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Technology / Re: Does a steam heat exchanger remove sensible heat?

« on: 19/04/2017 15:54:10 »

Thanks very much! Sorry I wasn't specific about definitions here. But @SeanB is correct, sensible heat is energy from temperature change, while latent heat is energy from phase change. So what you're saying is that sensible heat can be lost in a steam condensing heat exchanger?

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Technology / Does a steam heat exchanger remove sensible heat?

« on: 13/04/2017 23:58:22 »

We were assigned a group HW assignment that nobody (7 person class) can figure out. It starts pretty simple: Heat exchanger, saturated steam @ 200 psig, heating up process fluid from 80-200 F (heat capacity 7 J/g C), but here's the weird caveat: steam condensate returns to the steam boilers at 275 F. We've had problems where we have to calculate sensible heat loss from a pipe as a fluid returns, but could this sensible heat loss happen in the heat exchanger? As in, could the heat exchanger condense the steam and also remove sensible heat? None of us are sure if this happens in the real world.

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Physics, Astronomy & Cosmology / Does solar magnetism affect our atmosphere?

« on: 28/03/2012 18:55:06 »

I was wondering if the changing in the magnetic poles of our sun (which happens often on an astronomic scale) has an affect on the chemistry of our atmosphere. More specifically would it have an affect on the amount of carbon 14?

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Geek Speak / Does anything still use analog?

« on: 09/12/2011 15:24:21 »

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I don't know if this helps or changes anything.
Sorry about the bad quality.

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Geek Speak / Does anything still use analog?

« on: 08/12/2011 02:45:48 »

It's like the female end of the mini plugs, only bigger. It's a Casio CTK-515 which must be from the early 90's or before; either way, production was stopped a while ago.

Dang, I had no idea so many things still used analog.

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Geek Speak / Does anything still use analog?

« on: 07/12/2011 04:10:36 »

So I have an old Casio keyboard and was thinking about dusting it off and using it when I noted that there is a plug in labeled "phonics/output." The port is quite large (~.5 cm diameter -circular), and I was wondering if this is an analog connection. If so, does anything use analog anymore? I thought it was a "step lower" than digital.

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Chemistry / Can one make petri dish material from pasta?

« on: 06/10/2011 16:06:54 »

After making some pasta in very little water, I noticed that what water remained after I poured it out had congealed to a jello like blob. Is this because of the starch? And if so, would this work to grow bacterial cultures?

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Chemistry / How to change Ca(OH)2 to NaOH?

« on: 06/09/2011 04:50:34 »

I have a solution of Ca(OH)2 after producing some acetylene from CaC2. I just wanted to do something with it.

That makes me wonder if you have a very early automobile.

Oddly enough, a lot of early automobiles were electric. I suppose we have the Rockefellers to thank for having petro cars.

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Chemistry / How to change Ca(OH)2 to NaOH?

« on: 06/09/2011 00:09:40 »

I have a solution of Ca(OH)2 after producing some acetylene from CaC2. I just wanted to do something with it.

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Chemistry / How to change Ca(OH)2 to NaOH?

« on: 04/09/2011 21:19:41 »

Thanks, it appears to have worked.

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Chemistry / How to change Ca(OH)2 to NaOH?

« on: 31/08/2011 18:13:18 »

The title pretty much says it all, if I want to convert Ca(OH)2 to NaOH, what reaction would work? I was thinking Na2CO3 or Na2SO4, would either of those work?

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Chemistry / How to make zinc powder?

« on: 09/08/2011 03:17:58 »

I have to different chunks of zinc. One is a piece from an old roof (used to keep down moss), and the others I got a while ago from someone in my old school, I'm suspicious that they are from pennies but since he didn't sell it and I'm not going to sell it it's not going back into circulation.

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Chemistry / How to make zinc powder?

« on: 05/08/2011 17:11:54 »

I was hoping for a little less intensive method. I've tried, but just don't have the patience to sit down with a file and a chunk of zinc.

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Chemistry / How to make zinc powder?

« on: 04/08/2011 04:24:02 »

Anything that would?

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Chemistry / How to make zinc powder?

« on: 03/08/2011 05:30:58 »

I know of several ways to turn a chunk of zinc into powder: Electrolysis of a molten zinc salt; a more reactive metal in a solution of a zinc salt, taking a file to it. I was wondering if it would be possible to react zinc hydroxide with hydrogen peroxide Zn(OH)2 + H2O2 = Zn + 2H2O + O2. I know this can be done with more noble metals, but I'm not sure if it can be done with as reactive of a metal as zinc. Ideas? Any other methods?

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Physiology & Medicine / Re: Does blood pressure affect itchiness of mosquito bites?

« on: 30/07/2011 04:46:00 »

I doubt it, I've received these bites at temperatures 10 C apart, and from right when i get up to right before i go to bed. It might be body temperature, i don't know how much human body temperature fluctuates during sleep. I feel inclined to think it is from some sort of internal influence.

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Physiology & Medicine / Does blood pressure affect itchiness of mosquito bites?

« on: 23/07/2011 07:14:26 »

Here in the Pacific Northwest Mosquitoes are becoming quite prevalent as the weather warms. Over the past several days I have noticed that approximately 10-30 minutes before I usually wake up my bug bites from the previous day really begin to itch. My only guess is that this is somehow connected to my body trying to wake me up at the end of R.E.M. sleep. Does this seem like a step towards the correct answer? And if so, would it be something related to blood pressure or heart rate increase?

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The Environment / Nuclear Power Plant, should we support?

« on: 01/07/2011 05:56:32 »

Because money drives our world (much as I dislike this fact), and there is a energy demand that will not decrease, we currently have two choices: keep and build more nuclear power plants, or start using more fossil fuels.

Renewable energy sources do not produce enough energy to satisfy the inevitable rise in demand for more energy.

I disagree with Don_1, Germany is closing the power plants and is increasing the energy output from natural gas. Wind power simply will not generate enough energy for that country.

In the end we have to choose the lesser of two evils until we are able to harness fusion: http://science.discovery.com/stories/week/chinese-technology-wikileaks.html

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Chemistry / How does sodium nitrate make soil alkaline?

« on: 01/07/2011 05:36:24 »

Slightly off topic, but I was wondering, wouldn't using NaNO3 instead of KNO3 be very similar to salting the earth? And as a fertilizer wouldn't it do more harm than good?

-[I'm assuming the above spam will be deleted]-

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Chemistry / How to get silica from diatomaceous earth?

« on: 08/06/2011 15:52:27 »

Thanks, I've seen a reaction done where silica and aluminum powder react in a redox reaction akin to thermite (except energetic). I haven't done any calculations yet, which I suppose I should before actually trying the reaction.