Part of the trouble with understanding what Steam Machines are is the false dichotomy between PCs and consoles. The distinction between those two devices is mostly artificial. The real difference between a desktop PC and a console then is that consoles provide a stable and fixed hardware and software platform for the lifetime of the device.
This stability ensures that which allows developers to target and optimise to a standard platform. It is this stability that is entirely lacking for Steam Machines. They only provide Steam OS to preinstall on these devices and hope that developers will target it.
The actual machines are made by third parties like Alienware and Syber. Unlike the highly locked console devices where end-consumers cannot upgrade hardware, change OS, or write their own software, a Steam Machine is just a PC that comes with SteamOS preinstalled, includes a Steam controller, and looks like something designed for the living room rather than a desk.
You can change the OS, and in most cases upgrade most of the hardware components like RAM and disk drives. Consider the next largest valve, a DN32 but with a 25 mm trim. The outlet area of this valve is 0.
The DN32 bodied valve will be suitable because the outlet velocity is less than 0. The same procedure can be used to determine the conditions of the downstream steam for other upstream conditions. For instance, if the upstream steam is known to be wet, the downstream condition might be wet, dry saturated or superheated, depending on the pressure drop.
The allowable outlet velocity will depend on the downstream steam condition as previously outlined in this section, and observed in Example 6. Another problem is the possibility of erosion in the valve body caused by excessive velocity in the valve outlet. In Example 6. With anything more than a small pressure drop and wet steam, the steam will probably be dried to saturation point or even slightly superheated.
Control valves are not as efficient as nozzles in changing heat into kinetic energy. The path taken by steam through the valve inlet, the throat and into the valve outlet is relatively tortuous.
In a control valve a great deal more energy is lost to friction than in a nozzle, and, because It seems that control valves of differing types may appear to reach critical flow conditions at pressure drops other than those quoted above for nozzles.
Restricted flow passages through the seat of a valve and on the downstream side of the throat may mean that maximum flowrates may only be reached with somewhat greater pressure drops. A ball valve or butterfly valve may be so shaped that some pressure recovery is achieved downstream of the throat, so that maximum flow conditions are reached with an overall pressure drop rather less than expected. Complicated valve sizing equations can be used to take these and other criteria into consideration, and more than one standard exists incorporating such equations.
One such standard is IEC Unfortunately, the calculations are so complicated, they can only be used by computer software; manual calculation would be tedious and slow. Nevertheless, when sizing a control valve for a critical process application, such software is indispensable.
For example, IEC is designed to calculate other symptoms such as the noise levels generated by control valves, which are subjected to high pressure drops. Control valve manufacturers will usually have computer sizing and selection software complementing their own range of valves. However, a simple steam valve sizing equation, such as that shown in Equation 3.
As shown in the previous text, once this downstream pressure is reached, any further increase in pressure drop does not cause an increase in mass flowrate. This effect can be observed in Figure 6. The flow and expansion of steam through a control valve is a complex process. The advantage of this relatively simple formula is that it can be used with the aid of a simple calculator.
Note: If Equation 3. This is then taken as zero and the function within the square root sign becomes unity, and the equation is simplified as shown in Equation 6. Alternatively, valve-sizing or Kv charts can be used. Hence the Kv value is not only used for sizing valves but also as a means of comparing the capacity of alternative valve types and makes. Bringing together the information for steam valve sizing.
The difference between the above criteria defines the differential pressure across the valve at its full load condition.
These factors are required to determine the steam mass flowrate. A control valve is required for the application shown in Figure 6. The shell and tube heat exchanger manufacturer specifies that a steam pressure of 5 bar absolute is required in the tube bundle to satisfy a process demand of kW.
Wet steam, at dryness 0. Enthalpy of evaporation hfg at 5 bar a is 2 First, it is necessary to determine the steam state for the downstream condition of 5 bar a. By entering wet steam at 10 bar a, and 0. The heat exchanger design pressure is 5 bar a, and the total heat in dry saturated steam at this pressure is 2 The dryness fraction of the lower pressure steam is the quotient of the two total heat figures.
The steam flowrate can now be determined from Equation 2. Determine the required Kvr The pressure drop ratio at full load is larger than 0. A DN25 control valve with a Kvs of 10 is initially selected.
A calculation can now be carried out to determine if noise is an issue with this sized valve passing wet steam in the valve outlet.
The speed of sound in the valve outlet:. The DN25 control valve will therefore be unsuitable for this application where wet steam passes through the valve outlet. One solution to this problem is to fit a larger bodied valve with the same Kvs of 10 to reduce the wet steam outlet velocity. Consider Table 6. It can be seen from Table 6.
A better solution might be to fit a separator before the control valve. This will allow the smaller DN25 control valve to be used, and is preferred because:. If the apparatus working pressure is not known, it is sometimes possible to compromise.
It should be stressed that this method should only be used as a last resort, and that every effort should be made to determine the working pressures and flowrate. In this way, the selected control valve will more than likely be oversized.
To help this situation, an equal percentage valve will give better operational performance than a linear valve this is discussed in more detail in Module 6.
Sizing on an arbitrary pressure drop is not recommended for critical applications. The higher the pressure drop the better? It is usually better to size a steam valve with critical pressure drop occurring across the control valve at maximum load. This helps to reduce the size and cost of the control valve.
However, the application conditions may not allow this. For example, if the heat exchanger working pressure is 4. In this situation, sizing on critical pressure drop would have unduly reduced the size of the control valve, and the heat exchanger would be starved of steam. If it is impossible to increase the steam supply pressure, one solution is to install a larger heat exchanger operating at a lower pressure. In this way, the pressure drop will increase across the control valve.
This could result in a smaller valve but, unfortunately, a larger heat exchanger, because the heat exchanger operating pressure and temperature is now lower. However, a larger heat exchanger working at a lower pressure brings some advantages:. Like ball valves, gate valves are not usually used to regulate flow. One of the reasons for this is because the valving element can be damaged when in the partially open position. Similarly, they also limit the pressure drop across the valve when fully open.
However, setting the valve to the fully open or closed position requires the handle to be turned many times, which generally makes these valves have the longest operating times among those valve types mentioned here.
Diaphragm valves use a 'pinching' method to stop the valve flow using a flexible diaphragm. They are available in two types: weir and straight-way. The most commonly seen of the two is the weir-type. This is because the straight-way type requires additional stretching of the diaphragm, which can shorten the diaphragm's life-span. One of the major advantages of using diaphragm valves is that the valve components can be isolated from the process fluid.
Similarly, this construction helps prevent leakage of the fluid without the use of a gland seal packing as seen in other types of valves. One the other hand, the diaphragm becomes worn more easily and regular maintenance is necessary if the valve is used on a regular basis. These types of valves are generally not suited for very high temperature fluids and are mainly used on liquid systems. Note: There exists a valve for steam systems that goes by a similar name.
It is an automated valve with a diaphragm type actuator. This is often shortened to just 'diaphragm valve', so when a valve is referred to by this name, care must be taken to verify which type of valve it is. And you can earn real money from it, they told us! Buy these items, and the 3D artists who made them will get 25 percent of the profits. We're all in this together!
Talented 3D artists surged out of the woodwork, and the airwaves were saturated with feel-good stories of creators making very decent, livable wages off the sales of Demoman swords, machine gun skins and wacky couriers.
As far as Valve is concerned, it's a fantastic arrangement: You do all the hard work for free, knowing that you might never be paid, but hoping you will at some point. Valve sells your work to other people, and they take the overwhelming majority of the money from each transaction. Everyone's a winner Valve has lost nothing other than the sunk cost of the employee time spent maintaining the store, while gaining a lot of revenue.
The agreement itself states that you have no specific right to any payment, outside of the ability to upload the item. The specific Workshop agreement also forces you to keep the sales data itself confidential. Want to tell someone how well your items are selling? Too bad. Valve has just recently slashed royalties for Dota 2 creators to almost nothing , right on the eve of the next massive International tournament.
This artist has made tens of thousands of dollars from Steam Workshop item sales, and is still in love with the idea of content creation and modding, even if they're not overly optimistic about the future of the Steam Workshop.
Or, to look at things in a more cynical light: Valve is eager to provide the tools that enable you to work for free It feels like many of Valve's decisions, really: short term profit for them, but it screws over the long term viability of everyone else.
Dota 2 continues to grow — not least of all because the prize money for the International tournaments is literally donated by us, the players, who purchase interactive Compendiums and Battle Passes to raise prize money for the competitors from which Valve takes 75 percent.
I'm sure you can do the math. The numbers have stopped adding up. The International is a huge draw, Dota 2 is the most popular game on Steam, Steam Workshop artists are now being paid much less, and all the while Valve seems to scream blue murder if you ask impertinent questions like "Hey, listen: exactly how much money are you making?
It gets worse. The item re-sales are in full swing today, but that promised share of the profits for creators is still undelivered and Valve refuses to answer questions about where their money is. We emailed Valve for a comment on this issue before publishing the story, and have yet to hear back.
After all, if you don't say anything, you can't tell a lie to the internet, right? I asked this Steam Workshop artist what rights they had when it came to disputing decisions or outcomes with Valve about their work.
Fourteen years after Half-Life 2 — a game, by the way, that will likely never see a sequel unless it can be bundled with another leverageable platform — Good Guy Valve has smiled and exploited its way to a position of astonishing power and influence.
Their famous internal handbook "leaked" in , painting a beautiful picture of a free-spirited workplace where genuine creativity and absolute, unchecked innovation bubbled out like a freshwater spring in a magical forest.
Much like the ones on their famously mobile desks, the wheels on that particularly romanticized notion appear to have fallen off. Former Valve employees have come out to slam the internal culture as being a high-school like mix of cliques and backstabbing , with another engineer saying it was "the worst experience of my life" and with desk setups similar to a "panopticon prison".
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