Refrigeration System Having High-Efficiency Loop
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Solution Overview
Problem
Conventional refrigeration systems face limitations due to high temperature glide and potential thermal events or toxicity associated with new refrigerants, leading to restricted refrigerant charge and efficiency issues, particularly when using environmentally-friendly alternatives.
Innovation Solution
A high-efficiency secondary loop system with brazed-plate heat exchangers and a multi-position valve for flexible operation modes, incorporating thermal energy storage to shift energy use to non-peak times and utilize environmentally-friendly refrigerants, allowing for simultaneous charging and cooling with reduced refrigerant charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If environmentally-friendly refrigerants are used, then safety and environmental performance are improved, but refrigerant charge is restricted due to high temperature glide and potential thermal events
Solution Approach 1:
The system divides the refrigeration cycle into two separate loops: a primary loop containing the environmentally-friendly refrigerant (R-1234ye(E)) and a secondary loop containing a different refrigerant (R-134a). This segmentation allows each loop to use optimally suited refrigerants without being constrained by charge limits, while still achieving the desired environmental performance through the primary loop's eco-friendly refrigerant.
Solution Approach 2:
A heat exchanger serves as an intermediary between the primary and secondary loops, enabling thermal energy transfer without direct mixing of refrigerants. This allows the system to leverage the environmental benefits of R-1234ye(E) in the primary loop while using R-134a in the secondary loop to meet cooling or heating demands, effectively bypassing refrigerant charge restrictions.
2Adaptability or versatility
If a secondary fluid loop with thermal energy storage is added, then operational flexibility and energy efficiency are improved, but device complexity increases
Solution Approach 1:
The secondary fluid loop is designed to perform multiple functions: it can provide space heating through the indoor coil, charge/discharge thermal energy storage tanks, and supply refrigerant to the evaporator. The multi-position valve enables a single secondary loop to serve different operational modes (heating, cooling, thermal storage charging, thermal storage discharging), reducing the need for separate dedicated systems for each function.
Solution Approach 2:
The system employs a multi-position valve that can dynamically switch the secondary fluid loop between different configurations and operational modes. This dynamic control allows the system to adapt to varying heating and cooling demands, seamlessly transitioning between using the thermal energy storage tanks, the indoor coil for space heating, and the evaporator for refrigeration, thereby managing complexity through intelligent control rather than fixed architecture.
3Reliability
If refrigerant charge is reduced, then safety is improved, but heating and cooling performance may be compromised
Solution Approach 1:
The system changes the refrigerant parameter by using different refrigerants in different loops: R-1234ye(E) in the primary loop with restricted charge for safety, and R-134a in the secondary loop where it can be used in larger quantities without the same environmental constraints. This parameter change allows the system to maintain safety through reduced charge of the environmentally-sensitive refrigerant while preserving performance through adequate charge of the secondary refrigerant.
Solution Approach 2:
By segmenting the refrigeration system into primary and secondary loops with different refrigerants, the system can restrict the charge of R-1234ye(E) to safe levels while using R-134a in the secondary loop to provide sufficient heating and cooling capacity. The heat exchanger ensures efficient thermal transfer between loops, maintaining overall system performance despite the restricted primary refrigerant charge.
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 efficient operation with environmentally-friendly refrigerants by reducing refrigerant charge and enhancing flexibility and safety through thermal energy storage and advanced valve control, improving both heating and cooling performance.
Implementation Method 1
The secondary fluid loop is in thermal communication with the main fluid loop at the heat exchanger
Implementation Method 2
The secondary fluid loop includes a pump, a thermal energy storage, and a coil fluid line
Data Source
AI summary
A refrigeration system includes a main fluid loop and a secondary fluid loop. The main fluid loop includes a compressor and a heat exchanger that circulate a first working fluid. The secondary fluid loop circulates a second working fluid. The secondary fluid loop is in thermal communication with the main fluid loop at the heat exchanger. The secondary fluid loop includes a pump, a thermal energy storage, and a coil fluid line. The secondary fluid loop includes a multi-position valve configured to move between positions that selectively fluidly connect the heat exchanger, the pump, the thermal energy storage, and the coil fluid line.