Intermediate Heat Exchanger Layout for Low-Power Indoor HVAC
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Solution Overview
Problem
Conventional air-conditioning apparatuses face issues with refrigerant leakage indoors, leading to safety concerns and high energy consumption due to the transfer of high-pressure refrigerants, and the chiller system's large water conveying power is not energy-efficient.
Innovation Solution
The air-conditioning apparatus incorporates an intermediate heat exchanger for two-phase or supercritical refrigerant and a heat medium, a refrigeration cycle with a compressor, outdoor heat exchanger, and expansion valves, along with a heat medium circulation circuit and a controller to manage the compressor and pump, ensuring safe operation and reduced energy consumption by optimizing refrigerant flow and heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-pressure refrigerant is transferred into the indoor unit, then cooling or heating operation can be performed, but users may be subjected to adverse effects due to refrigerant leakage
Solution Approach 1:
The patent introduces an intermediate heat exchanger as a mediator between the outdoor unit and indoor unit. The refrigerant exchanges heat with water in the intermediate heat exchanger outdoors, and only the heated/cooled water is transferred to the indoor unit. This intermediary mechanism eliminates the need to transfer high-pressure refrigerant indoors, thereby resolving the safety hazard while maintaining cooling/heating functionality.
2Reliability
If the chiller transfers water into the indoor unit, then cooling or heating operation can be performed, but the conveying power of water is too large to be energy-saving
Solution Approach 1:
The patent applies partial action by transferring only a portion of the heat medium (water) to the indoor unit rather than the entire volume. The intermediate heat exchanger heats/cools water, and only the necessary amount is conveyed to the indoor unit for heat exchange. This partial transfer approach reduces the conveying power requirement compared to conventional chillers that transfer large volumes of water, thereby improving energy efficiency while maintaining operational stability.
3Stability of the object's composition
If the pump continues to operate after compressor stop, then refrigerant pressure may stabilize, but refrigeration cycle operation efficiency deteriorates
Solution Approach 1:
The patent implements feedback control where the controller monitors the operational state of the compressor and automatically controls the pump's operation accordingly. When the compressor stops based on thermo-off or operation stop instruction, the controller detects this state and automatically stops the pump after or almost at the same time. This feedback mechanism ensures that the pump does not continue operating unnecessarily, preventing energy waste while maintaining sufficient refrigerant pressure stability through coordinated shutdown.
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 ensures stable operation, prevents efficiency drops in the refrigeration cycle, and achieves high energy-saving performance by minimizing refrigerant pressure fluctuations and reducing water conveying power.
Implementation Method 1
at least one unit of an intermediate heat exchanger that exchanges heat between a refrigerant undergoing two-phase change or a refrigerant under a supercritical condition and a heat medium which is different from the refrigerant such as water and antifreezing liquid
Implementation Method 2
a refrigeration cycle in which a compressor, an outdoor heat exchanger, at least one expansion valve, and a refrigerant side flow path of the intermediate heat exchanger are connected via piping through which the refrigerant flows
Implementation Method 3
a refrigeration cycle in which a compressor, an outdoor heat exchanger, at least one expansion valve, and a refrigerant side flow path of the intermediate heat exchanger are connected via piping through which the refrigerant flows
Implementation Method 4
at least one unit of an intermediate heat exchanger that exchanges heat between a refrigerant undergoing two-phase change or a refrigerant under a supercritical condition
Data Source
AI summary
To provide an air-conditioning apparatus that is safer and has small conveying power for such as water at the indoor unit side can be made small. It is characterized in that a compressor 10 and a heat source side heat exchanger 12 are accommodated in a heat source apparatus 1, an intermediate heat exchanger 15 and a pump 21 in a relay unit 3, a use side heat exchanger 26 in an indoor unit 2, respectively, and when a controller 60 makes the compressor 10 stop based on the thermo-off due to decrease in the heat load in the use side heat exchanger 26 or an operation stop instruction, the controller 60 makes the pump 21 stop after the compressor 10 is stopped or almost at the same time as the stop.