Cryogenic Fuel Heating Installation With Closed-Circuit Phase Control
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Solution Overview
Problem
Existing systems for heating cryogenic fuel for aircraft turbine engines face challenges such as ice formation, lubricating oil viscosity issues, and uncontrollable phase changes due to the use of exhaust gases and lubricating oil as heat sources, leading to complex management and inefficiencies.
Innovation Solution
A system comprising a closed circuit with a heat-transfer fluid and a controlled pump to maintain the heat-transfer fluid in a single-phase liquid state, using various heat sources like bleed air, lubricating oil, and exhaust gases to heat the cryogenic fuel, with a single cryogenic fuel/heat-transfer fluid exchanger for efficient heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If exhaust gases are used to heat the cryogenic fuel, then heating is achieved, but water vapour transforms into ice on the heat exchanger wall
Solution Approach 1:
A heat-transfer fluid circulates in a closed circuit as an intermediary between the exhaust gases (or other heat sources) and the cryogenic fuel. This mediator allows heat transfer without direct contact between the cryogenic fuel and exhaust gases, preventing ice formation while enabling efficient heating through controlled heat exchange.
2Temperature
If lubricating oil is used to heat the cryogenic fuel, then heating is achieved, but the oil is cooled too far and becomes too viscous to lubricate
Solution Approach 1:
The heating system is segmented into multiple heat exchangers arranged in series, each handling a portion of the required heat transfer. This allows the lubricating oil to be cooled in controlled stages rather than being subjected to the full temperature differential, preventing excessive viscosity increase while still achieving the required fuel heating.
3Productivity
If liquid cryogenic fuel is rapidly injected onto hot walls of the heat exchanger, then heating occurs, but gas accumulates and pressure increases preventing circulation
Solution Approach 1:
The heat-transfer fluid circulates in advance through the closed circuit before cryogenic fuel injection begins, pre-cooling the heat exchanger walls to the appropriate temperature. This preliminary action prevents rapid vaporization of the fuel upon contact, avoiding gas accumulation and pressure buildup that would disrupt circulation.
4Temperature
If multiple two-phase exchangers are used to heat the cryogenic fuel, then heating is achieved, but system management becomes complicated
Solution Approach 1:
Multiple heat sources (exhaust gases, lubricating oil, bleed air) are merged into a single integrated closed circuit system with one heat-transfer fluid circulating through all heat exchangers in series. This consolidation simplifies system management compared to having separate two-phase exchanger systems for each heat source, while maintaining precise temperature control through the unified fluid circuit.
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
The system effectively controls the heating process, reducing ice formation risks, maintaining fluid phase stability, and enabling efficient heating to supercritical or gaseous states without multiple exchangers, thus simplifying management and enhancing operational efficiency.
Implementation Method 1
a cryogenic fuel/heat-transfer fluid heat exchanger enabling heating of the cryogenic fuel by an input of heat delivered by the heat-transfer fluid
Implementation Method 2
a closed circuit for circulation of a heat-transfer fluid, this closed circuit for circulation of the heat-transfer fluid comprises a pump for circulating said heat-transfer fluid
Implementation Method 3
said closed circuit for circulation of the heat-transfer fluid comprises a closed expansion vessel connected to said closed circuit upstream of said pump, and said pump is controlled by a central unit so as to ensure... the closed expansion vessel keeps the heat-transfer fluid circulating in said closed circuit at a pressure such that it remains in the liquid state and does not change phase
Implementation Method 4
Heating of the cryogenic fuel takes place in this single two-phase cryogenic fuel/heat-transfer fluid heat exchanger
Data Source
AI summary
A system for heating cryogenic fuel includes a storage take, a supply line, a closed circuit, a cryogenic fuel heat exchanger, one or more working fluid heat exchangers, and a controller The storage tank stores the cryogenic fuel in a liquid state. The supply line connects the storage tank to a combustion chamber of an aircraft turbine engine. The closed circuit circulates a heat-transfer fluid. The cryogenic fuel heat exchanger heats the cryogenic fuel by the heat-transfer fluid. The closed circuit includes a pump for circulating the heat-transfer fluid and a closed expansion vessel connected to the closed circuit. The controller controls the pump to ensure a heat-transfer fluid flow rate inside the closed circuit so that the closed expansion vessel keeps the heat-transfer fluid circulating in the closed circuit at a pressure such that the heat-transfer fluid remains in the liquid state and does not change phase.