Reciprocating Pump Stroke Control for Cryogenic Heat Exchanger Temperature
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The temperature of gaseous fuel discharged from a heat exchanger can drop below a predetermined minimum value due to cold engine coolant or insufficient residence time, leading to pump suspension and reduced fuel injection pressure, which is undesirable for internal combustion engines using liquefied gaseous fuels.
Innovation Solution
A method that monitors the temperature downstream of the heat exchanger and operates the pump in multiple modes, adjusting the amount of fluid pumped to increase the average residence time and temperature, using a reciprocating piston pump with hydraulic actuation to control the discharge and intake stroke lengths based on temperature, pressure, and pump efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump operates at high flow rate to meet engine fuel demand, then productivity is improved, but the residence time of fluid in heat exchanger becomes insufficient causing temperature to drop below minimum value
Solution Approach 1:
The pump operates in two dynamic modes: first mode for normal operation with higher flow rate, and second mode for cold conditions with reduced flow rate. The controller dynamically switches between modes based on temperature sensor feedback, allowing the system to adapt residence time to environmental conditions while maintaining productivity when possible.
Solution Approach 2:
The system changes the operating parameters of the pump by adjusting the amount of fluid pumped per cycle between two predetermined values. This parameter change allows sufficient residence time for heat exchange when temperatures are low, while maintaining higher productivity when temperatures are adequate.
2Temperature
If the residence time is increased by reducing pump flow rate, then temperature is improved, but productivity decreases
Solution Approach 1:
The system dynamically adjusts pump operation between two modes based on real-time temperature monitoring. When discharge temperature drops below the minimum value, the system switches to second mode with reduced flow rate to increase residence time. When temperature is sufficient, it returns to first mode for optimal productivity, thus dynamically balancing temperature requirements with productivity needs.
3Reliability
If the pump is suspended to prevent temperature drop below minimum value, then temperature reliability is improved, but fuel injection pressure decreases and engine operation is compromised
Solution Approach 1:
Instead of completely suspending the pump when temperature is low, the system applies partial action by reducing the pump flow rate to a second predetermined amount that is less than the first amount but still maintains positive fuel delivery. This partial operation is sufficient to increase residence time and prevent temperature drop while maintaining fuel injection pressure and engine operation.
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 approach prevents pump suspension during adverse conditions, maintaining sufficient fuel injection pressure and ensuring the gaseous fuel temperature remains above the minimum value, thereby improving engine operation and efficiency.
Implementation Method 1
waste heat from combustion is transferred to the liquefied gaseous fuel from the storage vessel causing it to evaporate
Implementation Method 2
the liquefied gas is pumped in a liquid state towards and through a heat exchanger where it undergoes a transition to either the supercritical state or the gas state
Implementation Method 3
A heat source is required in the heat exchanger to increase the temperature of the gaseous fuel above its boiling point
Data Source
Figure 1
Figure 2~4
Figure 5
AI summary
A reciprocating piston cryogenic pump has been suspended from stroking when process fluid discharge temperature from a vaporizer dropped below a threshold to prevent freezing of a heat exchange fluid circulating through the vaporizer and damage to downstream components. Suspension of the pump results in a decrease of process fluid pressure downstream of the vaporizer, which is undesirable. In the present technique, a temperature is monitored correlating to process fluid temperature downstream of the vaporizer. The amount of process fluid discharged from the pump in each cycle is adjusted as a function of the temperature such that the average residence time of the process fluid in the vaporizer is increased as the discharge amount decreases, increasing process fluid discharge temperature. The average mass flow rate of the process fluid through the vaporizer is unchanged regardless of pump discharge amount such that process fluid pressure downstream of the vaporizer is maintained.