Pulsed TXV Cooling Control for Evaporator Starvation and Flooding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cooling systems are inefficient due to high start-up energy requirements of compressor motors and inadequate refrigerant supply to evaporators, leading to reduced efficiency and potential compressor damage from liquid refrigerant flooding.
Innovation Solution
A cooling system utilizing a constant or variable speed compressor in conjunction with a pulsed operation thermostatic expansion valve (TXV) to control refrigerant flow, maintaining proper pressure and adapting to varying conditions for improved efficiency and reduced pull-down time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a compressor motor is used to provide cooling, then the cooling function is achieved, but the start-up energy requirements are high compared to maintenance energy
Solution Approach 1:
The system uses periodic cycling of the compressor motor with strategic start-up timing rather than continuous operation. The control system delays compressor start-up until refrigerant pressure reaches target levels, reducing the frequency of high-power start-up events while maintaining cooling effectiveness through periodic operation cycles.
2Device complexity
If capillary tubing is used to move refrigerant to the evaporator, then the system structure is simple, but the evaporator may be starved of refrigerant when pressure is insufficient
Solution Approach 1:
The system introduces a control system as an intermediary between the capillary tubing and evaporator. This control system monitors refrigerant pressure and strategically controls compressor start-up timing to ensure sufficient refrigerant pressure is available before the compressor operates, preventing evaporator starvation while maintaining the simple capillary tubing structure.
3Device complexity
If capillary tubing is used to control refrigerant flow, then the device is simple, but too much refrigerant may be provided to the evaporator during light loads causing flooding
Solution Approach 1:
The control system implements feedback monitoring of refrigerant pressure and compressor operation status. Based on this feedback, the system strategically controls compressor start-up timing and operation to match actual cooling loads, preventing over-supply of refrigerant to the evaporator during light loads and avoiding liquid flooding that could damage the compressor.
Solution Approach 2:
The system uses periodic compressor cycling with strategic timing rather than continuous operation. By delaying compressor start-up until appropriate pressure conditions are met and cycling the compressor periodically based on system needs, the system prevents continuous over-supply of refrigerant that would cause flooding during light load conditions.
4Speed
If the compressor is started frequently to maintain cooling, then the cooling response is fast, but the energy efficiency decreases due to repeated high start-up energy requirements
Solution Approach 1:
The control system performs preliminary monitoring of refrigerant pressure and system conditions before initiating compressor start-up. By preparing and delaying start-up until optimal pressure conditions are achieved, the system reduces the need for frequent restarts while maintaining fast cooling response when actually needed, thereby improving energy efficiency.
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 increased energy efficiency and reduced pull-down time by up to 300% and energy efficiency improvements of 10-20%, preventing evaporator starvation and compressor damage, while maintaining constant superheat and full evaporator surface utilization.
Implementation Method 1
at least one evaporator...piping for directing refrigerant from the at least one compressor to at least one condenser and from the at least one condenser to the at least one evaporator
Implementation Method 2
evaporator may be starved of refrigerant...evaporator surface utilization
Data Source
AI summary
A cooling system is disclosed. The cooling system may have an evaporator, an evaporator fan, a condenser, and at least one compressor. The compressor may be either a single speed or a variable speed compressor. In addition, the system can use a mechanical or electrical pulsed operation refrigerant flow control valve for controlling refrigerant flow to the evaporator.