Hot answers tagged

14

With pumping diesel, your main constraint should be safety, not cost. There are very good reasons diesel pumps aren't for sale for $5 on amazon. The main things you want to look at are 1) whether the wetted materials are compatible with diesel (EDPM and silicone for example will dissolve) and 2) how it is grounded. Many pumps can build up static charge ...


14

Have you looked at the size of one of those maritime diesel engines? They are larger than your car and need to deliver a lot of power to move and power the ship. That takes a lot of fuel so it's cheaper to burn more cheaper fuel even if it is of inferior quality. The bigger size also lets it use wider fuel lines so the viscosity is less of an issue. You also ...


9

It depends on what you mean by "diesel-like". If you mean an engine with compression ignition running on gaseous fuel, then the answer is no. The high autoignition temperature of fuels such as natural gas prohibits sparkless ignition of pure natural gas1. @mart is right that compression ignition engines running on gaseous fuels need a pilot fuel which ...


7

They are very nearly equal for typical four-stroke non-turbo diesels under load. A turbo diesel under load should have slightly more radiator loss than exhaust loss. At the bottom is a link to the technical spec sheet for a Cat 3412 powered genset. It's a probably a bit bigger than what you had in mind. It is a turbo with aftercooler (A/C in the doc below). ...


6

The internet has a range of values from 3 months to a year, depending largely on the political/economic interest of the site in question. Here's a couple quotes that you might want to follow up on: From springboardbiodiesel, The truth is that all fuels will degrade over time. In fact, the EPA reports that ULSD diesel has a shelf life of between 3-6 ...


6

But I'm thinking it may be better (more efficient maybe? less vibration maybe?) to run it in three-phase mode, with the load balanced among the three hot terminals. Correct. Figure 1. The load is constant through the generator cycle. Source: T. Davies - website not found. My thinking, based on my coarse understanding of generators, is that in three ...


5

From the Wikipedia article: All diesel engines can be considered to be lean-burning with respect to the total volume, however the fuel and air is not well mixed before the combustion. Most of the combustion occurs in rich zones around small droplets of fuel. Locally rich combustion like this is a source of NOx and particles.


5

A diesel engine for a car needs a fuel which is liquid even in winter. This fuel should contain a very small amount of sulfur to limit air pollution. The marine bunker oil is not liquid at room temperature, it has to be heated to about 50 °C before pumping out of the tank and to about 130 to 140 °C before injecting it into the cylinders. It contains a lot ...


5

Simple economics. Marine engines consume enormous amounts of fuel, so in order to reduce operating costs, they use the cheapest, least desirable sludge that the oil refineries can produce.


4

The only ones I know of are pilot-oil gas motors. The ones I know burn biogas or methane plus a small amount of oil, typically rape oil. The oil is neccesary for combustion but the biggest part of the power comes from the gasous fuel. Typically, the lower limit for oil consumption is about 5% (by energy content), the engines can run on oil solely. ...


4

The maximum efficiency of either the Diesel or a steam engine cycle is (assuming you can treat steam as an ideal gas): $$\eta_{Diesel} = 1 - \frac{1}{(\frac{V_{Max}}{V_{Min}})^{k-1}} \left[\frac{r_c^k-1}{k(r_c-1)}\right] $$ Where $k$ is the heat capacity ratio, and $r_c$ is the cutoff volume ratio - i.e. the ratio of volumes after and before the combustion ...


4

On this website, Wartsila states it has made diesel-gas engines and that the first ones have been operating for 70 000 hours.


3

Compared to Otto cycle engines, diesel engines have a smaller rpm range and, as they tend to have more mass (due to the higher compression ratio etc), tend to develop the torque earlier in the rev band and it tends to be a flatter curve through the range.


3

Revisiting the problem anew, it turns out that the units were interacting in a way I wasn't taking into account. When I asked this question, I had input $r_c$ and $r_0$ in cm. However, $\rho$ was in kg/m3, and $Q_0$ was in g/s; additionally, my $Q_0$ was too large (an Audi 3.3L V8 TDI achieves 0.014 g/s per injector). Surely enough, putting $r_c$ and $r_0$ ...


3

Diesel engines use compression to ignite fuel. Compression ignition requires higher compression ratios than Otto cycle engines. This results in parts that have to tolerate higher stresses, which means heavier parts. If you try to shrink a diesel engine down, you'll have small cylinders and everything else will be heavy (even the engine block). It's just not ...


3

1) In an engineering context efficiency has a very specific meaning ie it is the ratio between the energy you put into a system and the useful work that you get out. In itself this doesn't tell you very much about the amount of pollution produced in the process. Fuel economy is a bit different as it considers the overall energy(fuel) use of the car as a ...


2

Steam engines can expand the steam only so much before the water vapor starts to condense. In addition, the volume of the vapor increases significantly as it expands, making it difficult to obtain further work, as the cylinder size must increase to accommodate the volume of vapor passing through it. Most steam engines use three or four cylinders to expand ...


2

OK, fair warning: I am answering my own question and am not a engines person. So this could be wrong. The real limit in the engine is how hot certain parts can get without breaking. This temperature is related to the gas temperature after combustion via the cooling system and the cylinder design (convective heat transfer between the gas and the cylinder ...


2

If you count gasoline as "gas", many car manufacturers are already testing homogeneous charge compression ignition engines. It is where they use the compression stroke to ignite the fuel mixture in the cylinder. The fuel is not direct injected, it is premixed in the intake charge before it makes it into the cylinder, so diesel type direct injectors are not ...


2

The difference of few large cylinders or many small cylinders has less to do with running on steam or diesel, but more with the era in which the engines were built. Early engines (both steam and diesel) had few, large cylinders, probably because that is how engineers tried to make more powerful engines: make everything bigger. The realization that multiple ...


2

One important reason is that diesel fuel had a high molecular weight compared to gasoline this means that is is more difficult to disperse as it forms liquid droplets as opposed to vapour and even more importantly there are many more intermediate reactions involved in complete combustion. For example Hydrogen, H2 burns very easily in oxygen as combustion ...


2

The diesel engines are working on diesel cycle. The heat addition(ingnition) is taking place during the constant pressure process. After added energy is spent by the expansion of piston. The amount of expansion is fixed in terms of stroke length. So for given fixed pressure and fixed expansion we ought to get constant work output. That's why the torque ...


2

The higher torque comes from a relatively longer stroke, which is needed to develop the higher compression for a diesel. The longer stroke gives a longer "arm" for the piston to push on the crankshaft. Or , think of the longer crankshaft throws; distance from crankshaft center-line to the throw center-line. The affect is more apparent when the throws are in ...


2

Consider how much energy is needed to heat the fuel that is injected each time compared to the energy that can be recovered from the turbo-charger for example. One thing to note is that many of the diesel pumps (style DPA / inline high pressure) will compensate for changes in the density of the fuel according to the temperature, the modern common rail ...


2

There are model diesel engines, so technically it is possible. My guess in the case of car engines would be that it is about economics. Diesel engines are more expensive to manufacture (because they need to be stronger to withstand higher compression), but you earn that back in their better fuel efficiency and lower fuel taxes if you make enough kilometers. ...


2

While the other answers here are compelling, they're only half the truth. If you consult your manual you'll find that the generator load windings are reconfigured when using the mode selection switch to one of three output modes. In either mode, the full output of the generator is available, either as 104A@120V(1ph, one circuit), 52A@120/240(1ph/split, two ...


1

Everything that gets the mixture in the cylinder hotter makes for a more efficient combustion. That is because the power of the engine depends purely on the pressure exerted on the piston, and the effective pressure is caused by temperature rise, and nothing else. So yes, injecting hot diesel would make for a more efficient combustion, in theory. But it ...


1

My understanding: Petrol engines produce far more carbon monoxide. Carbon monoxide is a colourless, odourless and highly toxic gas. This makes running petrol engines indoors far more dangerous than running diesel engines indoors. Outdoors however carbon monoxide is not so bad. It's lighter than air so it won't tend to persist near ground level. Diesel ...


1

It's all about what comes out Two-stroke, forced-induction diesels have been a mainstay of heavy industry for quite some time (Detroit Diesel 71 series, EMD 567/645/715, never mind ship engines). However, they aren't as amenable to precise emissions control as their four-stroke counterparts. This can be shown by EMD's switch to the four-stroke J (EMD 1010)...


1

There have been smaller two stroke diesels produced (the Comma TS3 or the Detroit Diesels - very popular) but to make the TS3 work successfully they need forced induction -a Rootes blower was used. The 4-stroke tends to be used as their the fuel consumption is generally better while there are more components, another consideration is the ancillary component ...


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