Vapor Compression Control Using Path Temperature Feedback
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Solution Overview
Problem
Multi-zone vapor compression systems face inefficiencies due to persistent periodic variations in zone and heat exchanger temperatures, primarily caused by uneven refrigerant distribution in multi-path heat exchangers, which existing methods attempt to address with costly solutions that do not always achieve optimal results.
Innovation Solution
The system controls the thermal capacity of heat exchangers by exploiting non-uniform refrigerant distribution, using temperature sensors to measure path temperatures and adjust expansion valve openings to setpoints, allowing for smooth control without additional actuators, thereby independently managing thermal capacity across zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat exchangers are switched ON and OFF to control zone temperature, then zone temperature control is achieved, but persistent periodic variations in zone temperatures and heat exchanger temperatures occur, reducing system efficiency and occupant comfort
Solution Approach 1:
The patent applies periodic action by using duty cycling to alternate heat exchangers between ON and OFF modes in a controlled periodic manner. The controller selectively operates different heat exchangers in sequence, allowing each to complete full thermal cycles rather than频繁 switching, thereby reducing persistent periodic variations while maintaining zone temperature control.
2Use of energy by moving object
If refrigerant flow is split among multiple paths in a heat exchanger, then heat exchange efficiency is improved, but uneven distribution of refrigerant occurs, making thermal management difficult
Solution Approach 1:
The patent applies local quality by allowing different paths within the heat exchanger to have different refrigerant flow characteristics. Rather than forcing uniform distribution, the system accepts and manages the natural non-uniformity of refrigerant distribution across different paths, with each path contributing differently to the overall thermal management based on local conditions.
Solution Approach 2:
The patent uses feedback by implementing a controller that monitors zone temperatures and adjusts the duty cycling of heat exchangers accordingly. This feedback mechanism allows the system to compensate for uneven refrigerant distribution by selectively activating specific heat exchangers in specific zones, balancing the overall thermal performance despite non-uniform refrigerant flow distribution.
3Stability of the object's composition
If specialized header pipes or controllable valves are added to achieve even refrigerant distribution, then refrigerant distribution uniformity is improved, but system cost increases
Solution Approach 1:
The patent applies self-service by allowing the heat exchangers to naturally distribute refrigerant according to their own characteristics and the system's thermal demands, without requiring external intervention through specialized header pipes or controllable valves. The controller manages thermal balance by selecting which heat exchangers to operate, rather than trying to control refrigerant flow distribution within each heat exchanger.
Solution Approach 2:
The patent applies universality by using standard heat exchangers with simple inlet valves that serve multiple functions: refrigerant flow control, thermal management, and zone temperature regulation. Rather than requiring specialized components for each function, the system uses versatile heat exchangers that can be selectively operated to achieve both even thermal distribution and cost-effectiveness.
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 enables smooth control of thermal capacity in multi-zone vapor compression systems, reducing oscillations and energy inefficiencies, while maintaining low costs by leveraging existing sensors and actuators, thus improving occupant comfort and system efficiency.
Implementation Method 1
Vapor compression systems (VCS) move thermal energy between a low temperature environment and a high temperature environment in order to perform cooling or heating operations
Implementation Method 2
a valve for controlling an amount of the refrigerant entering the inlet header pipe
Implementation Method 3
a set of sensors for measuring temperatures of the refrigerant in each path of the set of paths
Data Source
AI summary
A vapor compression system includes a heat exchanger having an inlet header pipe connected to a set of paths for passing refrigerant to condition a controlled zone. The inlet header pipe splits the refrigerant into different paths. An amount of the refrigerant entering the inlet header pipe is controlled by a valve. The vapor compression system also includes a set of sensors for measuring temperatures of the refrigerant in each path of the set of paths and a controller including a processor for determining a position of the valve based on the measurements of at least one sensor from the set of sensors and a thermal capacity requested for the heat exchanger.