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Showing posts from 2018

Sensirion SDP810 Differential Pressure Sensor Code for Arduino

Lately I have been working a lot on a control system to emulate stack effect for use in the experimental setup I'm constructing. For the control system I'm using some small but extremely accurate and fast responding digital pressure differential sensors manufactured by Sensirion. The sensors are called SDP-810-125Pa, and while I've found two Arduino libraries intended for communication with these sensors, neither worked for what I'm doing, as I need to run the sensors in "continuous mode". I've therefore resorted to just communicating directly with the sensors over I2C using the build-in Arduino Wire.h library. This has turned out to not be too difficult (I managed it after all), and the Arduino code can still be kept pretty compact. I'm sharing the basic code below for anybody else using these sensors with Arduino MCU's. Also I've been in contact with a software developer at Sensirion who has told me that he is working on expanding their ardu…

Construction has begun

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Besides calculating and coding the best I've learned, actual construction of the test setup has now also begun. Luckily I have a dad with experience from the trades willing to lend me a hand.

More materials coming in

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I just picked up the ductwork and plywood I'll use to construct the experimental setup. In this regard I would like to thank Lindab A/S in Viby Denmark for donating high quality duct and fittings for the project, this stuff is a pleasure to work with.

Lab space with an ocean view

It has proven a lot more difficult to find a suitable lab space at the Engineering Departments facilities in Aarhus then I anticipated. The first floor where most labs are located has no operable windows and temporarily replacing glazing with plywood will apparently make me unpopular with both facility management, insurance companies, and the fire marshal. After a long day of meetings it looks like I'll be able to set up the experiment in the lighting lab on the roof however, so I'll get to enjoy a great view of the Aarhus bay as I work on the project!

Incoming electronic parts for lab testing

It's been a while since my last blog post as I've been enjoying a nice hiking vacation in Iceland. While I've been gone the last few electronic components I needed for the initial test setup have shown up in my mailbox, so you can expect some updates from the lab in the near future. I've also reached out to some of the authors I cite in my literature survey, and all the authors that I have heard back from have granted me permission to publish the literature survey featuring figures from their original publications here on this website. Once I have time I will therefore recompile the literature survey with these figures and upload it here. In many cases talking to these other authors of noteworthy publications within the field has also lead to some very interesting discussions that have reassured me that we are really onto something with this project. Stay tuned!

3D printer

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I bought a cheap Prusa I3 parts kit and build a 3D printer so that I can fabricate custom parts for the experimental setup during my thesis work. It's been a lot of fiddling around to get the printer to work properly but here it is printing the first custom part for the project!


By no means the newest, fastest, or fanciest 3D printer out there, but it was a lot of fun to make and it gets the job done.

Good news!

The Board of Studies at Aarhus Univiersity has just granted me an extension on my Masters Thesis deadline so that I can test the StackHR concept at the university during the Danish winter months. According to the head of faculty Kenny Sørensen this is the first time the board has granted such an extension prior to project start to a student at his engineering department!

Project report

I've now finished and turned in my report for the initial research project about the StackHR concept. The full report is available HERE. Enjoy the read!

Edit 23-06-2018:
I just realized that Aarhus Universities copyright agreement does not cover widespread publishing of student papers that feature figures from 3rd party sources. I have therefore removed all figures that were reprinted in the literature review section of the paper. Feel free to send me an email if you would like a copy of the original report with all the figures.

Edit 19-09-2018:
I've finally gotten around to update the report to only exclude figures by the people I wasn't able to get a hold of, just press the link above. Again, if you would like a copy of the original report with all the figures just send me an E-mail on info@stackhr.com.

Test Setup

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The research project during which I have been working on the StackHR concept is coming to an end soon as I'll have to finish up and turn in a report with all my findings by the end of this month.

Luckily that won't be the end of development on StackHR though!

For my master thesis project starting next semester, I will construct and perform tests on a prototype of a StackHR tube with guidance from my supervisor Professor Zhang. I very much look forward to this project and I have already started the first preparations. Below is a sketch I've made of the test setup I'm planning on using, but things might change somewhat down the road.


Yearly Energy Saving

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I've run calculations to investigate annual energy savings using the StackHR concept in place of traditional natural ventilation for Danish climate. The model assumed a Ø160 mm PVC pipe wrapped in 30 mm of glass fiber insulation as the outer tube, and a thin walled aluminium pipe as the inner tube. At no point did the heat recovery efficiency drop below 52%. On average it was found to be approximately 60% with an average flow rate of just over 2.5 L/s. With a standard deviation of 1.2, the flow rate is relatively stable attesting to the benefits of selecting stack effect as the driving force for the ventilation. Up to 4 of these tubes per slab segment (1200 mm wide) can be integrated, achieving an occupant density of 1 occupant per 8 m^2 floor area. For each of the StackHR tubes used, 228 kWh of heat per year is recovered and thereby saved in energy costs. I have added a new page describing the calculations and methodology as well as additional information about why one should cho…

How It Works

I have added a new page to this website explaining how StackHR works. Click the "HOW" link at the top of this page!

Website/ Blog Launch

StackHR is now online! It is my plan to keep this website updated with progress of the project as I go. StackHR has the potential to offer an environmentally friendly solution and to help improve indoor climate for people all over the world. I will be posting in English in order to make the site accessible to the largest number of visitors possible. That said, I am not a native English speaker, so please bear with any errors in grammar or sentence constructions.