Fuel Recirculation Loop Heat Exchanger Pressure Control
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Solution Overview
Problem
Existing fuel supply systems without a recirculation loop fail to maintain optimal fuel flow rates and pressures, leading to premature filter failure and increased risk of leakage, while systems with a recirculation loop face challenges in heat removal and filter longevity due to inconsistent return flow rates.
Innovation Solution
A fuel supply system with a recirculation loop that includes a heat exchanger positioned downstream of the fuel manifold, an orifice upstream of the heat exchanger, a pressure control valve, and a bypass line with a one-way valve, ensuring a controlled fuel flow rate and pressure to minimize filter load and prevent fuel leakage, while maintaining all fuel within the recirculation loop to avoid return to the tank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a recirculation loop is implemented to maintain high fuel flow rate through the fuel manifold, then fuel flow rate and pressure are improved, but fuel temperature increases and requires heat removal
Solution Approach 1:
A heat exchanger is introduced as an intermediary component in the recirculation loop to remove excess heat from the fuel. The heat exchanger allows thermal energy transfer from the hot recirculating fuel to the surrounding environment or to preheat incoming fuel, thereby resolving the temperature increase caused by continuous recirculation while maintaining the desired high fuel flow rate.
2Temperature
If return flow rate to the fuel tank is increased to remove heat from the fuel, then fuel temperature is controlled, but fuel flow rate through the primary fuel filter increases causing premature filter failure
Solution Approach 1:
The fuel flow path is segmented into multiple independent circuits: a recirculation loop for heat management and a separate return path to the fuel tank. By segmenting the system, the patent enables selective routing of fuel through the heat exchanger without forcing high flow rates through the primary fuel filter, thus controlling temperature while protecting the filter from excessive flow stress.
Solution Approach 2:
The heat exchanger serves as an intermediary that handles the heat removal function without requiring direct return flow through the fuel tank and primary filter. This intermediary approach allows thermal management to be achieved through the recirculation loop while minimizing or eliminating the need for high-volume return flow that would damage the filter.
3Duration of action of stationary object
If return flow rate to the fuel tank is decreased to protect the primary fuel filter, then filter lifespan is extended, but heat removal capability from the fuel is insufficient
Solution Approach 1:
The fuel circulation system is divided into a recirculation loop that handles heat removal and a separate return path to the fuel tank. This segmentation allows the recirculation loop to perform thermal management with minimal flow rates, while the return path to the tank remains independent and protected from high flow stresses, thus extending filter lifespan without compromising heat removal effectiveness.
Solution Approach 2:
The heat exchanger acts as an intermediary that enables efficient heat removal from the fuel during recirculation without requiring the fuel to return to the tank at high flow rates. This intermediary mechanism decouples the heat removal function from the return flow to the tank, allowing low flow rates that protect the filter while maintaining adequate thermal management.
4Stress or pressure
If high fuel flow rate is maintained in the recirculation loop, then fuel pressure is improved, but fuel pressure in the heat exchanger increases creating leakage risk
Solution Approach 1:
The system implements different pressure characteristics at different locations: high pressure is maintained in the recirculation loop and fuel manifold to ensure adequate fuel delivery, while the heat exchanger is designed to operate at lower pressure. Pressure control valves or flow restrictors are strategically placed to create this local quality difference, allowing high overall fuel pressure without creating excessive pressure in the heat exchanger that would cause leakage.
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 achieves a stable fuel flow rate and pressure above minimum requirements, maintaining low fuel pressure in the heat exchanger, minimizing filter load, and extending filter lifespan by ensuring all fuel recirculates through the loop, thus preventing unnecessary heat addition to the tank and debris introduction.
Implementation Method 1
the recirculation loop comprises a heat exchanger positioned downstream of the fuel manifold and upstream of the first node
Implementation Method 2
The recirculation loop may comprise an orifice positioned upstream of the heat exchanger and downstream of the fuel manifold
Data Source
AI summary
According to the present disclosure, a fuel supply system having a recirculation loop is provided. The fuel supply system comprises a fuel tank; a return line coupled fluidly to the fuel tank; a fuel manifold; and a recirculation loop, wherein the return line is coupled fluidly to the recirculation loop at a first node to return fuel from the recirculation loop to the fuel tank, and the recirculation loop comprises a heat exchanger positioned downstream of the fuel manifold and upstream of the first node. The recirculation loop may comprise an orifice positioned upstream of the heat exchanger and downstream of the fuel manifold. Additionally, the fuel supply system may further comprise a supply line coupled fluidly to the fuel tank and further coupled fluidly to the recirculation loop at a second node positioned upstream of the fuel manifold and downstream of the first node.