Isolated Refrigerant Loop Ice Storage for Flexible Building Cooling
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Solution Overview
Problem
Current refrigerant-based ice storage air conditioning systems face limitations in efficiency, cost, and flexibility, particularly in small commercial buildings, due to reliance on water chillers and complex refrigerant management designs, which hinder widespread adoption and versatility.
Innovation Solution
A refrigerant-based thermal energy storage and cooling system with a primary and secondary refrigerant loop, utilizing an isolating heat exchanger to isolate the condensing unit and ice-tank heat exchanger, allowing for different refrigerants and flexible operation modes, including ice-make, ice-melt, and direct cooling, with a refrigerant management vessel and liquid pump for efficient energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If water chillers are used for thermal energy storage, then cooling capacity can be achieved, but system efficiency is limited and manufacturing cost increases
Solution Approach 1:
The system changes the refrigerant parameters by using refrigerant-based thermal energy storage instead of water-based storage, operating at lower temperatures to leverage the higher specific heat capacity of refrigerants, thereby improving system efficiency while maintaining cost-effectiveness through optimized refrigerant cycle integration
Solution Approach 2:
The system utilizes phase change of refrigerant (liquid-vapor transition) in the storage tank to store and release thermal energy, replacing the conventional water-based sensible heat storage with latent heat storage, which significantly improves energy density and system efficiency
2Adaptability or versatility
If refrigerant loops are isolated with heat exchangers, then different refrigerants can be used and flexibility increases, but device complexity increases
Solution Approach 1:
The system segments the refrigerant system into separate loops (primary and secondary refrigerant loops) that are thermally coupled through heat exchangers, allowing independent selection of refrigerants for each loop based on specific application requirements without compromising system integrity
Solution Approach 2:
The system introduces heat exchangers as intermediary components between different refrigerant loops, enabling thermal energy transfer while maintaining physical separation and isolation of refrigerants, thus allowing versatile refrigerant selection without direct contamination or mixing issues
3Productivity
If ice storage is implemented to shift cooling loads, then peak demand power consumption decreases, but system cost and complexity increase for small commercial buildings
Solution Approach 1:
The system designs a multi-functional thermal energy storage system that can operate in different modes (ice storage, chilled water storage, direct refrigerant storage) and serve multiple purposes (peak load shifting, base load cooling, refrigerant management), making it adaptable to various building sizes and applications without requiring completely different system configurations
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 high efficiency and cost-effectiveness by isolating refrigerant loops, enabling the use of different refrigerants, and providing flexible operation modes, thus overcoming previous limitations and making thermal energy storage more practical for various building sizes and applications.
Implementation Method 1
an isolating heat exchanger disposed between the first refrigerant loop and the second refrigerant loop for thermal communication therebetween
Implementation Method 2
a tank filled with a fluid capable of a phase change between liquid and solid
Implementation Method 3
a condensing unit, the condensing unit comprising a compressor and a first condenser
Implementation Method 4
a condensing unit, the condensing unit comprising a compressor and a first condenser
Implementation Method 5
a first evaporator on a primary side of an isolating heat exchanger located downstream of the expansion device
Implementation Method 6
an expansion device connected downstream of the condensing unit
Implementation Method 7
a liquid refrigerant pump for distributing the second refrigerant from the refrigerant management vessel to the primary heat exchanger in the first time period and from the refrigerant management vessel to the load heat exchanger in the second time period
Implementation Method 8
a primary heat exchanger in fluid communication with the second condenser and that uses the second refrigerant from the second condenser to cool the fluid and to freeze at least a portion of the fluid within the tank
Implementation Method 9
a load heat exchanger connected to the refrigerant management vessel that transfers cooling capacity of the second refrigerant to a heat load during the second time period
Data Source
AI summary
Disclosed are a method and device for a refrigerant-based thermal storage system wherein a condensing unit and an ice-tank heat exchanger can be isolated through a second heat exchanger. The disclosed embodiments provide a refrigerant-based ice storage system with increased reliability, lower cost components, and reduced power consumption compared to non-isolated systems.