24
votes
Accepted
How do suction cups work?
TL;DR: Its not the air that's enclosed inside that creates the force, but the lack of air - or more precisely pressure.
First of all some nomenclature (this is for the closed type, there is also the ...
- 24.3k
3
votes
Accepted
How does indoor temperature factor in when determining ideal relative humidity in a home?
In the world of heating/ventilating/air conditioning engineering (a.k.a. "HVAC") there is a number called the comfort index (which you can search on) which takes both humidity and temperature into ...
- 15.3k
3
votes
Is it possible to create a compressed/freezed air energy storage solution that also purifies the air of pollutants?
Compressing air (for energy storage or other purposes) heats it up, expansion cools. For energy storage the heat has to be stored, a detailed description can be found here. Cooling air further would ...
- 4,791
3
votes
How do suction cups work?
When you push that onto a flat surface it pushes most of the air out.
The elasticity of the item makes want to flex and come off but the air pressure is pushing it onto the surface.
- 16k
3
votes
How to manufacture parts with complex air channels inside?
If you are opposed to 3D printing due to the requirement for mass production, then you may be able to work with an injection molding company to design a product that at least has the curved channels ...
- 571
3
votes
Ventilation setup high sleeper night cooling
I would recommend a modification Phil's answer: airflow is almost always better when the fan is exhausting to the outside - fans don't "like" back pressure and work most efficiently when dumping to an ...
- 4,259
2
votes
Ventilation setup high sleeper night cooling
Air hates to flow into corners, even if there is a fan. A thermally stratified box is about the most obstinate thing there is to make comfortable. The best solution would be to run a small duct ...
- 5,105
2
votes
Accepted
How an airlock works?
each "end" of the airlock has a valve in it which, when opened, allows the pressure between the inside of the airlock chamber and the pressure inside the adjacent chamber to equalize. Once this is ...
- 15.3k
2
votes
How can I determine pressure leakage in a pneumatic system?
Fit a dummy test hose with no leaks - a solid tube for example, then pressurise the system to a known value perhaps the maximum used +10%.
Then take readings every 10 seconds / 5 minutes (whatever is ...
- 16k
2
votes
Accepted
Will an empty spray can maintain a vacuum?
Figure 1. A typical aerosol valve. Source: Wikimedia.
An Internet image search will show that most aerosol valves are of the type shown in Figure 1. Here it should be clear that if the differential ...
- 11.1k
2
votes
Will an empty spray can maintain a vacuum?
The valve on such a can may be engineered to resist internal pressure in such a way as to seal when the can's contents are in place. If the can is completely empty and placed in a vacuum chamber, it's ...
- 7,307
2
votes
Accepted
Properties of air and gas mixture
A molar thermodynamic property $\bar{P}$ for a mixture containing ideal gases can generally be calculated from molar composition (mole fraction $z_j$) and individual component molar property $\bar{P}...
- 2,991
2
votes
Accepted
Suitable pipe suggestion required
You need a pipe rated for suction.
Or use a corrugated steel inner which won’t collapse - did that for one application…
- 16k
2
votes
Accepted
Analyzing the term $\frac{1}{c_s^2}\frac{dP}{dz}$ for atmospheric phenomena?
You might find more satisfying the justification given by Holden and Hakim in An Introduction to Dynamic Meteorology: "For buoyancy wave motions
[$\left|\frac{\rho}{\theta}\frac{d\theta}{dz}\...
- 1,620
2
votes
Can air currents be used to keep dust from settling on solar panels?
Our panels stay relatively dust free as they are at an angle of 70 degrees.
This means the rain flows off nicely taking dust with it and the snow slides off as well also taking dust with it.
Having ...
- 16k
2
votes
Accepted
The physics behind the condensation in tents?
They don't prevent condensation. They just reduce the chances of condensation getting onto your kit down to practically nothing, if you do it right.
The condensation stays on the inside of the outer ...
- 3,771
1
vote
Why carbon water filter can build air pressure inside (before installation)?
The filter may have come from a cooler environment, so the higher ambient temperature caused the air to expand that was inside the filter as the temperature equalised..
As you had sealed the inlet &...
- 16k
1
vote
What causes water to always drip from an electric furnace when its turned on?
You need to consider what materials were used in the lining and in the insulation. Some materials can give off a lot of water on heating, without being wet to start with. This is called water of ...
- 398
1
vote
What causes water to always drip from an electric furnace when its turned on?
You built it wet
Obviously you used damp materials to build the furnace. Turn it to a low setting and run it until it's dry. It's no more complicated than that.
- 7,148
1
vote
Optimized water droplet formation
There is research on the impact of water droplets on deep liquids and solid surfaces.
It seems the most significant factor in the outcome of the collision and its rather short span, in the range of a ...
- 22.8k
1
vote
Heating pump/refrigerator - calculate efficiency
Efficiency = heat moved versus energy consumed. For a heat pump this is either SEER or Coefficient of Performance. Heat moved compared to energy used should be around 2 to 5 in equivalent units (COP)...
- 7,148
1
vote
Can air currents be used to keep dust from settling on solar panels?
Wind will not stop collecting dust on the panels, due to the effect of the boundary layer. The speed of the layer of a stream of air next to a stationary surface is zero.
Otherwise, people would take ...
- 22.8k
1
vote
Can air currents be used to keep dust from settling on solar panels?
Given you are contemplating manufacturing solar panels, as an alternative, may I suggest you consider using something like self-cleaning glass and market your product as either "Smart Solar ...
- 9,752
1
vote
Accepted
Is this an isenthalpic process?
Let us presume that the process being considered is vaporization of liquid water to a gas state in dry air. As long as the temperature and pressure of the liquid water is constant during the process, ...
- 2,991
1
vote
Accurate method or instrument to measure density of shaving cream foam or whipped cream foam?
For a less messy way to determine the volume of shaving cream use a three dimension scanner and software that can determine the volume of scanned items.
Acquire some stainless steel, plastic or ...
- 9,752
1
vote
Is it possible to create a compressed/freezed air energy storage solution that also purifies the air of pollutants?
So two possibilities:
One, pre filter the air prior to cooling/freezing
Two, will the impurities freeze and soldify first? If so remove solids before final freezing.
Are you freezing the air to a ...
- 16k
1
vote
Is there an optical technology able to measure the temperature of dry air?
The fundamental problem is: how do you reject the optical signal from solids or liquids "behind" the air mass you want to measure? The esoteric methods reported in : https://pdfs.semanticscholar.org/...
- 4,259
1
vote
Why does the water pressure initially drop then stabilize when pressure testing a valve?
I can think of two reasons why this might happen, though I don't know for sure.
First, air trapped in the test piece could be slowly dissolving into the water, which will change the overall density ...
- 3,064
1
vote
How to manufacture parts with complex air channels inside?
Lost Foam Casting
Can produce many smaller structures
Can be scaled up for reasonable costs
Relatively cheap (compared to many other castings types and 3D printing).
Can produce items with channels, ...
- 316
1
vote
Ventilation setup high sleeper night cooling
From a simple physics perspective, please consider the following. A fan or blower located in or near the window will pull cooler air into the room. Ideally, you have to have a means to exhaust the ...
- 7,307
Only top scored, non community-wiki answers of a minimum length are eligible