Spring cleaning a.k.a. the seasonal purge of GTD inboxes

Spring cleaning a.k.a. the seasonal purge of GTD inboxes

University work never gets boring. It evolves continuously, so does the problems that must be taken care of. Every now and then, I set aside some time, think about my workflow on a higher level than usual, and check if the tools and methods that form my productivity system are up to the task.

The only thing that never changes is the fact that I rely on David Allen’s Getting Things Done in all my endeavors. The core principles of the GTD drive my workflow for years. I just can’t imagine how it is possible to survive without it.

When I sit down and think over underlying principle behind my workflows, the idea is to get rid of unnecessary clutter and simplify processes as much as reasonably possible. One of the most important aspects of efficient productivity is keeping under control all the points where the information enters your system. Frankly, at this point, life is way too complicated to keep and control just a single collection bucket or INBOX. That would be too much hassle, so I always use at least few. They all have to be regularly reviewed to keep things in order and up to date.

I just finished this year’s spring cleaning, so I can tell you a little about how my current data acquisition model looks like. Perhaps will find below some ideas to implement in your own productivity system.

Two types of INBOXes

The stuff can reach me through one of two categories of INBOXes: physical and digital. Physical inbox is simply a tray on my desk (one at home and one at work) where I put any piece of paper that needs to be taken care of. This is the old school inbox as described by David Allen in his book.

Digital inboxes are many, any relying on them is more complicated. Initially, I tried to build everything around a single digital collection bucket, but it didn’t work. There were many complications that slowed down the collection process. I decided to add inboxes for special purposes, which in the end brought me to five distinct locations dedicated to different aspects of my organized life. I combined them into two types: inboxes where people throw their stuff at me and inboxes where I control what kind of information enters my system.

So, lets take a look at the first category:

  • Email – most common and unavoidable entry point. This is the place where other people push information at me. I am regularly contacted by students, other researches, administration, etc. Email is necessary and requires constant review in order to stay under control. It is unlikely that I will ever get rid of email, but in some cases the number of emails can be reduced. This is why, nowadays, I rely on…
  • Instant messaging – Slack entered my life few years ago and made a revolution. We adopted it in our research team and basically got rid of our whole internal email communication. This is a place where my colleagues can always find me, question me, and send me requests for whatever they need.

In the next category of inboxes, I fully control what information enters my system. There are three kinds of inputs. They are complimentary and all play important role in my workflow.

  • Reminders – As the numer of my projects increased every year I needed to keep all of them under control in some kind of to-do system. The amount of information of enormous and very often, I have to be reminded to do something of to follow-up on something. In my case everything lands in OmniFocus, which is one of the best task and project managing application. Every time I need to write a reminder for some action to be taken in the future, it goes straight to my OmniFocus inbox. The principle is: every task must be actionable, thus it should start with a verb followed by some other information. For example “Buy hard drive.” or “Write summary of the Wang’s paper.” I also use tasks to organize follow-ups. Some reminders are there to notify me that I am still waiting for something and a follow-up is required. For example, “Waiting for the laboratory report.”. Whenever I consider to remember to do something, it makes a new task in OmniFocus.
  • Appointments – the second category of inputs. When a meeting is set I do not put the information to some inbox to deal with it later. Instead, I immediately create calendar entry, which usually takes 20-30 seconds and its done. In modern world, it would be extremely inefficient to create reminders about putting things in calendar. As David Allen pointed out, if something lands in your calendar, it must happen on a given time, or at all. Some people have calendars driven by their assistants or other people. That is also fine. For now, I prefer to set the scene on my own.
  • Other digital stuff – this category is the most important because it is the digital version of a traditional paper tray. Every scrap of potentially usable information, notes, photos, voice records, someday/maybe things (books to read, movies to watch, articles to skim, etc.), saved websites, everything goes right into this inbox. I will figure out what to do with it later. This is also the place where I delete most of stuff. Only limited number of things passes this check point and become resource materials.

This is how my set of inboxes looks like. It allows me to conduct the collecting phase in quite efficient manner. Five works for me, you might need more. It is good idea to keep this number to minimum because at one point everything will go through one of the above channels. It just need to work for you. So, what is your next action?

Photo by LudgerA on Pixabay.

How joining two COST Actions changed the way I think about research

How joining two COST Actions changed the way I think about research

Recently, I was asked several times what is the COST programme about and if it is worth considering at all. This is not a difficult question to answer. I joined two COST Actions and it influenced the way I understand scientific networking and research collaboration.

Everything started in 2016. Together with Agnieszka, the PhD student that I co-supervise, we established collaboration with the ILK-Dresden. We learned that they are involved in something called COST Action.  Few months later, we were flying to Spain for the NANOUPTAKE Management Committee meeting and the first Training School. It was just the beginning of collaboration that resulted in research, internship, more training schools, conferences, and joined papers…

Well then, what is the COST?

Chances are that being a researcher in a European country you have already heard about the COST (European Cooperation in Science and Technology). It is an EU-funded programme that helps to build and facilitate research and innovations networks. It is said that COST is Europe’s longest-running intergovernmental framework, as It was founded in 1971. Long before The Maastricht Treaty and establishment of the European Union as we know it today.

The networks funded by the COST Programme are called Actions, and there is a good reason for that. Networks often sit passively waiting for something to happen. Like a club that you join to be able to reach your colleagues only if necessary. COST Actions are more dynamic. People meet regularly and work together. They communicate, share knowledge, and solve problems… The COST (short from COST Programme) provides funds for all that networking activities: conferences, meetings, training schools, short scientific exchanges or other networking activities.

Joining the Action

So, what does it mean joining the COST Action? Well, I am currently a member of two. Both are huge and their aims are spectacular. Their topics are very different though, and my involvement is each of them is different as well.

The NANOUPTAKE aims to create a Europe-wide network of leading R+D+i institutions, and of key industries, to develop and foster the use of nanofluids as advanced heat transfer/thermal storage materials to increase the efficiency of heat exchange and storage systems. The members of NANOUPTAKE focus their research on various types of  nanofluids. Our own contributions are about properties of graphene oxide nanoparticles. We were able to observe some interesting things happening in a thermosyphon filled with this nanofluid. Research paper is underway. I will write more about it in a separate blog post after it is published.

The RESTORE (REthinking Sustainability TOwards a Regenerative Economy) is very different. Its goal is to affect a paradigm shift towards restorative sustainability for new and existing buildings across Europe. Here, a huge group of interdisciplinary researches is working on principles behind Restorative Sustainability, Processes, Methods and Tools for and Restorative Designs, and more. During the kick-off meeting, I volunteered to serve as a Science Communication Officer. It turned out to be a learning opportunity and, at the same time, a challenging adventure!

While being a contributor, you don’t have to change anything in your research activities. Well, almost… You can continue the research the same way as you’ve always done. The difference is that your work is now a part of a larger goal. As there is an audience to share knowledge and people to collaborate with, you will see your own research in a different way. You may suddenly find larger purpose!

This is a EU-funded project, which means that there are many rules to be followed. The structure of the COST Action, administrative procedures, reimbursements… everything is precisely explained in multiple documents at cost.eu website. For example, this is how you join an existing COST Action.

Being a part of the COST network can be leveraged in many ways. For example, you can use it to build consortium for H2020 grant. You can develop your PhD students by sending them to other institutions or laboratories for Short Term Scientific Mission (STSM). You can sent them for a dedicated Training School (all Actions organize specialized trainings), or perhaps some conference. All that can be funded from the budget of the Action (there are some limitations though).

Participation in the COST not only widened my horizons, but allowed me to meet incredible people from many countries. The experience is great, so I strongly encourage you to consider joining the Action and try yourself!

Stay safe after the recent Facebook crisis (using Pareto Principle)

Stay safe after the recent Facebook crisis (using Pareto Principle)

Chances are that you already heard about the Cambridge Analytica and the Facebook crisis. If, despite Mark Zuckerberg’s promises of fixing Facebook, you still have this creepy feeling of being exposed and manipulated, there are a few things that can give you at least some peace of mind.

So, what an ordinary user, can do in the world of dominating malicious corporations? Deleting all social media accounts could help, but it is an equivalent of nuclear strike. It may be easy for a teenager that wants to make a point, but those who constructed their businesses on social media may express some concerns.

We need to accept that social media are here to stay. Despite the fact that our concern about personal information is growing, Facebook will remain a very important part of our internet life. Whether we use it or not.

There are a few basic things that casual users can do to protect privacy. Let me tell you about the two tools that I always use on my computers. It is a great example of the Pareto Principle in action as these two methods are the effective 20% that produce 80% of results. They do not solve all the problems, but they significantly improve online safety.

The first thing that I immediately do after the operating system is up and running…

Modify the hosts file

Some websites are more dangerous than the others: shady pages with pirated content, malicious scripts, adult stuff, etc. There is always a chance that you will end up on such suspicious page. They pretend to be just another website, but behind the facade, harmful codes, spying scripts, and tracking cookies are hiding. It is very difficult for an average user to be always careful and aware, but there is a simple solution. You can prevent your computer from visiting such places by modifying the hosts file.

The hosts file is a system file that contains the lists of selected network addresses and assists in addressing network nodes in a computer network. It can be used to deny access to the dangerous corners of the net, block online advertising, or the domains of known malicious resources. The hosts file tells the system to redirect requests to another addresses that do not exist or are harmless.

Very elegant solution, especially if your machine is used by kids or elderly people that lack understanding how website content is manipulated to lure them to install spyware. The hosts file is used by system services on a very basic level. This means that not only browser, but other applications as well, will not be able to connect fishy servers. Many phishing emails will be rendered harmless as well.

Of course, the first step is to collect the list of dangerous domains. Fortunately, this work has been done already. Steven Black’s GitHub repository contains the hosts file made of 60-70k suspicious addresses. Even if your computer is otherwise unprotected, installing the hosts file will reduce the risk of exposure to malicious content. If you still use the default hosts file, just overwrite it with the one downloaded from GitHub. To learn how to edit the hosts file on Windows, Mac, and Linux, read this handy guide written by Christopher Welker (How-To Geek).

Install uBlock Origin

Once the hosts file is in place, the next step is to arm the browser with proper protection tools. The options are many, but I personally use and recommend uBlock Origin.

It is a free cross-platform browser extension for content-filtering (for Safari, Firefox, Chrome, and more…).  There are many ways to use it. For example, I let my browser to access social media servers only when I visit their homepages. Neither Facebook nor Twitter will see the other pages I visit because I allowed their scripts only on a few selected websites. It is very simple way to reduce the exposure, but the learning curve for uBlock’s advanced features may be steep.

In the end, the combination of uBlock Origin and modified hosts file will do wonders. You will immediately notice the difference as many websites will start to load much faster and look cleaner. Still, the most important outcome is improved privacy, as you become invisible to most of tracking scripts and cookies.

If you truly want to embark on a quest for complete internet privacy you will need to learn much more. The great place to start is http://privacytools.io. It is very comprehensive information source that offers knowledge, advice, tools, and many advanced methods to improve personal privacy while browsing the internet.

And of course, even the best plugin will not make any difference, if you keep putting your private personal information on public servers. But it is another story…

Photo by Scott Webb on Unsplash.

Five (plus one) tools for modern students and academics

Five (plus one) tools for modern students and academics

In order to survive modern college, both students and professors need tools that will help to deal with a huge amount of tasks and responsibilities. Luckily there are many applications designed to keep us organized, productive, and sane.

As many of students and academics, I rely heavily on my calendar. Setting it up and building up necessary habits took me years. Now, I can hardly imagine being able to function without its constant help. But calendar, despite being an essential tool, is not suitable for other things I have to take care of. That is becasue academic work also involves collecting and storing information, managing tasks and projects, outlining ideas and papers, and communicating with the team. Over time I simplified my toolbox down to five essential applications that help me to organize the whole process. Today I am gonna share with you the apps at the core of my workflow.

I need to mention that, as a long time Mac user, the software I rely upon is often exclusive to this particular platform. Still, you should be able to find suitable replacements on other platforms. Windows in particular offers many alternatives.

Collect and organize information

Evernote is the most powerful note-taking application I know. I’ve been its user since the very beginning and there is no real alternative. Yes, there are a few other competing , but no one offers such complete set of features that include (among many others) advanced search syntax, handwriting recognition (images!), and PDF annotation. Unfortunately, some features belong to the paid premium version.

Evernote is available on many different platforms and offers minimalistic web inferface. It is very easy to share notes with your colleagues or students. Very handy.

Despite being quite versatile, Evernote is not really optimized to be a literature manager for researchers. It can be used in such way, but is just not desinged to store thousands of academic papers in orderly manner. It is not only about notes. Academics need citation infomation, journal information, relation to other papers, ability to generate LaTeX citations, etc. All this can be done manually in Evernote, but there are better alternatives available. Personally, I use Mendeley. Thanks to its relationship with Elsevier, related papers search is fast and convenient. Mendeley allows me to manage a collection of few thousand research papers. Unfortunately, it started to evolve form a simple resource management system towards a communication platform similar to Research Gate. Nevertheless, Mendeley is the one resource manager I use for work.

Task management

OmniFocus is a task manager that is designed along the lines of the well known productivity system Getting Things Done, better known as GTD. The methodology created by David Allen, the world wide known productivity guru, is build on the idea of moving projects and tasks out of the mind to “the external brain”. Having handy and trusted list of projects and tasks takes burden out of our conscious. It allows to focus on the next necessary action instead of being overwhelmed by whole bunch of priorities and problems.

OmniFocus has been designed to be such trusted companion for your mind. Decade of development changed the application into a productivity monster. It is very intuitive tool for GTD enthusiasts, as it closely follows the main concepts from the book. OmniFocus comes in two versions: simple and professional. The killer feature that will make you longing for the professional edition is the ability to create custom prespectives. This is were OmniFocus truly shines as the GTD powerhouse.

The program works natively on Macs, so some of you might not be able to enjoy its features. Mac users are here for a treat, but it comes at a significant price. Good news is that there is substantial discount available for students and academics. There is no better choice for hardcore GTD practitioners.

Plan projects and write drafts

If you write or plan anything you need some kind of outliner. In another post I mentioned the importance of outlining before actual writing. Outlining application should allow you to create complex lists of things and then move them, edit them, collapse and group them. There are many applications that can do exactly that, including many free ones. So, if you want to try if the concept of outlining suits you, you can have a test run with Workflowy. It is a free outlining app that works in your browser (pro features come at price).

The application of my choice is OmniOutliner, very elegant and flexible. As it is in case of OmniFocus, OmniOutliner is native to Mac. Again, it comes in two versions: simple and professional. There are significant discounts for academics and students. Recently it became my main writing tool and the simple version is just enough for my needs. At least for now.  The outline and the draft of this post were also written in OmniOutliner.

Team communication

If there is one tool that substantially changed the way we communicate within our team, you guessed it, it is Slack. I grew up using IRC, so now having Slack as our main communication tool brings back memories. We just use is for communication, and it allowed us to get rid of internal emails. You can integrate Slack with almost all modern work tools, including almost all known cloud services. For example, it can be connected to Evernote and allow you to create or share notes with simple commands.

Honorable mention

There is one handy application that does not belong to my essential five, but I use it so much that is deserves honorable mention. It is called TextExpander and its sole purpose it to automate writing process. There are many recurring things that we have to write over and over. Try to think how many times you wrote you name and surname last week. TextExpander allows you to create a handy shortcuts (called snippets). Every time you write these few predefined sets of letters the application will substitute the correct long text in their place.

I started using TextExpander few weeks ago (the older standalone version), so there is a long way before I develop proper writing habits. Still, I already feel the difference, and so will you if you try this usefull little tool. As in case of almost all software for Mac, the conviniece comes at price. So, next time you plan to treat yourself (upcoming birthday?), you might want to consider TextExpander.

Photo by rawpixel.com on Unsplash.

Writing a thesis – some advice for first-timers

Writing a thesis – some advice for first-timers

Teaching is very important part of academic life. It is a never-ending cycle of all-to-similar problems and questions. Yet, there is one teaching responsibility that stands out from the others, i.e. being an academic means supervising writing of theses.

Usually, the thesis is the most complicated and the longest document that STEM students have to write since enrollment. They may have written structured essays (with a proper introduction, discussion, and conclusion), but nothing even remotely as complex and demanding as a full academic text. For this reason, writing a thesis is a difficult task. Even more so if the author lacks writing and reading habits. Compiling 40-60 pages of an academic text can be a particularly daunting experience.

Still, the work needs to be done. So, at the beginning of every semester, I discuss with all my students how to start writing a thesis. Over time, I developed a system and guidelines that helps them to write at their best.

This post is not a guide how to write a thesis. It is merely the discussion on how I set up collaboration between me and my students in a way that improve their writing process. If you are a student, you will learn here about some tools and techniques that will improve your writing. If you are a mentor, you might find below a few ideas on how to organize collaboration with your own mentees.

There are three things that I always discuss with every student that wants to write his/her thesis under my supervision. We establish rules that allow both of us to work in coordinated purposeful manner. First, I ask them to ditch Word and learn how to write everything in plain text LaTeX. Second, we establish a plan for our collaboration (an outline). Third, we agree to have regular meetings to discuss progress and problems.

Write everything in plain text

There are many ways to write an academic text. Normally, the process requires a word processor. So, for a long term users of Microsoft Word, it will be a tool of first choice. I would like to encourage you to try using much simpler editor (any editor) that lets you write efficiently in plain text.  Microsoft Word, despite its powerful features, is a distracting writing environment. It shines in business context, but it might hurt your academic writing.

Your goal should always be “extreme simplicity” because in such raw environment you will stop worrying about fonts and start thinking about words. For academics, the tool of choice is LaTeX, and chances are that you already know what LaTeX is.

Have you seen any LaTeX document lately? I am quite sure you have. They are very distinguishable because of their elegant and professional formatting. Even incoherent and badly written report appears like a work of an expert. As the final document looks awesome, it gives its author emotional feedback and stimulates his writing process in a good way.  I noticed that since we transitioned to LaTeX, theses became better thought over and generally more interesting. Engaged authors write better.

There are thousands and thousands of written and recorded tutorials on how to write in LaTeX, so I will not dig deeper here. All answers you need are a single search away.

And if you are curious, my personal editor of choice is Sublime Text. Very flexible and with built-in “distraction free mode”.

Start with the proper outline

I am telling all my students what every writer understands intuitively: writing should always start with a plan. Writing a thesis is a project. Writing a book is a project. Every project needs a plan, in this case an outline that contains synopsis details of all chapters, sections, and sub-sections.

Regardless complexity of the topic, the structure of thesis is usually quite simple. Like any other academic text it should contain: introduction, several body paragraphs, and conclusion. Body paragraphs (typically chapters) discuss separate topics, provide supporting details, introduce examples, and end with conclusions. It is very important to think about the contents before even typing the first letter.

Having to write an outline forces student to think about his thesis as a whole. Down the path, this will make writing much easier because the goal will be clear. I found that thanks to completion of this simple task, students stopped asking what else they should write about. On the contrary, their approach is now more proactive. They often inquire if it is a good idea to add more content because they feel it will improve their work.

If the thesis involves making designs and calculations (all my advised theses do), I ask students to focus on the introduction and literature review first. For STEM students, writing is challenging, require grit and determination. Usually, they are not accustomed to looking for and reading of sources, taking and reviewing notes.

Meet often and regularly

Being a thesis advisor means having to meet with the student to discuss contents of his work. After few years, I came to conclusion that it is necessary to meet often. Single session doesn’t have to be long – my own standard is 30 minutes. But it needs to happen every two weeks. More often if necessary. It is not only about the progress. Usually, all a student needs is a little push and a dose of motivation. Encouragement is more important than any substantive help.

One thing that I try to convey during those meetings is that writing a thesis takes time. The text will have to be rewritten. Its quality is a function of how many times that revision happened. Hemingway famously said that “The first draft of anything is s**t!”. Who am I to disagree with the master, but in case of thesis this is especially true. This is just something we all need to accept. Sooner, the better.

At the end of every meeting we set the date and the time for the next one. The appointment is an effect of negotiations with a student. I usually propose a date (plus minus few days). She agrees (or not) and declares how much progress she expects to make. It works.

Few years ago, I started to send calendar invitations. Many students rely on modern organizational tools. It is very convenient for them, as well as for me.

The above described process is very simple, but it works. I hope that you find some inspiration in my methods and they will improve your own writing/advising experience.

Photo by Sergey Zolkin on Unsplash.

Three things I learned during my stay at Stanford University

Three things I learned during my stay at Stanford University

Few years ago, I spent two months on certified training at Stanford University. I was a member of a larger group in the Top 500 Innovators Programme organised by Ministry of Science and Higher Education. We were sent to California to learn research commercialisation from the world’s best. We looked into forces and principles that stimulate cooperation between academics and business environments, hoping to implement the best practices back in Poland. Our goal was to absorb as much as possible and bring back the knowledge, but also the motivation and the spirit.

Looking back at the time I spent at Stanford University it was one of the greatest periods of my life. The place and the people that I shared this experience with, they left permanent mark and change me in several ways. For now, I want to tell you about three lessons…

Environment matters

One thing that surprised me was how quickly our group started to run at “Silicon Valley speed”. Scholars from Poland, taught and trained in the Central European country, we adapted to the Stanford way of work surprisingly fast. Very soon the new norm was long intensive study hours, followed by overnighters fueled by dozens of coffees and energy drinks.

It is not that all of us suddenly become productivity monsters. It was the place that demanded so much that we had no choice but to put extra hours. I don’t think it was healthy, but back then we felt like superheroes and nothing could stop us.

The environment pushed us to work at the limit. Every single thing around was there to inspire creative thought and team collaboration: white boards, open rooms, cafeterias, and the heroes… because you never knew who will show up at the corner. I gave up on a lunch once just to sneak into Melinda Gates seminar (this one), wouldn’t you?

There is only so long you can survive such intensive craziness, but the lesson learned was clear. In order to achieve you must find or build for yourself the setting that will properly inspire you. True, there is only one Silicon Valley, and many of us struggled upon return to Poland, where things moved at different pace. Still, that doesn’t mean that you can’t try to create your own little stimulating environment.

It will not be easy, and you will probably fail a few times. Still, do not get discouraged and remember that in Silicon Valley…

There are no failures, there are only lessons

One thing that you learn quickly at Stanford is that everything is a lesson. Every mistake you make is there to let you draw conclusions, correct, and try again… or “pivot” to something else. The one thing that you will be judged upon is the numer of attempts. Only those who don’t do anything are left in contempt. The mantra is “It is ok to fail.” and everything is about owning the mistakes and move forward.

Sure, life is often not that simple and some mistakes have bigger consequences than others, but at Stanford the experience is everything. It is hard to disregard people for their past mistakes. The failures are like battle scars. They are permanent, but it is up to you if they are the mark of shame or the sign of competence.

Once you get in your mind that there are no failures, only lessons, you quickly understand that the fastest way to success is to…

Get to know the people

There is only so much you can do alone. The entire Silicon Valley understands that. The great importance is given to working with the right people. Your true strength and degree of success depend on the team you work with.

At Stanford, homework was usually a team work. Groups were different in every class, and we needed to learn how to work with a different pack every time. Sometimes it was easy, sometimes not. We were quite diverse group of scholars at different age, career path, speciality, experience, and character. Every single one of us was looking for or wanted something different. But there we were, stuck with each other, needed to work together. So we did, and it was an amazing experience. The lesson was simple. There are great people around you, and you can work together with anyone. You just need to find what you have in common, and build on that.

The Top 500 Innovators Programme was an unbelievable experience. Over the years total five hundred people were trained at the top world universities: Stanford University (US), but also University of Berkeley California (US), and Cambridge University (UK). We came back to Poland motivated and full of ideas.

Years have passed and some of us are still in touch, some collaborate on research, some have became friends. Many are now involved in Top 500 Innovators Alumni Association. They are implementing the best practices right here in Poland, encouraging collaboration and building bridges between representatives of science, technology transfer, and business. Together, they have written many stories…

Ways to improve heat transfer during boiling at sub-atmospheric pressure

Ways to improve heat transfer during boiling at sub-atmospheric pressure

Low-pressure boiling of water is one of the most interesting research topics that I am currently involved in. Thing is, majority of modern refrigeration systems rely on a vapour compression cycle that is driven by grid electricity. It means that they rely on fossil fuels (still) and synthetic refrigerants, both with serious impact on the environment. It is critical to look into alternative potentially disruptive refrigeration solutions. Nowadays, the most promising developments are observed in thermally driven technologies that use low temperature energy sources, like adsorption and absorption cooling systems.

This is my first attempt to communicate research using blog post. It is my goal this year to improve scientific communication skills and learn how to write about research without too much jargon. Hope you will find the topic interesting, and if you are interested in details look into our papers listed is sources.

Unfortunately, thermally driven technologies using natural refrigerants need very low operating pressures. Let’s take water as an example. At atmospheric pressure, it boils at approx. 100°C. To use water for refrigeration, it should boil at 7-15°C. This means boiling at 1-2 kPa instead of 100 kPa. It is a technological challenge because the mechanism of evaporation under sub-atmospheric conditions is different than at higher pressuresThe studies on low pressure heat exchangers suitable for sorption systems are scarce. Available experimental results on boiling at higher pressures can not be extrapolated to low pressures. For all these reasons, it is necessary to study the physical principles of sub-atmospheric boiling heat transfer, and to determine how the geometry of the heat transfer surface influences the phase change behavior.

It is a fact that during boiling at few kPa the efficiency of heat exchangers is noticeably reduced. This can be overcome once by reduction of the size and thermal mass of evaporator. Optimised design would raise efficiency, reduce the investment cost and improve compactness of refrigeration systems.

Enhanced complex surfaces

There are various methods that allow to increase the heat transfer coefficient during boiling. For example, enhancement can be achieved with artificial nucleation sites or the roughness of the surface can be carefully controlled. We have focused our efforts on designing of enhanced structures that promote bubble nucleation, i.e. we studied complex surface constructs that cause heat transfer improvement.

We have conducted an experimental investigation of the behavior of pool boiling of water at sub-atmospheric pressure (0.75-4 kPa absolute, corresponding to a temperature range of 2.8-28.9°C) on complex surfaces. The structures were originally introduced and tested by Prof. Robert Pastuszko from Kielce University of Technology [1-2]. He analyzed boiling of several refrigerants at atmospheric pressure (including water) and observed that using complex surfaces improved heat transfer coefficients (HTC) in comparison to plain surfaces. We assumed that this will be also the case at very low pressures.

Complex boiling surfaces, if designed properly, facilitate bubble nucleation. Consisting of narrow passages and tunnels, they help to achieve constant inflow of liquid to the nucleation zone. The structures we used in our study are the two types of tunnel surfaces called: Narrow Tunnel Structures (NTS) and Tunnel Structures (TS). Both are finned surfaces partially covered with perforated copper foil that creates tunnels and nucleation sites.

Low-pressure boiling

To check the suitability of these structures under sub-atmospheric conditions, we have studied bubble creation on different surfaces. The process was recorded using a high speed camera. Bubble departure diameters and departure frequencies were determined on the basis of recorded material. Visual observations were supplemented with temperature and pressure measurements.

We found that among the analyzed surfaces the best heat transfer is achieved during boiling from the TS surface. This surface contains the thickest mini-fins that are bridged and covered with the perforated foil. In result, the thermal mass of the surface is the largest, the tunnels are smaller and the liquid evaporates faster. Nucleation process on the TS is very dynamic, which leads to small superheat (very important advantage if applied in sorption systems) and increased heat transfer coefficient (always demanded).


The research was conducted by Dr Tomasz Halon and myself (Wroclaw University of Science and Technology) in collaboration with Prof. Jocelyn Bonjour, Dr Romuald Rulliere, and Dr Sandra Michaie (Institut national des sciences appliquées de Lyon INSA, Centre d’Energétique et de Thermique de Lyon, France).

Details and conclusions were published in two research papers:


  1. Pastuszko R. Boiling heat transfer enhancement in subsurface horizontal and vertical tunnels. Exp Therm Fluid Sci 2008;32:1564-77
  2. Pastuszko R, Poniewski ME. Semi-analytical approach to boiling heat fluxes calculation in subsurface horizontal and vertical tunnels. Int J Therm Sci 2008;47:1169-83