Brine Heat Exchange Control for Higher COP Air Conditioning
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Solution Overview
Problem
Air-conditioning apparatuses using refrigeration cycles with heat transport via a heat medium, such as water or brine, exhibit lower air conditioning performance compared to direct expansion air conditioners, and there is a need to enhance system COP while reducing driving power and controlling actuators effectively without increasing product costs.
Innovation Solution
An air-conditioning apparatus with a primary-side cycle including a compressor, heat source side heat exchanger, and intermediate heat exchanger, and a secondary-side cycle with a pump and use side heat exchanger, where the temperature difference between the secondary-side heat transfer medium before and after the use side or intermediate heat exchanger is controlled to be larger during heating operations than cooling operations, allowing for adequate actuator control and improved COP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If heat is exchanged via a heat medium (water, brine) between refrigerant and indoor air, then refrigerant leakage risk is eliminated indoors, but air conditioning performance is lower compared to direct expansion air conditioners
Solution Approach 1:
The patent uses a heat medium (water or brine) as an intermediary substance to transfer thermal energy between the refrigerant cycle and indoor air. This mediator eliminates direct contact between refrigerant and indoor environment, removing leakage risks while maintaining heat exchange functionality through the intermediate fluid layer.
Solution Approach 2:
The patent replaces the direct mechanical/expansion system with a thermal field-based heat medium circulation system. Instead of direct refrigerant expansion in indoor coils, the system uses a pump-driven heat medium circulation loop with heat exchangers, substituting mechanical refrigerant distribution with a fluid circulation approach that improves safety.
2Loss of energy
If the temperature difference of the heat medium is increased to improve heat exchange efficiency, then system COP improves, but the driving power of the heat transporting medium increases
Solution Approach 1:
The patent dynamically adjusts the temperature difference of the heat medium based on operational conditions and load requirements. By making the temperature differential variable rather than fixed, the system optimizes the balance between heat exchange efficiency and pump power consumption, achieving high COP without excessive driving power.
Solution Approach 2:
The patent changes the temperature parameters of the heat medium (inlet and outlet temperatures) to optimize system performance. By controlling the temperature difference within specific ranges and adjusting these parameters according to operational mode (heating/cooling) and load conditions, the system achieves efficient heat transfer while limiting pump power requirements.
3Power
If the flow rate of the heat medium is increased to transport more heat energy, then heating/cooling capacity increases, but energy consumption of the pump increases
Solution Approach 1:
The patent optimizes the flow rate parameter of the heat medium to achieve the desired heating or cooling capacity while minimizing pump energy consumption. By carefully selecting and adjusting the flow rate within optimal ranges, the system balances capacity delivery with energy efficiency, avoiding excessive pump power requirements.
Solution Approach 2:
The patent maintains continuous heat transport through optimized heat medium circulation, ensuring that the pump operates efficiently at sustained flow rates rather than experiencing frequent start-stop cycles or variable rate fluctuations. This continuous operation at optimized parameters reduces overall energy consumption while maintaining required capacity.
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 configuration enables high COP operations by controlling the temperature differences and actuator settings according to the operation mode, enhancing the overall system performance and reducing energy inputs for the brine pump.
Implementation Method 1
an intermediate heat exchanger which exchanges heat between a primary-side heat transfer medium and a secondary-side heat transfer medium
Data Source
AI summary
An air-conditioning apparatus capable of achieving enhancement of the system COP while suppressing product cost. The air-conditioning apparatus controls the difference between the temperatures of brine at a position before and at a position after an indoor heat exchanger or at a position before and at a position after an intermediate heat exchanger to be a preset target value and to be larger at the time of a heating operation than at the time of a cooling operation.