Keep it simple.
Fill a 10,000 gallon insolated tank truck with 20C water, and run it in a loop to the Ni/H reactor. When the temperature of the water in the truck gets to 90C, the case is proven. On Mon, Aug 12, 2013 at 2:24 PM, Jed Rothwell <jedrothw...@gmail.com> wrote: > Defkalion's demonstration wasn't bad. Any demonstration is tough. > Something always goes wrong. It wasn't bad, but it could have been better. > I have done demonstrations and I have taught and given lectures so let me > offer a few suggestions based on this experience. > > Practice, practice, practice. Rehearse beforehand. Be sure you can > comfortably complete the presentation in the time allotted. This was their > biggest failing. > > Set up your props beforehand. As I explain below, in this case I would > have put a black drop cloth on the wall and brought in a meter stick, a > weight scale, and a bucket of water with a thermometer in it. > > Make yourself clear. Get to the point and stick to it. > > You need not write out every word, but it is a good idea to write down > your talking points in the order you intend to present them. > > Here is the sort of thing I would have said: > > ". . . The inlet temperature is 21°C, the outlet is 115°C. Here on the > screen we are computing enthalpy by the heat capacity of water. We ignore > the heat of vaporization. However, at this outlet temperature we know the > water has vaporized. Let's prove that. Let's take the outlet tube from the > sink and hold it up next to this black drop cloth. [Holding meter stick > next to plume.] As you see the plume of steam is around 80 cm long. The > first 20 cm are invisible, which means the steam is dry. > > Now let us show that our flowmeter is correct and the water is flowing at > 500 mL per minute. We will also show that the steam has about 1130 kJ of > enthalpy per minute. We have placed this bucket on the weight scale. As you > see it has 20 kg of water in it, and the water temperature is 21°C. Now > were going to submerge the hose under the water for about a minute and see > how much water condenses and how much the entire mass of water heats up. > Starting NOW. [Splash! 'Buku buku buku' as bubbles say in Japanese] > > [A minute later] Okay we removed the hose after one minute three seconds. > The weight of water has increased by 460 g. Some of the steam escaped from > the water but most of it condensed. We see that the temperature has risen > to 31°C . . ." > > And so forth. > > Prepare your tables and spreadsheets beforehand so you can describe > results smoothly without stopping to do a lot of arithmetic. You need not > state that the heat of vaporization is 2260 kJ per kilogram. The viewer can > look that up later on. You need not explain that the bucket when empty > weighs 820 g. The viewer knows about how much a plastic bucket weighs, and > can see you have taken that into account. Skip the details; get to the > point. > > As I said before, you demonstrate every key point twice, by two different > methods. Ideally, one method relies upon precision instruments and the > second method depends on first principles that are easily understood and > easily measured, even if they are somewhat crude. The two methods must be > completely different so that a single artifact cannot cause both to be > wrong. > > People sometimes say that in a lecture you should tell the audience what > you're going to say; tell them what you have to say; and then tell them > what you just told them. I think this is going too far, but it does not > hurt to repeat your key points at least once. > > I assume the people at Defkalion are doing similar demonstrations for > potential customers and investors. So I think they should polish up the > presentation and make it more convincing. > > - Jed > >
