Ladder Fill-Up Hydrogen Refueling Process
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Solution Overview
Problem
High-pressure gas refueling of hydrogen or compressed natural gas vehicles faces challenges due to interior tank heating during refueling, leading to reduced capacity and increased energy costs from cooling systems, necessitating efficient methods to manage temperature and fill time.
Innovation Solution
The implementation of a 'ladder fill-up' process using a Joule-Thomson valve and thermally insulated systems, which involves filling and emptying the tank in a controlled manner to maintain hydrogen temperature between 298.15 K and 358.15 K, eliminating the need for high-cost cooling systems and reducing fill time to less than one minute.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high pressure gas is transferred rapidly to fill the vehicle fuel tank, then the refueling time is reduced, but the interior temperature of the tank increases substantially
Solution Approach 1:
The refueling process is divided into multiple discrete steps (first step, second step, third step) with alternating filling and venting operations. The tank is filled to different pressure levels sequentially, with venting operations between steps to control temperature. This segmentation allows rapid filling while managing thermal effects through periodic pressure relief.
Solution Approach 2:
The system implements periodic venting operations during the refueling process, where the tank is filled for a period, then vented for a shorter period, and this cycle repeats. The venting duration is less than the filling duration in each cycle, creating a net filling effect while periodically removing heat through pressure relief. This periodic action enables high-speed refueling without excessive temperature rise.
2Temperature
If the gas flow rate is reduced to decrease interior temperature increases, then the temperature control is improved, but the refueling time increases significantly
Solution Approach 1:
The system rushes through rapid filling steps followed by brief venting steps, rather than maintaining a slow steady flow rate throughout. The venting operations are kept short (less than the filling operations) to minimize time loss while still achieving temperature control. This approach skips the time-consuming slow-fill process by using alternating rapid fill-vent cycles that net to controlled heating.
3Temperature
If conventional chillers are used to pre-cool the fuel gas, then the temperature control is improved, but the energy consumption and cost increase substantially
Solution Approach 1:
The system uses the tank's own pressure and temperature conditions to drive the refueling process without external cooling intervention. The alternating fill-vent cycles utilize the gas dynamics and thermodynamics within the system itself to manage temperature, rather than requiring external chillers to pre-cool the fuel gas. The venting operations naturally remove heat through pressure relief, making the system self-regulating.
Solution Approach 2:
The system converts the harmful effect of compression heating into a beneficial control mechanism. Instead of trying to prevent temperature rise through cooling, the system allows controlled heating during filling, then uses venting to remove excess heat and pressure. The temperature increase during filling becomes part of the control strategy rather than an unwanted side effect to be eliminated by energy-intensive cooling.
4Quantity of substance
If the tank is overfilled to compensate for temperature-induced capacity reduction, then the vehicle range is improved, but the tank pressure exceeds the designed pressure
Solution Approach 1:
The system continuously monitors tank pressure and temperature conditions to determine when to switch between filling and venting operations. Pressure sensors and temperature sensors provide feedback to the control system, which adjusts the valve operations accordingly. This feedback control ensures the tank is filled to the maximum safe capacity without exceeding design pressure limits, even as temperature varies during the refueling process.
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 method allows for safe and efficient filling of hydrogen fuel cell vehicle tanks, maintaining temperature within safe limits and reducing fill time while eliminating the need for expensive cooling systems, thereby enhancing operational efficiency and reducing energy consumption.
Implementation Method 1
The implementation of a 'ladder fill-up' process using a Joule-Thomson valve and thermally insulated systems
Implementation Method 2
The implementation of a 'ladder fill-up' process using a Joule-Thomson valve and thermally insulated systems
Data Source
AI summary
Gaseous fueling systems and methods are provided for dispensing fuel to a vehicle or container. The distribution systems speed up the filling process and may eliminate the use of expensive cooling systems required in the art. The methods utilize sequences of filling and emptying the vehicle gas storage tank to control the temperature of the gas inside the tank. The methods repeatedly dispense fuel to the vehicle fuel tank at a first flow rate and for a first period of time and remove fuel from the fuel tank at a second flow rate for a second period to maintain fuel temperature within a desired temperature range and until the vehicle fuel tank is filled to a desired level. In addition, the fill-up mass flowrate can be maximized to system capabilities so a fill-up can be can be completed in about one minute.