Heat pumps - Energy - Engineering
Our heat pump system uses an underground water tank and a solar/air collector as a heat source. We've designed and built this system from scratch ourselves: Theoretical calculations, numerical simulations, building the heat exchangers from off-the-shelf material, testing prototypes, testing components / sensors / heat pumps, optimizing the hydraulic setup of heat sink and heat source, programming the control units, developing software.
I have been the Theory Department of that enterprise, in charge of simulations and data analysis. My blog has been my way of publishing our research.
While we built that system, we also made drastic changes to the way we work: Reducing our air and car miles to nearly zero, and working mainly in remote projects today. This also includes heat pump projects!
Simulating Peak Ice (2017-05-02) 📌
Comparing measurements of the volume of ice in the tank with simulations - based on a model of the control logic, the varying performance factor of the heat pump, heat transport in ground, energy balances for the hot and cold tanks, heat transfer via heat exchangers connected in series.
Earth, Air, Water, and Ice. (2017-02-05) 📌
Data analysis of the heating season 2014/15 - when we turned off the solar/air collector to simulate a harsher winter. There are two kinds of energy balances: 1) The net energy stored in the tank - allowing for calculating the contribution of ground, and 2) the three heat exchangers connected in series in the brine circuit.
Re-Visiting Carnot's Theorem (2016-09-18) 📌
From the theory department: Why can’t there be any heat pump / heat engine better than Carnot’s reversible machine? A closer look at the proof by contradiction.
How Does It Work? (The Heat Pump System, That Is) (2016-01-07) 📌
The reply to numerous questions like: Can you explain - using images, with an animation - how the combination of ice/water tank and solar collector works? Here is a slide-show of operating statuses throughout a typical year.
Ice Storage Challenge: High Score! (2015-04-01) 📌
At the beginning of February we had turned off the solar collector to mimic a harsher winter. The ice cube, generated by our heat pump since then, stopped growing at about 15m3. About 10m3 of water remained unfrozen. Toying with theories about heat transport ...
Big Data, Big Plastic Worms, and How to Utilize Your Cellar (2014-09-07) 📌
Update on our heat pump system - the solar/air collector has been overhauled! And we look back with nostalgic feelings: What you never wanted to know about small houses and their earth cellars in Eastern Austria.
Art from Plastic and Wood (2014-05-31) 📌
Pictures of a solar collector built with a client. The water tank is located beneath the garage, and the collector installed on top of it, like a fence.
Infinite Loop: Theory and Practice Revisited. (2018-06-10)
Learning: Physics, computer science, and engineering. Formal education versus hands-on tinkering. I do have the former, but still think my actual education happens via the latter.
Can the Efficiency Be Greater Than One? (2018-04-09)
What is efficiency actually? The ratio of an output and an input energy – however these may be defined arbitrarily, and input and output are determined also by economics, not only by physics. So the answer is actially: Yes! I provide a non-exhaustive collection of examples.
The Heat Source Paradox (2018-01-19)
"A simple relation between a heat pump system’s key data; yet used in a misleading way in adverts: The worse the performance is, the smaller the heat source can be built."
Things You Find in Your Hydraulic Schematic (2018-01-12)
I am starting the New Year of Engineering Blogging at a lighter pace – don’t expect too much content this time!
Cooling Potential (2017-12-13)
We had an interesting discussion about the cooling potential of our heat pump system – in a climate warmer than ours. So we started to think about improving cooling power, by adding active cooling functionality.
Best of 2017 (2017-12-10)
What did I learn this year? Troubleshooting hydraulics is like debugging software. I really like classical thermodynamics.
Working Remotely (2017-12-02)
HTTP(s) (mis-)use connection magic enables me to work in a way I would have never envisaged 25 years ago - at the time when my most important 'files' were still contained in physical folders. I am able to work nearly remote-only, not only in IT projects.
Simulating Life-Forms (2): Cooling Energy (2017-11-28)
I found an incredibly detailed research report by the Australian government – about energy use in private homes, by appliance and purpose. It confirms my reluctance to 'predict' cooling energy as usage of air conditioning depends strongly on life-style choices.
The Collector Size Paradox (2017-11-01)
‘Collector harvest’ does not change much if we only use half the collector. Perhaps counter-intuitive but explained by the characteristics of heat exchangers connected in series: Especially if one of the heat exchangers (in the tank or collector) is already much superior to the other one, it does not help to optimize the good one further.
The usual number crunching – performance, energies, temperatures, ice, passive cooling – plus a summary of the system’s configuration and ‘cultural’ context.
Tinkering, Science, and (Not) Sharing It (2017-09-17)
That moment when you realize that your tinkering with PVC piping is actually science. Getting nostalgic about my nerdy childhood hobbies.
Simulations: Levels of Consciousness (2017-08-17)
Getting philosophical – what is a simulation (of our heat pump system), and what are the challenges? For modern buildings, simulating 'user behaviour' can be as critical as simulating 'physics' and control logic.
Heat Transport: What I Wrote So Far. (2017-07-14)
A list of all my blog posts focussing on heat transport, plus short summaries: Heat transfer and energy storage in our heat pump system, in ground, in ice. Analytical solutions versus numerical simulations versus maverick’s heuristics.
Mr. Bubble Was Confused. A Cliffhanger. (2017-04-08)
Our automated level sensor underestimated the volume of ice in the melting phase. In the coldest January since 30 years Mr. Bubble ware driven over the edge. He had to deal with a cliff … of ice.
Where to Find What? (2017-03-18)
A list of lists – our web resources related to the heat pump system. Bonus: Featuring The Chief Engineer's Art!
Ice Storage Hierarchy of Needs (2017-02-22)
Mulling upon ‘Peak Ice’ in our heat pump system – and detailed simulations versus simple energy accounting. Why the maximum volume of ice obtained in a season depends sensitively on the properties of ground and the collector.
Frozen Herbs and Latent Energy Storage (2017-01-20)
From root cellar to heat source … using pond liner. Sort of step-by-step instructions, using an every day analogon.
My Data Kraken - a Shapeshifter (2016-12-22)
Answer to the question: How do you analyze and consolidate your logging data? What is the biggest challenge? It’s the ongoing change of the ‘database schema’: New sensors, shuffled columns in log files, new calculated values…
An invention – an answer to: Can a compression heat pump be built in a completely different way? Yes, the pressure gradient can be created by centrifugal forces!
Similar results as last year, minus special research projects but plus a bit of nostalgia – when celebrating the 4th anniversary of starting up the system.
Hacking My Heat Pump - Part 2: Logging Energy Values (2016-08-24)
Connecting Raspberry Pi CAN bus logger to the Stiebel-Eltron heat pump and querying for temperature and energy values. Network traces and details of CAN frames, and automation of logging.
Extending logging infrastructure – automating reading off our heat pump’s internal energy meter by using Raspberry Pi as monitoring device. Before connecting to the heat pump hardware and software is set up and tested with a CAN bus I am familiar with.
Consolidated data from PV inverter’s logger, smart meter(s) and heat pump monitoring and control: Energy ‘generated’ by the PV panels, fed into the grid or supplied from grid, consumption in the house and by the heat pump in particular. 30% of total energy consumption was provided directly by the PV generator (no battery).
Comparing detailed time curves – illustrating why it is hard to raise self-consumption and self-sufficiency above statistical averages for homes without heat pumps: PV output, input energy for the heat pump’s compressor, and the home’s total smart meter balance.
Everything as a Service (2016-05-19)
Trying to predict the not-to-distant future of heating for consumers – following the ‘as a service’ philosophy introduced to software products long ago: Heating will be turned into monthly subscriptions bundled with internet access and bank accounts, and home owners will host aesthetically pleasing black-boxes operated by 'platforms'.
Alien Energy (2016-04-15)
Our photovoltaic generator is up and running for nearly a year. In this post I analyze the most remarkable day – as per our data logging, when we got nearly the generator’s rated power in mid-winter. Re-visiting the impact of temperature on output power, and the 'focusing' / 'edge of clouds' effect.
You need to get a feeling for numbers 'in renewable energy' - and it more than baffles me when authors of click-bait articles don't bother to the most basic cross-checks. It seems we lost the feel for 'what can power what' when engines replaces horses and humans.
Half a Year of Solar Power and Smart Metering (2015-12-07)
Daily and monthly balances of electrical energy, showing the amount of energy used by the heat pump's compressor versus energy consumed by appliances and control.
An account of the 19th century invention, based on the original German research reports.
Verified by analyzing our monitoring data - combining logging from our heat pump's control unit (UVR1611) and the PV inverter's logging.
Economics of the Solar Air Collector (2015-10-14)
My reply to an interesting question on measurement data for last season: Why invest in a solar collector if the performance factor decreases just a bit if you turn it off? Performance would not have been that high after turning the collector off hadn't we used the collector for months before.
Heat Pump System Data: Three Seasons 2012 - 2015 (2015-09-29)
Brief summary of last season's performance, plus back-of-the-envelope estimate of economics: Heat pump versus natural gas, based on costs of energy in Austria.
How to use the heat pump’s heat source – the underground water / ice tank – for natural cooling in summer (plus: a brief overview of the whole system, heating versus cooling modes).
Solar Energy, Batteries, and Autonomy (2015-07-15)
Third post on our PV generator - with data for the first two months, and my personal assessment of using battery storage.
Solar Power: Some Data for the First Month. (2015-06-17)
Figures and numbers from our PV generator's logging: Combining daily energy balances with data from our power meter, and tracking intermittent short and very high power spikes by parsing the inverter logger's website.
An Efficiency Greater Than 1? (2015-06-01)
The Coefficient of Performance of a heat pump is much greater than 1 which is due to the definition, omitting input 'ambient energy'. The rather high factor gives proof of the fact that heat pumps operate well above absolute zero.
Two Weeks After Lift-Off (2015-05-18)
An update on our photovoltaic energy generator: safety features, startup, and data for the first two weeks. Currently about 55% of the energy consumed by appliances and the heat pump come directly from the solar panels.
How to Evaluate a Heat Pump's Performance? (2015-04-21)
Definitions of performance indicators and how to determine them – comparing alternative methods, based on sensors available (Coefficient of Performance / Seasonal Performance Factor). Bonus: Cute math puzzle as the comparison boils down to: When is the ratio of averages equal to the average of ratios.
We Have Come a Long Way: Rooftop Solar Power Now! (2015-03-23)
"We had rebuilt half of our house but not installed solar panels – until recently. Here are some photos and a back-of-the-envelope assessment of economics of PV (in Austria); so now we harvest both energy inputs for the heat pump: Ambient and electrical energy."
Data Logging with UVR1611 - FAQ (2015-03-18)
What I would have wanted to read when I once made myself familiar with the freely programmable controller. This post is a response to some 'FAQ'.
The Ice Storage Challenge (2015-03-08)
We switched off the solar collector at the beginning of February 'for research purposes'. This is the status report!
Solar power and the impact of a solar eclipse. Soon we will contribute - our PV generator has already been ordered.
A Sublime Transition (2015-02-14)
Phase transitions between water, vapor, and ice: Last winter’s viral trend of freezing boiling water in mid-air, and discovering that scientists discuss such effects to this day.
A simplified simulation based on historical weather data: How large should this tank be so that it would hardly ever freeze completely in typical Eastern Austrian winters?
Personal Risk Assessment (2015-01-22)
The previous post on our ice-storage powered heat pump triggered an interesting discussion about the risk of a power outage. Is it more risky to pick a heat pump – compared to other systems?
We Want Ice! (2015-01-15)
Current measurement data showing the formation of ice in the 'ice storage' water tank. Winter is mild here, so there was only 1m3 ice so far. But we might partially deactivate the collector to test the generation of a bigger ice cube.
Physics, Science, Engineering, and a Lot of Fun (2014-12-17)
In overly correct legalese, my job titles according to our business licences are 1) Consulting Engineer in Applied Physics and 2) IT Consultant.
Cistern-Based Heat Pump - Research Done in 1993 (2014-12-14)
in Iowa. I stumbled upon a research report that described a heat pump similar to ours - except for the fact that the authors considered the collector not essential, based on a crude steady-state estimate of the heat flow from ground to the tank. Pionieering work though as they built the solution incl. data acquisition from scratch.
Engineering Links (2014-12-14)
Ressources I often use.
Being Creative with What Is Available (2014-11-27)
Build something from anything and to use whatever tool is at hand! Refers to anything we ever did or built - in the physics lab, as software developers, on designing the heat pump system.
Google and Heating Systems (2) (2014-11-15)
How things (in the Internet of Things) phone home and/or are accessed directly from the internet. Sometimes anonymously to my shock.
A 1970s Pioneer in Self-Sufficient Living (2014-11-08)
This is about heating power from compost and not even tagged with 'Heat Pump' - but nonetheless I can relate to Jean Pain's ideas. I know what it means to be driven by the quest for self-consistency in your life-style choices, your hobbies, and in the way you work.
Pumped Heat from the Tunnel (2014-10-04)
Summary of a press release that announced a EU 'Smart City' project. Cross-check of numbers for a large heat pump system. The heat source is water from a tunnel.
Normally, the water in the tank does not need to be drained or replaced. Except: You started pesky anaerobic reactions as you feed the bacteria in the water too much brine.
Digital Certificates and Heat Pumps ... (2014-08-04)
... an odd combination probably.
On the arcane nature of pipework, path integrals, and public key infrastructure.
This document also includes a more detailed description of the system and some configuration parameters.
Lost in Translation - an Overdue Update (2014-02-20)
Short overview and bold announcement of more technical documents to be translated to English.
Greatest Innovation Ever (2013-09-04)
Thoughts on the power grid - tangentially related to heat pumps that are often considered sort of buffer that will help to stabilize the smart grid (via demand side management).
Welcome to the Real World! (2013-08-14)
Actually an away note from my social media break - but also showing off our tomato plants, attached to the solar collector used as an espalier. I've included brief information on the operations of the collector in winter versus summer (cooling mode)-
Hydraulic design and short overview of our heat pump system that uses a water tank ('ice storage') 'powered by' an unglazed solar collector as its heat source.
Trading in IT Security for Heat Pumps? Seriously? (2013-01-22)
Personal essay on career transitions - PKI and heat pumps.
The First Heat Pump Ever Was Built in Austria (2012-12-10)
History on engineering - set in my home country.
Why Do Heat Pumps Pump Energy so Easily? (2012-05-10)
Brief (yes, really) explanation how a heat pump works.