Split-Circuit Air Conditioning for Indoor Refrigerant Isolation
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Solution Overview
Problem
Conventional air-conditioning apparatuses face issues with refrigerant leakage indoors and inefficient energy consumption due to longer water and anti-freezing liquid circulation paths, which can struggle to cope with increased cooling or heating loads.
Innovation Solution
An air-conditioning apparatus design that includes a refrigeration cycle with a compressor, refrigerant flow path switching apparatus, heat source side heat exchanger, intermediate heat exchangers for heat transfer between refrigerant and heat medium, and a separate heat medium circulation circuit, preventing refrigerant circulation indoors and optimizing heat exchange efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If refrigerant is made to circulate into the indoor unit, then heat exchange efficiency is improved, but refrigerant leakage into indoor space occurs
Solution Approach 1:
The system is divided into two separate circulation paths: a refrigerant circulation path (outdoor unit only) and a heat medium circulation path (outdoor unit to indoor unit). The refrigerant circulates only in the outdoor unit where it performs heat exchange with the heat medium, while the heat medium carries the thermal energy to the indoor unit. This segmentation eliminates refrigerant leakage into indoor spaces while maintaining heat exchange efficiency.
Solution Approach 2:
A heat medium (water or anti-freezing liquid) is introduced as an intermediary substance between the refrigerant and the indoor air. The refrigerant exchanges heat with the heat medium in the outdoor unit, and the heat medium then transports this heat to the indoor unit where it exchanges heat with the indoor air. This intermediary approach allows efficient heat transfer without direct refrigerant circulation indoors.
2Reliability
If heat medium circulation path is made longer to reach indoor unit, then no refrigerant passes through indoor unit (safety improved), but energy consumption for carrying heat increases
Solution Approach 1:
The circulation system is segmented into functional zones: the refrigerant circulation is confined to the outdoor unit, while the heat medium circulation connects the outdoor and indoor units. This segmentation allows the heat medium to travel only the necessary distance between units rather than creating a long circular path, reducing pumping energy requirements while maintaining safety.
Solution Approach 2:
The system changes the physical parameters of the heat transfer medium by using water or anti-freezing liquid with high specific heat capacity and thermal conductivity. These parameter changes allow the heat medium to efficiently carry heat over the required distance with minimal energy loss, reducing the pumping power needed despite the circulation path length.
3Productivity
If more heat medium is circulated to cope with increased air-conditioning load, then heating or cooling capacity is improved, but carrying power and energy consumption increase
Solution Approach 1:
The system utilizes the phase change properties of the refrigerant (evaporation and condensation) to achieve large heat transfer coefficients. This allows significant heat exchange to occur in the outdoor unit with relatively small temperature differences, enabling the heat medium to carry sufficient thermal energy to meet increased air-conditioning loads without requiring proportionally larger circulation rates or pumping power.
Solution Approach 2:
The refrigerant undergoes phase transitions (liquid to gas during evaporation, gas to liquid during condensation) in the outdoor unit, which provide intense heat exchange. This phase change mechanism allows the system to handle increased air-conditioning loads efficiently by maximizing heat transfer per unit of refrigerant circulated, thereby reducing the burden on the heat medium circulation system.
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 design ensures safety by preventing refrigerant ingress into indoor spaces and achieves energy-saving through reduced heat medium circulation power and shorter paths, effectively managing increased air-conditioning loads.
Implementation Method 1
a compressor (10) to compress the refrigerant
Implementation Method 2
a heat source side heat exchanger (12) to make the refrigerant exchange heat, intermediate heat exchangers (15a, 15b) for heat transfer between refrigerant and heat medium
Implementation Method 3
a pump (21) to make the heat medium related to heat exchange of each intermediate heat exchanger circulate
Implementation Method 4
a plurality of use side heat exchangers (26a to 26d) that exchange heat between the heat medium and the air related to the space subjected to air-conditioning
Data Source
AI summary
To obtain an air-conditioning apparatus that does not make a refrigerant circulate up to an indoor unit and further can achieve energy-saving. A refrigeration cycle is configured by connecting a compressor that pressurizes a refrigerant, a four-way valve that switches a circulation path of the refrigerant, a heat source side heat exchanger that performs heat exchange, expansion valves for pressure-adjusting the refrigerant, and a plurality of intermediate heat exchangers that performs heat exchange between the refrigerant and the heat medium to heat and cool the heat medium, with piping. A heat medium circuit is configured by connecting intermediate heat exchangers, pumps that pressurize the heat medium, and a plurality of use side heat exchangers that perform heat exchange between the heat medium and the air in the indoor space, with piping.