Cryogenic Reservoir Recirculation Line for Rapid Pressure Control
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Solution Overview
Problem
Existing systems for cryogenic liquid gas storage in vehicles face challenges in efficiently managing pressure and heat transfer during gas withdrawal, leading to slow pressure increase and limited delivery rates, especially after refueling, which complicates maintaining constant pressure and efficient engine power utilization.
Innovation Solution
The design incorporates a return line with an additional heat exchanger near the bottom of the storage container, allowing complete heat transfer to liquid gas without mixing phases, and uses a compressor that adjusts based on pressure changes, with heated gas blown in at higher temperatures to quickly increase container pressure, and a heat exchanger using heated water for efficient energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If gas is recirculated through a pump and blown upwards in a vertical pipe for heat exchange, then heat transfer to liquid gas occurs, but warm gas accumulates in the upper region without contributing to evaporation and liquid level drops
Solution Approach 1:
The return line is divided into two separate heat exchange sections: a first heat exchanger near the bottom for primary heat transfer, and a second heat exchanger in the upper region for final heat release. This segmentation ensures that warm gas contributes to evaporation at the bottom while releasing remaining heat in the upper region without accumulating there.
Solution Approach 2:
The return line is configured to extend vertically through different height levels of the storage tank, utilizing the vertical dimension to create staged heat exchange. The line enters near the bottom, extends upward through the liquid phase, and terminates in the gas phase, enabling heat transfer at multiple elevations.
2Stress or pressure
If pressure inside the container is increased by heating tank contents through external energy or heat exchanger, then gas can be supplied to consumer, but pipeline routing through container walls increases heat input when vehicle is stationary
Solution Approach 1:
The system uses the cold liquid gas itself as the heating medium for the return line. The return line is immersed in the liquid gas, allowing the liquid to absorb heat from the returning warm gas, thereby cooling the liquid and pre-heating it for the next evaporation cycle without external energy input.
Solution Approach 2:
The return line serves dual functions: it acts as both a gas recirculation conduit and an internal heat exchanger. The same line that returns warm gas to the container also serves as the heating element, eliminating the need for separate heating systems and reducing heat loss through wall routing.
3Productivity
If vaporized gas is conducted through another heat exchanger inside the container, then delivery amount can be increased, but the amount of heat that can be supplied is limited and pressure increase is slow
Solution Approach 1:
The return line continuously pre-heats the liquid gas by extracting heat from the returning warm gas before the liquid reaches the extraction point. This preliminary heating action ensures that the liquid is already warm and ready for rapid vaporization when pressure increase is needed, eliminating delays.
Solution Approach 2:
The return line operates continuously to transfer heat from the warm returning gas to the cold liquid gas. This continuous heat transfer process maintains the liquid at an elevated temperature, ensuring that vaporization can occur rapidly and sustainably without interruption or delay.
Data Source
Figure 1
Figure 2
AI summary
Disclosed is a reservoir for deep-frozen liquefied gas, comprising a removing device that is composed of a discharge branch and a recirculation branch. The discharge branch is formed by a discharge pipe (10) that is immersed in the reservoir and extends to the consumer via a heat exchanger (11) and a branching point (15). As a recirculation branch, a recirculation pipe (16) extends from the branching point (15) to an injection device in the reservoir via a compressor (17). The injection device is to evaporate a maximum of liquid as quickly as possible using the smallest possible recirculated amount. For this purpose, the recirculation pipe (16) forms another heat exchanger (22) near the bottom of the interior of the reservoir (1) and ends in the gas chamber (5) of the reservoir (1) by means of a blow-off port (24).