspi (Spanish, Google translation) to see how far this neat computer could be pushed before it overheated.

There are three main sources of heat on the Raspberry Pi: the voltage regulator, the USB/Ethernet controller and the Broadcom SoC. At idle, these parts read 49.9° C, 48.7° C and 53° C, respectively; a little hot to the touch, but still well within the temperature ranges given in the datasheets for these components.

The real test came via a stress test where the ARM CPU was at 100% utilization. The Broadcom SoC reached almost 65° C while the Ethernet controller and regulator managed to reach the mid-50s. Keeping in mind this test was performed at room temperature, we’d probably throw a heat sink on a Raspberry Pi if it’s going to be installed in an extreme environment such as a greenhouse or serving as a Floridian or Texan carputer.

Thanks [Alberto] for sending this in.

Building a Ranque-Hilsch vortex cooling tube

The Ranque-Hilsch vortex tube is an interesting piece of equipment. It can, without any moving parts or chemicals, separate hot and cold compressed gasses that are passed through it. Interestingly enough, you can cobble one together with very few parts for fairly cheap. [Otto Belden] tossed one together in a weekend back in 2009 just to see if he could do it. His results were fairly good and he shared some video tutorials on its construction.

His latest version, which you can see in the video below, takes compressed air at about 78degrees and spits out about 112degrees on the hot side and  8degrees on the cold side. Not too bad!

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CoolBot keeps your laser cutter from overheating

[Charles] wrote in to share the project he just built for the London Hackerspace. He calls it CoolBot, and as the name indicates it’s responsible for keeping the laser cutter from overheating.

At its heart the system is a water pump. It uses a plastic storage container as a reservoir, with an outfeed from the laser tube coming in the top of the lid. [Charles] mounted a temperature sensor using a 3D printed part to anchor it in the center of the return stream. An Arduino clone uses this sensor, as well as ambient room temperature and laser tube temperature sensors to decide when to switch on the cooling pump. As with any hackerspace add-on, this wouldn’t be complete without Internet connectivity so he included an Ethernet shield in the project box. Speaking of, that box uses panel-mount connectors to keep dust and water away from the electronics. But the lid of the controller box also includes a character LCD for quick reference.

Don’t miss [Charles'] explanation of the system in the video after the break.

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Keeping axolotl healthy and cool

The real life Mudkip Wooper Pokemon seen above is an axolotl, a salamander-like animal that lives in only one lake near Mexico City. These adorable animals can be bred in captivity, but keeping them is a challenge. [LRVICK] decided he didn’t want to throw down hundreds of dollars for an aquarium cooler so he built his own out of parts usually used for keeping computers nice and cold.

Commercial aquarium coolers that would meet the requirements start around $300 and go up from there. Not wanting to spend that much, [LRVICK] found a 77 Watt Peltier cooler for $5 and figured he could make it work. Off-the-shelf parts for water cooling CPUs were used to construct the aquarium cooler – a water block on the cold side, a huge heat sink and fan for the hot side, and a bunch of tubing goes up to the tank.

Now [LRVICK] has an axolotl housed in a very professional-looking aquarium that is a steady 65 degrees. He’s got a very nice build, and the axolotl looks very happy.

PC cooling using 1000 ft^2 geothermal

Are you still using heat sinks and fans to cool your computer? Lame. Tearing up your property to bury geothermal coils is definitely the way to go. [Romir] has been working on this for about a month and is just getting back data from the first multi-day tests. Take some time to dig through his original post. It includes something of a table-of-contents for the 35 updates he’s posted so far. Closed loop cooling seems to be trendy right now, we just didn’t expect to see a system this large as part of a personal project. The last one we looked at used just six meters of pipe.