Large Engine Cylinder Deactivation for Low-Load Gas Operation
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Solution Overview
Problem
Existing methods for operating large dual-fuel two-stroke engines, particularly in gas mode, face challenges in maintaining energy efficiency and low emissions across various load ranges, especially at lower loads, due to the inability to adjust the air-fuel ratio effectively, leading to increased fuel consumption and potential misfires.
Innovation Solution
A method for operating a longitudinally scavenged dual-fuel large diesel engine that adjusts the air-fuel ratio by deactivating at least one cylinder in reduction mode, ensuring the air-fuel ratio is optimized for the active cylinders, thereby maintaining efficient and low-emission operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the engine operates in gas mode with all cylinders active in the lower load range, then the air-fuel ratio becomes too high (too much air relative to fuel), but this leads to increased gas consumption and reduced energy efficiency
Solution Approach 1:
The engine is divided into active and inactive cylinders. By switching off one or more cylinders in the lower load range, the system segments the total cylinder count to match the actual power demand, thereby optimizing the air-fuel ratio in the remaining active cylinders and improving energy efficiency.
Solution Approach 2:
The operating parameters of the engine are dynamically changed by adjusting the number of active cylinders based on load conditions. This parameter change allows the air-fuel ratio in active cylinders to be optimized for each operating condition, preventing excessive gas consumption while maintaining energy efficiency.
2Power
If the engine operates in gas mode with all cylinders active, then the power output is sufficient, but the gas consumption increases and energy efficiency decreases in the lower load range
Solution Approach 1:
The engine operates with segmented cylinder activation where only the necessary number of cylinders are active based on power demand. This segmentation reduces gas consumption by ensuring that fuel is burned only in cylinders that are actually contributing to power output, eliminating waste in inactive cylinders.
Solution Approach 2:
Instead of running all cylinders at partial load (excessive action), the system uses partial action by activating only the required number of cylinders. This approach matches the power output to actual demand while minimizing gas consumption and energy loss.
3Loss of energy
If the engine switches to reduction mode by deactivating cylinders, then gas consumption is reduced, but the device complexity increases due to cylinder management
Solution Approach 1:
The engine control system is designed with multi-functionality to automatically manage cylinder activation and deactivation based on operating conditions. This universal control capability handles both full-load and partial-load operations without requiring separate manual intervention, thereby reducing the perceived complexity for the operator while achieving gas consumption reduction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces fuel consumption, especially at low loads, by utilizing all generated energy for piston movement and ensuring the air-fuel ratio remains within optimal limits, resulting in energy-efficient and environmentally friendly operation.
Implementation Method 1
combustion of the fuel generally occurs according to the principle of compression ignition or auto-ignition
Implementation Method 2
the intake air is typically supplied by a turbocharger, which generates an intake air pressure
Data Source
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AI summary
A method is proposed for operating a large engine having several cylinders (21) in a gas mode, wherein a premixed air-fuel mixture is provided in a combustion chamber by introducing a fuel, having an air-fuel ratio, wherein at least one control parameter is monitored which depends on the air-fuel ratio or on a load at which the large engine (20) is operated, and wherein the large engine (20) is operated in a reduction mode if the control parameter reaches a limit value, wherein in the reduction mode at least one cylinder (21) is deactivated so that the large engine (20) is operated with a reduced number of cylinders (21), and the air-fuel ratio is adjusted for the reduced number of cylinders (21). Furthermore, a large engine operated using such a method is proposed.