Tube-in-Tube Fluid Heater Control for Stable Single-Pass Outlet Temperature
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Solution Overview
Problem
Existing single pass fluid heater systems in refrigeration vapor compression cycles face challenges in maintaining stable outlet fluid temperatures, especially with long flow paths, leading to fluctuations during start-up and temperature changes, due to the delayed response of feedback control systems.
Innovation Solution
A control system that includes sensors to monitor the temperature and pressure of the working fluid at the condensing phase, a flow rate controller to adjust fluid flow relative to the condenser, and a PID controller to maintain a constant target temperature by processing signals from both sensors, ensuring rapid heat transfer and stable temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the flow rate of heated fluid is reduced to achieve greater temperature increases in a single pass heat exchanger, then the outlet temperature is improved, but the heat exchanger length increases due to reduction in overall Heat Transfer Coefficient
Solution Approach 1:
The patent changes the operating parameters of the heat exchanger by using variable speed pumps to dynamically adjust fluid flow rates, allowing the system to operate at optimal flow conditions that maintain high temperature lift without requiring excessive heat exchanger length. This parameter adjustment enables adaptation to different heating demands while keeping the heat exchanger compact.
Solution Approach 2:
The system implements dynamic control through variable speed pumps that can adjust flow rates in real-time based on heating requirements. This dynamic operation allows the heat exchanger to maintain efficient temperature transfer across varying conditions without requiring a fixed, overly long design to accommodate all possible flow rates.
2Manufacturing precision
If heated fluid temperature control valves are used to modulate flow and achieve set outlet temperature in single pass systems, then temperature control is improved, but the control becomes increasingly less reliable with longer flow paths due to delayed feedback response
Solution Approach 1:
The system uses variable speed pumps to proactively adjust flow rates before temperature deviations occur. By anticipating heating demands and pre-adjusting flow conditions, the system maintains stable outlet temperatures without relying on delayed feedback from long flow paths, thus improving both precision and reliability of temperature control.
Solution Approach 2:
The patent implements feedback control by monitoring outlet temperature and using this information to dynamically adjust pump speed and flow rate. This closed-loop control system continuously optimizes heating performance, maintaining reliable temperature control even in single pass systems with varying flow path lengths by responding to actual temperature conditions.
3Productivity
If multiple cycles at high flow rates are used to heat fluid to desired temperature, then the flow rate is maintained, but the system requires multiple passes which reduces efficiency compared to single pass methods
Solution Approach 1:
The system employs variable speed pumps to dynamically optimize flow rates for single-pass heating operations. By adjusting pump speed to match heating demands, the system achieves efficient temperature lift in a single pass through the heat exchanger, eliminating the need for multiple cycles while maintaining high productivity and reducing heating time.
Solution Approach 2:
The patent changes the flow rate parameter dynamically using variable speed pumps to optimize single-pass heating efficiency. By operating at the optimal flow rate for the given heating demand, the system maximizes temperature lift per pass, achieving desired heating in one pass rather than multiple cycles, thus improving productivity and reducing time loss.
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 reduced fluctuations in heated fluid outlet temperature and high efficiency by quickly responding to changes, maintaining a stable temperature lift of at least 10 degrees Celsius in a single pass, even during start-up and disturbances, compared to conventional methods.
Implementation Method 1
heat exchange with the working fluid
Implementation Method 2
temperature and/or pressure of the working fluid at the condensing phase
Data Source
AI summary
A fluid heater employs a vapor compression cycle system. The vapor compression cycle system includes an evaporator, at least one condenser and a working fluid. The fluid heater includes a fluid conduit which forms a tube-in-tube heat exchanger with the condenser to effect heating of the fluid. A sensor is positioned at the condensing zone of the working fluid, to determine the temperature of the working fluid at the condensing phase of the vapor compression cycle. The output of the sensor is used to control the flow rate of fluid through the fluid conduit in order to achieve a desired target temperature of the fluid leaving the conduit.