43
votes
Why not put servers in a refrigerator?
A refrigerator is basically a heat pump designed to achieve a temperature close to 0 °C. There are a couple of problems here:
Most refrigerators are way too weak to effectively tackle the heat output ...
- 431
21
votes
Accepted
Benefit of removing the center "engine hub" inside a fan
For a large and/or high speed fan, there are several mechanical disadvantages, for example
The outer ring is highly stressed and therefore heavy. It may also need a heavy containment system to avoid ...
- 12.5k
18
votes
Accepted
Why not put servers in a refrigerator?
We do. It's just an up-sized (i.e. more powerful) version of a refrigerator known as an air conditioning unit.
Essentially all server rooms and most spaces where PCs are located (speaking for the U.S.,...
- 296
12
votes
Why not put servers in a refrigerator?
refrigerator boxes tend to generate condensate
There are specifications for acceptable relative humidity (RH) for servers. Air conditioning in server rooms will maintain RH within the allowed limits ...
- 361
11
votes
Why not put servers in a refrigerator?
Here's a webpage from a random guy who put a light bulb in his refrigerator to see what would happen, and took careful data to monitor it. Results:
The next experiment was to put a 60-watt ...
- 211
9
votes
Accepted
How would adding a wind deflector in front of roof-mounted solar panels affect drag on an RV?
The concept of what you're doing is sound, and as Russell McMahon notes the efficiency gains could be significant enough to justify the change.
I'd strongly suggest that you consider adding a ramp to ...
- 1,966
8
votes
Converting air flow rate between kg/s and m^3/s
You need to consider the density of the air, which varies with temperature and air pressure. At 15 degrees Celsius, at sea level, the density of air is 1.225 ${kg}/{m^3}$. The table here gives air ...
- 9,462
8
votes
Is there a more active passive technique for removing humidity from the air besides salt blocks?
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 ...
- 3,701
7
votes
How do I calculate the max flow rate for a pump with no power restrictions?
This phenomenon is known as cavitation for pumping liquids - i.e. for anything that can change phase. If you are pumping gas, then the scenario really does come from choked flow.
Let's say you've ...
- 5,303
7
votes
Accepted
Airflow selection mechanism
Are you bound to the shape/configuration of part you constructed in your question? If not, a simple 3-way pneumatic solenoid valve would make this very simple and leak proof(relatively speaking). They ...
- 1,578
7
votes
How metal fittings seal connection without rubber gaskets?
The common pipe threads that are used in buildings for water and gas are tapered threads. The thread is cut on the cone rather than cylinder. In the US, these threads are called National Pipe Thread ...
- 1,045
7
votes
Benefit of removing the center "engine hub" inside a fan
Fans like the one on the right exist. These where first invented as rim-driven thrusters (rim driven is your search term, not centerless) for marine applications. The rim is the rotor of the electric ...
- 4,618
6
votes
How are wind tunnel models used when designing supersonic aircraft?
In the Fluid Dynamics community about 40 years ago, the group was primarily divided into experimentalists and theorists. However, at that time CFD was quite new, had to be run on expensive ...
- 493
6
votes
efficiency and flow separation
You are describing a very interesting engineering problem.
The requirement of a turbine is to convert fluid-energy into mechanical energy over a range conditions. Since the flow around the airfoils ...
- 1,202
6
votes
Accepted
How can I create uniform laminar flow in a short duct?
Quick and dirty CFD simulation of your problem using ANSYS Fluent 14.5: I used a 2D duct, 8" x 4" with a 45-degree angle going from the inlet pipes to the main chamber. Assuming 3 liters per hour ...
- 2,989
6
votes
Accepted
Fan performance curve
The yellow curve corresponds to a fan that will provide mostly a set pressure differential, say, keeping fumes from escaping a tank through elsewhere than dedicated vents. If there is a circumstance ...
- 6,123
5
votes
Converting air flow rate between kg/s and m^3/s
HVAC-Systems usually give a Volume-Flow-Rate, hence $m^3/s$. If you need Mass-Flow-Rate ($kg/s$) you simply need to multiply with the density ($\rho$) of the fluid. The density can be calculated using ...
- 1,202
5
votes
Accepted
How to minimize heat loss in an air extractor?
What you want is called a heat exchanger. Imagine two long air tubes with a thin wall between them. The air exiting the house travels in one tube, and entering air in the other, but in opposite ...
- 11.2k
5
votes
How does one create a draft in a room (with a single window)?
The fundamental problem is that hot air must leave the room and cold air must enter it, both at the same time through the same single opening. The conflicting forces will mostly cancel each other out,...
- 789
5
votes
How metal fittings seal connection without rubber gaskets?
In addition to tapered threads for creating seals, there are Compression Fittings which use a matching male and female mating low angle taper to create a sealing surface. When properly torqued, they ...
- 1,578
5
votes
Accepted
How do gas flow regulators avoid choking?
The short answer is that they don't. Choking is not a bad thing. For a gas flow regulator, it's actually a good thing, because under choking conditions, the mass-flow rate is no longer dependent on ...
5
votes
Accepted
How much does an evaporative cooler cool down a room
The capacity of an evaporative cooler depends on the relative humidity. The lowest theoretical temperature that the cooler can reach is the wet bulb temperature.
The wikipedia article has some ...
- 377
5
votes
Accepted
How do I choose a blower design for an induced draft brick kiln?
Normally fans are not custom built by a company that does not build fans. The concept of a centrifugal fan is not particularly complicated, but it is difficult to achieve target flow rate, pressure, ...
- 7,469
5
votes
Why not put servers in a refrigerator?
They've been doing that with computers for 30+ years. Back when computers were the size of refrigerators. They use to get a regular air conditioner. Build a platform for the computer to stand on. ...
- 51
4
votes
Foiling vortex traps around buildings
CFD
I ran this situation through a couple of simple 2D CFD models. As you can see from the pictures below, one way to keep debris from gathering in this area is to increase the velocity of wind in ...
- 10.6k
4
votes
Fan Sensors (Tachometer vs Locked Rotor)
It's a trade-off between the simplicity of the sensor and how comprehensive the reported data is. The locked rotor sensor only reports whether or not the motor is spinning, not how fast it's spinning ...
- 2,989
4
votes
What is the power and max flow rate required to rotate a 300 W wind turbine?
You need to push air through the turbine at 11 m/s, or just above. That's what the rated windspeed means: it's the lowest windspeed at which the turbine hits rated power, at standard atmospheric ...
- 3,701
4
votes
Accepted
Shouldn't enthalpies be equal in isentropic process?
Constant entropy doesn't mean constant temperature, the gas flow through nozzle is subject to change in pressure and velocity (continuity equation) due to the variation in cross section, and being ...
- 2,149
4
votes
Accepted
What's the difference between aircon modes Auto, Sun, Snowflake?
The sun is heating mode. When the room temperature reaches the set temperature, the air conditioner stops operating until the temperature falls below the set temperature and the starts operating again....
- 9,462
4
votes
Accepted
Passing by a semi truck on a highway
A truck speeding down a highway creates an envelope stream of high pressure air surrounding it.
This is basically a wake, composed of layers of high pressure shockwaves, created when the front of the ...
- 21k
Only top scored, non community-wiki answers of a minimum length are eligible