Liquid Piston CNG Refuelling System
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Solution Overview
Problem
Current compressed natural gas (CNG) refuelling systems face challenges such as gas loss and contamination, high energy requirements, and large, cumbersome storage tanks due to the need for significant compression and limited availability of refuelling facilities, which restrict the widespread adoption of CNG as a vehicle fuel.
Innovation Solution
A pressure vessel refuelling system utilizing an aqueous salt solution and a floating layer of immiscible mineral oil within the vessel, where the oil acts as a 'liquid piston' to maintain constant pressure, allowing for efficient and fast refuelling of CNG tanks with reduced power requirements and minimizing gas loss and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If significant compression is used to maintain high pressure in CNG storage, then the pressure is sufficient for refuelling, but the energy requirements and power demands become excessively high
Solution Approach 1:
The patent applies hydraulic principles by using a liquid piston (immiscible liquid) to transmit mechanical force for compressing and containing the CNG. The liquid piston converts linear motion into pressure application, enabling efficient high-pressure maintenance with reduced energy input compared to traditional mechanical compressors.
Solution Approach 2:
The immiscible liquid acts as an intermediary between the mechanical drive system and the CNG gas. Instead of direct mechanical compression of gas, the liquid piston mediates the force transmission, allowing for smoother, more efficient pressure application and maintenance with lower peak power demands.
2Productivity
If traditional refuelling systems are used, then refuelling can be performed, but gas loss and contamination occur
Solution Approach 1:
The immiscible liquid piston serves as a barrier and intermediary between the compression system and the CNG, preventing direct contact that would cause contamination. The liquid seal maintains gas integrity while allowing efficient transfer, eliminating the need for complex sealing mechanisms that could cause leaks and contamination.
Solution Approach 2:
The immiscible liquid creates an inert barrier environment between the CNG and potential contaminants in the mechanical system. This liquid seal prevents contamination from mechanical components while maintaining the refuelling process efficiency.
3Quantity of substance
If large storage tanks are used to store CNG, then sufficient fuel capacity is achieved, but the tanks become cumbersome and expensive
Solution Approach 1:
The hydraulic liquid piston system enables more compact storage vessel design by efficiently maintaining high pressure with smaller volume requirements. The liquid-driven pressure system allows for optimized vessel geometry that reduces overall size and weight while maintaining adequate fuel capacity.
4Adaptability or versatility
If conventional refuelling facilities are established, then refuelling can be provided, but the infrastructure becomes complex and costly
Solution Approach 1:
The patent replaces complex mechanical compression systems with a simpler liquid piston-driven system. This substitution reduces the mechanical complexity of refuelling facilities while maintaining refuelling capability, making infrastructure deployment more feasible and cost-effective.
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
Enables fast and efficient refuelling of multiple CNG vehicles simultaneously with lower peak power demands, reducing storage vessel size and energy consumption, while maintaining constant high pressure and minimizing gas loss and contamination, thus enhancing the feasibility of CNG as a vehicle fuel.
Implementation Method 1
A liquid layer of oil floating on top of the aqueous liquid, wherein the oil is immiscible with the aqueous liquid; natural gas at least partially filling the pressure vessel above the liquid layer of oil
Implementation Method 2
wherein a coalescing filter is in fluid communication with the pressure vessel and functions as a filter to remove particles of the oil from the natural gas after the natural gas exits the pressure vessel
Implementation Method 3
an aqeuous liquid comprising an aqeuous salt solution acting as both an anti-freeze and hydrate formation suppressant
Data Source
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AI summary
A pressure vessel refuelling system enables fast refuelling of Compressed Natural Gas (CNG) fuel tanks. The system includes a pressure vessel having a gas inlet/outlet port and a liquid inlet/outlet port; a first liquid at least partially filling the pressure vessel; a liquid layer of a second liquid floating on top of the first liquid, wherein the second liquid is immiscible with the first liquid; a gas at least partially filling the pressure vessel above the liquid layer of the second liquid, the gas in fluid communication with the gas inlet/outlet; and a pump in fluid communication with the liquid inlet/outlet of the pressure vessel, whereby the first liquid can be pumped or returned to/from storage into or out of the pressure vessel.