Copper Calculations

I’m planning on making some heat exchangers. It sounds fancy, but all I’m doing is coiling some soft copper pipe.

My goal is the most bang for my buck, so what’s the best way of arrangement of copper for dollars.

Here’s an example:

image of copper coil heat exchanger

My constraint: the water inlet and outlet are 3/4″ copper pipe.

For this analysis, I’m standardizing on a length of 50′ of coil.

The first obvious choice is using 3/4″ diameter to match the existing piping. A 50′ roll of soft copper pipe runs about $80 for 3/4″ diameter.

The main factor in heat transfer is surface area, so for a cylinder we need pi*d*h. The diameter is 3/4″ -> circumference of 2.356. For one foot, that’s 28.274 sq.in. of pipe. At $1.60 per foot, that’s 5.66 cents/sq.in.foot.

For cheaper, I could go with 1/2″ soft pipe. That would result in a faster flow though, which would give less time for heat to transfer, so I don’t know that it is a good choice. But we’ll look at it anyway.

The diameter is 1/2″ -> circumference of 1.571. For one foot, that’s 18.852 sq.in. of pipe. At $1.00 per foot, that’s 5.30 cents/sq.in.foot, a slightly better deal.

So the thinner pipe is slightly cheaper on a surface area basis. But the overall surface area is less and the water will flow faster so it won’t transfer heat as well, so that works counter to the point of a heat exchanger.

To get the same performance, we need the same cross section. Area of 3/4″ = 0.4418. Area of 1/2″ = 0.1963, or approximately half of the area of the 3/4″ diamter pipe. So if I double up the 1/2″ pipe, I can get the same flow as the 3/4″ pipe.

But what about surface area? That doubles! So slightly smaller cross section total, but (18.852 + 18.852)/28.274 = 33% more surface area. Looks like it is better heat transfer performance to have two 1/2″ pipes rather than one 3/4″ pipe.

Now let’s check the other part of the equation: cost.

The two 50′ pipes will cost double a single pipe (no, a 100′ pipe costs more than double, so I wouldn’t save anything by buying that and cutting it in half).

So 33% more performance for (100/80) = 25% more cost. Sounds like a good deal.

One more adjustment, just to make sure all the bases are covered: the area.

The 3/4″ pipe has (0.4418/(0.1963+0.1963)) = 12.5% more cross-sectional area. Which in theory would mean the water flows slower and has more time to absorb the heat.

So 33% more surface area but with a 12.5% reduction for flow rate, compared to 25% more cost for these two choices.

In conclusion, I’m going with the single 3/4″ pipe because it’s half the number of joints to solder therefore the double 1/2″ pipes are twice as likely to fail.

Iron is taken from the dust, And copper is smelted from rock.

Job 28:2

Help with Plurals

The English language is not very consistent. Today I’m proposing some singular/plural forms to help reduce the confusion.

For example, the plural of mouse is mice.
The plural of louse is lice.
The singular form of lice is louse.
But the singular form of dice is die.
It should be douse.

mouse -> mice
louse -> lice
douse -> dice
spouse -> spice
rouse -> rice
vouse -> vice
twouse -> twice

I don’t know how you can have a singular form of twice, but in case you should ever need it, there it is.

And, of course, we one ouse -> many ice.

Once I have spoken, and I will not answer; Even twice, and I will add nothing more.

Job 40:5

Construction Tips

Here is a construction tip for you:

image of post and lintel construction

image of post and lentil construction

Don’t confuse lintels with lentils.

Now after him was Shammah the son of Agee a Hararite. And the Philistines were gathered into a troop where there was a plot of ground full of lentils, and the people fled from the Philistines.

2 Samuel 23:11

Review of Beauty and the Beast

The wife and I went to see the reincarnation of Disney’s Beauty and the Beast.

It was okay.

The main story was still good. The movie was successful in that it conveyed the story. I laughed, I cried, etc.

But it was annoying in some aspects. I had known about the changes to LeFou, and I’m not going to discuss that aspect much – only to say that it was more of a distraction that anything else. I’ll liken deciding to watch this movie to what I heard a number of people say about voting for Trump. They did it in spite of his issues, not because of it, because it’s better than the alternative. Except in this case there were many alternatives and none of them was Hillary, so maybe the analogy breaks down there.

I had 3 main complaints about how the movie was inconsistent. Not necessarily inconsistent with the original movie, but rather inconsistent with itself.

  • Claims of Live Action : The big selling point of this movie is that it was a live-action version of the animated classic. Come see the movie you love, but with people doing the acting – it’s not animated! They might not have said those words directly, but that was the feeling that was portrayed.

    Except…

    The Beast was computer-animated, Lumiere and Cogworth were computer-animated, Mrs. Potts and Chip were computer animated, as were the wardrobe lady and the piano guy and the footstool dog and so on.

    It’s hard to accept that a movie is live action when so many of its main characters are not.

    And I didn’t like the CGI, especially with Lumiere. And the Be Our Guest song. And the Beast’s gait. You get the idea – it was distracting.

  • Setting and Accents : Was this set in England or France or America? The story says it’s in France, and part of it takes place in Paris. There are some French phrases thrown in for good measure. But only Lumiere attempts to have a French accent. Belle has a decidedly British accent, and the other main characters sound American. Of course, the best choice would be to have everyone with a French accent. But it wouldn’t have bothered me if everyone had a British accent, or American accent. If the movie is consistent, I wouldn’t notice it. But when the acecnts are all over the place, it is a distraction.
  • Progressive and Oppresive Villagers : I think I understand the director’s/producer’s intention behind casting people of different races, but again it was inconsistent with the story and was more of a distraction. It was inconsistent because those villagers must have been very progressive not only to allow different races to have prominent roles but also to accept mixed-race marriages. (Although the races were only combinations of blacks and whites – didn’t see many Asians in there.) Since the setting is 18th-century France, it was anachronistic. But let’s give the director the benefit of the doubt and assume he was just trying to promote racial harmony and was using this movie as the vehicle to do so. But then we see these same villagers oppress Belle because she dares to teach a girl to read.

    In the original movie, the “provincial” villagers seemed rather indifferent – they thought Belle was odd but didn’t think much of it, and certainly didn’t teach her a lesson for going against the village’s unwritten rules. But this new adaptation of the movie makes the villagers both more progressive and less progressive. Why couldn’t the director have the villagers be supportive of girls’ education? If this movie was to be the means by which equality and tolerance are promoted, why only with the subject of race and not with gender? Again, inconsistent.

One more thing that bothered me was the choice of fuzzy camera focus during pans. Things went extra fuzzy/blurry when the camera was moving. I assume this was the director’s choice, as I haven’t noticed it in other movies I’ve seen. I disagree with that choice, since it happened a few times and each time it took my mind out of the story because my mind was trying to figure out what went wrong with my eyes. Again, a distraction.

The movie wasn’t bad, overall. It just had a number of things wrong with it. See it if you want. But if you want your kids to see a good movie, just show them the original animated version.

Immediately the word concerning Nebuchadnezzar was fulfilled; and he was driven away from mankind and began eating grass like cattle, and his body was drenched with the dew of heaven until his hair had grown like eagles’ feathers and his nails like birds’ claws.

Daniel 4:33

Botanical Gardens Early Spring

We had a nice spring day last weekend, so we took the family to the local botanical gardens. They are not a scenic as they would be during the summer when more things are in bloom, but it was still good for the kids to get out and about.

Here are photos of the various paths, ranked from best to worst for walking with kids.

image of river at botanical gardens

Read the rest of this entry »

Graduation Speech Help

Since graduation season is just around the corner, there may be commencement speakers who are starting to write their speeches. I expect that most of those speakers were chosen because of some skill or accomplishment, which indicates they have the capacity to plan ahead and write well.

But for those commencement speakers who like to fly by the seat of their pants and are looking for some last-minute help, here is a handy guide.

The go-to phrase for graduation speeches is something about how the wish is for the students to not just survive, but thrive.

Don’t use that phrase.

I’m sure it wasn’t so bad the first dozen times, but now everyone has tired of hearing it.

My suggestion: find a different word from thrive.

That will throw off the audience. Start with the “not just survive” bit, but change it. Here are some other words that rhyme with survive.

  • strive
  • drive
  • chive
  • jive
  • dive
  • five
  • hive
  • alive

These words might or might not make any sense for your graduating class. But at least the audience won’t tune out the rest of the speech like they would with “thrive”.

Any other suggestions?

The others came out from the city to encounter them, so that they were trapped in the midst of Israel, some on this side and some on that side; and they slew them until no one was left of those who survived or escaped.

Joshua 8:22

Questionable Logo

There’s a company logo based on the Titanic. They won’t admit it, of course, but I found the connection.

First off, the Titanic:

image of the RMS Titanic sailing peacefully

Next, the Titanic as it is sinking (artist’s rendering):

image of the RMS Titanic sinking

Finally, the corporate logo:

image of the adidas logo

Looks about right, doesn’t it?

so they signaled to their partners in the other boat for them to come and help them. And they came and filled both of the boats, so that they began to sink.

Luke 5:7