Hacker News: 2DcAf

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Mon, 27 Apr 2026 11:32:35 +0000

Thank you for the compliment! I am touched by the generosity of the HN people today.

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Mon, 27 Apr 2026 09:09:26 +0000

It’s accessible with end-of-high school math: you need to be okay-ish with integration and derivation. Practicing engineers might find it a bit slow, but that’s for each to decide :-)

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Mon, 27 Apr 2026 08:36:23 +0000

Glad the book can help! Regarding image size, it’s on my todo list now (see thread further down the page).

I am using Payhip for the transaction, and then Paypal. Fees end up averaging 0,5€. Calculating in terms of percentage is not really helpful here at such low prices: there is an incompressible flat rate pretty much anywhere you go. See it differently: these intermediary fees go towards making the UX smooth, the payment secure, reducing fraud etc. I want to spend my energy on the content, not making a credit card form :-)

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Mon, 27 Apr 2026 07:05:37 +0000

I used to think that way about the publishing industry too, but I now think that this description is not deserved. Just observing it from an operational perspective: a laptop to type, software to edit, book printers that will talk to you, payment rails, and even access to world-class distribution: it’s all available to us now. On the other side of the market, students and teachers are not locked in either. Barriers to entry are nonexistent. For context, see the links I posted in my other comments on this page. It’s all in our hands!

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Mon, 27 Apr 2026 06:56:15 +0000

Thank you! ^^

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Mon, 27 Apr 2026 06:55:45 +0000

ha yes :-) Carnot died of cholera aged 36, and Rudolf Diesel committed suicide too. Maybe I should add an appendix about mental health at the end!

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Mon, 27 Apr 2026 06:50:43 +0000

The payment for the paid-for PDF is processed through Payhip. As far as I can test here in Germany no cell number is required. Maybe you trigger some extra verification that I don’t?

As for the email, I require it so that I can subscribe all of my readers to a weekly newsl… haha just joking. Juuuuust joking :-) If you try it, you will find that a bogus email address works just fine.

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Sun, 26 Apr 2026 19:58:22 +0000

that’s a really good place to start, thank you!

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Sun, 26 Apr 2026 19:56:23 +0000

Thank you! To be honest I think there is not much there because when I started 17 years ago my technical skills were much shallower, plotting a diagram to visualize/compare two models would have been quite a lot of work. But if I can be frank, at undergraduate level playing with equations of state is not expected nor a requirement. I’m happy to just say "there are others and they all have some common things". I‘d much rather the students and I spend our energy wrapping our heads around say the concept of entropy and what it allows us to do. Regardless, I appreciate your comment muchly (and shall look up CoolProp tomorrow).

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Sun, 26 Apr 2026 19:29:22 +0000

Thanks for that. At first glance, it looks like that is a good place to be, regarding images. I will still investigate when I find time.

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Sun, 26 Apr 2026 19:23:59 +0000

I have not kept a very close look on what’s going on. I would say that three things have changed since:

- tablets are everywhere in the classrooms now, so the number of places where a good PDF can do good is much bigger

- there are better workflows to get a high-quality PDF than LaTeX, so much frustration can be saved, and all that can be learned easily with AI tools

- in a sea of AI slop, all the humans are desperate for a One Good Resource they can trust

Go for it!!!!

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Sun, 26 Apr 2026 18:52:00 +0000

Following up with actual numbers for the project, from Lulu, in Euros: List Price 43 Print cost 11 Distribution fees (read: Amazon, 50% of selling price): 21.5 Lulu share of profit : 2 Rest to author: 8,5

Because of the different prices on different locales in different currencies the actual share I receive averages 7€ (gross revenue before income tax, although in my case the yearly income is too small to trigger it where I live).

For books sold directly on Lulu List price 43 Print cost 11 Lulu share of profit: 6.5 Rest to author: 25.5

The mindset should not be "this is all that’s left for me", however: a book is many things at once and for better or for worse, Amazon creates a big part of it. Kevin kelly has some excellent advice at https://kk.org/thetechnium/everything-i-know-about-self-publ...

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Sun, 26 Apr 2026 17:43:45 +0000

Indeed! Truth be told, I think the book really is missing a chapter on refrigeration systems. I had to call it done at some point for my own sanity. Maybe someone will jump in and add one someday!

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Sun, 26 Apr 2026 17:41:15 +0000

Thanks! I think most of the weight comes from the PNG diagrams, but I don’t actually know: I’ll put it on my to-do list to investigate, maybe there are some easy wins here.

New comment by 2DcAf in "Show HN: Free textbook on engineering thermodynamics"

2DcAf — Sun, 26 Apr 2026 17:38:53 +0000

Amazon takes the lion’s share, and then the rest of the pie looks very different depending on which route you go. Big publishers print in batches and have very low print/distribution costs. I ended up on the other end of the spectrum, self-publishing with Lulu (print-on-demand, so much higher costs). I wrote an article in French on exploring the economics of textbooks, from the open-source point of view, a few years back: https://framablog.org/2022/01/20/mais-ou-sont-les-livres-uni...

Show HN: Free textbook on engineering thermodynamics

2DcAf — Sun, 26 Apr 2026 15:17:34 +0000

Author here. Feel free to send questions of any kind.

Comments URL: https://news.ycombinator.com/item?id=47911013

Points: 189

# Comments: 47

New comment by 2DcAf in "Ask HN: Share your personal website"

2DcAf — Wed, 14 Jan 2026 18:19:43 +0000

https://ariadacapo.net/

Things Teachers Can Learn from the Aviation Industry

2DcAf — Wed, 01 May 2024 06:56:53 +0000

Article URL: https://ariadacapo.net/blog/2024-05-01-things-teachers-can-learn-from-the-aviation-industry/

Comments URL: https://news.ycombinator.com/item?id=40220331

Points: 1

# Comments: 0