10

Yes, there are indeed combined PV-T (photovoltaic-thermal) hybrid panels that turn some of the incident light into electricity, and have a circulating fluid and heat exchanger to put some of the heat into a heat store. There's very little take-up of them, because they're just not economic in most circumstances. The theory looks great: PV panels are more ...


9

Not all of the pollutants come directly from the fuel. Some (e.g. NOx) come from the air itself, based on the combustion temperature in the cylinder. Running a cylinder at a higher temperature (by leaning the mixture) results in both greater efficiency and greater NOx emissions. On the other hand, running the cylinder at a lower temperature reduces NOx ...


5

Sounds like you have covered your bases. The only thing I can recommend is gathering data and considering some scenerios to evaluate that data against. I am not an HVAC guy but can give you the 1000ft engineering perspective. Any of these trends would be helpful in debuggig the situation: Relative humidity and temperature at a discharge of the HVAC system ...


5

The easy question Do any of the components above have higher costs to society than CO2 per same unit of measure (e.g. gram, kilogram, or ton)? Yes, absolutely. This should come as no surprise given the composition of the exhaust—it's mostly inert gases. Water vapor, CO2 and nitrogen gas are all products of the various reactions taking place in the vehicle'...


4

You are essentially asking, "can a cyclone be designed that works without, or against gravity?" and the answer is, of course, yes. Most practical industrial designs can use gravity to increase efficiency or reduce cost, and the equations you've seen need this simplification, but a cyclone doesn't depend on gravity. You just need to whip the air around fast ...


4

Yes, Underground Detention is a thing. That Wikipedia article even mentions placing them under parking lots. The exact method that you propose is a little different than preconstructed vaults, but it is the same in the end. Pervious concrete on top of gravel with voids serves the same purpose but with much lower capacity. It is not really speeding up the ...


3

The temperature control in a fridge is pretty crude. The evaporator is in the freezer and the compressor is controlled with an electric thermostat. The fridge portion however relies on convection from the freezer. The temperature control from the fridge is sometimes nothing more than a slider that establishes how quickly the convected air moves. There are ...


3

As a practical and cost effective solution, I'd advise using aluminium foil, or tin foil as it's also called. Please realise that it's rather fragile, so it's best to glue it to a plastic foil or something to keep the wind from ripping it apart. It doesn't really matter if cracks get in the foil. Use the most shiny, reflective side of the foil as the outside....


3

I've worked quite a bit with vacuum pumps in the past and they certainly could get your slurry out of the tank however a complete rig can run in the $10,000 range. Another less expensive option is an airlift pump. This is nothing more than a tube that has compressed air blowing through it which in turn 'pushes' the slurry to the top of the pipe. It does so ...


3

There are way too many details to get into here. However, do the basic first order analysis. Determine whether there is enough solar power over a day to keep the greenhouse at some temperature. You say you know all the dimensions and insulation values. Pick a plausible temperature differential between inside and outside, and compute the power required to ...


3

The evaporation formula you have is a modification of the EPA method for calculating the evaporation rate. See here: Technical Guidance for Hazards Analysis look at Appendix G. The modified form I found in a paper by John Barry in CEP magazine. Somebody took the time to scan it and has it posted on the internet: Estimating Rates of Spreading and ...


3

Ships have loud horns because they need to be heard from far away. Because they can't stop abruptly. For cars it is less so, for scooters even less. A car's engine isn't powerful enough to drive a shiphorn, a scooter not powerful enough to power a car horn. You can go a louder than standard, but regulations prevent manufacturers from doing so, and fines ...


3

There is a device called a slip ring which does what @Solar Mike describes. They can be fairly cheap if obtained on the surplus market or even purchased new from here or here. They can be either hollow or solid shafts. Solid shaft models can be used as part of the axle (if mechanically strong enough) while the axle can pass through the middle of the hollow ...


2

In terms of bed capacity, dry gas—0% moisture, or as close as you can get—is generally optimal. Section 12.4 of Air Pollution Control (Cooper & Alley, 4th ed.) characterizes the impact of several factors on the theoretical equilibrium saturation capacity of a fixed-bed adsorption system: Thickness of the adsorption zone (in which the sorbent is not ...


2

The only or vastly major source of chemical oxygen demand (COD) should be your dissolved or suspended hydrocarbons, so a COD test could be the way to go. . I don't know hw confident you are in your analytical chemical and labwork skills. COD determintation requires handling of strong acids and oxidizers, would avoid without proper training. However, there ...


2

I'm not 100% familiar with english terms of art. However, according to this document, they are the same: The surface loading rate is a hydraulic loading factor expressed in terms of flow per surface area. This factor is also referred to as the “surface settling rate” or “surface overflow rate.” [...] Typical values of surface loading rates for primary ...


2

Option 4: Put it in the container, leave it on your doorstep and offer it for free on craigslist. You will likely find someone that regularly needs it and you can just email/text message them any time you set some out. People use waste vegetable oil to burn for heat, bio-diesel, soap making, animal feed, etc. Also note that disposing oil down the toilet is ...


2

The idea is not new, but using mirrors on the Earth's surface is a particularly inefficient way to go about it. A Lagrange-point sunshade is actually much more practical, and the thermal analysis has been worked out in some detail. You basically need to block about 2% of the sun's light currently reaching the Earth. Beware of unintended consequences!


2

TL;DR we use stupendous amounts of fossile fuels, capturing the carbon would require even more stupendous amounts of sodium hydroxide. The advantage of amines is that removing CO2 from amines only requires heat input and the amines can be recycled (though some degradation does occur). You describe a caustic scrubber, chemistry as outlined here. you would ...


2

While your AC is running, what is it's typical duty cycle? In other words, how long does it run during each cycle (i.e. 5 minutes on, 15 minutes off) to keep things cooled to your set point? If it doesn't run very long at all to keep things cool each time it runs, you may have a vastly over sized AC unit that isn't running long enough to actually remove ...


2

Delaying flowering would definitely be a better solution than attempting to save the flowers after the fact. Its definitely going to take some experimentation and hypothesis testing to determine what works for that tree variety. I have done a bit of plant research for an indoor aeroponic system that I operate with strawberries. Putting them in the ...


2

Coffee (stirring) sticks might work. After potting is complete these could be inserted vertically with the narrow edge against the side of the pot in multiple positions around the edge. Seeing as your pots are conical at the bottom you may insert one stick vertically down to the start of the cone and another one on the other side at an angle to form a ...


2

Put a disc on the side of the drum centered around the shaft it rotates on and have two, three or four concentric copper tracks for carbon brushes to rub on, spring loaded and they should work fine.


2

Slip rings are a straightforward solution to the problem, so long as the electrical noise they generate is small compared with the signals you want to measure. Since you are already using an Arduino, you might consider an alternative, which is to have a second, battery powered, Arduino attached to the rotating drum itself, and use that to transmit the data ...


1

White and silver are the most reflective (not absorb heat from the sun). There is some debate about which is more reflective. A white tarp is probably going to be cheaper.


1

I would suggest a reflective mylar film such as those used for survival blankets. That would be the most effective single layer solution. Adding additional layers of plastic would further insulate the ground from the warmer air in the tunnel.


1

One thing that comes to my mind are ice rink coolers. You could design similar pipe system that would keep surrounding ground cool. Few problems that could occur: - pipes are filled with antifreeze and leaks could cause ecological disaster and forbiden substances would penetrate fruit so you should find ecofriendly antifreeze - you need strong cooler unit ...


1

Using the +10 to +120°C psychrometric chart with sensible heating from 40°C, 95% RH to 60°C gives approximately 35% RH. If you need a more precise answer I would look up the formulas which can be found in ASHRAE Fundamentals or CIBSE Guide C. See image below for how to look this up on the chart:


1

From a study conducted by Oak Ridge National Labs: Light-Duty Idling Summary: • Idling beyond 30 seconds is excessive and should be avoided • Extended idling wastes fuel and causes reduction in fuel economy • Excessive idling can create engine wear and carbon soot buildup in the engine and components • Excessive idling can affect the life of ...


1

Underground storage can be used, but it is much more expensive. There are a variety of options such as concrete tanks, R-tanks, or piped storage. Whatever you go with, you need to ensure that you are able to collect stormwater from your site and convey it to your tanks. Using pervious pavement is usually difficult since it's hard to drain a large area to ...


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