LNG Fuel Supply System Supercooled Compression
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Solution Overview
Problem
Existing LNG fuel supply systems for ships inefficiently use energy by wasting electric energy in increasing the temperature of LNG during the compression process, which also prolongs the operation time of high-pressure pumps and increases heat permeation.
Innovation Solution
The system compresses LNG to a supercooled liquid state at high pressure using a pump, minimizing energy waste by focusing on pressure increase rather than temperature, and then uses a heat exchanger to heat the supercooled LNG to a combustion temperature using surplus waste heat, thereby optimizing energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If LNG is compressed to high pressure using a pump, then the pressure of LNG is increased to meet engine demands, but the temperature of LNG increases due to energy transfer, wasting electric energy
Solution Approach 1:
The patent changes the thermodynamic parameters of LNG by compressing it to supercritical state (pressure above critical pressure, temperature above critical temperature) before heating. This parameter change allows the LNG to be in a supercritical fluid state which has different thermal properties, enabling more efficient heat transfer and reducing the energy waste during compression. The pump compresses LNG to supercritical state, and then the heat exchanger efficiently heats the supercritical LNG to combustion temperature.
2Reliability
If the pump increases both pressure and temperature of LNG, then the engine can receive LNG at required conditions, but the operation time of the pump is prolonged and heat permeation increases
Solution Approach 1:
The patent segments the LNG processing into two distinct stages: first, the pump compresses LNG to supercritical state, and second, the heat exchanger heats the supercritical LNG to combustion temperature. This segmentation allows each component to perform its function more efficiently - the pump only needs to compress without worrying about temperature control, and the heat exchanger handles the heating process separately, thereby reducing the pump's operation time and minimizing heat permeation issues.
3Temperature
If conventional heat exchangers are used to heat LNG, then combustion temperature is achieved, but significant electric energy is wasted during the compression-heating process
Solution Approach 1:
The patent utilizes the phase transition of LNG to supercritical fluid state as the key mechanism. By compressing LNG to supercritical state and then heating it, the system takes advantage of the unique thermal properties of supercritical fluids which have high heat capacity and excellent heat transfer characteristics. This phase transition approach significantly reduces the energy waste compared to conventional heating methods, as the supercritical LNG can be heated more efficiently to the required combustion temperature.
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 reduces the electric energy consumption of the pump and enhances the use of heat energy available on ships, improving overall energy efficiency and reducing the operational time of high-pressure pumps.
Implementation Method 1
a pump provided on the fuel supply line, and configured to compress LNG discharged from the LNG storing tank at a high pressure
Implementation Method 2
The pump may phase change the LNG discharged from the LNG storing tank to the LNG in the supercooled liquid state having a higher pressure than a critical pressure and a lower temperature than a critical temperature
Implementation Method 3
a heat exchanger provided on the fuel supply line between the engine and the pump, and configured to heat the LNG supplied from the pump
Implementation Method 4
heats LNG in a supercooled liquid state at a combustion temperature demanded by an engine through a heat exchanger using surplus energy, which is easily obtainable from waste heat generated in various equipment including a boiler
Data Source
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AI summary
Disclosed is an LNG fuel supply system, including: a fuel supply line (21) connected from an LNG storing tank (10) to an engine (20); a pump (32) provided on the fuel supply line, and configured to change an LNG to the LNG in a supercooled liquid state by compressing the LNG discharged from the LNG storing tank at a high pressure; and a heat exchanger (40) provided on the fuel supply line between the engine and the pump, and configured to phase change the LNG in the supercooled liquid state to the LNG in a supercritical state by heating the LNG in the supercooled liquid state supplied from the pump.