Multi-Circuit HVAC Refrigerant-Sharing for Part Load Efficiency
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Solution Overview
Problem
Conventional HVAC systems face inefficiencies in heat transfer and power consumption under part load conditions, as they do not effectively utilize the heat transfer area of inactive circuits, leading to reduced net cooling capacity and increased energy usage.
Innovation Solution
A multi-circuit HVAC system that operates in a hybrid mode, allowing refrigerant-sharing between active and inactive circuits, and transitions between hybrid and conventional modes based on load conditions, balancing lubricant and refrigerant levels to ensure adequate operation under full load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional HVAC systems operate with inactive circuits under part load conditions, then the system structure remains simple and reliable, but heat transfer efficiency and net cooling capacity are reduced
Solution Approach 1:
The patent merges the active and inactive circuits by introducing a refrigerant sharing conduit that allows refrigerant to flow between circuits. The inactive circuit's heat transfer area is utilized by allowing refrigerant from the active circuit to flow through the inactive circuit's condenser, effectively combining the heat transfer areas of both circuits to increase net cooling capacity under part load conditions.
Solution Approach 2:
The system dynamically switches between conventional mode (valve closed, circuits separate) and hybrid mode (valve open, circuits connected) based on load conditions. The controller monitors system conditions and adjusts the valve position to optimize performance, making the system adaptable to varying part load and full load requirements.
2Loss of energy
If refrigerant-sharing occurs between active and inactive circuits, then heat transfer efficiency increases, but system control complexity increases
Solution Approach 1:
The controller implements feedback control by monitoring system conditions and adjusting the valve position accordingly. The controller receives signals about system operation and automatically opens or closes the valve to maintain optimal refrigerant distribution and heat transfer efficiency, reducing the need for manual intervention and simplifying operation despite the added complexity.
3Productivity
If the valve opens to allow refrigerant flow between circuits, then net cooling capacity increases, but refrigerant distribution control becomes more difficult
Solution Approach 1:
The system achieves self-service through the automatic control mechanism that monitors refrigerant flow conditions and adjusts the valve position autonomously. The controller manages refrigerant distribution based on system conditions without requiring manual operation, allowing the system to self-regulate refrigerant flow to optimize net cooling capacity while maintaining ease of 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
The hybrid mode increases heat transfer efficiency and net cooling capacity while reducing power consumption of the active compressor, and ensures sufficient operation by balancing resources between circuits, maintaining performance across varying load conditions.
Implementation Method 1
The first compressor may urge refrigerant in the first refrigerant circuit in a direction upstream to downstream in the first refrigerant circuit
Implementation Method 2
The second compressor may urge refrigerant in the second refrigerant circuit in a direction upstream to downstream in the second refrigerant circuit
Implementation Method 3
The first condenser and a second condenser
Data Source
AI summary
The present disclosure relates to a heating, ventilation, and/or air conditioning (HVAC) system that has a first circuit and a second circuit that each have a compressor and a condenser, a conduit extending from the second circuit downstream of the condenser to the first circuit upstream of the compressor, a valve along the conduit that may manage flow therethrough, and a controller that may operate the HVAC system in a first mode such that each circuit separately circulates the refrigerant in each circuit and transition to a second mode such that refrigerant-sharing occurs between the circuits. In response to a request to transition from the second mode to the first mode, the controller may determine an amount of refrigerant subcooling, compare the amount to a threshold value associated with the first mode, and instruct opening of the valve upon a determination that the amount is less than the threshold value.