13

Distributed DC power is actually used in some new construction. It's driven less by the efficiency of the transformer than by other logistics. Here in California, at least, we have a law (known as Title 24) which requires some fairly sophisticated controls of lighting, as well as fairly low power consumption per square foot. The control requirements include ...


12

Yes: Something like this has been commonly done in the U.S. for decades. Both Incandescent undercabinet lights and exterior low-voltage "landscape" lighting are often run from a single 12V transformer over 12-gauge wires. So there is code for it, and anyone who has built a computer recently knows that high-efficiency DC converters carry an upfront premium ...


11

If you can replicate what you report above under controlled conditions then you can retire for life next year. Really. The overwhelming opinion by all reputable test houses or suitably competent careful and honest individuals is that for combustion improvement by treating the **fuel* with magnets you'd be just as well off rubbing on snake oil - or drinking ...


10

The fridge works by pumping heat from its interior to its exterior. The amount of work it needs to do is proportional to the amount of heat entering the interior (and also the temperature difference between interior and exterior). There are two ways that heat gets into the interior: Putting warm objects into the fridge. Heat leaking through the walls of ...


10

In dry/arid areas a wind catcher tower in conjunction with a qanat is a great way to keep buildings cool. The underground water stays cool and cools the air passing over it that is drawn in through the wind catcher. However, in a humid climate you would want to isolate the incoming warm/moist air from the cool underground water. You could pass pipes through ...


8

Silica gel is the standard for most purposes. It's the desiccant you find inside those paper sachets packed with new electronic equipment. It consists of tiny beads of silicon dioxide that are nanometres across (so that a little material has a lot of surface area), and although it's called a gel, the material itself is hard at room temperature and pressure....


8

Simply put, power transmission is not free. Every time you have some energy over here, and you want to move it to over there, you are going to lose some of it in the process. In this case, if your engine is in the front and you want to drive the back wheels, you'll need some combination of gears, bearings, and shafts to transmit that power. Gears are ...


7

They are very nearly equal for typical four-stroke non-turbo diesels under load. A turbo diesel under load should have slightly more radiator loss than exhaust loss. At the bottom is a link to the technical spec sheet for a Cat 3412 powered genset. It's a probably a bit bigger than what you had in mind. It is a turbo with aftercooler (A/C in the doc below). ...


6

There are two aspects to this. First if your fridge is filled with anything other than air then you will save the energy associated with cold air escaping whenever you open the door. However if you put bottles of water in your fridge it will take a lot more work by the fridge to cool them down than the equivalent volume of air as a litre of water at room ...


6

If you have unused space in the fridge, then it's better to fill it with something than to leave it air. This is because every time you open the door, less air will be exchanged with the room, so less to cool again. If you're not going to open the fridge, then it doesn't matter. As others have already pointed out, putting the water bottles in the fridge ...


6

Your initial assumption is a bit flawed. You can not just draw the conclusion that all friction is the same. It is like saying all birds i know of can fly thus all birds can fly. Which is obviously untrue. Moreover, continuing this similie, you also imply that there is only one kind of flight. In reality friction is a highly complicated phenomena that ...


6

Generally gear trains with lower ratios are more efficient due to reduced amount of sliding action between the gear teeth in mesh, so the compound gear train would probably be a better solution. That also depends on the quality of the gears, center distances, bearings, lubrication and thermal considerations, but short answer is two stage would probably be ...


6

But I'm thinking it may be better (more efficient maybe? less vibration maybe?) to run it in three-phase mode, with the load balanced among the three hot terminals. Correct. Figure 1. The load is constant through the generator cycle. Source: T. Davies - website not found. My thinking, based on my coarse understanding of generators, is that in three ...


5

Because this question has proven a little more derisive than I had anticipated (where's that engineering sense of fun/humour?)- I thought I'd attempt an answer as well, if only to prove it's an engineering question which can be answered using the engineering method; although hopefully someone using something more than Google will be able to chip in with a ...


5

Something can only be 100% efficient when a lot of generous assumptions are taken into account. If you assume: No friction (turbine surface, turbulence, nozzle, or bearings) Perfect cup design (100% 180degree jet reversal) A dry wheel (no water is spun off) Not counting the gravitational potential to drop the water away from the wheel in the efficiency ...


4

It depends — can you run air through the plenum without simultaneously running the active heating/cooling system? If not, you'll never get the benefit of its thermal storage capacity. For example, when heating, the plenum will always be hotter than the slab, putting heat into it. In order to extract heat from the slab, you need to be able to put ...


4

Your "Bonus question" holds the answer here. Assuming that the two trains are perfectly identical, and that the power consumption is identical (which, if you have the same weight, motor, and size, it will be), you are down to transmission loss. The resistance of a conductor is R=L*Rho/A. L=length Rho=resistivity (material property) A=cross sectional area ...


4

There are many factors that make BLE low power, and I have attempted to address as many of them as possible. In order to better understand the power consumption differences between Bluetooth classic and BLE, it would helpful to look at some of the differences between the Bluetooth technologies. This would help appreciate the difference in power consumption. ...


4

We can try to answer this question by looking at existing equipment in terms of size and weight and make an educated guess from there if all this fits on a train. Our CC will consist of: Gas turbine Exhaust HX/Boiler Steam turbine with condensor and other aux. parts Transmission For the following, I will not match components exactly, but pick stuff that ...


4

when the cogeneration plant switches of upon reaching 85°C flow and without another heat source, there's no way to reach 95°C. Are you sure the switch-off happens at 85°C flow, and not at 75°C return to the cogernetion plant(this is a typical value for Otto-cycle cogeneration plants for the emergency cooler to kick in)? If you have other heat sources and ...


4

So, if I understand correctly you are proposing to use a turbine in the exhaust vents in order to reclaim the energy from the flowing air. However, in most cases the air is flowing due to forced flow, if you use a turbine to "suck" energy out the air then it tends to slow down. So then you would probably need to use bigger fans to push the air. So ...


4

There are many ways that one can achieve natural cooling and heating. However, the best solutions are very dependent on the situation. Also, the problem with most of these solutions is that you'd need to plan ahead (don't expect to incorporate them easily into an existing structure). And finally almost all of them are most effective for one or two story ...


4

The reason your utility company recommends to let the sunshine in is not to save on lighting energy. it is to take advantage of solar radition energy. a window can let the solar radiation in two ways, direct radiation and scatter radiation. The calculation of radiation energy has to do with many factors such as the geographical altitude and azimuth of the ...


3

The word that will unlock your searching is disaggregation - there's quite a lot of research going on right now into energy disaggregation. These generally involve some kind of learning algorithm, and the energy-disaggregation field is quite young, so you won't find a reliable off-the-shelf package. But you will find current research which will help you ...


3

Heat flux is directly proportional to gradient of temperature - in other words, if you have an imperfect insulation wall, it will pass the more heat the higher the temperature difference between its two sides. Say, your room temperature is 22°C. If the freezerless refrigerator internal temperature is 4°C, and the freezer temperature is -5°C, that's 18°C and ...


3

RV, camping, boating, and solar power industry might have had a significant influence in developing LED blubs powered by 12V DC. The automotive industry too might have had some influence. Some of the issues that make 12V DC lighting not be practical are: Structural: Majority of the home are power using 110/120/220/230/240 VAC. Converting these too 12V DC ...


3

The reality of generating electricity from nuclear fusion on an industrial scale is still a very long ways off. It is speculative high cost, high risk venture, with a potential high payoff far off into the future. Test reactors alone are >$100 million. The existing technical problems and challenges with nuclear fusion are very complex. We're talking ...


3

The main advantage of a rotary regenerator is that you can pack a lot more surface area into a given volume than with a shell and tube type device important for gas-gas heat exchange where heat capacities and heat transfer coefficients tend to be low compared to liquid-liquid. This obviously has advantages for packaging a turbine in a car. Essentially ...


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