11
votes
Can solar panels absorb heat for energy?
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 ...
- 3,751
9
votes
Accepted
Why does reducing the amount of emissions control improve the fuel economy of a car?
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 ...
- 6,874
5
votes
Accepted
Humidity in home is much higher than outside
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 ...
- 7,904
4
votes
Can a retention/detention pond and a parking-lot be constructed in the same site foot-print?
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 ...
- 10.7k
4
votes
Accepted
What colour of tarp will let in the least amount of heat?
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 ...
- 1,174
3
votes
What colour of tarp will let in the least amount of heat?
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 ...
- 1,076
3
votes
Accepted
Prolong frozen ground conditions (to trick fruit trees into flowering later)
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 ...
- 7,904
3
votes
Accepted
How large of an area of the earth's surface would we need to cover in mirrors to negate global warming?
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 ...
- 6,874
3
votes
Accepted
Store seeds at 1°C
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 ...
- 7,904
3
votes
Thermodynamics of an Arctic Greenhouse
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 ...
- 11.4k
3
votes
How can I calculate the evaporation rate for a hazmat spill?
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 ...
- 498
3
votes
Mapping of vehicle to its horn sound
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 ...
- 1,174
3
votes
How to install a wired sensor in a rotating bin without tangling the wires?
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 ...
- 248
3
votes
Why not use sodium hydroxide to reduce carbon dioxide emissions?
This is because the manufacture of NaOH requires energy, and if that energy comes from fossil fuels, then the net gain of the overall process is either zero or less than zero.
Net-positive CO2 ...
- 14.3k
2
votes
Gas cleaning in activated carbon filters - How much moisture is needed and why?
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 ...
- 3,211
2
votes
Inexpensive and moderately accurate (field) method of measuring THC (Total Hydrocarbon Content) in water
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 ...
- 4,772
2
votes
Difference between surface loading rate and surface overflow rate of sedimentation tanks
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 ...
- 4,772
2
votes
Is it better to throw used domestic cooking oil in toilet or within the garbage?
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 ...
- 7,904
2
votes
Why not use Sodium Hydroxide mist to precipitate carbon dioxide from hydrocarbon combustion exhaust
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 ...
- 4,772
2
votes
Accepted
Do cars that automatically turn off engines at idle save any significant fuel?
The main purpose for ECO modes in newer vehicles is actually driven by the EPA in an effort to reduce emissions. Manufacturers sell it as fuel economy/efficiency - which is not totally misleading but ...
- 36
2
votes
Humidity in home is much higher than outside
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 ...
- 130
2
votes
How to retrofit seed starting trays to prevent root circling
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 ...
- 10.3k
2
votes
How to install a wired sensor in a rotating bin without tangling the wires?
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, ...
- 12.5k
2
votes
Accepted
How much energy is needed for the USA to only use desalinated water?
Amount of Water Used
The amount of water used in the USA in 2015 for all uses other than thermoelectric power (1) (read: to cool power plants) was 189B gal/day, or 715M m^3/day.
Amount of Energy ...
- 173
2
votes
Accepted
Why regulations on refrigerant and not on efforts in preparing standard for leak proof refrigeration system?
Because you can control refrigerant at the source
If a refrigerant can't be manufactured, it will go away. As prices go up, keeping systems from leaking becomes more important. No one can control ...
- 6,544
1
vote
Mapping of vehicle to its horn sound
Needs to be heard (volume) within vehicle stopping distance.
- 489
1
vote
Accepted
How to retrofit seed starting trays to prevent root circling
Attach some L-shaped metal sheets or plastic parts in between holes? Attaching can be accomplished by, gluing, nailing, silicone, screwing, etc. depending on the size of the plates and your pots.
Or ...
- 906
1
vote
Solving heat loss equation associated with solar trough concentrators
Foundations
Energy Balance
Consider the picture below.
This shows a $dz$ segment of the tube. Neglect radiation to/from the air and sky. The energy balance becomes
$$\dot{q}_r + \dot{q}_{fi} = \...
- 2,878
1
vote
What colour of tarp will let in the least amount of heat?
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.
- 489
1
vote
Prolong frozen ground conditions (to trick fruit trees into flowering later)
Options:
Site location:
NE slopes get spring sun at a lower angle of attack, and so warm up more slowly.
In addition NOT being at the bottom of the slope may save you from pools of cold air.
...
Only top scored, non community-wiki answers of a minimum length are eligible