Diesel Injector and Water Tube Boiler Back-Pressure

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Discussion Overview

The discussion revolves around the pressures involved in diesel injectors and water tube boilers, focusing on the mechanics of fuel injection in diesel engines and the pressure dynamics within water tube boilers. It includes technical inquiries about the relationship between injection pressure and combustion chamber pressure, as well as the operational characteristics of water reservoirs in boilers.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how much pressure an injector needs to overcome relative to maximum combustion chamber pressure during detonation and the typical overlap between injection and detonation.
  • Another participant suggests that the injection pressure is sufficient, noting that the overlap between injection and combustion is more than 50%, but it varies based on the volume of fuel injected.
  • A participant expresses appreciation for the explanation regarding overlap, indicating that visual representations do not fully capture the engineering involved.
  • Concerns are raised about the clarity of the question regarding water tube boilers, with a suggestion to refer to a tutorial for better understanding.
  • One participant humorously acknowledges the connection between diesel injectors and water tube boilers as existing only in their imagination, while affirming that the water reservoirs are under pressure and are recharged under pressure.

Areas of Agreement / Disagreement

There is no consensus on the specifics of the pressure dynamics in diesel injectors or the operational characteristics of water tube boilers. Multiple viewpoints and uncertainties remain regarding both topics.

Contextual Notes

The discussion includes assumptions about the types of injection systems and boiler designs, which may influence the answers provided. Some claims are dependent on specific conditions or definitions that are not fully explored.

Silly Questions
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TL;DR
Certain powerplant components seem to be under a lot of pressure.
Diesel injector:
How much pressure relative to the maximum combustion chamber pressure during the sharpest phase of detonation does an injector need to be able to overcome to inject its full charge? How much overlap is typical between injection and detonation?

Water-tube boiler:
Are the water reservoirs at the bottom of the tubes under the same pressure as the steam manifold at the top? When the reservoirs are replenished while a ship is underway are they left in communication with the manifold? Are they replenished continuously or in cycles?
 
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I was able to find good answers to pressures in diesel injectors and power boilers in less than one minute by using my favorite search engine. What have you tried?
 
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Wikipedia.
 
Silly Questions said:
Diesel injector:
How much pressure relative to the maximum combustion chamber pressure during the sharpest phase of detonation does an injector need to be able to overcome to inject its full charge? How much overlap is typical between injection and detonation?
This will depend on the type of injection pump, or which version of the common rail system is employed. I can assure you that the injection pressure is sufficient.

A diesel engine injects fuel in a continuous burst. There should be no detonation, combustion begins a moment after injection begins and continues until after injection stops. There is more than 50% overlap, but it will vary dependent on the volume of fuel being injected.
 
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"There is more than 50% overlap."

The diagrams and animations I've seen don't do this feat of engineering justice. Thanks for your answer.
 
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Diesel injectors and Water Tube Boilers in one thread. That's a pretty big leap.o_O

Your question about the boilers doesn't make sense for all types of boilers. The link shows a brief tutorial on water tube boilers. Please read that before asking follow up questions. The picture is a figure from the tutorial.

https://www.electrical4u.com/water-tube-boiler-operation-and-types-of-water-tube-boiler/

1627681560412.png
 
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They're related by "what do you do about pressure in places where it might cause problems," but that relationship I admit exists only in my imagination.

From the reading I glean that the answer is "yes" to both questions of whether the reservoir is under pressure and is recharged under pressure. Thanks for the link!
 

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